services/strikeEngine.js

const axios = require("axios");
const crypto = require("crypto");

const Asset = require("../models/Asset");
const User = require("../models/User");
const Transaction = require("../models/Transaction");
const StrikeHistory = require("../models/StrikeHistory");
const { sendGlobal, sendToUser } = require('../utils/sendPush');

const WIN_PCT = {
  Silver:   [0.30, 0.15, 0.08],
  Gold:     [0.40, 0.20, 0.10],
  Platinum: [0.50, 0.25, 0.125]
};

const circularDiff = (a, b, mod) => {
  const diff = Math.abs(a - b);
  return Math.min(diff, mod - diff);
};

const secureShuffle = (arr) => {
  for (let i = arr.length - 1; i > 0; i--) {
    const j = crypto.randomInt(0, i + 1);
    [arr[i], arr[j]] = [arr[j], arr[i]];
  }
};

const sha256 = (payload) =>
  crypto.createHash("sha256").update(JSON.stringify(payload)).digest("hex");

async function runStrike({ triggeredBy = "CRON" } = {}) {
  if (global.isStrikeRunning) return;

  global.isStrikeRunning = true;
  global.lastStrikeStatus = "RUNNING";
  global.lastStrikeResult = null;

  try {
    // ⛔ prevent double strike per day
    const startOfDay = new Date();
    startOfDay.setUTCHours(0, 0, 0, 0);

    const already = await StrikeHistory.findOne({
      date: { $gte: startOfDay }
    });

    if (already) {
      global.lastStrikeStatus = "COMPLETED";
      return;
    }

    // 🔔 START EVENT
    await sendGlobal(
      "⚡ Strike Started!",
      triggeredBy === "ADMIN"
        ? "Admin manually triggered today's strike."
        : "The 8 PM Strike is LIVE.",
      "/"
    );

    // 1️⃣ BTC PRICE
    const { data } = await axios.get(
      "https://api.binance.com/api/v3/ticker/price?symbol=BTCUSDT"
    );

    const price = parseFloat(data.price).toFixed(2);

    const btcInt = price.split(".")[0];
    const btcLast3 = parseInt(btcInt.slice(-3));
    const btcLast6 = parseInt(btcInt.slice(-6));

    global.liveStrikeData = {
      price,
      btcLast3,
      btcLast6
    };

    // 2️⃣ POOL
    const txs = await Transaction.find({
      timestamp: { $gte: startOfDay },
      status: "Verified"
    });

    const totalPool = txs.reduce((s, t) => s + t.amount, 0);

    if (!totalPool) {
      global.lastStrikeStatus = "CANCELLED";
      return;
    }

    // 3️⃣ ASSETS
    const assets = await Asset.find({
      purchase_date: { $gte: startOfDay },
      status: "Held"
    }).populate("owner_id");

    // 4️⃣ LOW PARTICIPATION → CANCEL
    if (assets.length <= 3) {
      const prices = { Silver: 500, Gold: 1000, Platinum: 2500 };

      for (const a of assets) {
        await User.findByIdAndUpdate(a.owner_id._id, {
          $inc: { wallet_balance: prices[a.tier] }
        });
        a.status = "Burned";
        await a.save();
      }

      global.lastStrikeStatus = "CANCELLED";
      global.lastStrikeResult = { cancelled: true };

      await sendGlobal(
        "🚫 Strike Cancelled",
        "Low participation. Refunds issued.",
        "/profile"
      );

      return;
    }

    // 5️⃣ RANKING
    let ranked = assets.map(asset => {
      const kusLast6 = parseInt(asset.kus_id.slice(-6));
      const kusLast3 = kusLast6 % 1000;

      return {
        asset,
        diff3: circularDiff(kusLast3, btcLast3, 1000),
        diff6: circularDiff(kusLast6, btcLast6, 1_000_000)
      };
    });

    ranked.sort((a, b) => {
      if (a.diff3 !== b.diff3) return a.diff3 - b.diff3;
      if (a.diff6 !== b.diff6) return a.diff6 - b.diff6;
      return 0;
    });

    secureShuffle(ranked.slice(0, 3));

    // 6️⃣ WINNERS
    const historyWinners = [];

    for (let i = 0; i < 3; i++) {
      const { asset } = ranked[i];
      const pct = WIN_PCT[asset.tier][i];
      if (!pct) continue;

      const gross = totalPool * pct;
      const net = gross * (1 - 0.312);

      await User.findByIdAndUpdate(asset.owner_id._id, {
        $inc: { wallet_balance: net }
      });

      await Transaction.create({
        user_id: asset.owner_id._id,
        amount: net,
        status: "Verified",
        tier: asset.tier,
        utr: `STRIKE-${Date.now()}`
      });

      historyWinners.push({
        tier: asset.tier,
        user_id: asset.owner_id._id,
        amount: net,
        rank: i + 1,
        kus_id: asset.kus_id
      });

      await sendToUser(
        asset.owner_id._id,
        "🏆 YOU WON!",
        `Rank #${i + 1} in today's strike.`,
        "/profile"
      );
    }

    // 7️⃣ AUDIT
    const auditPayload = {
      price,
      btcLast3,
      btcLast6,
      pool: totalPool,
      participants: assets.map(a => a.kus_id),
      winners: historyWinners,
      triggeredBy
    };

    const auditHash = sha256(auditPayload);

    await StrikeHistory.create({
      target_price: price,
      winning_digits: btcLast3,
      total_pool: totalPool,
      audit_hash: auditHash,
      audit_payload: auditPayload,
      winners: historyWinners
    });

    // ✅ FINAL GLOBAL RESULT (frontend reads this)
    global.lastStrikeStatus = "COMPLETED";
    global.lastStrikeResult = {
      cancelled: false,
      winningDigits: btcLast3,
      winners: historyWinners
    };

    await sendGlobal(
      "🏁 Results Announced",
      "Strike completed successfully.",
      "/"
    );

  } catch (err) {
    console.error("❌ Strike failed:", err);
    global.lastStrikeStatus = "FAILED";
  } finally {
    global.isStrikeRunning = false;
    global.liveStrikeData = null;
    console.log("⚡ STRIKE ENDED ⚡");
  }
}


module.exports = { runStrike };