import fs from "node:fs";
import path from "node:path";
import { spawn, spawnSync } from "node:child_process";
import { fileURLToPath } from "node:url";
import net from "node:net";
import http from "node:http";
import https from "node:https";

const STACK_DIR_NAME = ".dev-stack";
const DEFAULT_TEMPORAL_CANDIDATES = [
  "temporal-sdk-python-1.24.0",
  "temporal-sdk-python-1.25.0",
  "temporal-sdk-python-1.26.0",
  "temporal-cli",
];

export function getDefaultTemporalCandidates(tempDirectory) {
  return DEFAULT_TEMPORAL_CANDIDATES.map((name) => path.join(tempDirectory, name));
}

export function resolveTemporalCli({
  pathLookupResult,
  candidatePaths,
  existingPaths,
}) {
  if (pathLookupResult && existingPaths.has(pathLookupResult)) {
    return pathLookupResult;
  }

  for (const candidatePath of candidatePaths) {
    if (existingPaths.has(candidatePath)) {
      return candidatePath;
    }
  }

  return null;
}

export function createStackConfig(frontendRoot, backendRoot = path.join(path.dirname(frontendRoot), "auto-virtual-tryon")) {
  const runtimeRoot = path.join(frontendRoot, STACK_DIR_NAME);
  const pidRoot = path.join(runtimeRoot, "pids");
  const logRoot = path.join(runtimeRoot, "logs");
  const temporalDatabaseFile = path.join(runtimeRoot, "temporal-cli-dev.db");
  const backendPython = path.join(backendRoot, ".venv", "bin", "python");
  const frontendNext = path.join(frontendRoot, "node_modules", ".bin", "next");

  return {
    frontendRoot,
    backendRoot,
    runtimeRoot,
    pidRoot,
    logRoot,
    temporalDatabaseFile,
    services: [
      {
        key: "temporal",
        cwd: runtimeRoot,
        port: 7233,
        command: [
          "__TEMPORAL_CLI__",
          "server",
          "start-dev",
          "--ip",
          "127.0.0.1",
          "--port",
          "7233",
          "--headless",
          "--db-filename",
          temporalDatabaseFile,
        ],
      },
      {
        key: "backend-api",
        cwd: backendRoot,
        port: 8000,
        command: [
          backendPython,
          "-m",
          "uvicorn",
          "app.main:app",
          "--host",
          "127.0.0.1",
          "--port",
          "8000",
        ],
      },
      {
        key: "backend-worker",
        cwd: backendRoot,
        port: null,
        command: [backendPython, "-m", "app.workers.runner"],
      },
      {
        key: "frontend",
        cwd: frontendRoot,
        port: 3000,
        command: [frontendNext, "dev", "--hostname", "127.0.0.1", "--port", "3000"],
      },
    ],
  };
}

export function selectServicesForLogs(services, serviceFilter) {
  if (!serviceFilter) {
    return services;
  }

  const matched = services.find((service) => service.key === serviceFilter);
  if (!matched) {
    const supportedKeys = services.map((service) => service.key).join(", ");
    throw new Error(`Unknown service "${serviceFilter}". Expected one of: ${supportedKeys}`);
  }

  return [matched];
}

export function formatServiceLogs(entries) {
  return entries
    .flatMap((entry, index) => {
      const header = `--- ${entry.key} (${entry.logFilePath}) ---`;
      const body = entry.lines.length > 0 ? entry.lines : ["(log file is empty)"];
      return [...(index === 0 ? [] : [""]), header, ...body];
    })
    .join("\n");
}

function ensureDirectory(directoryPath) {
  fs.mkdirSync(directoryPath, { recursive: true });
}

function getServicePidFile(config, serviceKey) {
  return path.join(config.pidRoot, `${serviceKey}.pid`);
}

function getServiceLogFile(config, serviceKey) {
  return path.join(config.logRoot, `${serviceKey}.log`);
}

function readLastLogLines(logFilePath, lineLimit) {
  if (!fs.existsSync(logFilePath)) {
    return ["(log file not found yet)"];
  }

  const raw = fs.readFileSync(logFilePath, "utf8");
  if (!raw.trim()) {
    return [];
  }

  const normalizedLines = raw.replace(/\r\n/g, "\n").split("\n");
  if (normalizedLines.at(-1) === "") {
    normalizedLines.pop();
  }

  return normalizedLines.slice(-lineLimit);
}

function readPid(pidFilePath) {
  if (!fs.existsSync(pidFilePath)) {
    return null;
  }

  const raw = fs.readFileSync(pidFilePath, "utf8").trim();
  if (!raw) {
    return null;
  }

  const parsed = Number(raw);
  return Number.isInteger(parsed) ? parsed : null;
}

function isPidRunning(pid) {
  if (!pid) {
    return false;
  }

  try {
    process.kill(pid, 0);
    return true;
  } catch {
    return false;
  }
}

function readProcessCommand(pid) {
  if (!pid) {
    return null;
  }

  const result = spawnSync("ps", ["-p", String(pid), "-o", "command="], {
    encoding: "utf8",
  });

  if (result.status !== 0) {
    return null;
  }

  const command = result.stdout.trim();
  return command.length > 0 ? command : null;
}

export function getServiceCommandMatchers(service) {
  switch (service.key) {
    case "temporal":
      return ["temporal", "server", "start-dev"];
    case "backend-api":
      return ["uvicorn", "app.main:app"];
    case "backend-worker":
      return ["app.workers.runner"];
    case "frontend":
      return ["next", "dev", "127.0.0.1", "3000"];
    default:
      return service.command.map((part) => path.basename(part));
  }
}

export function isServiceProcessMatch(service, processCommand) {
  if (!processCommand) {
    return false;
  }

  const normalizedCommand = processCommand.toLowerCase();
  return getServiceCommandMatchers(service).every((matcher) =>
    normalizedCommand.includes(matcher.toLowerCase()),
  );
}

export function isServiceHealthy(service, { pid, processCommand, portOpen }) {
  if (!pid || !isServiceProcessMatch(service, processCommand)) {
    return false;
  }

  if (service.port) {
    return portOpen;
  }

  return true;
}

function removePidFile(pidFilePath) {
  if (fs.existsSync(pidFilePath)) {
    fs.unlinkSync(pidFilePath);
  }
}

function pathExists(candidatePath) {
  try {
    fs.accessSync(candidatePath, fs.constants.X_OK);
    return true;
  } catch {
    return false;
  }
}

function getTemporalCliPath() {
  const pathLookup = spawnSync("which", ["temporal"], { encoding: "utf8" });
  const fromPath = pathLookup.status === 0 ? pathLookup.stdout.trim() : null;
  const tempDirectory = process.env.TMPDIR || "/tmp";
  const candidatePaths = getDefaultTemporalCandidates(tempDirectory);
  const existingPaths = new Set(
    [fromPath, ...candidatePaths].filter(Boolean).filter((candidatePath) => pathExists(candidatePath)),
  );

  return resolveTemporalCli({
    pathLookupResult: fromPath,
    candidatePaths,
    existingPaths,
  });
}

function materializeServices(config, temporalCliPath) {
  return config.services.map((service) => ({
    ...service,
    command: service.command.map((part) => (part === "__TEMPORAL_CLI__" ? temporalCliPath : part)),
  }));
}

function waitForPort(port, timeoutMs) {
  return new Promise((resolve, reject) => {
    const startedAt = Date.now();

    const attempt = () => {
      const socket = net.createConnection({ host: "127.0.0.1", port });
      socket.once("connect", () => {
        socket.end();
        resolve();
      });
      socket.once("error", () => {
        socket.destroy();
        if (Date.now() - startedAt >= timeoutMs) {
          reject(new Error(`Timed out waiting for port ${port}`));
          return;
        }
        setTimeout(attempt, 250);
      });
    };

    attempt();
  });
}

function waitForHttp(url, timeoutMs) {
  const client = url.startsWith("https://") ? https : http;
  return new Promise((resolve, reject) => {
    const startedAt = Date.now();

    const attempt = () => {
      const request = client.get(url, (response) => {
        response.resume();
        if (response.statusCode && response.statusCode < 500) {
          resolve();
          return;
        }

        if (Date.now() - startedAt >= timeoutMs) {
          reject(new Error(`Timed out waiting for ${url}`));
          return;
        }

        setTimeout(attempt, 250);
      });

      request.on("error", () => {
        if (Date.now() - startedAt >= timeoutMs) {
          reject(new Error(`Timed out waiting for ${url}`));
          return;
        }
        setTimeout(attempt, 250);
      });
    };

    attempt();
  });
}

function isLocalPortBusy(port) {
  return new Promise((resolve) => {
    const socket = net.createConnection({ host: "127.0.0.1", port });
    socket.once("connect", () => {
      socket.end();
      resolve(true);
    });
    socket.once("error", () => {
      socket.destroy();
      resolve(false);
    });
  });
}

function sleep(ms) {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

async function stopService(config, service) {
  const pidFilePath = getServicePidFile(config, service.key);
  const pid = readPid(pidFilePath);
  if (!pid) {
    return false;
  }

  if (!isPidRunning(pid)) {
    removePidFile(pidFilePath);
    return false;
  }

  const processCommand = readProcessCommand(pid);
  if (!isServiceProcessMatch(service, processCommand)) {
    removePidFile(pidFilePath);
    return false;
  }

  process.kill(-pid, "SIGTERM");
  for (let index = 0; index < 20; index += 1) {
    if (!isPidRunning(pid)) {
      removePidFile(pidFilePath);
      return true;
    }
    await sleep(250);
  }

  process.kill(-pid, "SIGKILL");
  removePidFile(pidFilePath);
  return true;
}

async function startService(config, service) {
  const pidFilePath = getServicePidFile(config, service.key);
  const logFilePath = getServiceLogFile(config, service.key);
  const existingPid = readPid(pidFilePath);

  if (existingPid && isPidRunning(existingPid)) {
    return { key: service.key, pid: existingPid, reused: true };
  }

  removePidFile(pidFilePath);

  if (service.port && (await isLocalPortBusy(service.port))) {
    throw new Error(`Port ${service.port} is already in use. Stop the existing process before running stack:start.`);
  }

  ensureDirectory(path.dirname(logFilePath));
  const logDescriptor = fs.openSync(logFilePath, "a");
  const child = spawn(service.command[0], service.command.slice(1), {
    cwd: service.cwd,
    detached: true,
    stdio: ["ignore", logDescriptor, logDescriptor],
    env: {
      ...process.env,
      BACKEND_BASE_URL: process.env.BACKEND_BASE_URL || "http://127.0.0.1:8000/api/v1",
    },
  });

  child.unref();
  fs.writeFileSync(pidFilePath, `${child.pid}\n`, "utf8");
  fs.closeSync(logDescriptor);

  if (service.key === "temporal") {
    await waitForPort(7233, 15_000);
  } else if (service.key === "backend-api") {
    await waitForHttp("http://127.0.0.1:8000/healthz", 15_000);
  } else if (service.key === "frontend") {
    await waitForHttp("http://127.0.0.1:3000", 20_000);
  } else {
    await sleep(1_500);
  }

  if (!isPidRunning(child.pid)) {
    throw new Error(`${service.key} exited early. Check ${logFilePath}`);
  }

  return { key: service.key, pid: child.pid, reused: false };
}

async function startStack() {
  const frontendRoot = process.cwd();
  const config = createStackConfig(frontendRoot);
  const temporalCliPath = getTemporalCliPath();

  if (!temporalCliPath) {
    throw new Error(
      "Temporal CLI not found. Install `temporal` or ensure the SDK-downloaded CLI exists under TMPDIR.",
    );
  }

  ensureDirectory(config.runtimeRoot);
  ensureDirectory(config.pidRoot);
  ensureDirectory(config.logRoot);

  const services = materializeServices(config, temporalCliPath);
  const startedServices = [];

  try {
    for (const service of services) {
      const result = await startService(config, service);
      startedServices.push(service);
      const marker = result.reused ? "reused" : "started";
      console.log(`${service.key}: ${marker} (pid ${result.pid})`);
    }

    console.log(`frontend: http://127.0.0.1:3000`);
    console.log(`backend: http://127.0.0.1:8000`);
    console.log(`temporal: 127.0.0.1:7233`);
  } catch (error) {
    for (const service of startedServices.reverse()) {
      await stopService(config, service);
    }
    throw error;
  }
}

async function stopStack() {
  const frontendRoot = process.cwd();
  const config = createStackConfig(frontendRoot);
  const temporalCliPath = getTemporalCliPath() || "__TEMPORAL_CLI__";
  const services = materializeServices(config, temporalCliPath);

  for (const service of [...services].reverse()) {
    const stopped = await stopService(config, service);
    console.log(`${service.key}: ${stopped ? "stopped" : "not running"}`);
  }
}

async function printStatus() {
  const frontendRoot = process.cwd();
  const config = createStackConfig(frontendRoot);
  const temporalCliPath = getTemporalCliPath() || "__TEMPORAL_CLI__";
  const services = materializeServices(config, temporalCliPath);

  for (const service of services) {
    const pidFilePath = getServicePidFile(config, service.key);
    const logFilePath = getServiceLogFile(config, service.key);
    const pid = readPid(pidFilePath);
    const processCommand =
      pid && isPidRunning(pid) ? readProcessCommand(pid) : null;
    const portOpen = service.port ? await isLocalPortBusy(service.port) : false;
    const running = isServiceHealthy(service, {
      pid,
      processCommand,
      portOpen,
    });
    if (!running && pid) {
      removePidFile(pidFilePath);
    }
    const displayPid = running ? pid : null;
    const portText = service.port ? ` port=${service.port}` : "";
    const logText = fs.existsSync(logFilePath) ? ` log=${logFilePath}` : "";
    console.log(`${service.key}: ${running ? "running" : "stopped"} pid=${displayPid ?? "-"}${portText}${logText}`);
  }
}

async function printLogs() {
  const frontendRoot = process.cwd();
  const config = createStackConfig(frontendRoot);
  const temporalCliPath = getTemporalCliPath() || "__TEMPORAL_CLI__";
  const services = materializeServices(config, temporalCliPath);
  const serviceFilter = process.env.SERVICE || null;
  const lineLimit = Number(process.env.LINES || "80");
  const selectedServices = selectServicesForLogs(services, serviceFilter);

  const entries = selectedServices.map((service) => {
    const logFilePath = getServiceLogFile(config, service.key);
    return {
      key: service.key,
      logFilePath,
      lines: readLastLogLines(logFilePath, Number.isFinite(lineLimit) && lineLimit > 0 ? lineLimit : 80),
    };
  });

  console.log(formatServiceLogs(entries));
}

async function main() {
  const command = process.argv[2];

  if (command === "start") {
    await startStack();
    return;
  }

  if (command === "stop") {
    await stopStack();
    return;
  }

  if (command === "status") {
    await printStatus();
    return;
  }

  if (command === "logs") {
    await printLogs();
    return;
  }

  console.error("Usage: node scripts/dev-stack/stack.mjs <start|stop|status|logs>");
  process.exitCode = 1;
}

const currentFilePath = fileURLToPath(import.meta.url);
if (process.argv[1] && path.resolve(process.argv[1]) === currentFilePath) {
  main().catch((error) => {
    console.error(error instanceof Error ? error.message : String(error));
    process.exitCode = 1;
  });
}