#!/usr/bin/env node
/**
 * Forge Verification Proxy — bridges Forge to Blockscout
 *
 * Strategy 1: Forward to Etherscan-compatible API with module/action in query
 * Strategy 2 (fallback): Forward to Blockscout v2 API
 *
 * Forge sends: POST with JSON { contractaddress, sourceCode, codeformat, ... }
 * Blockscout Etherscan API expects: ?module=contract&action=verifysourcecode (in URL)
 *
 * Usage: BLOCKSCOUT_URL=http://192.168.11.140:4000 node server.js
 *        Forge: --verifier-url "http://localhost:3080/"
 */

import http from 'node:http';

const PORT = parseInt(process.env.PORT || '3080', 10);
const BLOCKSCOUT_URL = (process.env.BLOCKSCOUT_URL || 'http://192.168.11.140:4000').replace(/\/$/, '');

/** Parse body as JSON or application/x-www-form-urlencoded (Forge/Etherscan style). */
function parseBody(req) {
  return new Promise((resolve, reject) => {
    let body = '';
    req.on('data', (chunk) => { body += chunk; });
    req.on('end', () => {
      if (!body || !body.trim()) {
        resolve({});
        return;
      }
      const contentType = (req.headers['content-type'] || '').toLowerCase();
      if (contentType.includes('application/x-www-form-urlencoded')) {
        try {
          const params = new URLSearchParams(body);
          const payload = {};
          for (const [k, v] of params) {
            if (v !== undefined && v !== '') payload[k] = v;
          }
          resolve(payload);
        } catch (e) {
          reject(e);
        }
        return;
      }
      try {
        resolve(JSON.parse(body));
      } catch (e) {
        reject(e);
      }
    });
    req.on('error', reject);
  });
}

function send(res, status, data) {
  res.writeHead(status, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify(data));
}

/**
 * Forward to Blockscout Etherscan API with module/action in query.
 * Same JSON body, but URL includes required params.
 */
async function forwardEtherscanFormat(payload) {
  const query = new URLSearchParams({ module: 'contract', action: 'verifysourcecode' });
  const path = `/api/?${query}`;
  // Blockscout's Etherscan-compatible endpoint expects classic form fields, not JSON.
  // Keep the Forge payload keys, but serialize them as application/x-www-form-urlencoded.
  const form = new URLSearchParams();
  for (const [key, value] of Object.entries(payload)) {
    if (value === undefined || value === null || value === '') continue;
    form.set(key, String(value));
  }
  const body = form.toString();
  const url = new URL(path, BLOCKSCOUT_URL);

  return new Promise((resolve, reject) => {
    const req = http.request(
      {
        hostname: url.hostname,
        port: url.port || (url.protocol === 'https:' ? 443 : 80),
        path: url.pathname + url.search,
        method: 'POST',
        headers: {
          'Content-Type': 'application/x-www-form-urlencoded',
          'Content-Length': Buffer.byteLength(body),
          Host: url.hostname + (url.port ? ':' + url.port : ''),
        },
      },
      (res) => {
        let data = '';
        res.on('data', (chunk) => { data += chunk; });
        res.on('end', () => {
          try {
            resolve({ status: res.statusCode, data: data ? JSON.parse(data) : {}, raw: data });
          } catch {
            resolve({ status: res.statusCode, data: null, raw: data });
          }
        });
      }
    );
    req.on('error', reject);
    req.write(body);
    req.end();
  });
}

/**
 * Forward to Blockscout v2 flattened-code verification API.
 */
async function forwardV2Flattened(payload) {
  const addr = payload.contractaddress || payload.contractAddress;
  const sourceCode = payload.sourceCode ?? payload.source_code;
  const codeformat = (payload.codeformat || '').toLowerCase();
  const isStandardJson =
    codeformat === 'solidity-standard-json-input' ||
    (typeof sourceCode === 'string' && sourceCode.trimStart().startsWith('{') && sourceCode.includes('"sources"'));

  const path = isStandardJson
    ? `/api/v2/smart-contracts/${addr}/verification/via/standard-input`
    : `/api/v2/smart-contracts/${addr}/verification/via/flattened-code`;

  const v2Body = {
    compiler_version: payload.compilerversion || payload.compilerVersion || 'v0.8.20+commit.a1b79de6',
    contract_name: payload.contractname || payload.contractName || 'Contract',
    license_type: payload.licensetype || payload.licenseType || 'mit',
    is_optimization_enabled: [true, '1', 1, 'true'].includes(payload.optimizationUsed ?? payload.optimization_used),
    optimization_runs: parseInt(payload.runs ?? payload.optimization_runs ?? '200', 10) || 200,
    evm_version: payload.evmversion || payload.evm_version || 'london',
    autodetect_constructor_args: payload.autodetectConstructorArguments !== false,
    source_code: typeof sourceCode === 'string' ? sourceCode : JSON.stringify(sourceCode),
  };
  if (payload.constructorArguments) v2Body.constructor_args = payload.constructorArguments;

  const body = JSON.stringify(v2Body);
  const url = new URL(path, BLOCKSCOUT_URL);

  return new Promise((resolve, reject) => {
    const req = http.request(
      {
        hostname: url.hostname,
        port: url.port || (url.protocol === 'https:' ? 443 : 80),
        path: url.pathname,
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'Content-Length': Buffer.byteLength(body),
        },
      },
      (res) => {
        let data = '';
        res.on('data', (chunk) => { data += chunk; });
        res.on('end', () => {
          try {
            resolve({ status: res.statusCode, data: data ? JSON.parse(data) : {}, raw: data });
          } catch {
            resolve({ status: res.statusCode, data: null, raw: data });
          }
        });
      }
    );
    req.on('error', reject);
    req.write(body);
    req.end();
  });
}

/**
 * Forward to Blockscout v2 verification API for Standard JSON input.
 */
async function forwardV2StandardInput(payload) {
  const addr = payload.contractaddress || payload.contractAddress;
  const sourceCode = payload.sourceCode ?? payload.source_code;
  const standardJson =
    typeof sourceCode === 'string'
      ? sourceCode
      : JSON.stringify(sourceCode);
  const path = `/api/v2/smart-contracts/${addr}/verification/via/standard-input`;
  const boundary = `----forge-verification-proxy-${Math.random().toString(16).slice(2)}`;
  const parts = [];
  const appendField = (name, value) => {
    if (value === undefined || value === null || value === '') return;
    parts.push(Buffer.from(`--${boundary}\r\n`));
    parts.push(Buffer.from(`Content-Disposition: form-data; name="${name}"\r\n\r\n`));
    parts.push(Buffer.from(`${value}\r\n`));
  };
  const appendFile = (name, filename, content, contentType = 'application/json') => {
    parts.push(Buffer.from(`--${boundary}\r\n`));
    parts.push(Buffer.from(`Content-Disposition: form-data; name="${name}"; filename="${filename}"\r\n`));
    parts.push(Buffer.from(`Content-Type: ${contentType}\r\n\r\n`));
    parts.push(Buffer.isBuffer(content) ? content : Buffer.from(String(content)));
    parts.push(Buffer.from('\r\n'));
  };

  const compilerVersion = payload.compilerversion || payload.compilerVersion || 'v0.8.20+commit.a1b79de6';
  const contractName = payload.contractname || payload.contractName || 'Contract';
  const licenseType = payload.licensetype || payload.licenseType || 'mit';
  const constructorArgs =
    payload.constructor_args ??
    payload.constructorArguments ??
    payload.constructorArgumentsHex ??
    payload.constructorArgs ??
    '';

  appendField('compiler_version', compilerVersion);
  appendField('contract_name', contractName);
  appendField('autodetect_constructor_args', String(payload.autodetectConstructorArguments !== false));
  appendField('license_type', licenseType);
  appendField('constructor_args', constructorArgs);
  if (payload.evmversion || payload.evm_version) appendField('evm_version', payload.evmversion || payload.evm_version);
  if (payload.optimizationUsed !== undefined || payload.optimization_used !== undefined) {
    appendField('is_optimization_enabled', String([true, '1', 1, 'true'].includes(payload.optimizationUsed ?? payload.optimization_used)));
  }
  if (payload.runs !== undefined || payload.optimization_runs !== undefined) {
    appendField('optimization_runs', String(parseInt(payload.runs ?? payload.optimization_runs ?? '200', 10) || 200));
  }
  appendFile('files[0]', 'standard-input.json', standardJson, 'application/json');
  parts.push(Buffer.from(`--${boundary}--\r\n`));
  const body = Buffer.concat(parts);
  const url = new URL(path, BLOCKSCOUT_URL);

  return new Promise((resolve, reject) => {
    const req = http.request(
      {
        hostname: url.hostname,
        port: url.port || (url.protocol === 'https:' ? 443 : 80),
        path: url.pathname,
        method: 'POST',
        headers: {
          'Content-Type': `multipart/form-data; boundary=${boundary}`,
          'Content-Length': body.length,
        },
      },
      (res) => {
        let data = '';
        res.on('data', (chunk) => { data += chunk; });
        res.on('end', () => {
          try {
            resolve({ status: res.statusCode, data: data ? JSON.parse(data) : {}, raw: data });
          } catch {
            resolve({ status: res.statusCode, data: null, raw: data });
          }
        });
      }
    );
    req.on('error', reject);
    req.write(body);
    req.end();
  });
}

function toEtherscanResponse(result) {
  const { status, data, raw } = result;
  if (status >= 200 && status < 300 && data?.status === '1') {
    return { status: '1', message: data.message || 'OK', result: data.result ?? 'Verification submitted' };
  }
  if (status >= 200 && status < 300) {
    return { status: '1', message: 'OK', result: data?.result ?? 'Verification submitted' };
  }
  // Blockscout may return HTML (502/500) or invalid JSON when DB/migrations fail
  let msg = data?.message || data?.error;
  if (!msg && raw) {
    if (raw.trimStart().startsWith('<')) {
      msg = 'Blockscout returned HTML (likely DB down or migrations needed). Run scripts/fix-blockscout-ssl-and-migrations.sh';
    } else if (raw.length > 200) {
      msg = raw.slice(0, 200) + '...';
    } else {
      msg = raw;
    }
  }
  return {
    status: '0',
    message: msg || 'Verification failed',
    result: null,
  };
}

/** Forward GET/other requests to Blockscout (getabi, checkverifystatus, etc.) */
function proxyToBlockscout(req, res) {
  let targetPath = (req.url || '/').startsWith('/api') ? req.url : '/api' + (req.url === '/' ? '' : req.url);
  // Blockscout redirects /api to /api/ — use /api/ to avoid 301
  if (targetPath.startsWith('/api?') || targetPath === '/api') {
    targetPath = '/api/' + (targetPath.slice(4) || '');
  }
  const url = new URL(targetPath, BLOCKSCOUT_URL);

  const proxyReq = http.request(
    {
      hostname: url.hostname,
      port: url.port || (url.protocol === 'https:' ? 443 : 80),
      path: url.pathname + url.search,
      method: req.method,
      headers: { host: url.host },
    },
    (proxyRes) => {
      const headers = { ...proxyRes.headers };
      delete headers['transfer-encoding'];
      res.writeHead(proxyRes.statusCode || 200, headers);
      proxyRes.pipe(res);
    }
  );
  proxyReq.on('error', (e) => {
    console.error('[forge-verification-proxy]', e.message);
    send(res, 502, { status: '0', message: 'Blockscout unreachable', result: null });
  });
  if (req.method === 'POST' || req.method === 'PUT') {
    req.pipe(proxyReq);
  } else {
    proxyReq.end();
  }
}

const server = http.createServer(async (req, res) => {
  res.setHeader('Access-Control-Allow-Origin', '*');
  if (req.method === 'OPTIONS') {
    res.writeHead(204);
    res.end();
    return;
  }

  const path = (req.url || '/').split('?')[0];

  if (req.method === 'GET') {
    await proxyToBlockscout(req, res);
    return;
  }

  if (req.method !== 'POST') {
    send(res, 405, { status: '0', message: 'Method not allowed', result: null });
    return;
  }

  let payload;
  try {
    payload = await parseBody(req);
  } catch (e) {
    send(res, 400, { status: '0', message: 'Invalid request body (JSON or form)', result: null });
    return;
  }

  if (!payload.contractaddress && !payload.contractAddress) {
    send(res, 400, {
      status: '0',
      message: 'Params contractaddress and sourceCode are required',
      result: null,
    });
    return;
  }

  const codeformat = (payload.codeformat || '').toLowerCase();
  const sourceCode = payload.sourceCode ?? payload.source_code;
  const isStandardJson =
    codeformat === 'solidity-standard-json-input' ||
    (typeof sourceCode === 'string' && sourceCode.trimStart().startsWith('{') && sourceCode.includes('"sources"'));
  // Etherscan API expects Standard JSON in sourceCode; flattened Solidity causes "Invalid JSON".
  // Try v2 API first for flattened code; use multipart standard-input when the payload is Standard JSON.
  const tryV2First = !isStandardJson;

  try {
    let result;
    let out;
    if (tryV2First) {
      result = await forwardV2Flattened(payload);
      out = toEtherscanResponse(result);
      if (out.status !== '1') {
        console.error('[forge-verification-proxy] v2 API failed:', out.message, '- trying Etherscan format...');
        result = await forwardEtherscanFormat(payload);
        const etherOut = toEtherscanResponse(result);
        send(res, 200, etherOut.status === '1' ? etherOut : out);
        return;
      }
    } else {
      result = await forwardV2StandardInput(payload);
      out = toEtherscanResponse(result);
      if (out.status !== '1') {
        console.error('[forge-verification-proxy] v2 standard-input failed:', out.message, '- trying Etherscan format...');
        result = await forwardEtherscanFormat(payload);
        const etherOut = toEtherscanResponse(result);
        send(res, 200, etherOut.status === '1' ? etherOut : out);
        return;
      }
    }
    send(res, 200, out);
  } catch (e) {
    console.error('[forge-verification-proxy]', e.message);
    send(res, 500, {
      status: '0',
      message: e.message || 'Proxy error',
      result: null,
    });
  }
});

server.listen(PORT, '0.0.0.0', () => {
  console.log(`[forge-verification-proxy] Listening on port ${PORT}`);
  console.log(`[forge-verification-proxy] Blockscout: ${BLOCKSCOUT_URL}`);
  console.log(`[forge-verification-proxy] Forge: --verifier-url "http://<host>:${PORT}/"`);
});