#!/usr/bin/env node
import http from 'node:http';
import { URL } from 'node:url';

function readJson(req) {
  return new Promise((resolve, reject) => {
    let body = '';
    req.setEncoding('utf8');
    req.on('data', (chunk) => {
      body += chunk;
    });
    req.on('end', () => {
      if (!body.trim()) {
        resolve({});
        return;
      }
      try {
        resolve(JSON.parse(body));
      } catch (err) {
        reject(err);
      }
    });
    req.on('error', reject);
  });
}

function sendJson(res, statusCode, payload) {
  res.writeHead(statusCode, { 'content-type': 'application/json; charset=utf-8' });
  res.end(JSON.stringify(payload));
}

export function createMockMemoryV2Service() {
  const state = {
    mem0: {
      writes: [],
      compacts: [],
    },
    letta: {
      messages: [],
      compacts: [],
    },
    langgraph: {
      resolves: [],
    },
  };

  function reset() {
    state.mem0.writes.length = 0;
    state.mem0.compacts.length = 0;
    state.letta.messages.length = 0;
    state.letta.compacts.length = 0;
    state.langgraph.resolves.length = 0;
  }

  async function handle(req, res) {
    const url = new URL(req.url, 'http://127.0.0.1');
    const pathname = url.pathname;

    if (req.method === 'GET' && pathname === '/health') {
      sendJson(res, 200, { ok: true, service: 'mock-memory-v2-services' });
      return;
    }

    if (req.method === 'POST' && pathname === '/__admin/reset') {
      reset();
      sendJson(res, 200, { ok: true });
      return;
    }

    if (req.method === 'GET' && pathname === '/__admin/state') {
      sendJson(res, 200, {
        ok: true,
        state,
      });
      return;
    }

    if (req.method === 'POST' && pathname === '/mem0/v1/memories') {
      const body = await readJson(req);
      state.mem0.writes.push(body);
      sendJson(res, 200, {
        saved: 1,
        analyzed: 1,
        memory_count: Array.isArray(body.messages) ? body.messages.length : 0,
      });
      return;
    }

    if (req.method === 'POST' && pathname === '/mem0/v1/memories/compact') {
      const body = await readJson(req);
      state.mem0.compacts.push(body);
      sendJson(res, 200, {
        analyzed: 1,
        memory_count: state.mem0.writes.filter((item) => item.user_id === body.user_id).length,
      });
      return;
    }

    if (req.method === 'POST' && /^\/letta\/v1\/agents\/[^/]+\/messages$/.test(pathname)) {
      const body = await readJson(req);
      const agentId = pathname.split('/')[4];
      state.letta.messages.push({ agentId, ...body });
      sendJson(res, 200, {
        saved: 1,
        analyzed: 0,
        memory_count: Array.isArray(body.messages) ? body.messages.length : 0,
      });
      return;
    }

    if (req.method === 'POST' && /^\/letta\/v1\/agents\/[^/]+\/memory\/compact$/.test(pathname)) {
      const body = await readJson(req);
      const agentId = pathname.split('/')[4];
      state.letta.compacts.push({ agentId, ...body });
      sendJson(res, 200, {
        analyzed: 1,
        memory_count: state.letta.messages.filter((item) => item.user_id === body.user_id).length,
      });
      return;
    }

    if (req.method === 'POST' && /^\/letta\/v1\/agents\/[^/]+\/memory$/.test(pathname)) {
      const body = await readJson(req);
      const agentId = pathname.split('/')[4];
      const messages = state.letta.messages
        .filter((item) => item.agentId === agentId && item.user_id === body.user_id)
        .flatMap((item) => Array.isArray(item.messages) ? item.messages : [])
        .map((item, index) => ({
          id: `letta-${index + 1}`,
          label: 'lifecycle',
          text: String(item.text ?? item.content ?? '').trim() || `letta-memory-${index + 1}`,
        }))
        .filter((item) => item.text);
      sendJson(res, 200, {
        memories: messages.length ? messages : ['letta lifecycle memory'],
        activeGoals: ['memory-v2'],
      });
      return;
    }

    if (req.method === 'POST' && pathname === '/langgraph/memory/resolve') {
      const body = await readJson(req);
      state.langgraph.resolves.push(body);
      sendJson(res, 200, {
        memories: [{
          id: 'langgraph-1',
          label: 'policy',
          text: `langgraph route for ${body.user_id ?? 'unknown-user'}`,
        }],
        activeGoals: ['route-memory'],
        behaviorSummary: null,
      });
      return;
    }

    sendJson(res, 404, { ok: false, message: 'not found' });
  }

  return {
    state,
    reset,
    createServer() {
      return http.createServer((req, res) => {
        Promise.resolve(handle(req, res)).catch((err) => {
          sendJson(res, 500, {
            ok: false,
            message: err instanceof Error ? err.message : String(err),
          });
        });
      });
    },
  };
}

export async function startMockMemoryV2Service({
  port = Number(process.env.MEMORY_V2_MOCK_PORT ?? 19400) || 19400,
  host = process.env.MEMORY_V2_MOCK_HOST ?? '127.0.0.1',
  stdout = process.stdout,
} = {}) {
  const service = createMockMemoryV2Service();
  const server = service.createServer();
  await new Promise((resolve, reject) => {
    server.once('error', reject);
    server.listen(port, host, resolve);
  });
  stdout.write(`${JSON.stringify({ ok: true, host, port }, null, 2)}\n`);
  return { service, server, host, port };
}

if (import.meta.url === `file://${process.argv[1]}`) {
  startMockMemoryV2Service().catch((err) => {
    console.error(err instanceof Error ? err.message : err);
    process.exitCode = 1;
  });
}