const express = require('express');
const db      = require('../../db');
const { authenticate } = require('../../middleware/auth');
const router  = express.Router();

// ── DB-Migration ──────────────────────────────────────────────────────────────
(function migrate() {
  db.exec(`
    CREATE TABLE IF NOT EXISTS kanban_columns (
      id         INTEGER PRIMARY KEY AUTOINCREMENT,
      user_id    INTEGER NOT NULL,
      title      TEXT    NOT NULL,
      color      TEXT    NOT NULL DEFAULT '#4ecdc4',
      position   INTEGER NOT NULL DEFAULT 0,
      created_at TEXT    NOT NULL DEFAULT (datetime('now','localtime'))
    );
    CREATE TABLE IF NOT EXISTS kanban_cards (
      id          INTEGER PRIMARY KEY AUTOINCREMENT,
      column_id   INTEGER NOT NULL REFERENCES kanban_columns(id) ON DELETE CASCADE,
      user_id     INTEGER NOT NULL,
      title       TEXT    NOT NULL,
      description TEXT    NOT NULL DEFAULT '',
      priority    TEXT    NOT NULL DEFAULT 'none',
      position    INTEGER NOT NULL DEFAULT 0,
      created_at  TEXT    NOT NULL DEFAULT (datetime('now','localtime')),
      updated_at  TEXT    NOT NULL DEFAULT (datetime('now','localtime'))
    );
  `);
  // Nachrüsten falls Tabelle schon existiert aber color fehlt
  const cols = db.pragma('table_info(kanban_columns)').map(c => c.name);
  if (!cols.includes('color')) {
    db.exec("ALTER TABLE kanban_columns ADD COLUMN color TEXT NOT NULL DEFAULT '#4ecdc4'");
  }
})();

const uid = req => req.user.id;

// ── Alle Spalten + Karten laden ───────────────────────────────────────────────
router.get('/board', authenticate, (req, res) => {
  const me = uid(req);
  const columns = db.prepare(
    'SELECT * FROM kanban_columns WHERE user_id=? ORDER BY position ASC, id ASC'
  ).all(me);
  const cards = db.prepare(
    'SELECT * FROM kanban_cards WHERE user_id=? ORDER BY position ASC, id ASC'
  ).all(me);
  const colMap = {};
  for (const c of columns) { c.cards = []; colMap[c.id] = c; }
  for (const card of cards) {
    if (colMap[card.column_id]) colMap[card.column_id].cards.push(card);
  }
  res.json({ columns });
});

// ── Spalte erstellen ──────────────────────────────────────────────────────────
router.post('/columns', authenticate, (req, res) => {
  const { title, color = '#4ecdc4' } = req.body;
  if (!title?.trim()) return res.status(400).json({ error: 'Titel fehlt' });
  const me = uid(req);
  const maxPos = db.prepare('SELECT MAX(position) as m FROM kanban_columns WHERE user_id=?').get(me);
  const pos = (maxPos?.m ?? -1) + 1;
  const r = db.prepare(
    "INSERT INTO kanban_columns (user_id,title,color,position) VALUES (?,?,?,?)"
  ).run(me, title.trim(), color, pos);
  res.json(db.prepare('SELECT * FROM kanban_columns WHERE id=?').get(r.lastInsertRowid));
});

// ── Spalte aktualisieren (Titel + Farbe) ─────────────────────────────────────
// Feste Route vor :param (Lesson Learned)
router.post('/columns/reorder', authenticate, (req, res) => {
  const { order } = req.body;
  if (!Array.isArray(order)) return res.status(400).json({ error: 'order fehlt' });
  const me = uid(req);
  const upd = db.prepare('UPDATE kanban_columns SET position=? WHERE id=? AND user_id=?');
  db.transaction(() => { for (let i = 0; i < order.length; i++) upd.run(i, order[i], me); })();
  res.json({ ok: true });
});

router.patch('/columns/:id', authenticate, (req, res) => {
  const me = uid(req);
  const col = db.prepare('SELECT * FROM kanban_columns WHERE id=? AND user_id=?').get(req.params.id, me);
  if (!col) return res.status(404).json({ error: 'Spalte nicht gefunden' });
  const title = req.body.title !== undefined ? req.body.title.trim() : col.title;
  const color = req.body.color !== undefined ? req.body.color       : col.color;
  if (!title) return res.status(400).json({ error: 'Titel fehlt' });
  db.prepare('UPDATE kanban_columns SET title=?, color=? WHERE id=?').run(title, color, col.id);
  res.json({ ok: true });
});

router.delete('/columns/:id', authenticate, (req, res) => {
  const me = uid(req);
  const col = db.prepare('SELECT * FROM kanban_columns WHERE id=? AND user_id=?').get(req.params.id, me);
  if (!col) return res.status(404).json({ error: 'Spalte nicht gefunden' });
  db.prepare('DELETE FROM kanban_columns WHERE id=?').run(col.id);
  res.json({ ok: true });
});

// ── Karten ────────────────────────────────────────────────────────────────────
router.post('/cards', authenticate, (req, res) => {
  const { column_id, title, description = '', priority = 'none' } = req.body;
  if (!column_id || !title?.trim()) return res.status(400).json({ error: 'column_id und title erforderlich' });
  const me = uid(req);
  const col = db.prepare('SELECT * FROM kanban_columns WHERE id=? AND user_id=?').get(column_id, me);
  if (!col) return res.status(404).json({ error: 'Spalte nicht gefunden' });
  const maxPos = db.prepare('SELECT MAX(position) as m FROM kanban_cards WHERE column_id=?').get(column_id);
  const pos = (maxPos?.m ?? -1) + 1;
  const r = db.prepare(
    "INSERT INTO kanban_cards (column_id,user_id,title,description,priority,position) VALUES (?,?,?,?,?,?)"
  ).run(column_id, me, title.trim(), description.trim(), priority, pos);
  res.json(db.prepare('SELECT * FROM kanban_cards WHERE id=?').get(r.lastInsertRowid));
});

router.patch('/cards/:id', authenticate, (req, res) => {
  const me = uid(req);
  const card = db.prepare('SELECT * FROM kanban_cards WHERE id=? AND user_id=?').get(req.params.id, me);
  if (!card) return res.status(404).json({ error: 'Karte nicht gefunden' });
  const title       = req.body.title       !== undefined ? req.body.title.trim()       : card.title;
  const description = req.body.description !== undefined ? req.body.description.trim() : card.description;
  const priority    = req.body.priority    !== undefined ? req.body.priority            : card.priority;
  if (!title) return res.status(400).json({ error: 'Titel darf nicht leer sein' });
  db.prepare(
    "UPDATE kanban_cards SET title=?,description=?,priority=?,updated_at=datetime('now','localtime') WHERE id=?"
  ).run(title, description, priority, card.id);
  res.json(db.prepare('SELECT * FROM kanban_cards WHERE id=?').get(card.id));
});

router.delete('/cards/:id', authenticate, (req, res) => {
  const me = uid(req);
  const card = db.prepare('SELECT * FROM kanban_cards WHERE id=? AND user_id=?').get(req.params.id, me);
  if (!card) return res.status(404).json({ error: 'Karte nicht gefunden' });
  db.prepare('DELETE FROM kanban_cards WHERE id=?').run(card.id);
  res.json({ ok: true });
});

router.post('/cards/:id/move', authenticate, (req, res) => {
  const { column_id, position } = req.body;
  const me = uid(req);
  const card = db.prepare('SELECT * FROM kanban_cards WHERE id=? AND user_id=?').get(req.params.id, me);
  if (!card) return res.status(404).json({ error: 'Karte nicht gefunden' });
  const targetColId = column_id !== undefined ? column_id : card.column_id;
  const col = db.prepare('SELECT * FROM kanban_columns WHERE id=? AND user_id=?').get(targetColId, me);
  if (!col) return res.status(404).json({ error: 'Zielspalte nicht gefunden' });
  const siblings = db.prepare(
    'SELECT id FROM kanban_cards WHERE column_id=? AND id!=? ORDER BY position ASC, id ASC'
  ).all(targetColId, card.id).map(r => r.id);
  const targetPos = position !== undefined
    ? Math.max(0, Math.min(position, siblings.length))
    : siblings.length;
  siblings.splice(targetPos, 0, card.id);
  const upd = db.prepare('UPDATE kanban_cards SET column_id=?, position=? WHERE id=?');
  db.transaction(() => { for (let i = 0; i < siblings.length; i++) upd.run(targetColId, i, siblings[i]); })();
  res.json({ ok: true });
});

module.exports = router;