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

/* ================================
   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.maxLevel;
  }
  return weights[weights.length - 1].maxLevel;
}

/* ================================
   Gewichte je Spielerlevel
================================ */
function getWeights(playerLevel) {
  if (playerLevel < 10) return [
    { maxLevel: 1, weight: 85 },
    { maxLevel: 2, weight: 15 },
  ];
  if (playerLevel < 20) return [
    { maxLevel: 1, weight: 65 },
    { maxLevel: 2, weight: 27 },
    { maxLevel: 3, weight: 8  },
  ];
  if (playerLevel < 30) return [
    { maxLevel: 1, weight: 55 },
    { maxLevel: 2, weight: 26 },
    { maxLevel: 3, weight: 13 },
    { maxLevel: 4, weight: 6  },
  ];
  if (playerLevel < 40) return [
    { maxLevel: 1, weight: 50 },
    { maxLevel: 2, weight: 25 },
    { maxLevel: 3, weight: 14 },
    { maxLevel: 4, weight: 7  },
    { maxLevel: 5, weight: 4  },
  ];
  return [
    { maxLevel: 1, weight: 47   },
    { maxLevel: 2, weight: 25   },
    { maxLevel: 3, weight: 15   },
    { maxLevel: 4, weight: 8    },
    { maxLevel: 5, weight: 4.5  },
    { maxLevel: 6, weight: 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 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.maxLevel));

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

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

    const result = [];
    for (let i = 0; i < 5; i++) {
      const targetLevel = weightedRandom(weights);
      let pool = allCards.filter(c => c.max_level === targetLevel);
      if (!pool.length) {
        for (let fb = targetLevel - 1; fb >= 1; fb--) {
          pool = allCards.filter(c => c.max_level === 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" });
  }
});

module.exports = router;