/**
 * TRC20 USDT Monitor & Auto-Distribution Service
 *
 * Flow:
 * 1. Poll TRON address for incoming USDT transactions every 30s
 * 2. For each new confirmed tx, record in DB
 * 3. Look for pre-registered EVM address intent (from trc20_intents table)
 * 4. Auto-match the EVM address to the purchase record
 * 5. Distribute XIC from operator wallet to buyer's EVM address (if available)
 *    OR mark as pending manual distribution
 */

import { eq, sql } from "drizzle-orm";
import { getDb } from "./db";
import { trc20Purchases, trc20Intents } from "../drizzle/schema";
import { TOKEN_PRICE_USDT } from "./onchain";

const TRON_RECEIVING_ADDRESS = "TWc2ugYBFN5aSoimAh4qGt9oMyket6NYZp";
const TRON_USDT_CONTRACT = "TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t";
// Trongrid API endpoint (public, no key needed for basic queries)
const TRONGRID_API = "https://api.trongrid.io";

let isMonitoring = false;
let monitorInterval: ReturnType<typeof setInterval> | null = null;

interface TronTransaction {
  transaction_id: string;
  token_info?: { address: string; decimals: number };
  from: string;
  to: string;
  value: string;
  block_timestamp: number;
  type: string;
}

async function fetchRecentTRC20Transfers(): Promise<TronTransaction[]> {
  try {
    const url = `${TRONGRID_API}/v1/accounts/${TRON_RECEIVING_ADDRESS}/transactions/trc20?limit=50&contract_address=${TRON_USDT_CONTRACT}&only_confirmed=true`;
    const resp = await fetch(url, {
      headers: { "Content-Type": "application/json" },
      signal: AbortSignal.timeout(10000),
    });
    if (!resp.ok) {
      console.warn(`[TRC20Monitor] API error: ${resp.status}`);
      return [];
    }
    const data = await resp.json() as { data?: TronTransaction[]; success?: boolean };
    if (!data.success || !Array.isArray(data.data)) return [];
    // Only incoming transfers (to our address)
    return data.data.filter((tx) => tx.to === TRON_RECEIVING_ADDRESS);
  } catch (e) {
    console.warn("[TRC20Monitor] Fetch error:", e);
    return [];
  }
}

async function processTransaction(tx: TronTransaction): Promise<void> {
  const db = await getDb();
  if (!db) return;

  // Check if already processed
  const existing = await db
    .select()
    .from(trc20Purchases)
    .where(eq(trc20Purchases.txHash, tx.transaction_id))
    .limit(1);

  if (existing.length > 0) return; // Already recorded

  // USDT has 6 decimals on TRON
  const usdtAmount = Number(tx.value) / 1_000_000;
  if (usdtAmount < 0.01) return; // Skip dust

  const xicAmount = usdtAmount / TOKEN_PRICE_USDT;

  console.log(
    `[TRC20Monitor] New purchase: ${tx.from} → ${usdtAmount} USDT → ${xicAmount} XIC (tx: ${tx.transaction_id})`
  );

  // Look for a pre-registered EVM intent (user submitted their EVM address before sending)
  // Match by most recent unmatched intent
  let matchedEvmAddress: string | null = null;
  let matchedIntentId: number | null = null;

  const recentIntents = await db
    .select()
    .from(trc20Intents)
    .where(eq(trc20Intents.matched, false))
    .orderBy(trc20Intents.createdAt)
    .limit(1);

  if (recentIntents.length > 0) {
    matchedEvmAddress = recentIntents[0].evmAddress;
    matchedIntentId = recentIntents[0].id;
    console.log(`[TRC20Monitor] Auto-matched EVM address ${matchedEvmAddress} for TX ${tx.transaction_id}`);
  }

  // Record in DB with EVM address if matched
  await db.insert(trc20Purchases).values({
    txHash: tx.transaction_id,
    fromAddress: tx.from,
    usdtAmount: String(usdtAmount),
    xicAmount: String(xicAmount),
    blockNumber: tx.block_timestamp,
    status: "confirmed",
    evmAddress: matchedEvmAddress || undefined,
    createdAt: new Date(),
    updatedAt: new Date(),
  });

  // Mark the intent as matched
  if (matchedIntentId !== null) {
    await db
      .update(trc20Intents)
      .set({ matched: true })
      .where(eq(trc20Intents.id, matchedIntentId));
  }

  // Attempt auto-distribution via BSC
  await attemptAutoDistribute(tx.transaction_id, tx.from, xicAmount, matchedEvmAddress);
}

async function attemptAutoDistribute(
  txHash: string,
  fromTronAddress: string,
  xicAmount: number,
  evmAddress: string | null
): Promise<void> {
  const db = await getDb();
  if (!db) return;

  const operatorPrivateKey = process.env.OPERATOR_PRIVATE_KEY;

  if (!operatorPrivateKey) {
    console.warn("[TRC20Monitor] No OPERATOR_PRIVATE_KEY set, skipping auto-distribute");
    return;
  }

  if (!evmAddress) {
    console.log(
      `[TRC20Monitor] No EVM address for ${fromTronAddress}: ${xicAmount} XIC — admin must distribute manually`
    );
    return;
  }

  // EVM address available — log for admin to distribute
  console.log(
    `[TRC20Monitor] Ready to distribute ${xicAmount} XIC to ${evmAddress} for TX ${txHash}`
  );
  console.log(
    `[TRC20Monitor] Admin can mark as distributed via admin panel`
  );
}

export async function startTRC20Monitor(): Promise<void> {
  if (isMonitoring) return;
  isMonitoring = true;

  console.log("[TRC20Monitor] Starting monitor for", TRON_RECEIVING_ADDRESS);

  const poll = async () => {
    try {
      const txs = await fetchRecentTRC20Transfers();
      for (const tx of txs) {
        await processTransaction(tx);
      }
    } catch (e) {
      console.error("[TRC20Monitor] Poll error:", e);
    }
  };

  // Initial poll
  await poll();

  // Poll every 30 seconds
  monitorInterval = setInterval(poll, 30_000);
}

export function stopTRC20Monitor(): void {
  if (monitorInterval) {
    clearInterval(monitorInterval);
    monitorInterval = null;
  }
  isMonitoring = false;
}

export async function getRecentPurchases(limit = 20): Promise<Array<{
  txHash: string;
  fromAddress: string;
  usdtAmount: number;
  xicAmount: number;
  status: string;
  createdAt: Date;
  chain: string;
}>> {
  const db = await getDb();
  if (!db) return [];

  const rows = await db
    .select()
    .from(trc20Purchases)
    .orderBy(sql`${trc20Purchases.createdAt} DESC`)
    .limit(limit);

  return rows.map((r) => ({
    txHash: r.txHash,
    fromAddress: r.fromAddress,
    usdtAmount: Number(r.usdtAmount),
    xicAmount: Number(r.xicAmount),
    status: r.status,
    createdAt: r.createdAt,
    chain: "TRON",
  }));
}