use a2::{Client, ClientConfig, DefaultNotificationBuilder, NotificationBuilder};
use log;
use nostr::event::EventId;
use nostr::key::PublicKey;
use nostr::types::Timestamp;
use nostr_sdk::JsonUtil;
use nostr_sdk::Kind;
use rusqlite;
use rusqlite::params;
use serde::Deserialize;
use serde::Serialize;
use tokio::sync::Mutex;
use std::collections::HashSet;
use tokio;

use super::nostr_network_helper::NostrNetworkHelper;
use super::ExtendedEvent;
use super::SqlStringConvertible;
use nostr::Event;
use r2d2;
use r2d2_sqlite::SqliteConnectionManager;
use std::fs::File;

// MARK: - NotificationManager

pub struct NotificationManager {
    db: Mutex<r2d2::Pool<SqliteConnectionManager>>,
    apns_topic: String,
    apns_client: Mutex<Client>,
    nostr_network_helper: Mutex<NostrNetworkHelper>,
}

impl NotificationManager {
    // MARK: - Initialization

    pub async fn new(
        db: r2d2::Pool<SqliteConnectionManager>,
        relay_url: String,
        apns_private_key_path: String,
        apns_private_key_id: String,
        apns_team_id: String,
        apns_environment: a2::client::Endpoint,
        apns_topic: String,
    ) -> Result<Self, Box<dyn std::error::Error>> {
        let mute_manager = NostrNetworkHelper::new(relay_url.clone()).await?;

        let connection = db.get()?;
        Self::setup_database(&connection)?;

        let mut file = File::open(&apns_private_key_path)?;

        let client = Client::token(
            &mut file,
            &apns_private_key_id,
            &apns_team_id,
            ClientConfig::new(apns_environment.clone()),
        )?;

        Ok(Self {
            apns_topic,
            apns_client: Mutex::new(client),
            db: Mutex::new(db),
            nostr_network_helper: Mutex::new(mute_manager),
        })
    }

    // MARK: - Database setup operations

    pub fn setup_database(db: &rusqlite::Connection) -> Result<(), rusqlite::Error> {
        // Initial schema setup
        
        db.execute(
            "CREATE TABLE IF NOT EXISTS notifications (
                id TEXT PRIMARY KEY,
                event_id TEXT,
                pubkey TEXT,
                received_notification BOOLEAN
            )",
            [],
        )?;

        db.execute(
            "CREATE INDEX IF NOT EXISTS notification_event_id_index ON notifications (event_id)",
            [],
        )?;

        db.execute(
            "CREATE TABLE IF NOT EXISTS user_info (
                id TEXT PRIMARY KEY,
                device_token TEXT,
                pubkey TEXT
            )",
            [],
        )?;

        db.execute(
            "CREATE INDEX IF NOT EXISTS user_info_pubkey_index ON user_info (pubkey)",
            [],
        )?;

        Self::add_column_if_not_exists(&db, "notifications", "sent_at", "INTEGER", None)?;
        Self::add_column_if_not_exists(&db, "user_info", "added_at", "INTEGER", None)?;
        
        // Notification settings migration (https://github.com/damus-io/damus/issues/2360)
        
        Self::add_column_if_not_exists(&db, "user_info", "zap_notifications_enabled", "BOOLEAN", Some("true"))?;
        Self::add_column_if_not_exists(&db, "user_info", "mention_notifications_enabled", "BOOLEAN", Some("true"))?;
        Self::add_column_if_not_exists(&db, "user_info", "repost_notifications_enabled", "BOOLEAN", Some("true"))?;
        Self::add_column_if_not_exists(&db, "user_info", "reaction_notifications_enabled", "BOOLEAN", Some("true"))?;
        Self::add_column_if_not_exists(&db, "user_info", "dm_notifications_enabled", "BOOLEAN", Some("true"))?;
        Self::add_column_if_not_exists(&db, "user_info", "only_notifications_from_following_enabled", "BOOLEAN", Some("false"))?;

        Ok(())
    }

    fn add_column_if_not_exists(
        db: &rusqlite::Connection,
        table_name: &str,
        column_name: &str,
        column_type: &str,
        default_value: Option<&str>,
    ) -> Result<(), rusqlite::Error> {
        let query = format!("PRAGMA table_info({})", table_name);
        let mut stmt = db.prepare(&query)?;
        let column_names: Vec<String> = stmt
            .query_map([], |row| row.get(1))?
            .filter_map(|r| r.ok())
            .collect();

        if !column_names.contains(&column_name.to_string()) {
            let query = format!(
                "ALTER TABLE {} ADD COLUMN {} {} {}",
                table_name, column_name, column_type, match default_value {
                    Some(value) => format!("DEFAULT {}", value),
                    None => "".to_string(),
                },
            );
            db.execute(&query, [])?;
        }
        Ok(())
    }

    // MARK: - Business logic

    pub async fn send_notifications_if_needed(
        &self,
        event: &Event,
    ) -> Result<(), Box<dyn std::error::Error>> {
        log::debug!(
            "Checking if notifications need to be sent for event: {}",
            event.id
        );
        let one_week_ago = nostr::Timestamp::now() - 7 * 24 * 60 * 60;
        if event.created_at < one_week_ago {
            log::debug!("Event is older than a week, not sending notifications");
            return Ok(());
        }
        
        if !Self::is_event_kind_supported(event.kind) {
            log::debug!("Event kind is not supported, not sending notifications");
            return Ok(());
        }

        let pubkeys_to_notify = self.pubkeys_to_notify_for_event(event).await?;

        log::debug!(
            "Sending notifications to {} pubkeys",
            pubkeys_to_notify.len()
        );

        for pubkey in pubkeys_to_notify {
            self.send_event_notifications_to_pubkey(event, &pubkey)
                .await?;
            {
                let db_mutex_guard = self.db.lock().await;
                db_mutex_guard.get()?.execute(
                    "INSERT OR REPLACE INTO notifications (id, event_id, pubkey, received_notification, sent_at)
                    VALUES (?, ?, ?, ?, ?)",
                    params![
                        format!("{}:{}", event.id, pubkey),
                        event.id.to_sql_string(),
                        pubkey.to_sql_string(),
                        true,
                        nostr::Timestamp::now().to_sql_string(),
                    ],
                )?;
            }
        }
        Ok(())
    }
    
    fn is_event_kind_supported(event_kind: nostr::Kind) -> bool {
        match event_kind {
            nostr_sdk::Kind::TextNote => true,
            nostr_sdk::Kind::EncryptedDirectMessage => true,
            nostr_sdk::Kind::Repost => true,
            nostr_sdk::Kind::GenericRepost => true,
            nostr_sdk::Kind::Reaction => true,
            nostr_sdk::Kind::ZapPrivateMessage => true,
            nostr_sdk::Kind::ZapRequest => false,
            nostr_sdk::Kind::ZapReceipt => true,
            _ => false,
        }
    }

    async fn pubkeys_to_notify_for_event(
        &self,
        event: &Event,
    ) -> Result<HashSet<nostr::PublicKey>, Box<dyn std::error::Error>> {
        let notification_status = self.get_notification_status(event).await?;
        let relevant_pubkeys = self.pubkeys_relevant_to_event(event).await?;
        let pubkeys_that_received_notification =
            notification_status.pubkeys_that_received_notification();
        let relevant_pubkeys_yet_to_receive: HashSet<PublicKey> = relevant_pubkeys
            .difference(&pubkeys_that_received_notification)
            .filter(|&x| *x != event.pubkey)
            .cloned()
            .collect();

        let mut pubkeys_to_notify = HashSet::new();
        for pubkey in relevant_pubkeys_yet_to_receive {
            let should_mute: bool = {
                let mut mute_manager_mutex_guard = self.nostr_network_helper.lock().await;
                mute_manager_mutex_guard
                    .should_mute_notification_for_pubkey(event, &pubkey)
                    .await
            };
            if !should_mute {
                pubkeys_to_notify.insert(pubkey);
            }
        }
        Ok(pubkeys_to_notify)
    }

    async fn pubkeys_relevant_to_event(
        &self,
        event: &Event,
    ) -> Result<HashSet<PublicKey>, Box<dyn std::error::Error>> {
        let mut relevant_pubkeys = event.relevant_pubkeys();
        let referenced_event_ids = event.referenced_event_ids();
        for referenced_event_id in referenced_event_ids {
            let pubkeys_relevant_to_referenced_event =
                self.pubkeys_subscribed_to_event_id(&referenced_event_id).await?;
            relevant_pubkeys.extend(pubkeys_relevant_to_referenced_event);
        }
        Ok(relevant_pubkeys)
    }

    async fn pubkeys_subscribed_to_event_id(
        &self,
        event_id: &EventId,
    ) -> Result<HashSet<PublicKey>, Box<dyn std::error::Error>> {
        let db_mutex_guard = self.db.lock().await;
        let connection = db_mutex_guard.get()?;
        let mut stmt = connection.prepare("SELECT pubkey FROM notifications WHERE event_id = ?")?;
        let pubkeys = stmt
            .query_map([event_id.to_sql_string()], |row| row.get(0))?
            .filter_map(|r| r.ok())
            .filter_map(|r: String| PublicKey::from_sql_string(r).ok())
            .collect();
        Ok(pubkeys)
    }

    async fn send_event_notifications_to_pubkey(
        &self,
        event: &Event,
        pubkey: &PublicKey,
    ) -> Result<(), Box<dyn std::error::Error>> {
        let user_device_tokens = self.get_user_device_tokens(pubkey).await?;
        for device_token in user_device_tokens {
            if !self.user_wants_notification(pubkey, device_token.clone(), event).await? {
                continue;
            }
            self.send_event_notification_to_device_token(event, &device_token)
                .await?;
        }
        Ok(())
    }
    
    async fn user_wants_notification(
        &self,
        pubkey: &PublicKey,
        device_token: String,
        event: &Event,
    ) -> Result<bool, Box<dyn std::error::Error>> {
        let notification_preferences = self.get_user_notification_settings(pubkey, device_token).await?;
        if notification_preferences.only_notifications_from_following_enabled {
            let mut nostr_network_helper_mutex_guard = self.nostr_network_helper.lock().await;
            if !nostr_network_helper_mutex_guard.does_pubkey_follow_pubkey(pubkey, &event.author()).await {
                return Ok(false);
            }
        }
        match event.kind {
            Kind::TextNote => Ok(notification_preferences.mention_notifications_enabled),   // TODO: Not 100% accurate
            Kind::EncryptedDirectMessage => Ok(notification_preferences.dm_notifications_enabled),
            Kind::Repost => Ok(notification_preferences.repost_notifications_enabled),
            Kind::GenericRepost => Ok(notification_preferences.repost_notifications_enabled),
            Kind::Reaction => Ok(notification_preferences.reaction_notifications_enabled),
            Kind::ZapPrivateMessage => Ok(notification_preferences.zap_notifications_enabled),
            Kind::ZapRequest => Ok(notification_preferences.zap_notifications_enabled),
            Kind::ZapReceipt => Ok(notification_preferences.zap_notifications_enabled),
            _ => Ok(false),
        }
    }

    async fn get_user_device_tokens(
        &self,
        pubkey: &PublicKey,
    ) -> Result<Vec<String>, Box<dyn std::error::Error>> {
        let db_mutex_guard = self.db.lock().await;
        let connection = db_mutex_guard.get()?;
        let mut stmt = connection.prepare("SELECT device_token FROM user_info WHERE pubkey = ?")?;
        let device_tokens = stmt
            .query_map([pubkey.to_sql_string()], |row| row.get(0))?
            .filter_map(|r| r.ok())
            .collect();
        Ok(device_tokens)
    }

    async fn get_notification_status(
        &self,
        event: &Event,
    ) -> Result<NotificationStatus, Box<dyn std::error::Error>> {
        let db_mutex_guard = self.db.lock().await;
        let connection = db_mutex_guard.get()?;
        let mut stmt = connection.prepare(
            "SELECT pubkey, received_notification FROM notifications WHERE event_id = ?",
        )?;
        let rows: std::collections::HashMap<PublicKey, bool> = stmt
            .query_map([event.id.to_sql_string()], |row| {
                Ok((row.get(0)?, row.get(1)?))
            })?
            .filter_map(|r: Result<(String, bool), rusqlite::Error>| r.ok())
            .filter_map(|r: (String, bool)| {
                let pubkey = PublicKey::from_sql_string(r.0).ok()?;
                let received_notification = r.1;
                Some((pubkey, received_notification))
            })
            .collect();

        let mut status_info = std::collections::HashMap::new();
        for row in rows {
            let (pubkey, received_notification) = row;
            status_info.insert(pubkey, received_notification);
        }

        Ok(NotificationStatus { status_info })
    }

    async fn send_event_notification_to_device_token(
        &self,
        event: &Event,
        device_token: &str,
    ) -> Result<(), Box<dyn std::error::Error>> {
        let (title, subtitle, body) = self.format_notification_message(event);

        log::debug!("Sending notification to device token: {}", device_token);

        let mut payload = DefaultNotificationBuilder::new()
            .set_title(&title)
            .set_subtitle(&subtitle)
            .set_body(&body)
            .set_mutable_content()
            .set_content_available()
            .build(device_token, Default::default());

        payload.options.apns_topic = Some(self.apns_topic.as_str());
        payload.data.insert("nostr_event", serde_json::Value::String(event.try_as_json()?));
        

        let apns_client_mutex_guard = self.apns_client.lock().await;
        let _response = apns_client_mutex_guard.send(payload).await?;

        log::info!("Notification sent to device token: {}", device_token);

        Ok(())
    }

    fn format_notification_message(&self, event: &Event) -> (String, String, String) {
        // NOTE: This is simple because the client will handle formatting. These are just fallbacks.
        let (title, body) = match event.kind {
            nostr_sdk::Kind::TextNote => ("New activity".to_string(), event.content.clone()),
            nostr_sdk::Kind::EncryptedDirectMessage => ("New direct message".to_string(), "Contents are encrypted".to_string()),
            nostr_sdk::Kind::Repost => ("Someone reposted".to_string(), event.content.clone()),
            nostr_sdk::Kind::Reaction => ("New reaction".to_string(), event.content.clone()),
            nostr_sdk::Kind::ZapPrivateMessage => ("New zap private message".to_string(), "Contents are encrypted".to_string()),
            nostr_sdk::Kind::ZapReceipt => ("Someone zapped you".to_string(), "".to_string()),
            _ => ("New activity".to_string(), "".to_string()),
        };
        (title, "".to_string(), body)
    }
    
    // MARK: - User device info and settings

    pub async fn save_user_device_info(
        &self,
        pubkey: nostr::PublicKey,
        device_token: &str,
    ) -> Result<(), Box<dyn std::error::Error>> {
        let current_time_unix = Timestamp::now();
        let db_mutex_guard = self.db.lock().await;
        db_mutex_guard.get()?.execute(
            "INSERT OR REPLACE INTO user_info (id, pubkey, device_token, added_at) VALUES (?, ?, ?, ?)",
            params![
                format!("{}:{}", pubkey.to_sql_string(), device_token), 
                pubkey.to_sql_string(),
                device_token,
                current_time_unix.to_sql_string()
            ],
        )?;
        Ok(())
    }

    pub async fn remove_user_device_info(
        &self,
        pubkey: nostr::PublicKey,
        device_token: &str,
    ) -> Result<(), Box<dyn std::error::Error>> {
        let db_mutex_guard = self.db.lock().await;
        db_mutex_guard.get()?.execute(
            "DELETE FROM user_info WHERE pubkey = ? AND device_token = ?",
            params![pubkey.to_sql_string(), device_token],
        )?;
        Ok(())
    }
    
    pub async fn get_user_notification_settings(
        &self,
        pubkey: &PublicKey,
        device_token: String,
    ) -> Result<UserNotificationSettings, Box<dyn std::error::Error>> {
        let db_mutex_guard = self.db.lock().await;
        let connection = db_mutex_guard.get()?;
        let mut stmt = connection.prepare(
            "SELECT zap_notifications_enabled, mention_notifications_enabled, repost_notifications_enabled, reaction_notifications_enabled, dm_notifications_enabled, only_notifications_from_following_enabled FROM user_info WHERE pubkey = ? AND device_token = ?",
        )?;
        let settings = stmt
            .query_row([pubkey.to_sql_string(), device_token], |row| {
                Ok(UserNotificationSettings {
                    zap_notifications_enabled: row.get(0)?,
                    mention_notifications_enabled: row.get(1)?,
                    repost_notifications_enabled: row.get(2)?,
                    reaction_notifications_enabled: row.get(3)?,
                    dm_notifications_enabled: row.get(4)?,
                    only_notifications_from_following_enabled: row.get(5)?,
                })
            })?;
        
        Ok(settings)
    }
    
    pub async fn save_user_notification_settings(
        &self,
        pubkey: &PublicKey,
        device_token: String,
        settings: UserNotificationSettings,
    ) -> Result<(), Box<dyn std::error::Error>> {
        let db_mutex_guard = self.db.lock().await;
        let connection = db_mutex_guard.get()?;
        connection.execute(
            "UPDATE user_info SET zap_notifications_enabled = ?, mention_notifications_enabled = ?, repost_notifications_enabled = ?, reaction_notifications_enabled = ?, dm_notifications_enabled = ?, only_notifications_from_following_enabled = ? WHERE pubkey = ? AND device_token = ?",
            params![
                settings.zap_notifications_enabled,
                settings.mention_notifications_enabled,
                settings.repost_notifications_enabled,
                settings.reaction_notifications_enabled,
                settings.dm_notifications_enabled,
                settings.only_notifications_from_following_enabled,
                pubkey.to_sql_string(),
                device_token,
            ],
        )?;
        Ok(())
    }
}

#[derive(Serialize, Deserialize, Debug)]
pub struct UserNotificationSettings {
    zap_notifications_enabled: bool,
    mention_notifications_enabled: bool,
    repost_notifications_enabled: bool,
    reaction_notifications_enabled: bool,
    dm_notifications_enabled: bool,
    only_notifications_from_following_enabled: bool
}

struct NotificationStatus {
    status_info: std::collections::HashMap<PublicKey, bool>,
}

impl NotificationStatus {
    fn pubkeys_that_received_notification(&self) -> HashSet<PublicKey> {
        self.status_info
            .iter()
            .filter(|&(_, &received_notification)| received_notification)
            .map(|(pubkey, _)| pubkey.clone())
            .collect()
    }
}