import { ChildProcessWithoutNullStreams, spawn } from "child_process";
import Emittery from "emittery";

export default function simpleSpawn(
  cmd: string,
  arg: string[]
): Promise<{ stdout: string; stderr: string }> {
  const process = spawn(cmd, arg);
  let output = "";
  let err = "";
  return new Promise((resolve, reject) => {
    process.on("close", (code) => {
      code === 0 ? resolve({ stdout: output, stderr: err }) : reject(err);
    });
    process.stdout.on("data", (data) => (output += data.toString("utf-8")));
    process.stderr.on("data", (data) => (err += data.toString("utf-8")));
  });
}

export class DeferedSpawn extends Emittery {
  constructor(private process: ChildProcessWithoutNullStreams) {
    super();
    this.on("data", (data) => console.log("data", data.toString()));
  }

  async waitForAnswer(): Promise<string> {
    return new Promise((resolve, reject) => {
      this.on("success", (data) => {
        resolve(data);
      });
      this.on("error", reject);
    });
  }

  async waitForNextData(): Promise<string | null> {
    console.log(
      "waiting for next data from",,
      this.process.spawnargs.join(" ")
    );
    return new Promise((resolve, reject) => {
      this.on("data", (data) => {
        console.log("got answer from process", this.process.spawnfile);
        resolve(data.toString("utf-8"));
      });
      this.on("error", (err) => {
        console.error("Rejecting from process", this.process.spawnfile, err);
        reject(err);
      });
      this.on("end", () => resolve(null));
    });
  }

  kill() {
    console.log("killing process!", this.process.spawnargs.join(" "));
    process.kill(-this.process.pid); // https://stackoverflow.com/a/49842576
  }

  write(data: string) {
    this.process.stdin.write(data);
  }
}

export function deferedSpawn(
  cmd: string,
  arg: string[]
): Promise<DeferedSpawn> {
  const process = spawn(cmd, arg, { detached: true });
  let spawned = false;
  let output = "";
  let err = "";
  const emitter = new DeferedSpawn(process);
  return new Promise((resolve, reject) => {
    process.stdout.on("data", (data) => {
      output += data.toString("utf-8");
      emitter.emit("data", data);
    });
    process.stderr.on("data", (data) => {
      err += data.toString("utf-8");
    });
    process.on("spawn", () => {
      resolve(emitter);
    });
    process.on("close", (code) => {
      if (!spawned) {
        reject(err);
      } else {
        console.log("!!!!!!!!!!!!!!!!!!!! PROCESS CLOSED");
        if (code === 0) {
          emitter.emit("success", output);
        } else {
          emitter.emit("error", err);
        }
        emitter.emit("end", { err, output });
      }
    });
  });
}