use crate::db::{ConnectionPool, DbError};
use crate::message_broker::MessageBroker;
use std::cmp::min;
use std::sync::atomic::Ordering;
use std::sync::Arc;
use std::time::Duration;

use super::base::{BaseWorker, Worker, WorkerState};

#[derive(Debug, Clone)]
struct ArrivedTransport {
    id: i32,
    source_branch_id: Option<i32>, // NULL wenn kein Branch in Source-Region
    target_branch_id: i32,
    product_id: Option<i32>, // NULL für leere Transporte
    size: i32,
    vehicle_id: i32,
    distance: f64,
    user_id: i32, // User-ID für Notifications
}

#[derive(Debug, Clone)]
struct StockInfo {
    stock_id: i32,
    total_capacity: i32,
    filled: i32,
}

// Ermittelt alle Transporte, die gemäß Distanz und Fahrzeuggeschwindigkeit bereits
// angekommen sein sollten. Die Reisezeit wird hier vereinfacht als
//   travel_minutes = distance / speed
// interpretiert, d.h. `speed` gibt die Einheiten "Distanz pro Minute" an.
const QUERY_GET_ARRIVED_TRANSPORTS: &str = r#"
    SELECT
        t.id,
        t.product_id,
        t.size,
        t.vehicle_id,
        t.source_region_id,
        t.target_region_id,
        b_target.id             AS target_branch_id,
        b_source.id             AS source_branch_id,
        rd.distance             AS distance,
        v.falukant_user_id      AS user_id
    FROM falukant_data.transport AS t
    JOIN falukant_data.vehicle AS v
      ON v.id = t.vehicle_id
    JOIN falukant_type.vehicle AS vt
      ON vt.id = v.vehicle_type_id
    JOIN falukant_data.region_distance AS rd
      ON ((rd.source_region_id = t.source_region_id
           AND rd.target_region_id = t.target_region_id)
          OR (rd.source_region_id = t.target_region_id
           AND rd.target_region_id = t.source_region_id))
     AND (rd.transport_mode = vt.transport_mode OR rd.transport_mode IS NULL)
    LEFT JOIN falukant_data.branch AS b_target
      ON b_target.region_id        = t.target_region_id
     AND b_target.falukant_user_id = v.falukant_user_id
    LEFT JOIN falukant_data.branch AS b_source
      ON b_source.region_id        = t.source_region_id
     AND b_source.falukant_user_id = v.falukant_user_id
    WHERE vt.speed > 0
      AND t.created_at
            + (rd.distance / vt.speed::double precision) * INTERVAL '1 minute'
          <= NOW();
"#;

// Verfügbare Lagerplätze in einem Branch, analog zur Logik im ProduceWorker.
const QUERY_GET_AVAILABLE_STOCKS: &str = r#"
    SELECT
        stock.id,
        stock.quantity AS total_capacity,
        (
            SELECT COALESCE(SUM(inventory.quantity), 0)
            FROM falukant_data.inventory
            WHERE inventory.stock_id = stock.id
        ) AS filled
    FROM falukant_data.stock stock
    JOIN falukant_data.branch branch
        ON stock.branch_id = branch.id
    WHERE branch.id = $1
    ORDER BY total_capacity DESC;
"#;

const QUERY_INSERT_INVENTORY: &str = r#"
    INSERT INTO falukant_data.inventory (
        stock_id,
        product_id,
        quantity,
        quality,
        produced_at
    ) VALUES ($1, $2, $3, $4, NOW());
"#;

const QUERY_UPDATE_VEHICLE_AFTER_TRANSPORT: &str = r#"
    UPDATE falukant_data.vehicle
       SET region_id      = $2,
           condition      = GREATEST(0, condition - $3::int),
           available_from = NOW(),
           updated_at     = NOW()
     WHERE id = $1;
"#;

const QUERY_DELETE_TRANSPORT: &str = r#"
    DELETE FROM falukant_data.transport
     WHERE id = $1;
"#;

/// Notification-Eintrag, analog zur Overproduction-Notification im ProduceWorker.
/// `tr` wird hier als JSON-String mit Übersetzungs-Key und Werten gespeichert.
const QUERY_ADD_TRANSPORT_WAITING_NOTIFICATION: &str = r#"
    INSERT INTO falukant_log.notification (
        user_id,
        tr,
        shown,
        created_at,
        updated_at
    ) VALUES ($1, $2, FALSE, NOW(), NOW());
"#;

pub struct TransportWorker {
    base: BaseWorker,
}

impl TransportWorker {
    pub fn new(pool: ConnectionPool, broker: MessageBroker) -> Self {
        Self {
            base: BaseWorker::new("TransportWorker", pool, broker),
        }
    }

    fn run_loop(pool: ConnectionPool, broker: MessageBroker, state: Arc<WorkerState>) {
        while state.running_worker.load(Ordering::Relaxed) {
            if let Err(err) = Self::process_arrived_transports(&pool, &broker) {
                eprintln!("[TransportWorker] Fehler in process_arrived_transports: {err}");
            }

            // Einmal pro Sekunde prüfen
            for _ in 0..1 {
                if !state.running_worker.load(Ordering::Relaxed) {
                    break;
                }
                std::thread::sleep(Duration::from_secs(1));
            }
        }
    }

    fn process_arrived_transports(
        pool: &ConnectionPool,
        broker: &MessageBroker,
    ) -> Result<(), DbError> {
        let transports = Self::load_arrived_transports(pool)?;

        for t in transports {
            if let Err(err) = Self::handle_arrived_transport(pool, broker, &t) {
                eprintln!(
                    "[TransportWorker] Fehler beim Verarbeiten von Transport {}: {err}",
                    t.id
                );
            }
        }

        Ok(())
    }

    fn load_arrived_transports(pool: &ConnectionPool) -> Result<Vec<ArrivedTransport>, DbError> {
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        conn.prepare("get_arrived_transports", QUERY_GET_ARRIVED_TRANSPORTS)?;
        let rows = conn.execute("get_arrived_transports", &[])?;

        let mut result = Vec::with_capacity(rows.len());
        for row in rows {
            let id = parse_i32(&row, "id", -1);
            let target_branch_id = parse_i32(&row, "target_branch_id", -1);
            // source_branch_id kann NULL sein (wenn kein Branch in Source-Region)
            let source_branch_id_str = row.get("source_branch_id");
            let source_branch_id = source_branch_id_str
                .and_then(|v| v.parse::<i32>().ok())
                .filter(|&x| x >= 0);
            // product_id kann NULL sein (für leere Transporte)
            let product_id_str = row.get("product_id");
            let product_id = product_id_str
                .and_then(|v| v.parse::<i32>().ok());
            let size = parse_i32(&row, "size", 0);
            let vehicle_id = parse_i32(&row, "vehicle_id", -1);
            let distance = parse_f64(&row, "distance", 0.0);
            let user_id = parse_i32(&row, "user_id", -1);

            // Für normale Transporte: product_id muss vorhanden sein und size > 0
            // Für leere Transporte: product_id ist NULL und size = 0
            let is_valid = if product_id.is_some() {
                // Normaler Transport mit Produkt
                id >= 0 && target_branch_id >= 0 && vehicle_id >= 0 && size > 0 && user_id >= 0
            } else {
                // Leerer Transport (ohne Produkt)
                id >= 0 && target_branch_id >= 0 && vehicle_id >= 0 && size == 0 && user_id >= 0
            };

            if is_valid {
                result.push(ArrivedTransport {
                    id,
                    source_branch_id,
                    target_branch_id,
                    product_id,
                    size,
                    vehicle_id,
                    distance,
                    user_id,
                });
            }
        }

        Ok(result)
    }

    fn handle_arrived_transport(
        pool: &ConnectionPool,
        broker: &MessageBroker,
        t: &ArrivedTransport,
    ) -> Result<(), DbError> {
        // Leere Transporte (ohne Produkt) werden anders behandelt
        if t.product_id.is_none() {
            // Leerer Transport: Nur Fahrzeug-Region aktualisieren und Transport löschen
            eprintln!(
                "[TransportWorker] Leerer Transport {} angekommen: Fahrzeug {} zurückgeholt",
                t.id, t.vehicle_id
            );
            Self::update_vehicle_after_transport(pool, t.vehicle_id, t.target_branch_id, t.distance)?;
            Self::delete_transport(pool, t.id)?;

            // Notifications für beide Branches
            if t.user_id > 0 {
                // Target-Branch: Transport angekommen
                let target_message = format!(
                    r#"{{"event":"transport_arrived","branch_id":{},"user_id":{},"empty":true}}"#,
                    t.target_branch_id, t.user_id
                );
                broker.publish(target_message);

                // Source-Branch: Transport entfernt (falls vorhanden)
                if let Some(source_branch_id) = t.source_branch_id {
                    let source_message = format!(
                        r#"{{"event":"transport_removed","branch_id":{},"user_id":{}}}"#,
                        source_branch_id, t.user_id
                    );
                    broker.publish(source_message);
                }
            }

            return Ok(());
        }

        // Normaler Transport mit Produkt:
        // 1) Waren in das Ziel-Branch-Lager einbuchen – wir erhalten die
        //    tatsächlich verbleibende Menge im Transportmittel zurück.
        let product_id = t.product_id.unwrap();
        let remaining_quantity =
            Self::add_to_inventory(pool, t.target_branch_id, product_id, t.size)?;

        let delivered = t.size.saturating_sub(remaining_quantity);

        if remaining_quantity <= 0 {
            // Alles konnte eingelagert werden:
            // 2) Fahrzeug-Region & Zustand aktualisieren
            Self::update_vehicle_after_transport(pool, t.vehicle_id, t.target_branch_id, t.distance)?;

            // 3) Transport-Eintrag löschen
            Self::delete_transport(pool, t.id)?;

            // Notifications für beide Branches
            if t.user_id > 0 {
                // Target-Branch: Transport angekommen und Inventar aktualisiert
                let target_transport_message = format!(
                    r#"{{"event":"transport_arrived","branch_id":{},"user_id":{},"product_id":{},"quantity":{}}}"#,
                    t.target_branch_id, t.user_id, product_id, delivered
                );
                broker.publish(target_transport_message);

                let target_inventory_message = format!(
                    r#"{{"event":"inventory_updated","branch_id":{},"user_id":{}}}"#,
                    t.target_branch_id, t.user_id
                );
                broker.publish(target_inventory_message);

                // Source-Branch: Transport entfernt (falls vorhanden)
                if let Some(source_branch_id) = t.source_branch_id {
                    let source_message = format!(
                        r#"{{"event":"transport_removed","branch_id":{},"user_id":{}}}"#,
                        source_branch_id, t.user_id
                    );
                    broker.publish(source_message);
                }
            }
        } else {
            // Es konnte nur ein Teil (oder nichts) eingelagert werden:
            // - Transport bleibt in der Tabelle bestehen
            // - Größe im Transport anpassen, damit nur der verbliebene Rest
            //   beim nächsten Durchlauf erneut versucht wird.
            if delivered > 0 {
                Self::update_transport_size(pool, t.id, remaining_quantity)?;

                // Notification: Teilweise eingelagert, Inventar aktualisiert
                if t.user_id > 0 {
                    let target_inventory_message = format!(
                        r#"{{"event":"inventory_updated","branch_id":{},"user_id":{}}}"#,
                        t.target_branch_id, t.user_id
                    );
                    broker.publish(target_inventory_message);
                }
            }

            // Nutzer informieren, dass Ware noch im Transportmittel liegt.
            if t.user_id > 0 {
                if let Err(err) = Self::insert_transport_waiting_notification(
                    pool,
                    t.user_id,
                    product_id,
                    remaining_quantity,
                ) {
                    eprintln!(
                        "[TransportWorker] Fehler beim Schreiben der Transport-Waiting-Notification: {err}"
                    );
                }
            }
        }

        Ok(())
    }

    fn add_to_inventory(
        pool: &ConnectionPool,
        branch_id: i32,
        product_id: i32,
        quantity: i32,
    ) -> Result<i32, DbError> {
        let stocks = Self::get_available_stocks(pool, branch_id)?;

        let mut remaining_quantity = quantity;

        for stock in stocks {
            if remaining_quantity <= 0 {
                break;
            }

            let free_capacity = stock.total_capacity - stock.filled;
            if free_capacity <= 0 {
                continue;
            }

            let to_store = min(remaining_quantity, free_capacity);
            Self::store_in_stock(pool, stock.stock_id, product_id, to_store)?;
            remaining_quantity -= to_store;
        }

        Ok(remaining_quantity)
    }

    fn get_available_stocks(pool: &ConnectionPool, branch_id: i32) -> Result<Vec<StockInfo>, DbError> {
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        conn.prepare("transport_get_stocks", QUERY_GET_AVAILABLE_STOCKS)?;
        let rows = conn.execute("transport_get_stocks", &[&branch_id])?;

        let mut result = Vec::with_capacity(rows.len());
        for row in rows {
            let stock_id = parse_i32(&row, "id", -1);
            let total_capacity = parse_i32(&row, "total_capacity", 0);
            let filled = parse_i32(&row, "filled", 0);

            if stock_id >= 0 {
                result.push(StockInfo {
                    stock_id,
                    total_capacity,
                    filled,
                });
            }
        }

        Ok(result)
    }

    fn store_in_stock(
        pool: &ConnectionPool,
        stock_id: i32,
        product_id: i32,
        quantity: i32,
    ) -> Result<(), DbError> {
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        conn.prepare("transport_insert_inventory", QUERY_INSERT_INVENTORY)?;

        // Qualität für Transporte zunächst konservativ auf 100 setzen. Eine
        // spätere Erweiterung könnte Qualitätseinbußen durch lange Strecken
        // oder schlechten Fahrzeugzustand berücksichtigen.
        let quality: i32 = 100;

        conn.execute(
            "transport_insert_inventory",
            &[&stock_id, &product_id, &quantity, &quality],
        )?;

        Ok(())
    }

    fn update_vehicle_after_transport(
        pool: &ConnectionPool,
        vehicle_id: i32,
        target_branch_id: i32,
        distance: f64,
    ) -> Result<(), DbError> {
        // Hole die Ziel-Region über den Branch
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        // Region des Branches abrufen
        const QUERY_GET_BRANCH_REGION: &str = r#"
            SELECT region_id
              FROM falukant_data.branch
             WHERE id = $1
             LIMIT 1;
        "#;

        conn.prepare("get_branch_region", QUERY_GET_BRANCH_REGION)?;
        let rows = conn.execute("get_branch_region", &[&target_branch_id])?;

        let region_id = rows
            .get(0)
            .and_then(|r| r.get("region_id"))
            .and_then(|v| v.parse::<i32>().ok())
            .unwrap_or(-1);

        if region_id < 0 {
            return Err(DbError::new(format!(
                "Konnte Region für Branch {} nicht bestimmen",
                target_branch_id
            )));
        }

        conn.prepare(
            "update_vehicle_after_transport",
            QUERY_UPDATE_VEHICLE_AFTER_TRANSPORT,
        )?;

        let distance_int = distance.round() as i32;

        conn.execute(
            "update_vehicle_after_transport",
            &[&vehicle_id, &region_id, &distance_int],
        )?;

        Ok(())
    }

    fn delete_transport(pool: &ConnectionPool, transport_id: i32) -> Result<(), DbError> {
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        conn.prepare("delete_transport", QUERY_DELETE_TRANSPORT)?;
        conn.execute("delete_transport", &[&transport_id])?;

        Ok(())
    }

    fn update_transport_size(
        pool: &ConnectionPool,
        transport_id: i32,
        new_size: i32,
    ) -> Result<(), DbError> {
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        const QUERY_UPDATE_TRANSPORT_SIZE: &str = r#"
            UPDATE falukant_data.transport
               SET size = $2,
                   updated_at = NOW()
             WHERE id = $1;
        "#;

        conn.prepare("update_transport_size", QUERY_UPDATE_TRANSPORT_SIZE)?;
        conn.execute("update_transport_size", &[&transport_id, &new_size])?;

        Ok(())
    }

    fn get_branch_user_id(pool: &ConnectionPool, branch_id: i32) -> Result<i32, DbError> {
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        const QUERY_GET_BRANCH_USER: &str = r#"
            SELECT falukant_user_id
              FROM falukant_data.branch
             WHERE id = $1
             LIMIT 1;
        "#;

        conn.prepare("get_branch_user", QUERY_GET_BRANCH_USER)?;
        let rows = conn.execute("get_branch_user", &[&branch_id])?;

        let user_id = rows
            .get(0)
            .and_then(|r| r.get("falukant_user_id"))
            .and_then(|v| v.parse::<i32>().ok())
            .unwrap_or(-1);

        Ok(user_id)
    }

    fn insert_transport_waiting_notification(
        pool: &ConnectionPool,
        user_id: i32,
        product_id: i32,
        remaining_quantity: i32,
    ) -> Result<(), DbError> {
        let mut conn = pool
            .get()
            .map_err(|e| DbError::new(format!("DB-Verbindung fehlgeschlagen: {e}")))?;

        conn.prepare(
            "add_transport_waiting_notification",
            QUERY_ADD_TRANSPORT_WAITING_NOTIFICATION,
        )?;

        let notification = format!(
            r#"{{"tr":"transport.waiting","productId":{},"value":{}}}"#,
            product_id, remaining_quantity
        );

        conn.execute(
            "add_transport_waiting_notification",
            &[&user_id, &notification],
        )?;

        Ok(())
    }
}

impl Worker for TransportWorker {
    fn start_worker_thread(&mut self) {
        let pool = self.base.pool.clone();
        let broker = self.base.broker.clone();

        self.base
            .start_worker_with_loop(move |state: Arc<WorkerState>| {
                TransportWorker::run_loop(pool.clone(), broker.clone(), state);
            });
    }

    fn stop_worker_thread(&mut self) {
        self.base.stop_worker();
    }

    fn enable_watchdog(&mut self) {
        self.base.start_watchdog();
    }
}

fn parse_i32(row: &crate::db::Row, key: &str, default: i32) -> i32 {
    row.get(key)
        .and_then(|v| v.parse::<i32>().ok())
        .unwrap_or(default)
}

fn parse_f64(row: &crate::db::Row, key: &str, default: f64) -> f64 {
    row.get(key)
        .and_then(|v| v.parse::<f64>().ok())
        .unwrap_or(default)
}