use std::{collections::HashMap, sync::{Arc, atomic::{AtomicU64, Ordering}}};
use crate::database::Database;
use tokio::sync::{broadcast, RwLock};
use serde::Serialize;

const CHANNEL_CAPACITY: usize = 256;

#[derive(Debug, Clone)]
pub struct SmtpConfig {
    pub host: String, pub port: u16, pub username: String, pub password: String, pub from: String, pub public_url: String
}

#[derive(Debug, Clone)]
pub struct NoteUpdate {
    pub content: String,
    pub revision_id: i64,
    pub updated_at: String,
    pub author: Option<String>,
    pub owner_map: String,
}

#[derive(Debug, Clone, Serialize)]
pub struct PresenceUser {
    pub name: String,
    pub color: Option<String>,
}

#[derive(Debug, Clone)]
pub enum RoomEvent {
    Document(NoteUpdate),
    Presence(Vec<PresenceUser>),
    Chat { sender: String, text: String },
}

#[derive(Debug)]
pub struct AppState {
    pub db: Database,
    pub asset_version: String,
    pub storage: crate::storage::Storage,
    pub upload_max_size_bytes: usize,
    pub file_cache_max_age_seconds: u64,
    pub smtp: Option<SmtpConfig>,
    pub registration_enabled: bool,
    pub account_confirmation_required: bool,
    pub frontend_log_level: String,
    pub anonymous_access_token_ttl_days: i64,
    pub user_session_ttl_days: i64,
    channels: RwLock<HashMap<String, broadcast::Sender<RoomEvent>>>,
    presence: RwLock<HashMap<String, HashMap<u64, PresenceUser>>>,
    next_connection_id: AtomicU64,
}

impl AppState {
    pub fn new(db: Database, asset_version: String, storage: crate::storage::Storage, upload_max_size_bytes: usize, file_cache_max_age_seconds: u64, smtp: Option<SmtpConfig>, registration_enabled: bool, account_confirmation_required: bool, frontend_log_level: String, anonymous_access_token_ttl_days: i64, user_session_ttl_days: i64) -> Self {
        Self { db, asset_version, storage, upload_max_size_bytes, file_cache_max_age_seconds, smtp, registration_enabled, account_confirmation_required, frontend_log_level, anonymous_access_token_ttl_days, user_session_ttl_days, channels: RwLock::new(HashMap::new()), presence: RwLock::new(HashMap::new()), next_connection_id: AtomicU64::new(1) }
    }
    async fn channel_for_key(&self, key: String) -> broadcast::Sender<RoomEvent> {
        if let Some(sender) = self.channels.read().await.get(&key) { return sender.clone(); }
        let mut channels = self.channels.write().await;
        channels.entry(key).or_insert_with(|| broadcast::channel(CHANNEL_CAPACITY).0).clone()
    }
    pub fn note_room_key(workspace_slug: &str, note_slug: &str) -> String { format!("workspace:{workspace_slug}/{note_slug}") }
    pub fn pad_room_key(slug: &str) -> String { format!("pad:{slug}") }
    pub async fn note_channel(&self, workspace_slug: &str, note_slug: &str) -> broadcast::Sender<RoomEvent> { self.channel_for_key(Self::note_room_key(workspace_slug, note_slug)).await }
    pub async fn pad_channel(&self, slug: &str) -> broadcast::Sender<RoomEvent> { self.channel_for_key(Self::pad_room_key(slug)).await }
    pub async fn join_room(&self, key: &str, nickname: String, color: Option<String>) -> (u64, Vec<PresenceUser>) {
        let id = self.next_connection_id.fetch_add(1, Ordering::Relaxed);
        let mut presence = self.presence.write().await;
        let room = presence.entry(key.to_owned()).or_default();
        room.insert(id, PresenceUser { name: nickname, color });
        (id, sorted_users(room))
    }
    pub async fn update_room_color(&self, key: &str, id: u64, color: Option<String>) -> Vec<PresenceUser> {
        let mut presence = self.presence.write().await;
        if let Some(room) = presence.get_mut(key) {
            if let Some(user) = room.get_mut(&id) { user.color = color; }
            sorted_users(room)
        } else { Vec::new() }
    }
    pub async fn leave_room(&self, key: &str, id: u64) -> Vec<PresenceUser> {
        let mut presence = self.presence.write().await;
        if let Some(room) = presence.get_mut(key) {
            room.remove(&id);
            let users = sorted_users(room);
            let empty = room.is_empty();
            if empty { presence.remove(key); }
            users
        } else { Vec::new() }
    }
}

fn sorted_users(room: &HashMap<u64, PresenceUser>) -> Vec<PresenceUser> {
    let mut users: Vec<PresenceUser> = room.values().cloned().collect();
    users.sort_by_key(|value| value.name.to_lowercase());
    users
}

pub type SharedState = Arc<AppState>;