import pool from '../config/database';
import logger from '../utils/logger';
import {
  Fahrzeug,
  FahrzeugListItem,
  FahrzeugDetail,
  FahrzeugWartungslog,
  CreateFahrzeugData,
  UpdateFahrzeugData,
  CreateWartungslogData,
  FahrzeugStatus,
  VehicleStats,
  InspectionAlert,
} from '../models/vehicle.model';

class VehicleService {
  // =========================================================================
  // FLEET OVERVIEW
  // =========================================================================

  async getAllVehicles(): Promise<FahrzeugListItem[]> {
    try {
      const result = await pool.query(`
        SELECT
          id, bezeichnung, kurzname, amtliches_kennzeichen,
          baujahr, hersteller, besatzung_soll, status, status_bemerkung,
          bild_url, paragraph57a_faellig_am, paragraph57a_tage_bis_faelligkeit,
          naechste_wartung_am, wartung_tage_bis_faelligkeit, naechste_pruefung_tage
        FROM fahrzeuge_mit_pruefstatus
        ORDER BY bezeichnung ASC
      `);

      return result.rows.map((row) => ({
        ...row,
        paragraph57a_tage_bis_faelligkeit: row.paragraph57a_tage_bis_faelligkeit != null
          ? parseInt(row.paragraph57a_tage_bis_faelligkeit, 10) : null,
        wartung_tage_bis_faelligkeit: row.wartung_tage_bis_faelligkeit != null
          ? parseInt(row.wartung_tage_bis_faelligkeit, 10) : null,
        naechste_pruefung_tage: row.naechste_pruefung_tage != null
          ? parseInt(row.naechste_pruefung_tage, 10) : null,
      })) as FahrzeugListItem[];
    } catch (error) {
      logger.error('VehicleService.getAllVehicles failed', { error });
      throw new Error('Failed to fetch vehicles');
    }
  }

  // =========================================================================
  // VEHICLE DETAIL
  // =========================================================================

  async getVehicleById(id: string): Promise<FahrzeugDetail | null> {
    try {
      const vehicleResult = await pool.query(
        `SELECT * FROM fahrzeuge_mit_pruefstatus WHERE id = $1`,
        [id]
      );

      if (vehicleResult.rows.length === 0) return null;

      const row = vehicleResult.rows[0];

      const wartungslogResult = await pool.query(
        `SELECT * FROM fahrzeug_wartungslog
         WHERE fahrzeug_id = $1
         ORDER BY datum DESC, created_at DESC`,
        [id]
      );

      const vehicle: FahrzeugDetail = {
        id:                    row.id,
        bezeichnung:           row.bezeichnung,
        kurzname:              row.kurzname,
        amtliches_kennzeichen: row.amtliches_kennzeichen,
        fahrgestellnummer:     row.fahrgestellnummer,
        baujahr:               row.baujahr,
        hersteller:            row.hersteller,
        typ_schluessel:        row.typ_schluessel,
        besatzung_soll:        row.besatzung_soll,
        status:                row.status as FahrzeugStatus,
        status_bemerkung:      row.status_bemerkung,
        standort:              row.standort,
        bild_url:              row.bild_url,
        paragraph57a_faellig_am: row.paragraph57a_faellig_am ?? null,
        naechste_wartung_am:     row.naechste_wartung_am ?? null,
        created_at:            row.created_at,
        updated_at:            row.updated_at,
        paragraph57a_tage_bis_faelligkeit: row.paragraph57a_tage_bis_faelligkeit != null
          ? parseInt(row.paragraph57a_tage_bis_faelligkeit, 10) : null,
        wartung_tage_bis_faelligkeit: row.wartung_tage_bis_faelligkeit != null
          ? parseInt(row.wartung_tage_bis_faelligkeit, 10) : null,
        naechste_pruefung_tage: row.naechste_pruefung_tage != null
          ? parseInt(row.naechste_pruefung_tage, 10) : null,
        wartungslog: wartungslogResult.rows.map(r => ({
          ...r,
          kosten: r.kosten != null ? Number(r.kosten) : null,
        })) as FahrzeugWartungslog[],
      };

      return vehicle;
    } catch (error) {
      logger.error('VehicleService.getVehicleById failed', { error, id });
      throw new Error('Failed to fetch vehicle');
    }
  }

  // =========================================================================
  // CRUD
  // =========================================================================

  async createVehicle(data: CreateFahrzeugData, createdBy: string): Promise<Fahrzeug> {
    try {
      const result = await pool.query(
        `INSERT INTO fahrzeuge (
           bezeichnung, kurzname, amtliches_kennzeichen, fahrgestellnummer,
           baujahr, hersteller, typ_schluessel, besatzung_soll,
           status, status_bemerkung, standort, bild_url,
           paragraph57a_faellig_am, naechste_wartung_am
         ) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14)
         RETURNING *`,
        [
          data.bezeichnung,
          data.kurzname              ?? null,
          data.amtliches_kennzeichen ?? null,
          data.fahrgestellnummer     ?? null,
          data.baujahr               ?? null,
          data.hersteller            ?? null,
          data.typ_schluessel        ?? null,
          data.besatzung_soll        ?? null,
          data.status                ?? FahrzeugStatus.Einsatzbereit,
          data.status_bemerkung      ?? null,
          data.standort              ?? 'Feuerwehrhaus',
          data.bild_url              ?? null,
          data.paragraph57a_faellig_am ?? null,
          data.naechste_wartung_am     ?? null,
        ]
      );

      const vehicle = result.rows[0] as Fahrzeug;
      logger.info('Vehicle created', { id: vehicle.id, by: createdBy });
      return vehicle;
    } catch (error) {
      logger.error('VehicleService.createVehicle failed', { error, createdBy });
      throw new Error('Failed to create vehicle');
    }
  }

  async updateVehicle(id: string, data: UpdateFahrzeugData, updatedBy: string): Promise<Fahrzeug> {
    try {
      const fields: string[] = [];
      const values: unknown[] = [];
      let p = 1;

      const addField = (col: string, value: unknown) => {
        fields.push(`${col} = $${p++}`);
        values.push(value);
      };

      if (data.bezeichnung           !== undefined) addField('bezeichnung',           data.bezeichnung);
      if (data.kurzname              !== undefined) addField('kurzname',              data.kurzname);
      if (data.amtliches_kennzeichen !== undefined) addField('amtliches_kennzeichen', data.amtliches_kennzeichen);
      if (data.fahrgestellnummer     !== undefined) addField('fahrgestellnummer',     data.fahrgestellnummer);
      if (data.baujahr               !== undefined) addField('baujahr',               data.baujahr);
      if (data.hersteller            !== undefined) addField('hersteller',            data.hersteller);
      if (data.typ_schluessel        !== undefined) addField('typ_schluessel',        data.typ_schluessel);
      if (data.besatzung_soll        !== undefined) addField('besatzung_soll',        data.besatzung_soll);
      if (data.status                !== undefined) addField('status',                data.status);
      if (data.status_bemerkung      !== undefined) addField('status_bemerkung',      data.status_bemerkung);
      if (data.standort              !== undefined) addField('standort',              data.standort);
      if (data.bild_url              !== undefined) addField('bild_url',              data.bild_url);
      if (data.paragraph57a_faellig_am !== undefined) addField('paragraph57a_faellig_am', data.paragraph57a_faellig_am);
      if (data.naechste_wartung_am     !== undefined) addField('naechste_wartung_am',     data.naechste_wartung_am);

      if (fields.length === 0) {
        throw new Error('No fields to update');
      }

      values.push(id);
      const result = await pool.query(
        `UPDATE fahrzeuge SET ${fields.join(', ')} WHERE id = $${p} AND deleted_at IS NULL RETURNING *`,
        values
      );

      if (result.rows.length === 0) {
        throw new Error('Vehicle not found');
      }

      const vehicle = result.rows[0] as Fahrzeug;
      logger.info('Vehicle updated', { id, by: updatedBy });
      return vehicle;
    } catch (error) {
      logger.error('VehicleService.updateVehicle failed', { error, id, updatedBy });
      throw error;
    }
  }

  async deleteVehicle(id: string, deletedBy: string): Promise<void> {
    try {
      const result = await pool.query(
        `UPDATE fahrzeuge
         SET deleted_at = NOW()
         WHERE id = $1 AND deleted_at IS NULL
         RETURNING id`,
        [id]
      );

      if (result.rows.length === 0) {
        throw new Error('Vehicle not found');
      }

      logger.info('Vehicle soft-deleted', { id, by: deletedBy });
    } catch (error) {
      logger.error('VehicleService.deleteVehicle failed', { error, id });
      throw error;
    }
  }

  // =========================================================================
  // STATUS MANAGEMENT
  // =========================================================================

  async updateVehicleStatus(
    id: string,
    status: FahrzeugStatus,
    bemerkung: string,
    updatedBy: string,
    io?: any
  ): Promise<void> {
    const client = await pool.connect();
    try {
      await client.query('BEGIN');

      const oldResult = await client.query(
        `SELECT bezeichnung, status FROM fahrzeuge WHERE id = $1 AND deleted_at IS NULL FOR UPDATE`,
        [id]
      );

      if (oldResult.rows.length === 0) {
        await client.query('ROLLBACK');
        throw new Error('Vehicle not found');
      }

      const { bezeichnung, status: oldStatus } = oldResult.rows[0];

      await client.query(
        `UPDATE fahrzeuge SET status = $1, status_bemerkung = $2 WHERE id = $3`,
        [status, bemerkung || null, id]
      );

      await client.query('COMMIT');

      logger.info('Vehicle status updated', { id, from: oldStatus, to: status, by: updatedBy });

      if (io) {
        io.emit('vehicle:statusChanged', {
          vehicleId:   id,
          bezeichnung,
          oldStatus,
          newStatus:   status,
          bemerkung:   bemerkung || null,
          updatedBy,
          timestamp:   new Date().toISOString(),
        });
      }
    } catch (error) {
      await client.query('ROLLBACK').catch(() => {});
      logger.error('VehicleService.updateVehicleStatus failed', { error, id });
      throw error;
    } finally {
      client.release();
    }
  }

  // =========================================================================
  // MAINTENANCE LOG
  // =========================================================================

  async addWartungslog(
    fahrzeugId: string,
    data: CreateWartungslogData,
    createdBy: string
  ): Promise<FahrzeugWartungslog> {
    try {
      const check = await pool.query(
        `SELECT 1 FROM fahrzeuge WHERE id = $1 AND deleted_at IS NULL`,
        [fahrzeugId]
      );
      if (check.rows.length === 0) {
        throw new Error('Vehicle not found');
      }

      const result = await pool.query(
        `INSERT INTO fahrzeug_wartungslog (
           fahrzeug_id, datum, art, beschreibung,
           km_stand, kraftstoff_liter, kosten, externe_werkstatt, erfasst_von
         ) VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9)
         RETURNING *`,
        [
          fahrzeugId,
          data.datum,
          data.art               ?? null,
          data.beschreibung,
          data.km_stand          ?? null,
          data.kraftstoff_liter  ?? null,
          data.kosten            ?? null,
          data.externe_werkstatt ?? null,
          createdBy,
        ]
      );

      const entry = result.rows[0] as FahrzeugWartungslog;
      logger.info('Wartungslog entry added', { entryId: entry.id, fahrzeugId, by: createdBy });
      return entry;
    } catch (error) {
      logger.error('VehicleService.addWartungslog failed', { error, fahrzeugId });
      throw error;
    }
  }

  async getWartungslogForVehicle(fahrzeugId: string): Promise<FahrzeugWartungslog[]> {
    try {
      const result = await pool.query(
        `SELECT * FROM fahrzeug_wartungslog
         WHERE fahrzeug_id = $1
         ORDER BY datum DESC, created_at DESC`,
        [fahrzeugId]
      );
      return result.rows.map(r => ({
        ...r,
        kosten: r.kosten != null ? Number(r.kosten) : null,
      })) as FahrzeugWartungslog[];
    } catch (error) {
      logger.error('VehicleService.getWartungslogForVehicle failed', { error, fahrzeugId });
      throw new Error('Failed to fetch maintenance log');
    }
  }

  // =========================================================================
  // DASHBOARD KPI
  // =========================================================================

  async getVehicleStats(): Promise<VehicleStats> {
    try {
      const totalsResult = await pool.query(`
        SELECT
          COUNT(*)                                          AS total,
          COUNT(*) FILTER (WHERE status = 'einsatzbereit') AS einsatzbereit,
          COUNT(*) FILTER (
            WHERE status IN ('ausser_dienst_wartung','ausser_dienst_schaden')
          )                                                AS ausser_dienst,
          COUNT(*) FILTER (WHERE status = 'in_lehrgang')  AS in_lehrgang
        FROM fahrzeuge
        WHERE deleted_at IS NULL
      `);

      const alertResult = await pool.query(`
        SELECT
          COUNT(*) FILTER (
            WHERE (
              (paragraph57a_faellig_am IS NOT NULL AND paragraph57a_faellig_am::date - CURRENT_DATE BETWEEN 0 AND 30)
              OR
              (naechste_wartung_am IS NOT NULL AND naechste_wartung_am::date - CURRENT_DATE BETWEEN 0 AND 30)
            )
          ) AS inspections_due,
          COUNT(*) FILTER (
            WHERE (
              (paragraph57a_faellig_am IS NOT NULL AND paragraph57a_faellig_am::date < CURRENT_DATE)
              OR
              (naechste_wartung_am IS NOT NULL AND naechste_wartung_am::date < CURRENT_DATE)
            )
          ) AS inspections_overdue
        FROM fahrzeuge
        WHERE deleted_at IS NULL
      `);

      const totals = totalsResult.rows[0] ?? { total: '0', einsatzbereit: '0', ausser_dienst: '0', in_lehrgang: '0' };
      const alerts = alertResult.rows[0] ?? { inspections_due: '0', inspections_overdue: '0' };

      return {
        total:              parseInt(totals.total ?? '0', 10),
        einsatzbereit:      parseInt(totals.einsatzbereit ?? '0', 10),
        ausserDienst:       parseInt(totals.ausser_dienst ?? '0', 10),
        inLehrgang:         parseInt(totals.in_lehrgang ?? '0', 10),
        inspectionsDue:     parseInt(alerts.inspections_due ?? '0', 10),
        inspectionsOverdue: parseInt(alerts.inspections_overdue ?? '0', 10),
      };
    } catch (error) {
      logger.error('VehicleService.getVehicleStats failed', { error });
      throw new Error('Failed to fetch vehicle stats');
    }
  }

  async getUpcomingInspections(daysAhead: number): Promise<InspectionAlert[]> {
    try {
      const result = await pool.query(
        `SELECT
           id AS fahrzeug_id,
           bezeichnung,
           kurzname,
           paragraph57a_faellig_am,
           paragraph57a_faellig_am::date - CURRENT_DATE AS paragraph57a_tage,
           naechste_wartung_am,
           naechste_wartung_am::date - CURRENT_DATE     AS wartung_tage
         FROM fahrzeuge
         WHERE
           deleted_at IS NULL
           AND (
             (paragraph57a_faellig_am IS NOT NULL AND paragraph57a_faellig_am::date - CURRENT_DATE <= $1)
             OR
             (naechste_wartung_am IS NOT NULL AND naechste_wartung_am::date - CURRENT_DATE <= $1)
           )
         ORDER BY LEAST(
           CASE WHEN paragraph57a_faellig_am IS NOT NULL
                THEN paragraph57a_faellig_am::date - CURRENT_DATE END,
           CASE WHEN naechste_wartung_am IS NOT NULL
                THEN naechste_wartung_am::date - CURRENT_DATE END
         ) ASC NULLS LAST`,
        [daysAhead]
      );

      const alerts: InspectionAlert[] = [];

      for (const row of result.rows) {
        if (row.paragraph57a_faellig_am !== null && row.paragraph57a_tage !== null) {
          const tage = parseInt(row.paragraph57a_tage, 10);
          if (tage <= daysAhead) {
            alerts.push({
              fahrzeugId:  row.fahrzeug_id,
              bezeichnung: row.bezeichnung,
              kurzname:    row.kurzname,
              type:        '57a',
              faelligAm:   row.paragraph57a_faellig_am,
              tage,
            });
          }
        }
        if (row.naechste_wartung_am !== null && row.wartung_tage !== null) {
          const tage = parseInt(row.wartung_tage, 10);
          if (tage <= daysAhead) {
            alerts.push({
              fahrzeugId:  row.fahrzeug_id,
              bezeichnung: row.bezeichnung,
              kurzname:    row.kurzname,
              type:        'wartung',
              faelligAm:   row.naechste_wartung_am,
              tage,
            });
          }
        }
      }

      alerts.sort((a, b) => a.tage - b.tage);
      return alerts;
    } catch (error) {
      logger.error('VehicleService.getUpcomingInspections failed', { error, daysAhead });
      throw new Error('Failed to fetch inspection alerts');
    }
  }
}

export default new VehicleService();