const fs = require('fs').promises;
const dns = require('dns').promises;
const state = require('../../../infrastructure/state');
const { logError, logWarn, logInfo } = require('../../../infrastructure/logger');
const { saveSelectorCache } = require('../cache');
const { broadcast } = require('../websocket');

const localDnsFile = process.env.LOCAL_DNS_FILE || 'cache/local_dns.json';

async function handleLocalDnsRoutes(req, res) {
  const urlPath = req.urlPath || new URL(req.url, `https://${req.headers.host}`).pathname;
  const method = req.method;

  if (method === 'GET' && urlPath === '/api/local-dns') {
    try {
      let records = state.localDnsRecords || [];
      let conflicts = [];
      const domains = new Set([...state.domainsWithBoth, ...state.versionPreferences.keys()]);
      for (const domain of domains) {
        let publicIP = state.publicIpForDomain[domain];
        if (!publicIP && state.versionPreferences.has(domain)) {
          try {
            const ips = await dns.resolve4(domain);
            publicIP = ips[0] || 'N/A';
            state.publicIpForDomain[domain] = publicIP;
          } catch (err) {
            logWarn('Admin', `Failed to resolve public IP for ${domain}: ${err.message}`);
            publicIP = 'N/A';
          }
        }
        conflicts.push({
          domain,
          version: state.versionPreferences.get(domain) || 'p2p',
          publicIP: publicIP || 'N/A'
        });
      }
      records = records.map((rec, index) => ({ ...rec, index }));
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify({ records, conflicts }));
    } catch (err) {
      logError('Admin', `Failed to fetch local DNS and conflicts: ${err.message}`);
      res.writeHead(500);
      res.end(JSON.stringify({ error: 'Failed to fetch local DNS and conflicts' }));
    }
    return true;
  }

  if (method === 'GET' && urlPath === '/api/selector-cache') {
    try {
      const preferences = Object.fromEntries(state.versionPreferences);
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify(preferences));
    } catch (err) {
      logError('Admin', `Failed to fetch selector cache: ${err.message}`);
      res.writeHead(500);
      res.end(JSON.stringify({ error: 'Failed to fetch selector cache' }));
    }
    return true;
  }

  if (method === 'POST' && urlPath === '/api/add-local-dns') {
    let body = '';
    req.on('data', chunk => { body += chunk; });
    req.on('end', async () => {
      try {
        const record = JSON.parse(body);
        if (!record.name || !record.type || !record.ttl || isNaN(record.ttl)) {
          throw new Error('Missing or invalid required fields: name, type, ttl');
        }
        record.class = record.class || 'IN';
        let records = state.localDnsRecords || [];
        records.push(record);
        await fs.writeFile(localDnsFile, JSON.stringify(records, null, 2));
        state.localDnsRecords = records;
        broadcast({ type: 'update-local-dns' });
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('OK');
      } catch (err) {
        logError('Admin', `Failed to add local DNS record: ${err.message}`);
        res.writeHead(500);
        res.end(err.message);
      }
    });
    return true;
  }

  if (method === 'POST' && urlPath === '/api/update-local-dns') {
    let body = '';
    req.on('data', chunk => { body += chunk; });
    req.on('end', async () => {
      try {
        const { index, record } = JSON.parse(body);
        if (!record.name || !record.type || !record.ttl || isNaN(record.ttl)) {
          throw new Error('Missing or invalid required fields: name, type, ttl');
        }
        let records = state.localDnsRecords || [];
        if (index >= 0 && index < records.length) {
          record.class = record.class || 'IN';
          records[index] = record;
          await fs.writeFile(localDnsFile, JSON.stringify(records, null, 2));
          state.localDnsRecords = records;
          broadcast({ type: 'update-local-dns' });
          res.writeHead(200, { 'Content-Type': 'text/plain' });
          res.end('OK');
        } else {
          res.writeHead(400);
          res.end('Invalid index');
        }
      } catch (err) {
        logError('Admin', `Failed to update local DNS record: ${err.message}`);
        res.writeHead(500);
        res.end(err.message);
      }
    });
    return true;
  }

  if (method === 'POST' && urlPath === '/api/delete-local-dns') {
    let body = '';
    req.on('data', chunk => { body += chunk; });
    req.on('end', async () => {
      try {
        const { index } = JSON.parse(body);
        let records = state.localDnsRecords || [];
        if (index >= 0 && index < records.length) {
          records.splice(index, 1);
          await fs.writeFile(localDnsFile, JSON.stringify(records, null, 2));
          state.localDnsRecords = records;
          broadcast({ type: 'update-local-dns' });
          res.writeHead(200, { 'Content-Type': 'text/plain' });
          res.end('OK');
        } else {
          res.writeHead(400);
          res.end('Invalid index');
        }
      } catch (err) {
        logError('Admin', `Failed to delete local DNS record: ${err.message}`);
        res.writeHead(500);
        res.end(err.message);
      }
    });
    return true;
  }

  if (method === 'POST' && urlPath === '/api/update-version-preference') {
    let body = '';
    req.on('data', chunk => { body += chunk; });
    req.on('end', async () => {
      try {
        const { domain, version } = JSON.parse(body);
        if (version !== 'p2p' && version !== 'public') {
          res.writeHead(400);
          res.end('Invalid version, must be "p2p" or "public"');
          return;
        }
        state.versionPreferences.set(domain, version);
        await saveSelectorCache();
        broadcast({ type: 'update-local-dns' });
        logInfo('Admin', `Updated version preference for ${domain} to ${version}`);
        res.writeHead(200, { 'Content-Type': 'text/plain' });
        res.end('OK');
      } catch (err) {
        logError('Admin', `Failed to update version preference: ${err.message}`);
        res.writeHead(500);
        res.end(err.message);
      }
    });
    return true;
  }

  return false;
}

module.exports = { handleLocalDnsRoutes };