use crate::{models::NotificationSettings, state::AppState};
use chrono::Utc;
use serde_json::{json, Value};
use std::{
    collections::HashMap,
    sync::{Mutex, OnceLock},
};

static LAST_SENT: OnceLock<Mutex<HashMap<String, i64>>> = OnceLock::new();

fn important_kind(kind: &str) -> bool {
    matches!(
        kind,
        "device.offline"
            | "device.recovered"
            | "automation.fired"
            | "automation.error"
            | "zone.target_timeout"
            | "zone.action_error"
            | "house.mode"
            | "house.preset"
            | "device.communication_error"
    )
}

fn alert_type_enabled(cfg: &NotificationSettings, kind: &str) -> bool {
    let types = &cfg.alert_types;
    if kind == "ha.sensor_stale" {
        return types.stale_sensor;
    }
    if kind.starts_with("ha.sensor_") {
        return types.sensor_errors;
    }
    if matches!(
        kind,
        "device.offline" | "device.communication_error" | "device.command_unconfirmed"
    ) {
        return types.communication;
    }
    if kind == "zone.target_timeout" {
        return types.target_timeout;
    }
    if kind.starts_with("automation.") {
        return types.automation;
    }
    if kind == "zone.sensor_discrepancy" {
        return types.sensor_discrepancy;
    }
    if matches!(
        kind,
        "zone.action_error"
            | "zone.mode_change_off_error"
            | "zone.local_power_error"
            | "zone.device_missing"
            | "zone.temporary_quick_thermostat_cancelled"
            | "zone.temporary_quick_thermostat_poweroff_error"
            | "group.power_error"
    ) {
        return types.control_errors;
    }
    if important_kind(kind) {
        return types.important_events;
    }
    types.other
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum DeliveryDecision {
    NotApplicable,
    Silent(&'static str),
    Send,
}

fn delivery_decision(cfg: &NotificationSettings, level: &str, kind: &str) -> DeliveryDecision {
    let candidate = level == "error" || level == "warn" || important_kind(kind);
    if !candidate {
        return DeliveryDecision::NotApplicable;
    }
    if !cfg.enabled {
        return DeliveryDecision::Silent("notifications_disabled");
    }
    if !alert_type_enabled(cfg, kind) {
        return DeliveryDecision::Silent("alert_type_disabled");
    }
    if level != "error" && level != "warn" && cfg.mode != "important" {
        return DeliveryDecision::Silent("mode_filtered");
    }
    DeliveryDecision::Send
}

fn cooldown_key(cfg: &NotificationSettings, kind: &str, metadata: &Value) -> String {
    let entity = metadata
        .get("device_id")
        .or_else(|| metadata.get("zone_id"))
        .or_else(|| metadata.get("automation_id"))
        .and_then(Value::as_str)
        .unwrap_or("global");
    format!("{}:{}:{}", cfg.provider, kind, entity)
}

fn take_cooldown(cfg: &NotificationSettings, kind: &str, metadata: &Value) -> bool {
    let now = Utc::now().timestamp();
    let key = cooldown_key(cfg, kind, metadata);
    let map = LAST_SENT.get_or_init(|| Mutex::new(HashMap::new()));
    let Ok(mut map) = map.lock() else {
        return false;
    };
    if let Some(last) = map.get(&key) {
        if now - *last < cfg.cooldown_seconds.max(30) as i64 {
            return false;
        }
    }
    map.insert(key, now);
    true
}

fn with_notification_status(
    metadata: &Value,
    status: &str,
    reason: Option<&str>,
    provider: &str,
) -> Value {
    let mut updated = match metadata {
        Value::Object(map) => Value::Object(map.clone()),
        other => json!({"data": other}),
    };
    let mut notification = serde_json::Map::new();
    notification.insert("status".into(), Value::String(status.into()));
    if let Some(reason) = reason {
        notification.insert("reason".into(), Value::String(reason.into()));
    }
    if !provider.trim().is_empty() {
        notification.insert("provider".into(), Value::String(provider.into()));
    }
    if let Some(object) = updated.as_object_mut() {
        object.insert("notification".into(), Value::Object(notification));
    }
    updated
}

fn persist_notification_status(
    state: &AppState,
    event_id: Option<i64>,
    metadata: &Value,
    status: &str,
    reason: Option<&str>,
    provider: &str,
) {
    let Some(event_id) = event_id else {
        return;
    };
    let updated = with_notification_status(metadata, status, reason, provider);
    match state.db.update_event_metadata(event_id, &updated) {
        Ok(true) => state.broadcast("log.updated", json!({"id": event_id, "metadata": updated})),
        Ok(false) => tracing::warn!(event_id, "cannot update missing event log metadata"),
        Err(err) => tracing::warn!(event_id, error=?err, "cannot update event log metadata"),
    }
}

pub async fn dispatch(
    state: AppState,
    event_id: Option<i64>,
    level: String,
    kind: String,
    message: String,
    metadata: Value,
) {
    let cfg = state.settings.read().await.notifications.clone();
    match delivery_decision(&cfg, &level, &kind) {
        DeliveryDecision::NotApplicable => return,
        DeliveryDecision::Silent(reason) => {
            persist_notification_status(
                &state,
                event_id,
                &metadata,
                "silent",
                Some(reason),
                &cfg.provider,
            );
            return;
        }
        DeliveryDecision::Send => {}
    }
    if !take_cooldown(&cfg, &kind, &metadata) {
        persist_notification_status(
            &state,
            event_id,
            &metadata,
            "silent",
            Some("cooldown"),
            &cfg.provider,
        );
        return;
    }
    let title = format!(
        "GREE Controller - {}",
        if level == "error" {
            "error"
        } else if level == "warn" {
            "warning"
        } else {
            "event"
        }
    );
    let result = match cfg.provider.as_str() {
        "pushover" => send_pushover(&state, &cfg, &title, &message).await,
        "slack" => {
            send_webhook(
                &cfg.slack_webhook_url,
                json!({"text": format!("*{}*\\n{}", title, message)}),
            )
            .await
        }
        "discord" => {
            send_webhook(
                &cfg.discord_webhook_url,
                json!({"content": format!("**{}**\\n{}", title, message)}),
            )
            .await
        }
        _ => Err("unsupported notification provider".into()),
    };
    match result {
        Ok(()) => {
            persist_notification_status(&state, event_id, &metadata, "sent", None, &cfg.provider)
        }
        Err(err) => {
            persist_notification_status(
                &state,
                event_id,
                &metadata,
                "failed",
                Some("delivery_failed"),
                &cfg.provider,
            );
            tracing::warn!(provider=%cfg.provider, error=%err, "notification delivery failed");
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn sensor_discrepancy_has_its_own_notification_toggle() {
        let mut cfg = NotificationSettings::default();
        cfg.alert_types.control_errors = true;
        cfg.alert_types.sensor_discrepancy = false;
        assert!(!alert_type_enabled(&cfg, "zone.sensor_discrepancy"));
        assert!(alert_type_enabled(&cfg, "zone.action_error"));

        cfg.alert_types.control_errors = false;
        cfg.alert_types.sensor_discrepancy = true;
        assert!(alert_type_enabled(&cfg, "zone.sensor_discrepancy"));
        assert!(!alert_type_enabled(&cfg, "zone.action_error"));
    }

    #[test]
    fn disabled_alert_type_is_recorded_as_silent() {
        let mut cfg = NotificationSettings::default();
        cfg.enabled = true;
        cfg.mode = "important".into();
        cfg.alert_types.sensor_discrepancy = false;

        assert_eq!(
            delivery_decision(&cfg, "warn", "zone.sensor_discrepancy"),
            DeliveryDecision::Silent("alert_type_disabled")
        );
    }

    #[test]
    fn ordinary_info_event_has_no_notification_status() {
        let cfg = NotificationSettings::default();
        assert_eq!(
            delivery_decision(&cfg, "info", "zone.quick_control"),
            DeliveryDecision::NotApplicable
        );
    }
}

async fn send_pushover(
    state: &AppState,
    cfg: &NotificationSettings,
    title: &str,
    message: &str,
) -> Result<(), String> {
    if cfg.pushover_app_token.trim().is_empty() || cfg.pushover_user_key.trim().is_empty() {
        return Err("Pushover credentials are incomplete".into());
    }
    let response = state
        .http
        .post("https://api.pushover.net/1/messages.json")
        .form(&[
            ("token", cfg.pushover_app_token.as_str()),
            ("user", cfg.pushover_user_key.as_str()),
            ("title", title),
            ("message", message),
        ])
        .send()
        .await
        .map_err(|e| e.to_string())?;
    if response.status().is_success() {
        Ok(())
    } else {
        Err(format!("Pushover HTTP {}", response.status()))
    }
}

async fn send_webhook(url: &str, body: Value) -> Result<(), String> {
    let parsed = url::Url::parse(url).map_err(|_| "invalid webhook URL".to_string())?;
    if parsed.scheme() != "https" {
        return Err("webhook URL must use HTTPS".into());
    }
    let host = parsed.host_str().unwrap_or_default().to_ascii_lowercase();
    let allowed = host == "hooks.slack.com" || host == "discord.com" || host == "discordapp.com";
    if !allowed {
        return Err("webhook host is not supported".into());
    }
    let client = reqwest::Client::builder()
        .redirect(reqwest::redirect::Policy::none())
        .timeout(std::time::Duration::from_secs(10))
        .build()
        .map_err(|e| e.to_string())?;
    let response = client
        .post(parsed)
        .json(&body)
        .send()
        .await
        .map_err(|e| e.to_string())?;
    if response.status().is_success() {
        Ok(())
    } else {
        Err(format!("webhook HTTP {}", response.status()))
    }
}

pub async fn test(state: &AppState, cfg: NotificationSettings) -> Result<(), String> {
    match cfg.provider.as_str() {
        "pushover" => send_pushover(state, &cfg, "GREE Controller", "Test notification").await,
        "slack" => {
            send_webhook(
                &cfg.slack_webhook_url,
                json!({"text":"GREE Controller - test notification"}),
            )
            .await
        }
        "discord" => {
            send_webhook(
                &cfg.discord_webhook_url,
                json!({"content":"GREE Controller - test notification"}),
            )
            .await
        }
        _ => Err("unsupported notification provider".into()),
    }
}