import http from 'node:http';
import path from 'node:path';
import { pathToFileURL } from 'node:url';
import {
  createDeepSearchEngine,
  createPortalGatewayResearchLlmResolver,
} from './deep-search-engine.mjs';
import { createDeepSearchStore } from './deep-search-store.mjs';
import { searchGithubCode } from './mindsearch-providers.mjs';

function sendJson(res, status, body) {
  const payload = JSON.stringify(body);
  res.writeHead(status, {
    'content-type': 'application/json; charset=utf-8',
    'content-length': Buffer.byteLength(payload),
    'cache-control': 'no-store',
  });
  res.end(payload);
}

async function readJson(req, { maxBytes = 1_000_000 } = {}) {
  const chunks = [];
  let size = 0;
  for await (const chunk of req) {
    size += chunk.length;
    if (size > maxBytes) {
      const error = new Error('Request body is too large');
      error.status = 413;
      throw error;
    }
    chunks.push(chunk);
  }
  if (!chunks.length) return {};
  try {
    return JSON.parse(Buffer.concat(chunks).toString('utf8'));
  } catch {
    const error = new Error('Request body must be valid JSON');
    error.status = 400;
    throw error;
  }
}

function publicTask(task, { includeContent = false, includeEvents = false } = {}) {
  if (!task) return null;
  return {
    ...task,
    sources: task.sources?.map((source) => ({
      ...source,
      ...(!includeContent ? { content: undefined } : {}),
    })),
    ...(!includeEvents ? { events: undefined } : {}),
  };
}

function matchTaskPath(pathname, suffix = '') {
  const match = pathname.match(new RegExp(`^/v1/research/([^/]+)${suffix}$`));
  return match ? decodeURIComponent(match[1]) : null;
}

function canAccessTask(task, requestUserId) {
  return !requestUserId || !task?.userId || task.userId === requestUserId;
}

export function createDeepSearchHttpServer({
  engine,
  secret = process.env.TKMIND_DEEP_SEARCH_SECRET || '',
  githubToken = process.env.GITHUB_TOKEN || '',
  githubSearch = searchGithubCode,
  logger = console,
} = {}) {
  if (!engine) throw new Error('Deep Search engine is required');
  return http.createServer(async (req, res) => {
    const url = new URL(req.url ?? '/', 'http://deep-search.local');
    if (url.pathname === '/health' && req.method === 'GET') {
      return sendJson(res, 200, {
        ...engine.getHealth(),
        providers: {
          github: { configured: Boolean(githubToken) },
        },
      });
    }
    if (secret && req.headers['x-secret-key'] !== secret) {
      return sendJson(res, 401, { code: 'UNAUTHORIZED', message: 'Invalid service secret' });
    }
    const requestUserId = String(req.headers['x-user-id'] ?? '').trim();
    try {
      if (url.pathname === '/v1/providers/github/search' && req.method === 'POST') {
        if (!githubToken) {
          const error = new Error('GitHub search token is not configured');
          error.status = 503;
          throw error;
        }
        const input = await readJson(req, { maxBytes: 32_000 });
        const query = String(input.query ?? '').trim();
        if (!query || query.length > 500) {
          const error = new Error('query must be 1-500 characters');
          error.status = 400;
          throw error;
        }
        const limit = Math.max(1, Math.min(20, Number(input.limit ?? 10) || 10));
        const results = await githubSearch(query, {
          limit,
          token: githubToken,
        });
        return sendJson(res, 200, {
          query,
          results,
          service: 'tkmind-deep-search',
        });
      }
      if (url.pathname === '/v1/search' && req.method === 'POST') {
        const input = await readJson(req);
        const results = await engine.search(input);
        return sendJson(res, 200, { query: input.query, results, service: 'tkmind-deep-search' });
      }
      if (url.pathname === '/v1/research' && req.method === 'POST') {
        const input = await readJson(req);
        const task = engine.start({
          ...input,
          userId: requestUserId || input.userId || null,
          llmProviderKeyId: input.llmProviderKeyId || input.llm_provider_key_id || '',
          llmModel: input.llmModel || input.llm_model || '',
        });
        return sendJson(res, 202, {
          task_id: task.taskId,
          status: task.status,
          service: task.service,
        });
      }
      if (url.pathname === '/v1/research' && req.method === 'GET') {
        const tasks = engine.listTasks(url.searchParams.get('limit'))
          .filter((task) => canAccessTask(task, requestUserId));
        return sendJson(res, 200, { tasks });
      }
      const eventTaskId = matchTaskPath(url.pathname, '/events');
      if (eventTaskId && req.method === 'GET') {
        const task = engine.getTask(eventTaskId);
        if (!task) return sendJson(res, 404, { code: 'NOT_FOUND', message: 'Research task not found' });
        if (!canAccessTask(task, requestUserId)) {
          return sendJson(res, 403, { code: 'FORBIDDEN', message: 'Research task belongs to another user' });
        }
        res.writeHead(200, {
          'content-type': 'text/event-stream',
          'cache-control': 'no-cache, no-transform',
          connection: 'keep-alive',
        });
        for (const event of task.events ?? []) {
          res.write(`id: ${event.seq}\nevent: ${event.type}\ndata: ${JSON.stringify(event.payload)}\n\n`);
        }
        const unsubscribe = engine.subscribe(eventTaskId, (event) => {
          res.write(`event: ${event.type}\ndata: ${JSON.stringify(event.payload)}\n\n`);
          if (['completed', 'failed', 'cancelled'].includes(event.type)) res.end();
        });
        const heartbeat = setInterval(() => res.write(': heartbeat\n\n'), 15_000);
        const cleanup = () => {
          clearInterval(heartbeat);
          unsubscribe();
        };
        req.once('close', cleanup);
        res.once('close', cleanup);
        return;
      }
      const taskId = matchTaskPath(url.pathname);
      if (taskId && req.method === 'GET') {
        const task = engine.getTask(taskId);
        if (!task) return sendJson(res, 404, { code: 'NOT_FOUND', message: 'Research task not found' });
        if (!canAccessTask(task, requestUserId)) {
          return sendJson(res, 403, { code: 'FORBIDDEN', message: 'Research task belongs to another user' });
        }
        return sendJson(res, 200, publicTask(task, {
          includeContent: url.searchParams.get('include_content') === '1',
          includeEvents: url.searchParams.get('include_events') === '1',
        }));
      }
      if (taskId && req.method === 'DELETE') {
        const existing = engine.getTask(taskId);
        if (existing && !canAccessTask(existing, requestUserId)) {
          return sendJson(res, 403, { code: 'FORBIDDEN', message: 'Research task belongs to another user' });
        }
        const task = engine.cancel(taskId);
        if (!task) return sendJson(res, 404, { code: 'NOT_FOUND', message: 'Research task not found' });
        return sendJson(res, 202, publicTask(task));
      }
      return sendJson(res, 404, { code: 'NOT_FOUND', message: 'Route not found' });
    } catch (error) {
      logger.warn?.('[deep-search] request failed', error);
      return sendJson(res, Number(error?.status) || 400, {
        code: 'REQUEST_FAILED',
        message: String(error?.message ?? error),
      });
    }
  });
}

export function startDeepSearchServer({
  host = process.env.TKMIND_DEEP_SEARCH_HOST || '127.0.0.1',
  port = Number(process.env.TKMIND_DEEP_SEARCH_PORT || 20100),
  databasePath = process.env.TKMIND_DEEP_SEARCH_DB
    || path.join(process.cwd(), '.deep-search', 'research.sqlite'),
  logger = console,
} = {}) {
  const store = createDeepSearchStore({ databasePath });
  const engine = createDeepSearchEngine({
    store,
    llm: null,
    llmResolver: createPortalGatewayResearchLlmResolver(),
  });
  const server = createDeepSearchHttpServer({ engine, logger });
  server.listen(port, host, () => {
    logger.info?.(`[deep-search] listening on http://${host}:${port}`);
  });
  const close = async () => {
    await new Promise((resolve) => server.close(resolve));
    store.close();
  };
  return { server, engine, store, close };
}

const invokedPath = process.argv[1] ? pathToFileURL(path.resolve(process.argv[1])).href : '';
if (import.meta.url === invokedPath) {
  const runtime = startDeepSearchServer();
  const shutdown = async () => {
    await runtime.close();
    process.exit(0);
  };
  process.once('SIGINT', shutdown);
  process.once('SIGTERM', shutdown);
}