import Client from "ssh2-sftp-client";
import { readFileSync } from "node:fs";
import process from "node:process";
import { Worker, isMainThread, workerData } from "node:worker_threads";

type Config = {
  host: string;
  port: number;
  username: string;
  password: string;
};

type Profiles = Record<string, Config>;

type ConfigFile = {
  profiles: Profiles;
};

const CONFIG_PATH = new URL("./config.json", import.meta.url);

function loadConfig(configArg?: string): Config {
  let configFile: ConfigFile;

  try {
    configFile = JSON.parse(readFileSync(CONFIG_PATH, "utf-8")) as ConfigFile;
  } catch (error) {
    throw new Error(
      `Could not read config file at ${CONFIG_PATH.href}. Copy config.example.json to config.json and fill in your credentials.`,
    );
  }

  const profiles = configFile.profiles ?? {};
  const profileName = configArg ?? "default";
  const config = profiles[profileName];

  if (!config) {
    throw new Error(
      `Unknown profile "${profileName}". Available profiles: ${Object.keys(profiles).join(", ")}`,
    );
  }

  if (!config.host || !config.username || !config.password) {
    throw new Error(
      `Profile "${profileName}" is missing host, username, or password in config.json.`,
    );
  }

  return { ...config, port: Number(config.port) || 22 };
}

class SftpService {
  private readonly config: Config;

  constructor(config: Config) {
    this.config = config;
  }

  async uploadFile(sourcePath: string, remotePath: string) {
    const client = new Client();

    try {
      await client.connect(this.config);
      await client.put(sourcePath, remotePath);
    } catch (error) {
      if (error instanceof Error) {
        console.error(error.message);
      }
    } finally {
      await client.end();
    }
  }

  async deleteFile(remotePath: string) {
    const client = new Client();

    try {
      await client.connect(this.config);
      await client.delete(remotePath);
    } catch (error) {
      if (error instanceof Error) {
        console.error(error.message);
      }
    } finally {
      await client.end();
    }
  }
}

function runWorker(runIndex: number, configArg?: string): Promise<void> {
  return new Promise((resolve, reject) => {
    const worker = new Worker(new URL(import.meta.url), {
      workerData: { runIndex, configArg },
    });

    worker.on("exit", (code) => {
      if (code !== 0) {
        reject(new Error(`Worker ${runIndex} exited with code ${code}`));
      } else {
        resolve();
      }
    });

    worker.on("error", (err) => reject(err));
  });
}

async function executeIteration(runIndex: number, configArg?: string) {
  const sftp = new SftpService(loadConfig(configArg));

  const remotePath = `./${runIndex}-test.txt`;
  const sourcePath = "./test.txt";

  console.log(`[Worker ${runIndex}] Starting run number ${runIndex}`);

  console.log(`[Worker ${runIndex}] Uploading file...`);
  await sftp.uploadFile(sourcePath, remotePath);
  console.log(`[Worker ${runIndex}] File uploaded`);

  console.log(`[Worker ${runIndex}] Deleting file...`);
  await sftp.deleteFile(remotePath);
  console.log(`[Worker ${runIndex}] File deleted`);
}

async function main() {
  if (isMainThread) {
    const configArg = process.argv[2];
    const TOTAL_RUNS = 6;

    console.log(`[Main] Spawning ${TOTAL_RUNS} parallel workers...`);

    const workerPromises: Promise<void>[] = [];

    for (let i = 0; i < TOTAL_RUNS; i++) {
      workerPromises.push(runWorker(i, configArg));
    }

    await Promise.all(workerPromises);
    console.log("[Main] All workers completed execution successfully.");
  } else {
    const { runIndex, configArg } = workerData;
    await executeIteration(runIndex, configArg);
  }
}

await main();