pub(crate) mod ldap;
mod local;

use argon2::{
    Argon2,
    password_hash::{PasswordHash, PasswordHasher, PasswordVerifier, SaltString},
};
use axum::{
    Json,
    extract::{Path as AxumPath, State},
    http::{HeaderMap, StatusCode},
    response::Redirect,
};
use chrono::{Duration, Utc};
use lettre::{
    AsyncSmtpTransport, AsyncTransport, Message, Tokio1Executor,
    message::{Mailbox, MultiPart, SinglePart, header::ContentType},
    transport::smtp::authentication::Credentials,
};
use rand_core::{OsRng, RngCore};
use serde::{Deserialize, Serialize};
use sha2::{Digest, Sha256};
use sqlx::FromRow;
use tracing::{debug, info, warn};

use crate::{
    queries,
    state::{SharedState, SmtpConfig},
};

const MIN_PASSWORD: usize = 8;
const MAX_PASSWORD: usize = 128;
const MAX_NICKNAME: usize = 40;

#[derive(Debug, Clone, FromRow)]
pub struct User {
    pub id: i64,
    pub nickname: String,
    pub email: String,
    pub password_hash: String,
    pub confirmed_at: Option<String>,
}

#[derive(Deserialize)]
pub struct IdentityRequest {
    nickname: String,
    #[serde(default)]
    session_token: Option<String>,
}
#[derive(Deserialize)]
pub struct RegisterRequest {
    nickname: String,
    email: String,
    password: String,
}
#[derive(Deserialize)]
pub struct LoginRequest {
    email: String,
    password: String,
}
#[derive(Deserialize)]
pub struct ConfirmAccountRequest {
    token: String,
}
#[derive(Deserialize)]
pub struct ResendConfirmationRequest {
    email: String,
}
#[derive(Deserialize)]
pub struct ResetRequest {
    email: String,
}
#[derive(Deserialize)]
pub struct ResetConfirmRequest {
    token: String,
    password: String,
}
#[derive(Deserialize)]
pub struct ProfileUpdateRequest {
    #[serde(default)]
    nickname: Option<String>,
    #[serde(default)]
    new_email: Option<String>,
    #[serde(default)]
    new_password: Option<String>,
    #[serde(default)]
    password: String,
    #[serde(default)]
    editor_color: Option<String>,
}
#[derive(Deserialize)]
pub struct DeleteAccountRequest {
    password: String,
}
#[derive(Deserialize)]
pub struct AccountActionConfirmRequest {
    token: String,
}
#[derive(Deserialize)]
pub struct ResourceActionRequest {
    kind: String,
    slug: String,
    #[serde(default)]
    password: Option<String>,
}
#[derive(Serialize, FromRow)]
pub struct ResourceItem {
    slug: String,
    title: String,
    protected: i64,
    updated_at: String,
    #[sqlx(rename = "private")]
    #[serde(rename = "private")]
    private_resource: i64,
    owned: i64,
    permission: String,
    shared_by: String,
}

#[derive(Deserialize)]
pub struct PrivacyRequest {
    kind: String,
    slug: String,
    private: bool,
}
#[derive(Deserialize)]
pub struct ShareUsersRequest {
    kind: String,
    slug: String,
    emails: String,
    permission: String,
}
#[derive(Deserialize)]
pub struct RemoveShareRequest {
    kind: String,
    slug: String,
    email: String,
}
#[derive(Deserialize)]
pub struct CreateShareLinkRequest {
    kind: String,
    slug: String,
    permission: String,
    expires_at: Option<String>,
}
#[derive(Deserialize)]
pub struct UpdateShareLinkRequest {
    kind: String,
    slug: String,
    token: String,
    permission: String,
    expires_at: Option<String>,
}
#[derive(Deserialize)]
pub struct RevokeShareLinkRequest {
    kind: String,
    slug: String,
    token: String,
}

#[derive(Serialize)]
pub struct ResourceList {
    workspaces: Vec<ResourceItem>,
    pads: Vec<ResourceItem>,
}
#[derive(Serialize)]
pub struct SessionResponse {
    token: String,
    nickname: String,
    email: String,
    expires_at: String,
    directory_managed: bool,
    directory_display_name: Option<String>,
    directory_organization: Option<String>,
    suggested_nickname: Option<String>,
    editor_color: Option<String>,
}
#[derive(Serialize)]
pub struct IdentityResponse {
    nickname: String,
    registered: bool,
}
#[derive(Serialize)]
pub struct RegisterResponse {
    token: Option<String>,
    nickname: String,
    email: String,
    expires_at: Option<String>,
    confirmation_required: bool,
    message: String,
}

pub async fn identity(
    State(state): State<SharedState>,
    Json(req): Json<IdentityRequest>,
) -> Result<Json<IdentityResponse>, AuthError> {
    if state.ldap.is_some() && req.session_token.is_none() {
        return Err(AuthError::unauthorized(
            "Log in with your organization account.",
        ));
    }
    let nickname = validate_nickname(&req.nickname)?;
    debug!(nickname = %nickname, has_session = req.session_token.is_some(), "identity check requested");
    match find_user_by_nickname(&state, &nickname).await? {
        None => {
            debug!(nickname = %nickname, "nickname is available for guest use");
            Ok(Json(IdentityResponse {
                nickname,
                registered: false,
            }))
        }
        Some(user) => {
            let token = req.session_token.as_deref().ok_or_else(|| {
                AuthError::unauthorized("This nickname is registered. Log in to use it.")
            })?;
            let current = user_from_token(&state, token).await?.ok_or_else(|| {
                AuthError::unauthorized("Your session has expired. Log in again.")
            })?;
            if current.id != user.id {
                return Err(AuthError::unauthorized(
                    "This nickname belongs to another account.",
                ));
            }
            info!(user_id = user.id, nickname = %user.nickname, "registered identity authorized");
            Ok(Json(IdentityResponse {
                nickname: user.nickname,
                registered: true,
            }))
        }
    }
}

pub async fn register(
    State(state): State<SharedState>,
    Json(req): Json<RegisterRequest>,
) -> Result<(StatusCode, Json<RegisterResponse>), AuthError> {
    if state.ldap.is_some() {
        return Err(AuthError::forbidden(
            "Local registration is disabled while LDAP authentication is enabled.",
        ));
    }
    if !state.registration_enabled {
        warn!("registration attempt rejected because registration is disabled");
        return Err(AuthError::forbidden("Registration is disabled."));
    }
    if state.account_confirmation_required && state.smtp.is_none() {
        return Err(AuthError::service_unavailable(
            "Account confirmation requires SMTP configuration.",
        ));
    }
    let nickname = validate_nickname(&req.nickname)?;
    let email = validate_email(&req.email)?;
    info!(nickname = %nickname, email_domain = %email_domain(&email), "registration requested");
    validate_password(&req.password)?;
    let nickname_key = normalize(&nickname);
    let email_key = normalize(&email);
    if find_user_by_nickname(&state, &nickname).await?.is_some() {
        return Err(AuthError::conflict("This nickname is already registered."));
    }
    if find_user_by_email(&state, &email).await?.is_some() {
        return Err(AuthError::conflict(
            "This e-mail address is already registered.",
        ));
    }
    let hash = hash_password(&req.password)?;
    let confirmed_at = (!state.account_confirmation_required).then(|| Utc::now().to_rfc3339());
    sqlx::query(queries::get(state.db.kind(), queries::AUTH_INSERT_USER))
        .bind(&nickname)
        .bind(nickname_key)
        .bind(&email)
        .bind(email_key)
        .bind(hash)
        .bind(confirmed_at)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    let user = find_user_by_nickname(&state, &nickname)
        .await?
        .ok_or_else(|| AuthError::internal("Failed to create the account."))?;

    let mut confirmation_token = None;
    if state.smtp.is_some() {
        let token = random_confirmation_token();
        if state.account_confirmation_required {
            let expires = (Utc::now() + Duration::hours(24)).to_rfc3339();
            let mut tx = state.db.pool().begin().await.map_err(AuthError::database)?;
            sqlx::query(queries::get(
                state.db.kind(),
                queries::AUTH_DELETE_CONFIRMATION_TOKENS_BY_USER,
            ))
            .bind(user.id)
            .execute(&mut *tx)
            .await
            .map_err(AuthError::database)?;
            sqlx::query(queries::get(
                state.db.kind(),
                queries::AUTH_INSERT_CONFIRMATION_TOKEN,
            ))
            .bind(hash_token(&token))
            .bind(user.id)
            .bind(expires)
            .execute(&mut *tx)
            .await
            .map_err(AuthError::database)?;
            tx.commit().await.map_err(AuthError::database)?;
            confirmation_token = Some(token.as_str());
        }
        if let Err(error) =
            send_registration_email(state.smtp.as_ref().unwrap(), &user, confirmation_token).await
        {
            if state.account_confirmation_required {
                if let Err(delete_error) =
                    sqlx::query(queries::get(state.db.kind(), queries::AUTH_DELETE_USER))
                        .bind(user.id)
                        .execute(state.db.pool())
                        .await
                {
                    tracing::error!(error=%delete_error, user_id=user.id, "failed to roll back account after confirmation e-mail error");
                }
                return Err(error);
            }
            warn!(
                user_id = user.id,
                "account created, but registration e-mail could not be sent"
            );
        }
    } else {
        warn!(
            user_id = user.id,
            "account created without registration e-mail because SMTP is not configured"
        );
    }

    if state.account_confirmation_required {
        info!(user_id = user.id, nickname = %user.nickname, "account registered; confirmation required");
        return Ok((
            StatusCode::CREATED,
            Json(RegisterResponse {
                token: None,
                nickname: user.nickname,
                email: user.email,
                expires_at: None,
                confirmation_required: true,
                message:
                    "Account created. Check your e-mail and confirm the account before logging in."
                        .into(),
            }),
        ));
    }

    let session = create_session(&state, &user).await?;
    info!(user_id = user.id, nickname = %user.nickname, "account registered and session created");
    Ok((
        StatusCode::CREATED,
        Json(RegisterResponse {
            token: Some(session.token),
            nickname: session.nickname,
            email: session.email,
            expires_at: Some(session.expires_at),
            confirmation_required: false,
            message: "Account created.".into(),
        }),
    ))
}

pub async fn login(
    State(state): State<SharedState>,
    Json(req): Json<LoginRequest>,
) -> Result<Json<SessionResponse>, AuthError> {
    if state.ldap.is_some() {
        ldap::login(&state, &req.email, &req.password)
            .await
            .map(Json)
    } else {
        local::login(&state, &req.email, &req.password)
            .await
            .map(Json)
    }
}

pub async fn resend_confirmation(
    State(state): State<SharedState>,
    Json(req): Json<ResendConfirmationRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    if !state.account_confirmation_required {
        return Err(AuthError::bad_request(
            "Account confirmation is not enabled.",
        ));
    }
    let smtp = state
        .smtp
        .as_ref()
        .ok_or_else(|| AuthError::service_unavailable("SMTP is not configured."))?;
    let email = validate_email(&req.email)?;
    let user = find_user_by_email(&state, &email).await?.ok_or_else(|| {
        AuthError::bad_request("No unconfirmed account exists for this e-mail address.")
    })?;
    if user.confirmed_at.is_some() {
        return Err(AuthError::bad_request("This account is already confirmed."));
    }
    let last_created: Option<String> = sqlx::query_scalar(queries::get(
        state.db.kind(),
        queries::AUTH_LATEST_CONFIRMATION_CREATED_AT,
    ))
    .bind(user.id)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    if let Some(value) = last_created {
        if let Ok(created) = chrono::DateTime::parse_from_rfc3339(&value) {
            let available = created.with_timezone(&Utc) + Duration::minutes(10);
            if available > Utc::now() {
                let seconds = (available - Utc::now()).num_seconds().max(1);
                return Err(AuthError::bad_request(&format!(
                    "A new confirmation e-mail can be sent in {} minute(s).",
                    (seconds + 59) / 60
                )));
            }
        }
    }
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_DELETE_CONFIRMATION_TOKENS_BY_USER,
    ))
    .bind(user.id)
    .execute(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let token = random_confirmation_token();
    let token_hash = hash_token(&token);
    let expires_at = (Utc::now() + Duration::hours(24)).to_rfc3339();
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_INSERT_CONFIRMATION_TOKEN,
    ))
    .bind(token_hash)
    .bind(user.id)
    .bind(expires_at)
    .execute(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    send_registration_email(smtp, &user, Some(&token)).await?;
    Ok(Json(
        serde_json::json!({"ok":true,"message":"A new confirmation e-mail has been sent."}),
    ))
}

pub async fn confirm_account(
    State(state): State<SharedState>,
    Json(req): Json<ConfirmAccountRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let now_time = Utc::now();
    let now = now_time.to_rfc3339();
    let token_hash = hash_token(req.token.trim());
    let row: Option<(i64, String, Option<String>)> = sqlx::query_as(queries::get(
        state.db.kind(),
        queries::AUTH_FIND_CONFIRMATION_TOKEN,
    ))
    .bind(&token_hash)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let (user_id, expires_at, used_at) = row.ok_or_else(|| {
        AuthError::bad_request("The confirmation link is invalid or has expired.")
    })?;
    let expires_at = chrono::DateTime::parse_from_rfc3339(&expires_at)
        .map_err(|_| AuthError::bad_request("The confirmation link is invalid or has expired."))?
        .with_timezone(&Utc);
    if used_at.is_some() || expires_at <= now_time {
        return Err(AuthError::bad_request(
            "The confirmation link is invalid or has expired.",
        ));
    }
    let mut tx = state.db.pool().begin().await.map_err(AuthError::database)?;
    let consumed = sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_CONSUME_CONFIRMATION_TOKEN,
    ))
    .bind(&now)
    .bind(&token_hash)
    .bind(&now)
    .execute(&mut *tx)
    .await
    .map_err(AuthError::database)?;
    if consumed.rows_affected() != 1 {
        return Err(AuthError::bad_request(
            "The confirmation link is invalid or has expired.",
        ));
    }
    let confirmed = sqlx::query(queries::get(state.db.kind(), queries::AUTH_CONFIRM_USER))
        .bind(&now)
        .bind(&now)
        .bind(user_id)
        .execute(&mut *tx)
        .await
        .map_err(AuthError::database)?;
    if confirmed.rows_affected() != 1 {
        return Err(AuthError::internal("The account could not be confirmed."));
    }
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_DELETE_CONFIRMATION_TOKENS_BY_USER,
    ))
    .bind(user_id)
    .execute(&mut *tx)
    .await
    .map_err(AuthError::database)?;
    tx.commit().await.map_err(AuthError::database)?;
    info!(user_id, "account confirmed");
    Ok(Json(
        serde_json::json!({"ok": true, "message": "Account confirmed. You can now log in."}),
    ))
}

async fn directory_profile_metadata(
    state: &SharedState,
    user: &User,
) -> Result<(bool, Option<String>, Option<String>, Option<String>), AuthError> {
    let row: Option<(String, Option<String>)> = sqlx::query_as(queries::get(
        state.db.kind(),
        queries::AUTH_DIRECTORY_PROFILE_BY_USER,
    ))
    .bind(user.id)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let Some((provider, display_name)) = row else {
        return Ok((false, None, None, None));
    };
    if provider == "local" {
        return Ok((false, None, None, None));
    }
    let display_name = display_name.filter(|value| !value.trim().is_empty());
    let organization = state
        .ldap
        .as_ref()
        .map(|config| config.organization.trim().to_owned())
        .filter(|value| !value.is_empty());
    let suggested = suggested_directory_nickname(display_name.as_deref(), &user.email);
    Ok((true, display_name, organization, suggested))
}

fn suggested_directory_nickname(display_name: Option<&str>, email: &str) -> Option<String> {
    if let Some(display_name) = display_name {
        let words: Vec<&str> = display_name
            .split_whitespace()
            .filter(|word| !word.is_empty())
            .collect();
        if words.len() >= 2 {
            let first = words.first().copied().unwrap_or_default();
            let last = words.last().copied().unwrap_or_default();
            let candidate = format!("{}.{}", first, last).to_lowercase();
            if let Ok(value) = validate_nickname(&candidate) {
                return Some(value);
            }
        }
    }
    email
        .split('@')
        .next()
        .filter(|value| !value.trim().is_empty())
        .and_then(|value| validate_nickname(&value.to_lowercase()).ok())
}

pub async fn me(
    State(state): State<SharedState>,
    headers: HeaderMap,
) -> Result<Json<SessionResponse>, AuthError> {
    let token = bearer(&headers).ok_or_else(|| AuthError::unauthorized("Not logged in."))?;
    let user = user_from_token(&state, token)
        .await?
        .ok_or_else(|| AuthError::unauthorized("Your session has expired."))?;
    debug!(user_id = user.id, "session validation successful");
    let expires_at: String = sqlx::query_scalar(queries::get(
        state.db.kind(),
        queries::AUTH_SESSION_EXPIRES_AT,
    ))
    .bind(token)
    .fetch_one(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let (directory_managed, directory_display_name, directory_organization, suggested_nickname) =
        directory_profile_metadata(&state, &user).await?;
    let editor_color: Option<String> = sqlx::query_scalar(queries::get(
        state.db.kind(),
        queries::AUTH_EDITOR_COLOR_BY_USER,
    ))
    .bind(user.id)
    .fetch_one(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    Ok(Json(SessionResponse {
        token: token.into(),
        nickname: user.nickname,
        email: user.email,
        expires_at,
        directory_managed,
        directory_display_name,
        directory_organization,
        suggested_nickname,
        editor_color,
    }))
}

pub async fn update_profile(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<ProfileUpdateRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let user = require_user(&state, &headers).await?;
    let (directory_managed, _, _, _) = directory_profile_metadata(&state, &user).await?;

    if directory_managed {
        if req
            .new_email
            .as_deref()
            .is_some_and(|value| !value.trim().is_empty())
            || req
                .new_password
                .as_deref()
                .is_some_and(|value| !value.is_empty())
        {
            return Err(AuthError::forbidden(
                "E-mail and password are managed by LDAP/AD.",
            ));
        }
    } else if !verify_password(&user.password_hash, &req.password) {
        return Err(AuthError::unauthorized(
            "The current password is incorrect.",
        ));
    }

    let mut nickname = user.nickname.clone();
    if let Some(value) = req.nickname.as_deref() {
        nickname = validate_nickname(value)?;
        if normalize(&nickname) != normalize(&user.nickname)
            && find_user_by_nickname(&state, &nickname).await?.is_some()
        {
            return Err(AuthError::conflict("This nickname is already registered."));
        }
        sqlx::query(queries::get(state.db.kind(), queries::AUTH_UPDATE_NICKNAME))
            .bind(&nickname)
            .bind(normalize(&nickname))
            .bind(Utc::now().to_rfc3339())
            .bind(user.id)
            .execute(state.db.pool())
            .await
            .map_err(AuthError::database)?;
    }

    let mut email_pending = false;
    if !directory_managed {
        if let Some(value) = req
            .new_password
            .as_deref()
            .filter(|value| !value.is_empty())
        {
            validate_password(value)?;
            let hash = hash_password(value)?;
            sqlx::query(queries::get(state.db.kind(), queries::AUTH_UPDATE_PASSWORD))
                .bind(hash)
                .bind(Utc::now().to_rfc3339())
                .bind(user.id)
                .execute(state.db.pool())
                .await
                .map_err(AuthError::database)?;
        }

        if let Some(value) = req
            .new_email
            .as_deref()
            .filter(|value| !value.trim().is_empty())
        {
            let email = validate_email(value)?;
            if normalize(&email) != normalize(&user.email) {
                if find_user_by_email(&state, &email).await?.is_some() {
                    return Err(AuthError::conflict(
                        "This e-mail address is already registered.",
                    ));
                }
                let smtp = state
                    .smtp
                    .as_ref()
                    .ok_or_else(|| AuthError::service_unavailable("SMTP is not configured."))?;
                create_account_action(&state, &user, "email", Some(&email), smtp).await?;
                email_pending = true;
            }
        }
    }

    if let Some(value) = req.editor_color.as_deref() {
        let color = validate_editor_color(value)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::AUTH_UPDATE_EDITOR_COLOR,
        ))
        .bind(color)
        .bind(Utc::now().to_rfc3339())
        .bind(user.id)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    }

    Ok(Json(serde_json::json!({
        "ok": true,
        "nickname": nickname,
        "editor_color": req.editor_color.as_deref(),
        "email_pending": email_pending,
        "message": if email_pending {
            "Profile updated. Confirm the new e-mail address using the link sent to it."
        } else {
            "Profile updated."
        }
    })))
}

pub async fn request_account_deletion(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<DeleteAccountRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    if state.ldap.is_some() {
        return Err(AuthError::forbidden(
            "LDAP accounts cannot be deleted here.",
        ));
    }
    let user = require_user(&state, &headers).await?;
    if !verify_password(&user.password_hash, &req.password) {
        return Err(AuthError::unauthorized(
            "The current password is incorrect.",
        ));
    }
    let smtp = state
        .smtp
        .as_ref()
        .ok_or_else(|| AuthError::service_unavailable("SMTP is not configured."))?;
    create_account_action(&state, &user, "delete", None, smtp).await?;
    Ok(Json(
        serde_json::json!({"ok":true,"message":"A confirmation link has been sent to your e-mail address."}),
    ))
}

pub async fn confirm_account_action(
    State(state): State<SharedState>,
    Json(req): Json<AccountActionConfirmRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let now = Utc::now();
    let hash = hash_token(req.token.trim());
    let row: Option<(i64, String, Option<String>, String, Option<String>)> = sqlx::query_as(
        queries::get(state.db.kind(), queries::AUTH_ACCOUNT_ACTION_BY_TOKEN),
    )
    .bind(&hash)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let (user_id, action, payload, expires_at, used_at) = row.ok_or_else(|| {
        AuthError::bad_request("The confirmation link is invalid or has expired.")
    })?;
    let expires = chrono::DateTime::parse_from_rfc3339(&expires_at)
        .map_err(|_| AuthError::bad_request("The confirmation link is invalid or has expired."))?
        .with_timezone(&Utc);
    if used_at.is_some() || expires <= now {
        return Err(AuthError::bad_request(
            "The confirmation link is invalid or has expired.",
        ));
    }
    let mut tx = state.db.pool().begin().await.map_err(AuthError::database)?;
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_CONSUME_ACCOUNT_ACTION,
    ))
    .bind(now.to_rfc3339())
    .bind(&hash)
    .execute(&mut *tx)
    .await
    .map_err(AuthError::database)?;
    let message = if action == "email" {
        let email = payload.ok_or_else(|| AuthError::internal("Missing e-mail change payload."))?;
        if find_user_by_email(&state, &email).await?.is_some() {
            return Err(AuthError::conflict(
                "This e-mail address is already registered.",
            ));
        }
        sqlx::query(queries::get(state.db.kind(), queries::AUTH_UPDATE_EMAIL))
            .bind(&email)
            .bind(normalize(&email))
            .bind(now.to_rfc3339())
            .bind(user_id)
            .execute(&mut *tx)
            .await
            .map_err(AuthError::database)?;
        "E-mail address changed."
    } else if action == "delete" {
        sqlx::query(queries::get(state.db.kind(), queries::AUTH_DELETE_USER))
            .bind(user_id)
            .execute(&mut *tx)
            .await
            .map_err(AuthError::database)?;
        "Account deleted."
    } else {
        return Err(AuthError::bad_request("Unknown account action."));
    };
    tx.commit().await.map_err(AuthError::database)?;
    Ok(Json(serde_json::json!({"ok":true,"message":message})))
}

async fn create_account_action(
    state: &SharedState,
    user: &User,
    action: &str,
    payload: Option<&str>,
    smtp: &SmtpConfig,
) -> Result<(), AuthError> {
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_DELETE_ACCOUNT_ACTIONS,
    ))
    .bind(user.id)
    .bind(action)
    .execute(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let token = random_token();
    let expires = (Utc::now() + Duration::hours(1)).to_rfc3339();
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_INSERT_ACCOUNT_ACTION,
    ))
    .bind(hash_token(&token))
    .bind(user.id)
    .bind(action)
    .bind(payload)
    .bind(expires)
    .bind(Utc::now().to_rfc3339())
    .execute(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    send_account_action(smtp, user, action, payload, &token).await
}

async fn send_account_action(
    smtp: &SmtpConfig,
    user: &User,
    action: &str,
    payload: Option<&str>,
    token: &str,
) -> Result<(), AuthError> {
    let site = smtp.public_url.trim_end_matches('/');
    let url = format!("{site}/?account_action_token={token}");
    let sender = smtp
        .from
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid SMTP_FROM."))?;
    let target = if action == "email" {
        payload.unwrap_or(&user.email)
    } else {
        &user.email
    };
    let recipient = target
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid recipient address."))?;
    let (subject, title, copy) = if action == "email" {
        (
            "Confirm your new RustPad e-mail",
            "Confirm e-mail change",
            "Confirm the new e-mail address within one hour.",
        )
    } else {
        (
            "Confirm RustPad account deletion",
            "Confirm account deletion",
            "Confirm permanent account deletion within one hour.",
        )
    };
    let text = format!(
        "Hello {},\n\n{}\n{}\n\nIf you did not request this, ignore this message.",
        user.nickname, copy, url
    );
    let html = format!(
        r#"<!doctype html><html lang="en"><body style="margin:0;padding:24px;background:#f4f4f5;font-family:Arial,sans-serif;color:#18181b"><div style="max-width:560px;margin:0 auto;padding:24px;background:#fff;border-radius:10px"><h1 style="margin-top:0;font-size:22px">{}</h1><p>Hello {},</p><p>{}</p><p><a href="{}" style="display:inline-block;padding:11px 18px;background:#2563eb;color:#fff;text-decoration:none;border-radius:6px">Confirm action</a></p><p style="font-size:13px;overflow-wrap:anywhere"><a href="{}">{}</a></p><p>If you did not request this, ignore this message.</p></div></body></html>"#,
        title, user.nickname, copy, url, url, url
    );
    let message = Message::builder()
        .from(sender)
        .to(recipient)
        .subject(subject)
        .multipart(
            MultiPart::alternative()
                .singlepart(
                    SinglePart::builder()
                        .header(ContentType::TEXT_PLAIN)
                        .body(text),
                )
                .singlepart(
                    SinglePart::builder()
                        .header(ContentType::TEXT_HTML)
                        .body(html),
                ),
        )
        .map_err(|_| AuthError::internal("Failed to build account confirmation e-mail."))?;
    send_message(smtp, message, "account action e-mail").await
}

pub async fn resources(
    State(state): State<SharedState>,
    headers: HeaderMap,
) -> Result<Json<ResourceList>, AuthError> {
    let user = require_user(&state, &headers).await?;
    let workspaces = sqlx::query_as::<_, ResourceItem>(queries::get(
        state.db.kind(),
        queries::USER_LIST_WORKSPACES,
    ))
    .bind(user.id)
    .bind(user.id)
    .fetch_all(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let pads =
        sqlx::query_as::<_, ResourceItem>(queries::get(state.db.kind(), queries::USER_LIST_PADS))
            .bind(user.id)
            .bind(user.id)
            .fetch_all(state.db.pool())
            .await
            .map_err(AuthError::database)?;
    Ok(Json(ResourceList { workspaces, pads }))
}

pub async fn update_resource(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<ResourceActionRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let user = require_user(&state, &headers).await?;
    let hash = match req
        .password
        .as_deref()
        .map(str::trim)
        .filter(|v| !v.is_empty())
    {
        Some(v) => {
            validate_password(v)?;
            Some(hash_password(v)?)
        }
        None => None,
    };
    ensure_owner(&state, user.id, &req.kind, &req.slug).await?;
    let query = match req.kind.as_str() {
        "workspace" => queries::USER_SET_WORKSPACE_PASSWORD,
        "pad" => queries::USER_SET_PAD_PASSWORD,
        _ => return Err(AuthError::bad_request("Unknown resource type.")),
    };
    sqlx::query(queries::get(state.db.kind(), query))
        .bind(hash)
        .bind(req.slug.trim())
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    sqlx::query(queries::get(
        state.db.kind(),
        queries::RESOURCE_ACCESS_TOKENS_DELETE_BY_RESOURCE,
    ))
    .bind(req.kind.as_str())
    .bind(req.slug.trim())
    .execute(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    Ok(Json(serde_json::json!({"ok":true})))
}

pub async fn delete_resource(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<ResourceActionRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let user = require_user(&state, &headers).await?;
    ensure_owner(&state, user.id, &req.kind, &req.slug).await?;
    let query = match req.kind.as_str() {
        "workspace" => {
            if let Some(workspace) = crate::db::find_workspace(&state.db, req.slug.trim())
                .await
                .map_err(AuthError::database)?
            {
                let notes = crate::db::list_notes(&state.db, workspace.id)
                    .await
                    .map_err(AuthError::database)?;
                for note in notes {
                    let files = crate::db::list_note_files(&state.db, note.id)
                        .await
                        .map_err(AuthError::database)?;
                    for file in files {
                        crate::storage::delete_url_file(
                            &state.storage,
                            "notes",
                            note.id,
                            &file.url,
                        )
                        .await
                        .map_err(|_| AuthError::internal("Failed to delete workspace files."))?;
                    }
                }
            }
            queries::USER_DELETE_WORKSPACE
        }
        "pad" => {
            if let Some(pad) = crate::db::find_pad(&state.db, req.slug.trim())
                .await
                .map_err(AuthError::database)?
            {
                let files = crate::db::list_pad_files(&state.db, pad.id)
                    .await
                    .map_err(AuthError::database)?;
                for file in files {
                    crate::storage::delete_url_file(&state.storage, "pads", pad.id, &file.url)
                        .await
                        .map_err(|_| AuthError::internal("Failed to delete pad files."))?;
                }
            }
            queries::USER_DELETE_PAD
        }
        _ => return Err(AuthError::bad_request("Unknown resource type.")),
    };
    sqlx::query(queries::get(
        state.db.kind(),
        queries::RESOURCE_ACCESS_TOKENS_DELETE_BY_RESOURCE,
    ))
    .bind(req.kind.as_str())
    .bind(req.slug.trim())
    .execute(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    sqlx::query(queries::get(state.db.kind(), query))
        .bind(req.slug.trim())
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    Ok(Json(serde_json::json!({"ok":true})))
}

pub async fn optional_user(
    state: &SharedState,
    headers: &HeaderMap,
) -> Result<Option<User>, AuthError> {
    match bearer(headers) {
        Some(token) => user_from_token(state, token).await,
        None => Ok(None),
    }
}

async fn require_user(state: &SharedState, headers: &HeaderMap) -> Result<User, AuthError> {
    optional_user(state, headers)
        .await?
        .ok_or_else(|| AuthError::unauthorized("Log in first."))
}

async fn ensure_owner(
    state: &SharedState,
    user_id: i64,
    kind: &str,
    slug: &str,
) -> Result<(), AuthError> {
    let query = match kind {
        "workspace" => queries::USER_OWNS_WORKSPACE,
        "pad" => queries::USER_OWNS_PAD,
        _ => return Err(AuthError::bad_request("Unknown resource type.")),
    };
    let count: i64 = sqlx::query_scalar(queries::get(state.db.kind(), query))
        .bind(user_id)
        .bind(slug.trim())
        .fetch_one(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    if count == 0 {
        return Err(AuthError::forbidden(
            "This item does not belong to your account.",
        ));
    }
    Ok(())
}

pub async fn set_resource_privacy(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<PrivacyRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let user = require_user(&state, &headers).await?;
    ensure_owner(&state, user.id, &req.kind, &req.slug).await?;
    let query = match req.kind.as_str() {
        "workspace" => queries::USER_SET_WORKSPACE_PRIVACY,
        "pad" => queries::USER_SET_PAD_PRIVACY,
        _ => return Err(AuthError::bad_request("Unknown resource type.")),
    };
    sqlx::query(queries::get(state.db.kind(), query))
        .bind(req.private)
        .bind(req.slug.trim())
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    Ok(Json(serde_json::json!({"ok":true})))
}

pub async fn share_resource_users(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<ShareUsersRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let owner = require_user(&state, &headers).await?;
    ensure_owner(&state, owner.id, &req.kind, &req.slug).await?;
    let permission = validate_permission(&req.permission)?;
    if state.share_confirmation_required && state.smtp.is_none() {
        return Err(AuthError::service_unavailable(
            "Share confirmation requires SMTP configuration.",
        ));
    }
    let emails: Vec<String> = req
        .emails
        .split(',')
        .map(|v| normalize(v))
        .filter(|v| !v.is_empty())
        .collect();
    if emails.is_empty() || emails.len() > 100 {
        return Err(AuthError::bad_request(
            "Enter between 1 and 100 registered e-mail addresses.",
        ));
    }
    let mut missing = Vec::new();
    for email in emails {
        let user = find_user_by_email(&state, &email).await?;
        let Some(user) = user else {
            missing.push(email);
            continue;
        };
        if user.confirmed_at.is_none() {
            missing.push(format!("{} (account not activated)", email));
            continue;
        }
        if user.id == owner.id {
            continue;
        }

        sqlx::query(queries::get(
            state.db.kind(),
            queries::RESOURCE_PERMISSION_DELETE_USER,
        ))
        .bind(&req.kind)
        .bind(req.slug.trim())
        .bind(user.id)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::SHARE_INVITATION_DELETE_USER,
        ))
        .bind(&req.kind)
        .bind(req.slug.trim())
        .bind(user.id)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;

        if state.share_confirmation_required {
            let token = random_token();
            let token_hash = hash_token(&token);
            let expires_at = (Utc::now() + Duration::days(7)).to_rfc3339();
            sqlx::query(queries::get(
                state.db.kind(),
                queries::SHARE_INVITATION_INSERT,
            ))
            .bind(&token_hash)
            .bind(&req.kind)
            .bind(req.slug.trim())
            .bind(user.id)
            .bind(permission)
            .bind(owner.id)
            .bind(&expires_at)
            .execute(state.db.pool())
            .await
            .map_err(AuthError::database)?;
            if let Err(error) = send_share_invitation(
                state.smtp.as_ref().unwrap(),
                &owner,
                &user,
                &req.kind,
                req.slug.trim(),
                permission,
                &token,
            )
            .await
            {
                let _ = sqlx::query(queries::get(
                    state.db.kind(),
                    queries::SHARE_INVITATION_DELETE_TOKEN,
                ))
                .bind(&token_hash)
                .execute(state.db.pool())
                .await;
                return Err(error);
            }
        } else {
            sqlx::query(queries::get(
                state.db.kind(),
                queries::RESOURCE_PERMISSION_INSERT,
            ))
            .bind(&req.kind)
            .bind(req.slug.trim())
            .bind(user.id)
            .bind(permission)
            .execute(state.db.pool())
            .await
            .map_err(AuthError::database)?;
        }
    }
    if !missing.is_empty() {
        return Err(AuthError::bad_request(&format!(
            "No registered account for: {}",
            missing.join(", ")
        )));
    }
    Ok(Json(
        serde_json::json!({"ok":true,"confirmation_required":state.share_confirmation_required}),
    ))
}

pub async fn accept_share_invitation(
    State(state): State<SharedState>,
    AxumPath(token): AxumPath<String>,
) -> Result<Redirect, AuthError> {
    let token_hash = hash_token(token.trim());
    let row: Option<(String, String, i64, String, String, Option<String>)> = sqlx::query_as(
        queries::get(state.db.kind(), queries::SHARE_INVITATION_FIND_TOKEN),
    )
    .bind(&token_hash)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let (kind, slug, user_id, permission, expires_at, accepted_at) = row.ok_or_else(|| {
        AuthError::bad_request("The sharing invitation is invalid or has expired.")
    })?;
    let expires = chrono::DateTime::parse_from_rfc3339(&expires_at)
        .map_err(|_| AuthError::bad_request("The sharing invitation is invalid or has expired."))?
        .with_timezone(&Utc);
    if accepted_at.is_none() {
        if expires <= Utc::now() {
            return Err(AuthError::bad_request(
                "The sharing invitation is invalid or has expired.",
            ));
        }
        let mut tx = state.db.pool().begin().await.map_err(AuthError::database)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::RESOURCE_PERMISSION_DELETE_USER,
        ))
        .bind(&kind)
        .bind(&slug)
        .bind(user_id)
        .execute(&mut *tx)
        .await
        .map_err(AuthError::database)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::RESOURCE_PERMISSION_INSERT,
        ))
        .bind(&kind)
        .bind(&slug)
        .bind(user_id)
        .bind(&permission)
        .execute(&mut *tx)
        .await
        .map_err(AuthError::database)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::SHARE_INVITATION_ACCEPT,
        ))
        .bind(Utc::now().to_rfc3339())
        .bind(&token_hash)
        .execute(&mut *tx)
        .await
        .map_err(AuthError::database)?;
        tx.commit().await.map_err(AuthError::database)?;
    }
    let target = if kind == "workspace" {
        format!("/w/{slug}")
    } else {
        format!("/p/{slug}")
    };
    Ok(Redirect::to(&target))
}

pub async fn remove_resource_user(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<RemoveShareRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let owner = require_user(&state, &headers).await?;
    ensure_owner(&state, owner.id, &req.kind, &req.slug).await?;
    let email = normalize(&req.email);
    if let Some(user) = find_user_by_email(&state, &email).await? {
        sqlx::query(queries::get(
            state.db.kind(),
            queries::RESOURCE_PERMISSION_DELETE_USER,
        ))
        .bind(&req.kind)
        .bind(req.slug.trim())
        .bind(user.id)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::SHARE_INVITATION_DELETE_USER,
        ))
        .bind(&req.kind)
        .bind(req.slug.trim())
        .bind(user.id)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    }
    Ok(Json(serde_json::json!({"ok":true})))
}

pub async fn resource_sharing(
    State(state): State<SharedState>,
    headers: HeaderMap,
    axum::extract::Query(params): axum::extract::Query<std::collections::HashMap<String, String>>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let owner = require_user(&state, &headers).await?;
    let kind = params
        .get("kind")
        .ok_or_else(|| AuthError::bad_request("Missing kind."))?;
    let slug = params
        .get("slug")
        .ok_or_else(|| AuthError::bad_request("Missing slug."))?;
    ensure_owner(&state, owner.id, kind, slug).await?;
    let users: Vec<(String, String, String)> = sqlx::query_as(queries::get(
        state.db.kind(),
        queries::RESOURCE_SHARING_USERS,
    ))
    .bind(kind)
    .bind(slug)
    .fetch_all(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let links: Vec<(String, Option<String>, String, Option<String>, String)> = sqlx::query_as(
        queries::get(state.db.kind(), queries::RESOURCE_SHARING_LINKS),
    )
    .bind(kind)
    .bind(slug)
    .fetch_all(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let pending: Vec<(String, String, String, String)> = sqlx::query_as(queries::get(
        state.db.kind(),
        queries::RESOURCE_SHARING_PENDING,
    ))
    .bind(kind)
    .bind(slug)
    .fetch_all(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    Ok(Json(
        serde_json::json!({"users":users.into_iter().map(|(email,nickname,permission)|serde_json::json!({"email":email,"nickname":nickname,"permission":permission})).collect::<Vec<_>>(), "pending":pending.into_iter().map(|(email,nickname,permission,expires_at)|serde_json::json!({"email":email,"nickname":nickname,"permission":permission,"expires_at":expires_at})).collect::<Vec<_>>(), "links":links.into_iter().map(|(token_hash,token,permission,expires_at,created_at)|serde_json::json!({"token_hash":token_hash,"token":token,"permission":permission,"expires_at":expires_at,"created_at":created_at})).collect::<Vec<_>>() }),
    ))
}

pub async fn create_share_link(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<CreateShareLinkRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let owner = require_user(&state, &headers).await?;
    ensure_owner(&state, owner.id, &req.kind, &req.slug).await?;
    let permission = validate_permission(&req.permission)?;
    validate_share_expiration(req.expires_at.as_deref())?;
    let token = random_token();
    let token_hash = hash_token(&token);
    sqlx::query(queries::get(state.db.kind(), queries::SHARE_LINK_INSERT))
        .bind(token_hash)
        .bind(&token)
        .bind(&req.kind)
        .bind(req.slug.trim())
        .bind(permission)
        .bind(&req.expires_at)
        .bind(owner.id)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    let base = if req.kind == "workspace" {
        format!("/w/{}", req.slug.trim())
    } else {
        format!("/p/{}", req.slug.trim())
    };
    Ok(Json(
        serde_json::json!({"token":token,"url":format!("{base}?share={token}"),"permission":permission,"expires_at":req.expires_at}),
    ))
}

pub async fn update_share_link(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<UpdateShareLinkRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let owner = require_user(&state, &headers).await?;
    ensure_owner(&state, owner.id, &req.kind, &req.slug).await?;
    let permission = validate_permission(&req.permission)?;
    validate_share_expiration(req.expires_at.as_deref())?;
    let result = sqlx::query(queries::get(state.db.kind(), queries::SHARE_LINK_UPDATE))
        .bind(permission)
        .bind(&req.expires_at)
        .bind(req.token.trim())
        .bind(&req.kind)
        .bind(req.slug.trim())
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    if result.rows_affected() == 0 {
        return Err(AuthError::bad_request(
            "Share link was not found or is already revoked.",
        ));
    }
    Ok(Json(
        serde_json::json!({"ok":true,"permission":permission,"expires_at":req.expires_at}),
    ))
}

pub async fn revoke_share_link(
    State(state): State<SharedState>,
    headers: HeaderMap,
    Json(req): Json<RevokeShareLinkRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let owner = require_user(&state, &headers).await?;
    ensure_owner(&state, owner.id, &req.kind, &req.slug).await?;
    sqlx::query(queries::get(state.db.kind(), queries::SHARE_LINK_REVOKE))
        .bind(Utc::now().to_rfc3339())
        .bind(req.token.trim())
        .bind(&req.kind)
        .bind(req.slug.trim())
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    Ok(Json(serde_json::json!({"ok":true})))
}

fn validate_permission(value: &str) -> Result<&str, AuthError> {
    match value {
        "ro" | "rw" => Ok(value),
        _ => Err(AuthError::bad_request("Permission must be ro or rw.")),
    }
}

fn validate_share_expiration(value: Option<&str>) -> Result<(), AuthError> {
    let Some(value) = value else {
        return Ok(());
    };
    let expires = chrono::DateTime::parse_from_rfc3339(value)
        .map_err(|_| AuthError::bad_request("Invalid expiration date."))?
        .with_timezone(&Utc);
    if expires <= Utc::now() {
        return Err(AuthError::bad_request("Expiration must be in the future."));
    }
    Ok(())
}

pub async fn is_resource_owner(
    state: &SharedState,
    kind: &str,
    slug: &str,
    token: Option<&str>,
) -> Result<bool, AuthError> {
    let Some(token) = token.filter(|v| !v.is_empty()) else {
        return Ok(false);
    };
    let Some(user) = user_from_token(state, token).await? else {
        return Ok(false);
    };
    Ok(ensure_owner(state, user.id, kind, slug).await.is_ok())
}

pub async fn resource_permission(
    state: &SharedState,
    kind: &str,
    slug: &str,
    token: Option<&str>,
) -> Result<Option<String>, AuthError> {
    let Some(token) = token.filter(|v| !v.is_empty()) else {
        return Ok(None);
    };
    if let Some(user) = user_from_token(state, token).await? {
        let owns = ensure_owner(state, user.id, kind, slug).await.is_ok();
        if owns {
            return Ok(Some("rw".into()));
        }
        let permission: Option<String> = sqlx::query_scalar(queries::get(
            state.db.kind(),
            queries::RESOURCE_PERMISSION_BY_USER,
        ))
        .bind(kind)
        .bind(slug)
        .bind(user.id)
        .fetch_optional(state.db.pool())
        .await
        .map_err(AuthError::database)?;
        return Ok(permission);
    }
    let now = Utc::now().to_rfc3339();
    let permission: Option<String> = sqlx::query_scalar(queries::get(
        state.db.kind(),
        queries::SHARE_LINK_PERMISSION,
    ))
    .bind(hash_token(token))
    .bind(kind)
    .bind(slug)
    .bind(now)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    Ok(permission)
}

pub async fn logout(
    State(state): State<SharedState>,
    headers: HeaderMap,
) -> Result<Json<serde_json::Value>, AuthError> {
    if let Some(token) = bearer(&headers) {
        let result = sqlx::query(queries::get(
            state.db.kind(),
            queries::AUTH_DELETE_SESSION_BY_TOKEN,
        ))
        .bind(token)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
        info!(rows_affected = result.rows_affected(), "logout processed");
    } else {
        debug!("logout requested without an active session");
    }
    Ok(Json(serde_json::json!({"ok": true})))
}

pub async fn request_reset(
    State(state): State<SharedState>,
    Json(req): Json<ResetRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    let email = validate_email(&req.email)?;
    info!(email_domain = %email_domain(&email), "password reset requested");
    let smtp = state.smtp.as_ref().ok_or_else(|| {
        AuthError::service_unavailable("Password reset is not configured on this server.")
    })?;
    if let Some(user) = find_user_by_email(&state, &email).await? {
        let token = random_token();
        let expires = (Utc::now() + Duration::minutes(30)).to_rfc3339();
        let mut tx = state.db.pool().begin().await.map_err(AuthError::database)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::AUTH_DELETE_RESET_TOKENS_BY_USER,
        ))
        .bind(user.id)
        .execute(&mut *tx)
        .await
        .map_err(AuthError::database)?;
        sqlx::query(queries::get(
            state.db.kind(),
            queries::AUTH_INSERT_RESET_TOKEN,
        ))
        .bind(hash_token(&token))
        .bind(user.id)
        .bind(expires)
        .execute(&mut *tx)
        .await
        .map_err(AuthError::database)?;
        tx.commit().await.map_err(AuthError::database)?;
        send_reset(smtp, &user, &token).await?;
        info!(user_id = user.id, "password reset e-mail sent");
    } else {
        debug!(email_domain = %email_domain(&email), "password reset requested for unknown account");
    }
    Ok(Json(
        serde_json::json!({"ok": true, "message": "If the account exists, a reset link has been sent."}),
    ))
}

pub async fn confirm_reset(
    State(state): State<SharedState>,
    Json(req): Json<ResetConfirmRequest>,
) -> Result<Json<serde_json::Value>, AuthError> {
    validate_password(&req.password)?;
    info!("password reset confirmation requested");
    let now_time = Utc::now();
    let now = now_time.to_rfc3339();
    let token_hash = hash_token(req.token.trim());
    let token_row: Option<(i64, String, Option<String>)> = sqlx::query_as(queries::get(
        state.db.kind(),
        queries::AUTH_FIND_RESET_TOKEN,
    ))
    .bind(&token_hash)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    let (user_id, expires_at, used_at) = token_row
        .ok_or_else(|| AuthError::bad_request("The reset link is invalid or has expired."))?;
    let expires_at = chrono::DateTime::parse_from_rfc3339(&expires_at)
        .map_err(|_| AuthError::bad_request("The reset link is invalid or has expired."))?
        .with_timezone(&Utc);
    if used_at.is_some() || expires_at <= now_time {
        warn!(
            user_id,
            used = used_at.is_some(),
            expired = expires_at <= now_time,
            "password reset token rejected"
        );
        return Err(AuthError::bad_request(
            "The reset link is invalid or has expired.",
        ));
    }
    let password_hash = hash_password(&req.password)?;
    let mut tx = state.db.pool().begin().await.map_err(AuthError::database)?;
    let consumed = sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_CONSUME_RESET_TOKEN,
    ))
    .bind(&now)
    .bind(&token_hash)
    .bind(&now)
    .execute(&mut *tx)
    .await
    .map_err(AuthError::database)?;
    if consumed.rows_affected() != 1 {
        return Err(AuthError::bad_request(
            "The reset link is invalid or has expired.",
        ));
    }
    let updated = sqlx::query(queries::get(state.db.kind(), queries::AUTH_UPDATE_PASSWORD))
        .bind(password_hash)
        .bind(&now)
        .bind(user_id)
        .execute(&mut *tx)
        .await
        .map_err(AuthError::database)?;
    if updated.rows_affected() != 1 {
        return Err(AuthError::internal("The account could not be updated."));
    }
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_DELETE_RESET_TOKENS_BY_USER,
    ))
    .bind(user_id)
    .execute(&mut *tx)
    .await
    .map_err(AuthError::database)?;
    sqlx::query(queries::get(
        state.db.kind(),
        queries::AUTH_DELETE_SESSIONS_BY_USER,
    ))
    .bind(user_id)
    .execute(&mut *tx)
    .await
    .map_err(AuthError::database)?;
    tx.commit().await.map_err(AuthError::database)?;
    info!(
        user_id,
        "password reset completed and existing sessions revoked"
    );
    Ok(Json(serde_json::json!({"ok": true})))
}

pub async fn user_from_token(state: &SharedState, token: &str) -> Result<Option<User>, AuthError> {
    let now = Utc::now();
    let now_rfc3339 = now.to_rfc3339();
    let user =
        sqlx::query_as::<_, User>(queries::get(state.db.kind(), queries::AUTH_USER_BY_SESSION))
            .bind(token)
            .bind(&now_rfc3339)
            .fetch_optional(state.db.pool())
            .await
            .map_err(AuthError::database)?;

    if let Some(user) = user {
        let expires_at = (now + Duration::days(state.user_session_ttl_days)).to_rfc3339();
        let refreshed = sqlx::query(queries::get(state.db.kind(), queries::AUTH_REFRESH_SESSION))
            .bind(&expires_at)
            .bind(token)
            .bind(&now_rfc3339)
            .execute(state.db.pool())
            .await
            .map_err(AuthError::database)?;
        if refreshed.rows_affected() == 1 {
            debug!(user_id = user.id, expires_at = %expires_at, "authentication session extended");
            Ok(Some(user))
        } else {
            Ok(None)
        }
    } else {
        sqlx::query(queries::get(
            state.db.kind(),
            queries::AUTH_DELETE_SESSION_BY_TOKEN,
        ))
        .bind(token)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
        Ok(None)
    }
}

pub async fn authorize_nickname(
    state: &SharedState,
    nickname: Option<String>,
    token: Option<String>,
) -> Result<Option<String>, String> {
    let Some(nickname) = nickname else {
        return Ok(None);
    };
    let nickname = validate_nickname(&nickname).map_err(|e| e.message)?;
    let registered = find_user_by_nickname(state, &nickname)
        .await
        .map_err(|_| "Database error".to_string())?;
    match registered {
        None => Ok(Some(nickname)),
        Some(owner) => {
            let Some(token) = token else {
                return Err("This nickname is registered. Log in to use it.".into());
            };
            let current = user_from_token(state, &token)
                .await
                .map_err(|_| "Database error".to_string())?;
            match current {
                Some(user) if user.id == owner.id => Ok(Some(owner.nickname)),
                _ => Err("This nickname belongs to another account or the session expired.".into()),
            }
        }
    }
}

async fn create_session(state: &SharedState, user: &User) -> Result<SessionResponse, AuthError> {
    let token = random_token();
    let expires_at = (Utc::now() + Duration::days(state.user_session_ttl_days)).to_rfc3339();
    sqlx::query(queries::get(state.db.kind(), queries::AUTH_INSERT_SESSION))
        .bind(&token)
        .bind(user.id)
        .bind(&expires_at)
        .execute(state.db.pool())
        .await
        .map_err(AuthError::database)?;
    debug!(user_id = user.id, expires_at = %expires_at, "authentication session created");
    let (directory_managed, directory_display_name, directory_organization, suggested_nickname) =
        directory_profile_metadata(state, user).await?;
    let editor_color: Option<String> = sqlx::query_scalar(queries::get(
        state.db.kind(),
        queries::AUTH_EDITOR_COLOR_BY_USER,
    ))
    .bind(user.id)
    .fetch_one(state.db.pool())
    .await
    .map_err(AuthError::database)?;
    Ok(SessionResponse {
        token,
        nickname: user.nickname.clone(),
        email: user.email.clone(),
        expires_at,
        directory_managed,
        directory_display_name,
        directory_organization,
        suggested_nickname,
        editor_color,
    })
}
async fn find_user_by_nickname(
    state: &SharedState,
    nickname: &str,
) -> Result<Option<User>, AuthError> {
    sqlx::query_as::<_, User>(queries::get(
        state.db.kind(),
        queries::AUTH_USER_BY_NICKNAME,
    ))
    .bind(normalize(nickname))
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)
}
async fn find_user_by_external_id(
    state: &SharedState,
    provider: &str,
    external_id: &str,
) -> Result<Option<User>, AuthError> {
    sqlx::query_as::<_, User>(queries::get(
        state.db.kind(),
        queries::AUTH_USER_BY_EXTERNAL_ID,
    ))
    .bind(provider)
    .bind(external_id)
    .fetch_optional(state.db.pool())
    .await
    .map_err(AuthError::database)
}

async fn find_user_by_email(state: &SharedState, email: &str) -> Result<Option<User>, AuthError> {
    sqlx::query_as::<_, User>(queries::get(state.db.kind(), queries::AUTH_USER_BY_EMAIL))
        .bind(normalize(email))
        .fetch_optional(state.db.pool())
        .await
        .map_err(AuthError::database)
}
fn validate_editor_color(value: &str) -> Result<String, AuthError> {
    let value = value.trim();
    if value.len() == 7
        && value.starts_with('#')
        && value[1..].chars().all(|c| c.is_ascii_hexdigit())
    {
        Ok(value.to_ascii_lowercase())
    } else {
        Err(AuthError::bad_request("Invalid editor color."))
    }
}

fn validate_nickname(v: &str) -> Result<String, AuthError> {
    let v = v.trim();
    if v.is_empty() || v.chars().count() > MAX_NICKNAME {
        return Err(AuthError::bad_request(
            "Nickname must contain 1 to 40 characters.",
        ));
    }
    if v.chars().any(|c| c.is_control()) {
        return Err(AuthError::bad_request(
            "Nickname contains invalid characters.",
        ));
    }
    Ok(v.into())
}
fn validate_email(value: &str) -> Result<String, AuthError> {
    let value = value.trim();

    if value.len() > 320 || !value.contains('@') || value.starts_with('@') || value.ends_with('@') {
        return Err(AuthError::bad_request("Enter a valid e-mail address."));
    }

    Ok(value.into())
}

fn validate_password(value: &str) -> Result<(), AuthError> {
    if value.len() < MIN_PASSWORD || value.len() > MAX_PASSWORD {
        return Err(AuthError::bad_request(
            "Password must contain 8 to 128 characters.",
        ));
    }

    Ok(())
}

fn normalize(value: &str) -> String {
    value.trim().to_lowercase()
}

fn hash_password(value: &str) -> Result<String, AuthError> {
    let salt = SaltString::generate(&mut OsRng);

    Argon2::default()
        .hash_password(value.as_bytes(), &salt)
        .map(|hash| hash.to_string())
        .map_err(|_| AuthError::internal("Failed to secure the password."))
}

fn verify_password(hash: &str, value: &str) -> bool {
    PasswordHash::new(hash)
        .ok()
        .and_then(|hash| {
            Argon2::default()
                .verify_password(value.as_bytes(), &hash)
                .ok()
        })
        .is_some()
}

fn random_token() -> String {
    random_hex_token::<32>()
}

fn random_confirmation_token() -> String {
    random_hex_token::<32>()
}

fn random_hex_token<const N: usize>() -> String {
    let mut bytes = [0_u8; N];
    let mut rng = OsRng;
    rng.fill_bytes(&mut bytes);

    bytes.iter().map(|byte| format!("{byte:02x}")).collect()
}

fn hash_token(value: &str) -> String {
    format!("{:x}", Sha256::digest(value.as_bytes()))
}

fn bearer(headers: &HeaderMap) -> Option<&str> {
    headers
        .get("authorization")?
        .to_str()
        .ok()?
        .strip_prefix("Bearer ")
}

async fn send_registration_email(
    smtp: &SmtpConfig,
    user: &User,
    token: Option<&str>,
) -> Result<(), AuthError> {
    let site = smtp.public_url.trim_end_matches('/');
    let sender = smtp
        .from
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid SMTP_FROM."))?;
    let recipient = user
        .email
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid recipient address."))?;

    let builder = Message::builder().from(sender).to(recipient);

    let message = match token {
        Some(token) => {
            let confirmation_url = format!("{site}/?confirm_token={token}");
            let subject = "Confirm your RustPad account";
            let text_body = format!(
                "Hello {},\n\nYour RustPad account has been created.\nNickname: {}\nSite: {}\n\nConfirm the account within 24 hours by opening this link:\n{}\n",
                user.nickname, user.nickname, site, confirmation_url
            );
            let html_body = format!(
                r#"<!doctype html>
<html lang="en">
  <body style="margin: 0; padding: 24px; background: #f4f4f5; font-family: Arial, sans-serif; color: #18181b;">
    <div style="max-width: 560px; margin: 0 auto; padding: 24px; background: #ffffff; border-radius: 10px;">
      <h1 style="margin-top: 0; font-size: 22px;">Confirm your RustPad account</h1>
      <p>Hello {},</p>
      <p>Your RustPad account has been created.</p>
      <p><strong>Nickname:</strong> {}<br><strong>Site:</strong> {}</p>
      <p>Confirm the account within 24 hours:</p>
      <p><a href="{}" style="display: inline-block; padding: 11px 18px; background: #2563eb; color: #ffffff; text-decoration: none; border-radius: 6px;">Confirm account</a></p>
      <p style="font-size: 13px; color: #52525b;">If the button does not work, open this address:</p>
      <p style="font-size: 13px; overflow-wrap: anywhere;"><a href="{}">{}</a></p>
    </div>
  </body>
</html>"#,
                user.nickname,
                user.nickname,
                site,
                confirmation_url,
                confirmation_url,
                confirmation_url
            );

            builder
                .subject(subject)
                .multipart(
                    MultiPart::alternative()
                        .singlepart(
                            SinglePart::builder()
                                .header(ContentType::TEXT_PLAIN)
                                .body(text_body),
                        )
                        .singlepart(
                            SinglePart::builder()
                                .header(ContentType::TEXT_HTML)
                                .body(html_body),
                        ),
                )
                .map_err(|_| AuthError::internal("Failed to build registration e-mail."))?
        }
        None => {
            let subject = "Your RustPad account has been created";
            let text_body = format!(
                "Hello {},\n\nYour RustPad account has been created.\nNickname: {}\nSite: {}\n",
                user.nickname, user.nickname, site
            );
            let html_body = format!(
                r#"<!doctype html>
<html lang="en">
  <body style="margin: 0; padding: 24px; background: #f4f4f5; font-family: Arial, sans-serif; color: #18181b;">
    <div style="max-width: 560px; margin: 0 auto; padding: 24px; background: #ffffff; border-radius: 10px;">
      <h1 style="margin-top: 0; font-size: 22px;">Your RustPad account is ready</h1>
      <p>Hello {},</p>
      <p>Your RustPad account has been created.</p>
      <p><strong>Nickname:</strong> {}</p>
      <p><a href="{}" style="display: inline-block; padding: 11px 18px; background: #2563eb; color: #ffffff; text-decoration: none; border-radius: 6px;">Open RustPad</a></p>
    </div>
  </body>
</html>"#,
                user.nickname, user.nickname, site
            );

            builder
                .subject(subject)
                .multipart(
                    MultiPart::alternative()
                        .singlepart(
                            SinglePart::builder()
                                .header(ContentType::TEXT_PLAIN)
                                .body(text_body),
                        )
                        .singlepart(
                            SinglePart::builder()
                                .header(ContentType::TEXT_HTML)
                                .body(html_body),
                        ),
                )
                .map_err(|_| AuthError::internal("Failed to build registration e-mail."))?
        }
    };

    send_message(smtp, message, "registration e-mail").await
}

async fn send_share_invitation(
    smtp: &SmtpConfig,
    owner: &User,
    recipient_user: &User,
    kind: &str,
    slug: &str,
    permission: &str,
    token: &str,
) -> Result<(), AuthError> {
    let site = smtp.public_url.trim_end_matches('/');
    let accept_url = format!("{site}/share-invitations/{token}/accept");
    let resource_label = if kind == "workspace" {
        "workspace"
    } else {
        "note"
    };
    let access_label = if permission == "rw" {
        "view and edit"
    } else {
        "view"
    };
    let sender = smtp
        .from
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid SMTP_FROM."))?;
    let recipient = recipient_user
        .email
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid recipient address."))?;
    let subject = format!(
        "{} shared a RustPad {} with you",
        owner.nickname, resource_label
    );
    let text_body = format!(
        "Hello {},\n\n{} shared the {} '{}' with you ({access_label}).\nAccept the invitation within 7 days:\n{}\n\nIf you were not expecting this invitation, ignore this message.",
        recipient_user.nickname, owner.nickname, resource_label, slug, accept_url
    );
    let html_body = format!(
        r#"<!doctype html><html lang="en"><body style="margin:0;padding:24px;background:#f4f4f5;font-family:Arial,sans-serif;color:#18181b"><div style="max-width:560px;margin:0 auto;padding:24px;background:#fff;border-radius:10px"><h1 style="margin-top:0;font-size:22px">A RustPad {resource_label} was shared with you</h1><p>Hello {},</p><p><strong>{}</strong> shared <strong>{}</strong> with you. Permission: <strong>{access_label}</strong>.</p><p><a href="{}" style="display:inline-block;padding:11px 18px;background:#2563eb;color:#fff;text-decoration:none;border-radius:6px">Accept invitation</a></p><p style="font-size:13px;color:#52525b">This link expires in 7 days.</p><p style="font-size:13px;color:#52525b;word-break:break-all">If the button does not work, copy and paste this link into your browser:<br><a href="{}" style="color:#2563eb">{}</a></p></div></body></html>"#,
        recipient_user.nickname, owner.nickname, slug, accept_url, accept_url, accept_url
    );
    let message = Message::builder()
        .from(sender)
        .to(recipient)
        .subject(subject)
        .multipart(
            MultiPart::alternative()
                .singlepart(
                    SinglePart::builder()
                        .header(ContentType::TEXT_PLAIN)
                        .body(text_body),
                )
                .singlepart(
                    SinglePart::builder()
                        .header(ContentType::TEXT_HTML)
                        .body(html_body),
                ),
        )
        .map_err(|_| AuthError::internal("Failed to build sharing invitation e-mail."))?;
    send_message(smtp, message, "sharing invitation e-mail").await
}

async fn send_message(smtp: &SmtpConfig, message: Message, label: &str) -> Result<(), AuthError> {
    let mut builder = if smtp.port == 465 {
        AsyncSmtpTransport::<Tokio1Executor>::relay(&smtp.host)
    } else {
        AsyncSmtpTransport::<Tokio1Executor>::starttls_relay(&smtp.host)
    }
    .map_err(|error| {
        tracing::error!(error = %error, host = %smtp.host, port = smtp.port, "invalid SMTP configuration");
        AuthError::internal("Invalid SMTP configuration.")
    })?
    .port(smtp.port);

    if !smtp.username.is_empty() {
        builder = builder.credentials(Credentials::new(
            smtp.username.clone(),
            smtp.password.clone(),
        ));
    }

    builder.build().send(message).await.map_err(|error| {
        tracing::error!(error = %error, host = %smtp.host, port = smtp.port, message_type = label, "SMTP delivery failed");
        AuthError::service_unavailable(
            "The e-mail could not be sent. Check the SMTP configuration.",
        )
    })?;

    Ok(())
}

async fn send_reset(smtp: &SmtpConfig, user: &User, token: &str) -> Result<(), AuthError> {
    let site = smtp.public_url.trim_end_matches('/');
    let reset_url = format!("{site}/?reset_token={token}");
    let sender = smtp
        .from
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid SMTP_FROM."))?;
    let recipient = user
        .email
        .parse::<Mailbox>()
        .map_err(|_| AuthError::internal("Invalid recipient address."))?;

    let text_body = format!(
        "Hello {},\n\nUse this link within 30 minutes to set a new password:\n{}\n\nIf you did not request this, ignore this message.",
        user.nickname, reset_url
    );
    let html_body = format!(
        r#"<!doctype html>
<html lang="en">
  <body style="margin: 0; padding: 24px; background: #f4f4f5; font-family: Arial, sans-serif; color: #18181b;">
    <div style="max-width: 560px; margin: 0 auto; padding: 24px; background: #ffffff; border-radius: 10px;">
      <h1 style="margin-top: 0; font-size: 22px;">Reset your RustPad password</h1>
      <p>Hello {},</p>
      <p>Use the button below within 30 minutes to set a new password.</p>
      <p><a href="{}" style="display: inline-block; padding: 11px 18px; background: #2563eb; color: #ffffff; text-decoration: none; border-radius: 6px;">Reset password</a></p>
      <p style="font-size: 13px; color: #52525b;">If the button does not work, open this address:</p>
      <p style="font-size: 13px; overflow-wrap: anywhere;"><a href="{}">{}</a></p>
      <p>If you did not request a password reset, ignore this message.</p>
    </div>
  </body>
</html>"#,
        user.nickname, reset_url, reset_url, reset_url
    );

    let message = Message::builder()
        .from(sender)
        .to(recipient)
        .subject("RustPad password reset")
        .multipart(
            MultiPart::alternative()
                .singlepart(
                    SinglePart::builder()
                        .header(ContentType::TEXT_PLAIN)
                        .body(text_body),
                )
                .singlepart(
                    SinglePart::builder()
                        .header(ContentType::TEXT_HTML)
                        .body(html_body),
                ),
        )
        .map_err(|_| AuthError::internal("Failed to build reset e-mail."))?;

    send_message(smtp, message, "password reset e-mail").await
}

pub struct AuthError {
    status: StatusCode,
    pub message: String,
}
impl AuthError {
    fn bad_request(m: &str) -> Self {
        Self {
            status: StatusCode::BAD_REQUEST,
            message: m.into(),
        }
    }
    fn unauthorized(m: &str) -> Self {
        Self {
            status: StatusCode::UNAUTHORIZED,
            message: m.into(),
        }
    }
    fn forbidden(m: &str) -> Self {
        Self {
            status: StatusCode::FORBIDDEN,
            message: m.into(),
        }
    }
    fn conflict(m: &str) -> Self {
        Self {
            status: StatusCode::CONFLICT,
            message: m.into(),
        }
    }
    fn internal(m: &str) -> Self {
        Self {
            status: StatusCode::INTERNAL_SERVER_ERROR,
            message: m.into(),
        }
    }
    fn service_unavailable(m: &str) -> Self {
        Self {
            status: StatusCode::SERVICE_UNAVAILABLE,
            message: m.into(),
        }
    }
    fn database(e: sqlx::Error) -> Self {
        tracing::error!(error=%e,"authentication database error");
        Self::internal("Database error.")
    }
}

fn email_domain(email: &str) -> &str {
    email
        .rsplit_once('@')
        .map(|(_, domain)| domain)
        .unwrap_or("invalid")
}
impl axum::response::IntoResponse for AuthError {
    fn into_response(self) -> axum::response::Response {
        (
            self.status,
            Json(serde_json::json!( {
                "error":self.message
            }
            )),
        )
            .into_response()
    }
}