const express = require("express");
const router = express.Router();
const db = require("../database/database");
const { getMaxRarity } = require("../utils/rarity");

/* ================================
   Gewichtete Zufallsauswahl
================================ */
function weightedRandom(weights) {
  const total = weights.reduce((s, w) => s + w.weight, 0);
  let r = Math.random() * total;
  for (const entry of weights) {
    r -= entry.weight;
    if (r <= 0) return entry.rarity;
  }
  return weights[weights.length - 1].rarity;
}

/* ================================
   Gewichte je Spielerlevel
================================ */
function getWeights(playerLevel) {
  if (playerLevel < 10)
    return [
      { rarity: 1, weight: 95 }, // 95%
      { rarity: 2, weight: 5 }, //  5%
    ];
  if (playerLevel < 20)
    return [
      { rarity: 1, weight: 87 }, // 87%
      { rarity: 2, weight: 11 }, // 11%
      { rarity: 3, weight: 2 }, //  2%
    ];
  if (playerLevel < 30)
    return [
      { rarity: 1, weight: 80 }, // 80%
      { rarity: 2, weight: 14 }, // 14%
      { rarity: 3, weight: 4 }, //  4%
      { rarity: 4, weight: 2 }, //  2%
    ];
  if (playerLevel < 40)
    return [
      { rarity: 1, weight: 75 }, // 75%
      { rarity: 2, weight: 16 }, // 16%
      { rarity: 3, weight: 5 }, //  5%
      { rarity: 4, weight: 3 }, //  3%
      { rarity: 5, weight: 1 }, //  1%
    ];
  return [
    { rarity: 1, weight: 60 }, // 60.0%
    { rarity: 2, weight: 25 }, // 25.0%
    { rarity: 3, weight: 9 }, //  9.0%
    { rarity: 4, weight: 4 }, //  4.0%
    { rarity: 5, weight: 1.5 }, //  1.5%
    { rarity: 6, weight: 0.5 }, //  0.5%
  ];
}

/* ================================
   GET /api/booster/cards
   Alle Karten inkl. Stats für Slot-Animation
================================ */
router.get("/booster/cards", async (req, res) => {
  if (!req.session?.user)
    return res.status(401).json({ error: "Nicht eingeloggt" });
  try {
    const [cards] = await db.query(
      "SELECT id, name, image, icon, max_level, rarity, attack, defends, cooldown, `range`, `race` FROM cards ORDER BY id",
    );
    res.json(cards);
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ================================
   POST /api/booster/open
   5 gewichtete Zufallskarten inkl. Stats
================================ */
router.post("/booster/open", async (req, res) => {
  if (!req.session?.user)
    return res.status(401).json({ error: "Nicht eingeloggt" });

  const userId = req.session.user.id;
  try {
    const [[account]] = await db.query(
      "SELECT level FROM accounts WHERE id = ?",
      [userId],
    );
    const playerLevel = account?.level ?? 1;
    const weights = getWeights(playerLevel);
    const maxAllowed = Math.max(...weights.map((w) => w.rarity));

    const [allCards] = await db.query(
      "SELECT id, name, image, icon, max_level, rarity, attack, defends, cooldown, `range`, `race` FROM cards WHERE rarity <= ?",
      [maxAllowed],
    );

    if (!allCards.length)
      return res.status(400).json({ error: "Keine Karten verfügbar" });

    const result = [];
    for (let i = 0; i < 5; i++) {
      const targetRarity = weightedRandom(weights);
      let pool = allCards.filter((c) => parseInt(c.rarity) === targetRarity);
      if (!pool.length) {
        for (let fb = targetRarity - 1; fb >= 1; fb--) {
          pool = allCards.filter((c) => parseInt(c.rarity) === fb);
          if (pool.length) break;
        }
      }
      if (!pool.length) pool = allCards;
      result.push(pool[Math.floor(Math.random() * pool.length)]);
    }

    res.json({ cards: result, playerLevel });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler" });
  }
});

/* ================================
   POST /api/booster/save
   Gezogene Karten in user_cards speichern
   Body: { cardIds: [1, 2, 3, 4, 5] }
================================ */
router.post("/booster/save", async (req, res) => {
  if (!req.session?.user)
    return res.status(401).json({ error: "Nicht eingeloggt" });

  const userId = req.session.user.id;
  const cardIds = req.body?.cardIds;

  if (!Array.isArray(cardIds) || cardIds.length === 0) {
    return res.status(400).json({ error: "Keine Karten übergeben" });
  }

  try {
    for (const cardId of cardIds) {
      await db.query(
        `INSERT INTO user_cards (user_id, card_id, amount)
         VALUES (?, ?, 1)
         ON DUPLICATE KEY UPDATE amount = amount + 1`,
        [userId, cardId],
      );
    }
    res.json({ success: true });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: "DB Fehler beim Speichern" });
  }
});

/* ================================
   POST /api/booster/wood-donate
   100 Holz bezahlen → 1 zufällige Rarity-3 Karte
================================ */
router.post("/booster/wood-donate", async (req, res) => {
  if (!req.session?.user)
    return res.status(401).json({ error: "Nicht eingeloggt" });

  const userId = req.session.user.id;
  try {
    // Holz prüfen
    const [[currency]] = await db.query(
      "SELECT wood FROM account_currency WHERE account_id = ?",
      [userId],
    );
    if (!currency || currency.wood < 100) {
      return res.status(400).json({ error: "Nicht genug Holz (100 benötigt)" });
    }

    // Spielerlevel → passende Rarity bestimmen
    const [[acc]] = await db.query("SELECT level FROM accounts WHERE id = ?", [userId]);
    const woodRarity = getMaxRarity(acc?.level ?? 1);

    const [pool] = await db.query(
      "SELECT id, name, image, icon, max_level, rarity, attack, defends, cooldown, `range`, `race` FROM cards WHERE rarity = ?",
      [woodRarity]
    );
    if (!pool.length)
      return res.status(400).json({ error: `Keine Rarity-${woodRarity} Karten verfügbar` });

    // 100 Holz abziehen
    await db.query(
      "UPDATE account_currency SET wood = wood - 100 WHERE account_id = ?",
      [userId],
    );

    // 1 zufällige Rarity-3 Karte ziehen
    const card = pool[Math.floor(Math.random() * pool.length)];

    // Direkt in user_cards speichern
    await db.query(
      `INSERT INTO user_cards (user_id, card_id, amount) VALUES (?, ?, 1)
       ON DUPLICATE KEY UPDATE amount = amount + 1`,
      [userId, card.id],
    );

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

/* ================================
   POST /api/booster/gold-donate
   100 Gold bezahlen → 1 zufällige Rarity-4 Karte
================================ */
router.post("/booster/gold-donate", async (req, res) => {
  if (!req.session?.user)
    return res.status(401).json({ error: "Nicht eingeloggt" });

  const userId = req.session.user.id;
  try {
    const [[currency]] = await db.query(
      "SELECT gold FROM account_currency WHERE account_id = ?",
      [userId],
    );
    if (!currency || currency.gold < 100) {
      return res.status(400).json({ error: "Nicht genug Gold (100 benötigt)" });
    }

    // Spielerlevel → 1 Rarity über dem Maximum (Bonus für Gold)
    const [[accG]] = await db.query("SELECT level FROM accounts WHERE id = ?", [userId]);
    const goldRarity = Math.min(getMaxRarity(accG?.level ?? 1) + 1, 6);

    const [pool] = await db.query(
      "SELECT id, name, image, icon, max_level, rarity, attack, defends, cooldown, `range`, `race` FROM cards WHERE rarity = ?",
      [goldRarity]
    );
    if (!pool.length)
      return res.status(400).json({ error: `Keine Rarity-${goldRarity} Karten verfügbar` });

    await db.query(
      "UPDATE account_currency SET gold = gold - 100 WHERE account_id = ?",
      [userId],
    );

    const card = pool[Math.floor(Math.random() * pool.length)];

    await db.query(
      `INSERT INTO user_cards (user_id, card_id, amount) VALUES (?, ?, 1)
       ON DUPLICATE KEY UPDATE amount = amount + 1`,
      [userId, card.id],
    );

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

module.exports = router;