/**
 * TASKMATE - Subtask Routes
 * =========================
 * CRUD für Unteraufgaben/Checkliste
 */

const express = require('express');
const router = express.Router();
const { getDb } = require('../database');
const logger = require('../utils/logger');
const { validators } = require('../middleware/validation');

/**
 * GET /api/subtasks/:taskId
 * Alle Unteraufgaben einer Aufgabe
 */
router.get('/:taskId', (req, res) => {
  try {
    const db = getDb();
    const subtasks = db.prepare(`
      SELECT * FROM subtasks WHERE task_id = ? ORDER BY position
    `).all(req.params.taskId);

    res.json(subtasks.map(s => ({
      id: s.id,
      taskId: s.task_id,
      title: s.title,
      completed: !!s.completed,
      position: s.position
    })));
  } catch (error) {
    logger.error('Fehler beim Abrufen der Subtasks:', { error: error.message });
    res.status(500).json({ error: 'Interner Serverfehler' });
  }
});

/**
 * POST /api/subtasks
 * Neue Unteraufgabe erstellen
 */
router.post('/', (req, res) => {
  try {
    const { taskId, title } = req.body;

    // Validierung
    const titleError = validators.required(title, 'Titel') ||
      validators.maxLength(title, 200, 'Titel');
    if (titleError) {
      return res.status(400).json({ error: titleError });
    }

    const db = getDb();

    // Task prüfen
    const task = db.prepare('SELECT * FROM tasks WHERE id = ?').get(taskId);
    if (!task) {
      return res.status(404).json({ error: 'Aufgabe nicht gefunden' });
    }

    // Alle bestehenden Subtasks um eine Position nach unten verschieben
    db.prepare(`
      UPDATE subtasks SET position = position + 1 WHERE task_id = ?
    `).run(taskId);

    // Neue Subtask an Position 0 erstellen (immer an erster Stelle)
    const result = db.prepare(`
      INSERT INTO subtasks (task_id, title, position)
      VALUES (?, ?, 0)
    `).run(taskId, title);

    // Task updated_at aktualisieren
    db.prepare('UPDATE tasks SET updated_at = CURRENT_TIMESTAMP WHERE id = ?').run(taskId);

    const subtask = db.prepare('SELECT * FROM subtasks WHERE id = ?').get(result.lastInsertRowid);

    logger.info(`Subtask erstellt: ${title} in Task ${taskId}`);

    // WebSocket
    const io = req.app.get('io');
    io.to(`project:${task.project_id}`).emit('subtask:created', {
      taskId,
      subtask: {
        id: subtask.id,
        taskId: subtask.task_id,
        title: subtask.title,
        completed: false,
        position: subtask.position
      }
    });

    res.status(201).json({
      id: subtask.id,
      taskId: subtask.task_id,
      title: subtask.title,
      completed: false,
      position: subtask.position
    });
  } catch (error) {
    logger.error('Fehler beim Erstellen des Subtasks:', { error: error.message });
    res.status(500).json({ error: 'Interner Serverfehler' });
  }
});

/**
 * PUT /api/subtasks/:id
 * Unteraufgabe aktualisieren
 */
router.put('/:id', (req, res) => {
  try {
    const subtaskId = req.params.id;
    const { title, completed } = req.body;

    const db = getDb();

    const subtask = db.prepare('SELECT * FROM subtasks WHERE id = ?').get(subtaskId);
    if (!subtask) {
      return res.status(404).json({ error: 'Unteraufgabe nicht gefunden' });
    }

    // Validierung
    if (title) {
      const titleError = validators.maxLength(title, 200, 'Titel');
      if (titleError) {
        return res.status(400).json({ error: titleError });
      }
    }

    db.prepare(`
      UPDATE subtasks SET
        title = COALESCE(?, title),
        completed = COALESCE(?, completed)
      WHERE id = ?
    `).run(title || null, completed !== undefined ? (completed ? 1 : 0) : null, subtaskId);

    // Task updated_at aktualisieren
    db.prepare('UPDATE tasks SET updated_at = CURRENT_TIMESTAMP WHERE id = ?').run(subtask.task_id);

    const updated = db.prepare('SELECT * FROM subtasks WHERE id = ?').get(subtaskId);
    const task = db.prepare('SELECT project_id FROM tasks WHERE id = ?').get(subtask.task_id);

    // WebSocket
    const io = req.app.get('io');
    io.to(`project:${task.project_id}`).emit('subtask:updated', {
      taskId: subtask.task_id,
      subtask: {
        id: updated.id,
        taskId: updated.task_id,
        title: updated.title,
        completed: !!updated.completed,
        position: updated.position
      }
    });

    res.json({
      id: updated.id,
      taskId: updated.task_id,
      title: updated.title,
      completed: !!updated.completed,
      position: updated.position
    });
  } catch (error) {
    logger.error('Fehler beim Aktualisieren des Subtasks:', { error: error.message });
    res.status(500).json({ error: 'Interner Serverfehler' });
  }
});

/**
 * PUT /api/subtasks/:id/position
 * Unteraufgabe-Position ändern
 */
router.put('/:id/position', (req, res) => {
  try {
    const subtaskId = req.params.id;
    const { newPosition } = req.body;

    const db = getDb();

    const subtask = db.prepare('SELECT * FROM subtasks WHERE id = ?').get(subtaskId);
    if (!subtask) {
      return res.status(404).json({ error: 'Unteraufgabe nicht gefunden' });
    }

    const oldPosition = subtask.position;
    const taskId = subtask.task_id;

    if (newPosition > oldPosition) {
      db.prepare(`
        UPDATE subtasks SET position = position - 1
        WHERE task_id = ? AND position > ? AND position <= ?
      `).run(taskId, oldPosition, newPosition);
    } else if (newPosition < oldPosition) {
      db.prepare(`
        UPDATE subtasks SET position = position + 1
        WHERE task_id = ? AND position >= ? AND position < ?
      `).run(taskId, newPosition, oldPosition);
    }

    db.prepare('UPDATE subtasks SET position = ? WHERE id = ?').run(newPosition, subtaskId);

    const subtasks = db.prepare(
      'SELECT * FROM subtasks WHERE task_id = ? ORDER BY position'
    ).all(taskId);

    const task = db.prepare('SELECT project_id FROM tasks WHERE id = ?').get(taskId);

    // WebSocket
    const io = req.app.get('io');
    io.to(`project:${task.project_id}`).emit('subtasks:reordered', {
      taskId,
      subtasks: subtasks.map(s => ({
        id: s.id,
        title: s.title,
        completed: !!s.completed,
        position: s.position
      }))
    });

    res.json({
      subtasks: subtasks.map(s => ({
        id: s.id,
        taskId: s.task_id,
        title: s.title,
        completed: !!s.completed,
        position: s.position
      }))
    });
  } catch (error) {
    logger.error('Fehler beim Verschieben des Subtasks:', { error: error.message });
    res.status(500).json({ error: 'Interner Serverfehler' });
  }
});

/**
 * DELETE /api/subtasks/:id
 * Unteraufgabe löschen
 */
router.delete('/:id', (req, res) => {
  try {
    const subtaskId = req.params.id;
    const db = getDb();

    const subtask = db.prepare('SELECT * FROM subtasks WHERE id = ?').get(subtaskId);
    if (!subtask) {
      return res.status(404).json({ error: 'Unteraufgabe nicht gefunden' });
    }

    const taskId = subtask.task_id;

    db.prepare('DELETE FROM subtasks WHERE id = ?').run(subtaskId);

    // Positionen neu nummerieren
    const remaining = db.prepare(
      'SELECT id FROM subtasks WHERE task_id = ? ORDER BY position'
    ).all(taskId);

    remaining.forEach((s, idx) => {
      db.prepare('UPDATE subtasks SET position = ? WHERE id = ?').run(idx, s.id);
    });

    // Task updated_at aktualisieren
    db.prepare('UPDATE tasks SET updated_at = CURRENT_TIMESTAMP WHERE id = ?').run(taskId);

    const task = db.prepare('SELECT project_id FROM tasks WHERE id = ?').get(taskId);

    // WebSocket
    const io = req.app.get('io');
    io.to(`project:${task.project_id}`).emit('subtask:deleted', {
      taskId,
      subtaskId
    });

    res.json({ message: 'Unteraufgabe gelöscht' });
  } catch (error) {
    logger.error('Fehler beim Löschen des Subtasks:', { error: error.message });
    res.status(500).json({ error: 'Interner Serverfehler' });
  }
});

module.exports = router;