import crypto from 'crypto';

const BASE = 'https://web3.okx.com';

// Signature rule:
//   GET  → body = "", requestPath includes query string (e.g., "/api/v6/dex/pre-transaction/gas-price?chainIndex=1")
//   POST → body = JSON string of request body, requestPath is path only (e.g., "/api/v6/dex/pre-transaction/gas-limit")
//   Note: Endpoints #1-2, #6 are GET; endpoints #3-5 are POST
async function okxFetch(method: 'GET' | 'POST', path: string, body?: object) {
  const timestamp = new Date().toISOString();
  const bodyStr = body ? JSON.stringify(body) : '';
  const sign = crypto
    .createHmac('sha256', process.env.OKX_SECRET_KEY!)
    .update(timestamp + method + path + bodyStr)
    .digest('base64');
  const headers: Record<string, string> = {
    'OK-ACCESS-KEY': process.env.OKX_API_KEY!,
    'OK-ACCESS-SIGN': sign,
    'OK-ACCESS-PASSPHRASE': process.env.OKX_PASSPHRASE!,
    'OK-ACCESS-TIMESTAMP': timestamp,
    'Content-Type': 'application/json',
  };
  const res = await fetch(`${BASE}${path}`, {
    method,
    headers,
    ...(body && { body: bodyStr }),
  });
  if (res.status === 429) throw { code: 'RATE_LIMITED', msg: 'Rate limited — retry with backoff', retryable: true };
  if (res.status >= 500) throw { code: `HTTP_${res.status}`, msg: 'Server error', retryable: true };
  const json = await res.json();
  if (json.code !== '0') throw { code: json.code, msg: json.msg || 'API error', retryable: false };
  return json.data;
}

// Get current gas price on Ethereum
const gasPrice = await okxFetch('GET', '/api/v6/dex/pre-transaction/gas-price?' + new URLSearchParams({
  chainIndex: '1',
}));
// → gasPrice[].normal, gasPrice[].min, gasPrice[].max (legacy)
// → gasPrice[].eip1559Protocol.suggestBaseFee, .proposePriorityFee (EIP-1559)
console.log(`Gas price: ${gasPrice[0].eip1559Protocol?.suggestBaseFee ?? gasPrice[0].normal} wei`);

// Broadcast a signed EVM transaction
const result = await okxFetch('POST', '/api/v6/dex/pre-transaction/broadcast-transaction', {
  signedTx: '0xf86c...signed_hex',
  chainIndex: '1',
  address: '0xYourWallet',
});
// → result[].orderId — use with /post-transaction/orders to track
console.log(`Broadcast success, orderId: ${result[0].orderId}`);

1. okx-dex-swap    /aggregator/swap                                → get tx calldata { from, to, data, value, gas }
       ↓ user signs the tx locally
2. okx-onchain-gateway /pre-transaction/broadcast-transaction      → broadcast signed tx → orderId
3. okx-onchain-gateway /post-transaction/orders                    → track order status until confirmed

1. okx-onchain-gateway /pre-transaction/simulate                   → check if tx will succeed
       ↓ simulation passes (no revert)
2. okx-onchain-gateway /pre-transaction/broadcast-transaction      → broadcast signed tx
3. okx-onchain-gateway /post-transaction/orders                    → track order status

1. okx-wallet-portfolio /balance/token-balances-by-address         → verify ETH balance
       ↓ sufficient balance confirmed
2. okx-dex-swap    /aggregator/swap                                → get swap tx calldata
       ↓ user signs
3. okx-onchain-gateway /pre-transaction/broadcast-transaction      → broadcast
4. okx-onchain-gateway /post-transaction/orders                    → track

{
  "code": "0",
  "data": [{
    "normal": "20000000000",
    "min": "15000000000",
    "max": "30000000000",
    "supporteip1559": true,
    "eip1559Protocol": {
      "suggestBaseFee": "18000000000",
      "baseFee": "18000000000",
      "proposePriorityFee": "2000000000",
      "safePriorityFee": "1000000000",
      "fastPriorityFee": "3000000000"
    }
  }],
  "msg": ""
}

{
  "code": "0",
  "data": [{ "gasLimit": "21000" }],
  "msg": ""
}

{
  "code": "0",
  "data": [{
    "intention": "Token Swap",
    "assetChange": [{"assetType": "token", "name": "USDC", "symbol": "USDC", "decimals": 6, "address": "0xa0b8...", "rawValue": "-100000000"}],
    "gasUsed": "145000",
    "failReason": "",
    "risks": []
  }],
  "msg": ""
}

{
  "code": "0",
  "data": [{ "orderId": "123456789", "txHash": "0xabc...def" }],
  "msg": ""
}

{
  "code": "0",
  "data": [{
    "cursor": "1",
    "orders": [{
      "orderId": "123456789",
      "txHash": "0xabc...def",
      "chainIndex": "1",
      "address": "0x...",
      "txStatus": "2",
      "failReason": ""
    }]
  }],
  "msg": ""
}

GET /api/v6/dex/pre-transaction/gas-price?chainIndex=1
-> Display:
  Base fee: 18 Gwei
  Max fee: 25 Gwei
  Priority fee: 2 Gwei

POST /api/v6/dex/pre-transaction/simulate
Body: {
  "chainIndex": "1",
  "fromAddress": "0xYourWallet",
  "toAddress": "0xDexContract",
  "txAmount": "1000000000000000000",
  "extJson": { "inputData": "0x..." }
}
-> Display:
  Simulation: SUCCESS (failReason is empty)
  Estimated gas: 145,000
  Intent: Token Swap

POST /api/v6/dex/pre-transaction/broadcast-transaction
Body: {
  "signedTx": "0xf86c...signed",
  "chainIndex": "1",
  "address": "0xYourWallet"
}
-> Display:
  Broadcast successful!
  Order ID: 123456789
  Tx Hash: 0xabc...def

GET /api/v6/dex/post-transaction/orders?address=0xYourWallet&chainIndex=1&orderId=123456789
-> Response: data[0].orders[0] contains order details
-> Display:
  Order 123456789: Success (txStatus=2)
  Tx Hash: 0xabc...def
  Confirmed on-chain