const express = require("express");
const router  = express.Router();
const db      = require("../database/database");

/* ========================
   Auth Middleware
======================== */

function requireLogin(req, res, next) {
  if (!req.session.user) return res.status(401).json({ error: "Nicht eingeloggt" });
  next();
}

router.use(requireLogin);

/* ════════════════════════════════════════════
   GET /api/card-groups
   Alle Kartengruppen
════════════════════════════════════════════ */

router.get("/card-groups", async (req, res) => {
  try {
    const [groups] = await db.query("SELECT * FROM card_groups ORDER BY id");
    res.json(groups);
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ════════════════════════════════════════════
   GET /api/cards?group_id=X&page=Y&limit=Z
   Alle Karten (Admin-/Gruppen-Ansicht, kein Besitz)
════════════════════════════════════════════ */

router.get("/cards", async (req, res) => {
  const { group_id, page = 1, limit = 12 } = req.query;
  const offset = (page - 1) * limit;

  try {
    const [cards] = await db.query(
      `SELECT c.*, cg.name AS group_name, cg.color AS group_color,
              c.attack, c.defends, c.cooldown, c.\`range\`, c.\`race\`
       FROM cards c
       LEFT JOIN card_groups cg ON cg.id = c.group_id
       WHERE c.group_id = ?
       LIMIT ? OFFSET ?`,
      [group_id, parseInt(limit), parseInt(offset)]
    );
    const [[{ total }]] = await db.query(
      "SELECT COUNT(*) AS total FROM cards WHERE group_id = ?",
      [group_id]
    );
    res.json({ cards, total, page: parseInt(page), totalPages: Math.ceil(total / limit) });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ════════════════════════════════════════════
   GET /api/user-cards?group_id=X&page=Y&limit=Z
   Karten die der Spieler besitzt (mit amount)
════════════════════════════════════════════ */

router.get("/user-cards", async (req, res) => {
  const userId = req.session.user.id;
  const { group_id, page = 1, limit = 18 } = req.query;
  const offset = (page - 1) * limit;

  try {
    const [cards] = await db.query(
      `SELECT
         uc.card_id,
         uc.amount,
         c.name,
         c.image,
         c.rarity,
         cg.name  AS group_name,
         cg.color AS group_color,
         c.attack,
         c.defends,
         c.cooldown,
         c.\`range\`,
         c.\`race\`
       FROM user_cards uc
       JOIN cards       c  ON c.id        = uc.card_id
       JOIN card_groups cg ON cg.id       = c.group_id
       WHERE uc.user_id = ? AND c.group_id = ?
       ORDER BY c.id
       LIMIT ? OFFSET ?`,
      [userId, group_id, parseInt(limit), parseInt(offset)]
    );

    const [[{ total }]] = await db.query(
      `SELECT COUNT(*) AS total
       FROM user_cards uc
       JOIN cards c ON c.id = uc.card_id
       WHERE uc.user_id = ? AND c.group_id = ?`,
      [userId, group_id]
    );

    res.json({ cards, total, page: parseInt(page), totalPages: Math.ceil(total / limit) });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ════════════════════════════════════════════
   GET /api/decks
   Alle Decks des Spielers
════════════════════════════════════════════ */

router.get("/decks", async (req, res) => {
  const userId = req.session.user.id;
  try {
    const [decks] = await db.query(
      `SELECT d.id, d.name,
              COALESCE(SUM(dc.amount), 0) AS card_count
       FROM decks d
       LEFT JOIN deck_cards dc ON dc.deck_id = d.id
       WHERE d.user_id = ?
       GROUP BY d.id
       ORDER BY d.created_at`,
      [userId]
    );
    res.json(decks);
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ════════════════════════════════════════════
   POST /api/decks  { name }
   Neues Deck erstellen (max. 10 pro Spieler)
════════════════════════════════════════════ */

router.post("/decks", async (req, res) => {
  const userId = req.session.user.id;
  const { name } = req.body;

  if (!name || !name.trim()) {
    return res.status(400).json({ error: "Name darf nicht leer sein." });
  }

  try {
    const [[{ count }]] = await db.query(
      "SELECT COUNT(*) AS count FROM decks WHERE user_id = ?",
      [userId]
    );
    if (count >= 10) {
      return res.status(400).json({ error: "Maximale Anzahl von 10 Decks erreicht." });
    }

    const [result] = await db.query(
      "INSERT INTO decks (user_id, name) VALUES (?, ?)",
      [userId, name.trim()]
    );
    res.status(201).json({ id: result.insertId, name: name.trim(), card_count: 0 });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ════════════════════════════════════════════
   GET /api/decks/:id/cards
   Karten eines bestimmten Decks
════════════════════════════════════════════ */

router.get("/decks/:id/cards", async (req, res) => {
  const userId = req.session.user.id;
  const deckId = req.params.id;

  try {
    // Deck gehört dem Spieler?
    const [[deck]] = await db.query(
      "SELECT id FROM decks WHERE id = ? AND user_id = ?",
      [deckId, userId]
    );
    if (!deck) return res.status(404).json({ error: "Deck nicht gefunden." });

    const [cards] = await db.query(
      `SELECT
         dc.card_id,
         LEAST(dc.amount, COALESCE(uc.amount, 0)) AS amount,
         c.name,
         c.image,
         c.rarity,
         c.attack,
         c.defends,
         c.cooldown,
         c.\`range\`,
         c.\`race\`
       FROM deck_cards dc
       JOIN  cards      c  ON c.id        = dc.card_id
       LEFT JOIN user_cards uc ON uc.card_id = dc.card_id
                               AND uc.user_id = ?
       WHERE dc.deck_id = ?
         AND COALESCE(uc.amount, 0) > 0
       ORDER BY c.name`,
      [userId, deckId]
    );
    res.json(cards);
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ════════════════════════════════════════════
   POST /api/decks/:id/cards  { card_id, level }
   Karte zum Deck hinzufügen
════════════════════════════════════════════ */

router.post("/decks/:id/cards", async (req, res) => {
  const userId = req.session.user.id;
  const deckId = req.params.id;
  const { card_id } = req.body;

  if (!card_id) return res.status(400).json({ error: "card_id fehlt." });

  try {
    // Deck gehört dem Spieler?
    const [[deck]] = await db.query(
      "SELECT id FROM decks WHERE id = ? AND user_id = ?",
      [deckId, userId]
    );
    if (!deck) return res.status(404).json({ error: "Deck nicht gefunden." });

    // Besitzt der Spieler diese Karte?
    const [[owned]] = await db.query(
      "SELECT amount FROM user_cards WHERE user_id = ? AND card_id = ?",
      [userId, card_id]
    );
    if (!owned) return res.status(400).json({ error: "Du besitzt diese Karte nicht." });

    // Deck-Gesamtzahl prüfen (max 30)
    const [[{ total }]] = await db.query(
      "SELECT COALESCE(SUM(amount), 0) AS total FROM deck_cards WHERE deck_id = ?",
      [deckId]
    );
    if (total >= 30) {
      return res.status(400).json({ error: "Deck ist voll (max. 30 Karten)." });
    }

    // Rarity > 5: max. 1× im Deck
    const [[cardInfo]] = await db.query(
      "SELECT rarity FROM cards WHERE id = ?",
      [card_id]
    );
    const [[existing]] = await db.query(
      "SELECT amount FROM deck_cards WHERE deck_id = ? AND card_id = ?",
      [deckId, card_id]
    );

    if (parseInt(cardInfo?.rarity) > 5 && existing) {
      return res.status(400).json({ error: "Karten ab Rarity 6 dürfen nur einmal im Deck sein." });
    }

    // Nicht mehr einfügen als besessen
    const currentInDeck = existing ? existing.amount : 0;
    if (currentInDeck >= owned.amount) {
      return res.status(400).json({ error: "Du hast keine weiteren Exemplare dieser Karte." });
    }

    // Einfügen oder erhöhen
    if (existing) {
      await db.query(
        "UPDATE deck_cards SET amount = amount + 1 WHERE deck_id = ? AND card_id = ?",
        [deckId, card_id]
      );
    } else {
      await db.query(
        "INSERT INTO deck_cards (deck_id, card_id, amount) VALUES (?, ?, 1)",
        [deckId, card_id]
      );
    }

    res.json({ success: true });
  } catch (err) {
    // DB-Trigger Fehler (45000) sauber weitergeben
    if (err.sqlState === "45000") {
      return res.status(400).json({ error: err.message });
    }
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ════════════════════════════════════════════
   DELETE /api/decks/:id/cards  { card_id, level }
   Karte aus Deck entfernen (amount - 1, bei 0 löschen)
════════════════════════════════════════════ */

router.delete("/decks/:id/cards", async (req, res) => {
  const userId = req.session.user.id;
  const deckId = req.params.id;
  const { card_id } = req.body;

  if (!card_id) return res.status(400).json({ error: "card_id fehlt." });

  try {
    // Deck gehört dem Spieler?
    const [[deck]] = await db.query(
      "SELECT id FROM decks WHERE id = ? AND user_id = ?",
      [deckId, userId]
    );
    if (!deck) return res.status(404).json({ error: "Deck nicht gefunden." });

    const [[entry]] = await db.query(
      "SELECT id, amount FROM deck_cards WHERE deck_id = ? AND card_id = ?",
      [deckId, card_id]
    );
    if (!entry) return res.status(404).json({ error: "Karte nicht im Deck." });

    if (entry.amount > 1) {
      await db.query(
        "UPDATE deck_cards SET amount = amount - 1 WHERE id = ?",
        [entry.id]
      );
    } else {
      await db.query("DELETE FROM deck_cards WHERE id = ?", [entry.id]);
    }

    res.json({ success: true });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

module.exports = router;