/**
 * Wallet operations across chains: balance, transactions, build unsigned send tx.
 * Non-custodial: server NEVER signs — клиент подписывает приватом.
 */
import { ethers } from 'ethers';
import { env } from '../config/env';

export type ChainCode = 'ETH' | 'BTC' | 'SOL' | 'TRX' | 'BSC';

const TIMEOUT_MS = 15_000;

// ── External APIs ──
const BLOCKSTREAM = 'https://blockstream.info/api';
const TRONGRID = 'https://api.trongrid.io';
const BSC_RPC = 'https://bsc-dataseed.binance.org';
const ETH_RPC = 'https://ethereum-rpc.publicnode.com';
const SOL_RPC = 'https://api.mainnet-beta.solana.com';

const USDT_TRC20 = 'TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t';
const USDT_BEP20 = '0x55d398326f99059fF775485246999027B3197955';
const USDT_ERC20 = '0xdAC17F958D2ee523a2206206994597C13D831ec7';

const ERC20_ABI = [
  'function balanceOf(address owner) view returns (uint256)',
  'function transfer(address to, uint256 amount) returns (bool)',
  'function decimals() view returns (uint8)',
];

// ─────────────────────── BALANCE ───────────────────────

export interface BalanceResult {
  chain: ChainCode;
  address: string;
  native: string; // в smallest units (satoshi/wei/lamports/sun)
  tokens?: Record<string, string>; // например { USDT: "12345678" }
}

export async function getBalance(chain: ChainCode, address: string): Promise<BalanceResult> {
  switch (chain) {
    case 'BTC':
      return { chain, address, native: await btcBalance(address) };
    case 'TRX': {
      const { trx, usdt } = await trxBalance(address);
      return { chain, address, native: trx, tokens: { USDT: usdt } };
    }
    case 'BSC': {
      const { native, tokens } = await evmBalance(BSC_RPC, address, [{ symbol: 'USDT', addr: USDT_BEP20 }]);
      return { chain, address, native, tokens };
    }
    case 'ETH': {
      const { native, tokens } = await evmBalance(ETH_RPC, address, [{ symbol: 'USDT', addr: USDT_ERC20 }]);
      return { chain, address, native, tokens };
    }
    case 'SOL':
      return { chain, address, native: await solBalance(address) };
  }
}

async function btcBalance(address: string): Promise<string> {
  const res = await fetchJson(`${BLOCKSTREAM}/address/${address}`);
  const stats = res.chain_stats;
  const sat = BigInt(stats.funded_txo_sum) - BigInt(stats.spent_txo_sum);
  return sat.toString();
}

async function trxBalance(address: string): Promise<{ trx: string; usdt: string }> {
  const headers: Record<string, string> = { Accept: 'application/json' };
  if (env.tronApiKey) headers['TRON-PRO-API-KEY'] = env.tronApiKey;

  const accRes = await fetchJson(`${TRONGRID}/v1/accounts/${address}`, { headers });
  const trx = accRes.data?.[0]?.balance ? String(accRes.data[0].balance) : '0';

  // USDT TRC20 balance
  const usdtRes = await fetchJson(`${TRONGRID}/wallet/triggerconstantcontract`, {
    method: 'POST',
    headers: { ...headers, 'Content-Type': 'application/json' },
    body: JSON.stringify({
      owner_address: address,
      contract_address: USDT_TRC20,
      function_selector: 'balanceOf(address)',
      parameter: tronAddressToHex(address).padStart(64, '0'),
      visible: true,
    }),
  });
  const usdtHex = usdtRes.constant_result?.[0];
  const usdt = usdtHex && !/^0+$/.test(usdtHex) ? BigInt('0x' + usdtHex).toString() : '0';

  return { trx, usdt };
}

async function evmBalance(
  rpc: string,
  address: string,
  tokens: { symbol: string; addr: string }[],
): Promise<{ native: string; tokens: Record<string, string> }> {
  const provider = new ethers.providers.StaticJsonRpcProvider(rpc);
  const native = await withTimeout(provider.getBalance(address), TIMEOUT_MS, 'EVM balance timeout');

  const tokenBalances: Record<string, string> = {};
  await Promise.all(
    tokens.map(async ({ symbol, addr }) => {
      try {
        const c = new ethers.Contract(addr, ERC20_ABI, provider);
        const bal: ethers.BigNumber = await withTimeout(c.balanceOf(address), TIMEOUT_MS, `${symbol} balance timeout`);
        tokenBalances[symbol] = bal.toString();
      } catch {
        tokenBalances[symbol] = '0';
      }
    }),
  );

  return { native: native.toString(), tokens: tokenBalances };
}

async function solBalance(address: string): Promise<string> {
  const res = await fetchJson(SOL_RPC, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      jsonrpc: '2.0',
      id: 1,
      method: 'getBalance',
      params: [address],
    }),
  });
  return String(res.result?.value ?? 0);
}

// ─────────────────────── TRANSACTIONS ───────────────────────

export interface TxItem {
  txid: string;
  timestamp: number | null; // unix seconds
  direction: 'in' | 'out' | 'self';
  amount?: string;
  token?: string;
  to?: string;
  from?: string;
}

export async function getTransactions(chain: ChainCode, address: string, limit: number): Promise<TxItem[]> {
  switch (chain) {
    case 'BTC':
      return btcTransactions(address, limit);
    case 'TRX':
      return trxTransactions(address, limit);
    case 'BSC':
      return scanTransactions('https://api.bscscan.com/api', env.bscscanApiKey, address, limit);
    case 'ETH':
      return scanTransactions('https://api.etherscan.io/api', env.etherscanApiKey, address, limit);
    case 'SOL':
      return solTransactions(address, limit);
  }
}

async function scanTransactions(
  apiBase: string,
  apiKey: string | null,
  address: string,
  limit: number,
): Promise<TxItem[]> {
  if (!apiKey) return [];

  const url = new URL(apiBase);
  url.searchParams.set('module', 'account');
  url.searchParams.set('action', 'txlist');
  url.searchParams.set('address', address);
  url.searchParams.set('startblock', '0');
  url.searchParams.set('endblock', '99999999');
  url.searchParams.set('page', '1');
  url.searchParams.set('offset', String(Math.min(limit, 100)));
  url.searchParams.set('sort', 'desc');
  url.searchParams.set('apikey', apiKey);

  const res = await fetchJson(url.toString());
  if (res.status !== '1' || !Array.isArray(res.result)) return [];

  return (res.result as any[]).slice(0, limit).map((tx) => {
    const isOut = String(tx.from).toLowerCase() === address.toLowerCase();
    return {
      txid: tx.hash,
      timestamp: tx.timeStamp ? parseInt(tx.timeStamp, 10) : null,
      direction: (isOut ? 'out' : 'in') as TxItem['direction'],
      amount: tx.value || undefined,
      from: tx.from,
      to: tx.to,
    };
  });
}

async function btcTransactions(address: string, limit: number): Promise<TxItem[]> {
  const txs = await fetchJson(`${BLOCKSTREAM}/address/${address}/txs`);
  return (txs as any[]).slice(0, limit).map((tx) => {
    const inSelf = tx.vin.some((v: any) => v.prevout?.scriptpubkey_address === address);
    const outSelf = tx.vout.some((v: any) => v.scriptpubkey_address === address);
    const direction: TxItem['direction'] = inSelf && outSelf ? 'self' : inSelf ? 'out' : 'in';
    return {
      txid: tx.txid,
      timestamp: tx.status?.block_time ?? null,
      direction,
      amount: String(
        tx.vout
          .filter((v: any) => (direction === 'in' ? v.scriptpubkey_address === address : v.scriptpubkey_address !== address))
          .reduce((s: bigint, v: any) => s + BigInt(v.value), 0n),
      ),
    };
  });
}

async function trxTransactions(address: string, limit: number): Promise<TxItem[]> {
  const headers: Record<string, string> = { Accept: 'application/json' };
  if (env.tronApiKey) headers['TRON-PRO-API-KEY'] = env.tronApiKey;

  const res = await fetchJson(
    `${TRONGRID}/v1/accounts/${address}/transactions?limit=${limit}`,
    { headers },
  );
  return ((res.data as any[]) || []).slice(0, limit).map((tx) => {
    const contract = tx.raw_data?.contract?.[0];
    const value = contract?.parameter?.value;
    const fromAddr = value?.owner_address ? hexToTron(value.owner_address) : '';
    const toAddr = value?.to_address ? hexToTron(value.to_address) : '';
    const isOut = fromAddr === address;
    return {
      txid: tx.txID,
      timestamp: tx.block_timestamp ? Math.floor(tx.block_timestamp / 1000) : null,
      direction: (isOut ? 'out' : 'in') as TxItem['direction'],
      amount: value?.amount ? String(value.amount) : undefined,
      from: fromAddr || undefined,
      to: toAddr || undefined,
    };
  });
}

async function solTransactions(address: string, limit: number): Promise<TxItem[]> {
  const res = await fetchJson(SOL_RPC, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      jsonrpc: '2.0',
      id: 1,
      method: 'getSignaturesForAddress',
      params: [address, { limit }],
    }),
  });
  return ((res.result as any[]) || []).map((sig) => ({
    txid: sig.signature,
    timestamp: sig.blockTime ?? null,
    direction: 'self' as const, // без deep parsing — направление неизвестно
  }));
}

// ─────────────────────── BUILD SEND (UNSIGNED TX) ───────────────────────

export interface BuildSendParams {
  chain: ChainCode;
  from: string;
  to: string;
  amount: string;
  token?: string; // 'USDT' и т.д.; для native перевода — undefined
}

export type UnsignedTx =
  | { kind: 'btc'; from: string; to: string; amountSat: string; utxos: any[]; feeRateSatPerVb: number }
  | { kind: 'tron'; transaction: any }
  | { kind: 'evm'; to: string; data: string; value: string; chainId: number; gasLimit?: string }
  | { kind: 'solana'; instructions: any; recentBlockhash: string };

export async function buildSend(p: BuildSendParams): Promise<UnsignedTx> {
  switch (p.chain) {
    case 'BTC':
      return buildBtcSend(p);
    case 'TRX':
      return buildTrxSend(p);
    case 'BSC':
      return buildEvmSend(p, BSC_RPC, 56, USDT_BEP20);
    case 'ETH':
      return buildEvmSend(p, ETH_RPC, 1, USDT_ERC20);
    case 'SOL':
      return buildSolSend(p);
  }
}

async function buildBtcSend(p: BuildSendParams): Promise<UnsignedTx> {
  if (p.token) throw new Error('BTC tokens not supported');
  const utxos = await fetchJson(`${BLOCKSTREAM}/address/${p.from}/utxo`);
  const fees = await fetchJson(`${BLOCKSTREAM}/fee-estimates`);
  const confirmed = ((utxos as any[]) || []).filter((u) => u.status?.confirmed);

  return {
    kind: 'btc',
    from: p.from,
    to: p.to,
    amountSat: p.amount,
    utxos: confirmed.map((u) => ({ txid: u.txid, vout: u.vout, value: u.value })),
    feeRateSatPerVb: Math.ceil((fees as any)['3'] ?? (fees as any)['6'] ?? 5),
  };
}

async function buildTrxSend(p: BuildSendParams): Promise<UnsignedTx> {
  const headers: Record<string, string> = { 'Content-Type': 'application/json' };
  if (env.tronApiKey) headers['TRON-PRO-API-KEY'] = env.tronApiKey;

  if (!p.token) {
    // Native TRX
    const res = await fetchJson(`${TRONGRID}/wallet/createtransaction`, {
      method: 'POST',
      headers,
      body: JSON.stringify({ owner_address: p.from, to_address: p.to, amount: Number(p.amount), visible: true }),
    });
    return { kind: 'tron', transaction: res };
  }

  if (p.token.toUpperCase() === 'USDT') {
    // TRC20 USDT
    const param = tronAddressToHex(p.to).padStart(64, '0') + BigInt(p.amount).toString(16).padStart(64, '0');
    const res = await fetchJson(`${TRONGRID}/wallet/triggersmartcontract`, {
      method: 'POST',
      headers,
      body: JSON.stringify({
        owner_address: p.from,
        contract_address: USDT_TRC20,
        function_selector: 'transfer(address,uint256)',
        parameter: param,
        fee_limit: 100_000_000,
        call_value: 0,
        visible: true,
      }),
    });
    return { kind: 'tron', transaction: res };
  }

  throw new Error(`Token ${p.token} not supported on TRX`);
}

async function buildEvmSend(p: BuildSendParams, rpc: string, chainId: number, usdtAddr: string): Promise<UnsignedTx> {
  if (!ethers.utils.isAddress(p.to)) throw new Error('Invalid recipient address');

  if (!p.token) {
    return { kind: 'evm', to: p.to, data: '0x', value: ethers.BigNumber.from(p.amount).toHexString(), chainId };
  }

  if (p.token.toUpperCase() === 'USDT') {
    const iface = new ethers.utils.Interface(ERC20_ABI);
    const data = iface.encodeFunctionData('transfer', [p.to, p.amount]);
    return { kind: 'evm', to: usdtAddr, data, value: '0x0', chainId };
  }

  throw new Error(`Token ${p.token} not supported on ${chainId === 56 ? 'BSC' : 'ETH'}`);
}

async function buildSolSend(p: BuildSendParams): Promise<UnsignedTx> {
  const {
    Connection,
    PublicKey,
    SystemProgram,
    Transaction,
  } = await import('@solana/web3.js');

  const conn = new Connection(SOL_RPC, 'confirmed');

  let fromPk: InstanceType<typeof PublicKey>;
  let toPk: InstanceType<typeof PublicKey>;
  try {
    fromPk = new PublicKey(p.from);
    toPk = new PublicKey(p.to);
  } catch {
    throw new Error('Invalid Solana address');
  }

  const { blockhash, lastValidBlockHeight } = await conn.getLatestBlockhash();
  const tx = new Transaction({
    feePayer: fromPk,
    blockhash,
    lastValidBlockHeight,
  });

  if (!p.token) {
    // Native SOL transfer
    tx.add(
      SystemProgram.transfer({
        fromPubkey: fromPk,
        toPubkey: toPk,
        lamports: BigInt(p.amount),
      }),
    );
  } else {
    // SPL token transfer (manual instruction — не тянем @solana/spl-token)
    const TOKEN_PROGRAM_ID = new PublicKey('TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA');
    const ASSOCIATED_TOKEN_PROGRAM_ID = new PublicKey('ATokenGPvbdGVxr1b2hvZbsiqW5xWH25efTNsLJA8knL');

    const mint = solMintFor(p.token);
    if (!mint) throw new Error(`Unsupported SOL token: ${p.token}`);

    const fromAta = await deriveAta(new PublicKey(mint), fromPk, TOKEN_PROGRAM_ID, ASSOCIATED_TOKEN_PROGRAM_ID);
    const toAta = await deriveAta(new PublicKey(mint), toPk, TOKEN_PROGRAM_ID, ASSOCIATED_TOKEN_PROGRAM_ID);

    // Transfer instruction (instruction tag = 3 для SPL Token Transfer)
    const data = Buffer.alloc(9);
    data.writeUInt8(3, 0);
    data.writeBigUInt64LE(BigInt(p.amount), 1);

    tx.add({
      programId: TOKEN_PROGRAM_ID,
      keys: [
        { pubkey: fromAta, isSigner: false, isWritable: true },
        { pubkey: toAta, isSigner: false, isWritable: true },
        { pubkey: fromPk, isSigner: true, isWritable: false },
      ],
      data,
    });
  }

  // Сериализуем сообщение (без подписей) для клиента
  const serialized = tx.serialize({ requireAllSignatures: false, verifySignatures: false });

  return {
    kind: 'solana',
    instructions: serialized.toString('base64'),
    recentBlockhash: blockhash,
  };
}

function solMintFor(symbol: string): string | null {
  const map: Record<string, string> = {
    USDT: 'Es9vMFrzaCERmJfrF4H2FYD4KCoNkY11McCe8BenwNYB',
    USDC: 'EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v',
  };
  return map[symbol] ?? null;
}

async function deriveAta(
  mint: any,
  owner: any,
  tokenProgramId: any,
  associatedTokenProgramId: any,
): Promise<any> {
  const { PublicKey } = await import('@solana/web3.js');
  const [pda] = await PublicKey.findProgramAddress(
    [owner.toBuffer(), tokenProgramId.toBuffer(), mint.toBuffer()],
    associatedTokenProgramId,
  );
  return pda;
}

// ─────────────────────── HELPERS ───────────────────────

const BASE58_ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';

function tronAddressToHex(address: string): string {
  let num = 0n;
  for (const ch of address) {
    const i = BASE58_ALPHABET.indexOf(ch);
    if (i === -1) throw new Error('Invalid base58 character in TRON address');
    num = num * 58n + BigInt(i);
  }
  const hex = num.toString(16).padStart(50, '0');
  return hex.slice(2, 42); // 20 bytes без префикса 0x41
}

function hexToTron(hex: string): string {
  // Формат TronGrid: 41xxxx (20 bytes after prefix). Это base58check.
  // Для простоты возвращаем как есть hex (можно улучшить на full base58check если нужно).
  return hex;
}

async function fetchJson(url: string, init?: RequestInit): Promise<any> {
  const controller = new AbortController();
  const t = setTimeout(() => controller.abort(), TIMEOUT_MS);
  try {
    const res = await fetch(url, { ...init, signal: controller.signal });
    if (!res.ok) {
      const body = await res.text().catch(() => '');
      throw new Error(`Upstream ${res.status}: ${body.slice(0, 200)}`);
    }
    return await res.json();
  } finally {
    clearTimeout(t);
  }
}

function withTimeout<T>(promise: Promise<T>, ms: number, msg: string): Promise<T> {
  return new Promise<T>((resolve, reject) => {
    const t = setTimeout(() => reject(new Error(msg)), ms);
    promise.then(
      (v) => { clearTimeout(t); resolve(v); },
      (e) => { clearTimeout(t); reject(e); },
    );
  });
}