/*
 *  This file is part of CoCalc: Copyright © 2020 Sagemath, Inc.
 *  License: AGPLv3 s.t. "Commons Clause" – see LICENSE.md for details
 */

const { writeFile, readFile, unlink } = require("fs");
const tmp = require("tmp");
const { callback } = require("awaiting");
const { spawn } = require("child_process");
import { Options } from "./index";

function close(proc, cb): void {
  proc.on("close", (code) => cb(undefined, code));
}

// ref: https://github.com/rust-lang/rustfmt ... but the configuration comes with project specific toml files

function run_rustfmt(input_path: string) {
  return spawn("rustfmt", [input_path]);
}

function cleanup_error(out: string, tmpfn: string): string {
  return out
    .split("\n")
    .filter((line) => line.indexOf(tmpfn) < 0)
    .join("\n");
}

export async function rust_format(
  input: string,
  options: Options,
  logger: any
): Promise<string> {
  // create input temp file
  const input_path: string = await callback(tmp.file);
  try {
    // logger.debug(`rustfmt tmp file: ${input_path}`);
    await callback(writeFile, input_path, input);

    // spawn the html formatter
    let formatter;

    switch (options.parser) {
      case "rustfmt":
        formatter = run_rustfmt(input_path /*, logger*/);
        break;
      default:
        throw Error(`Unknown Rust code formatting utility '${options.parser}'`);
    }
    // stdout/err capture
    let stdout: string = "";
    let stderr: string = "";
    // read data as it is produced.
    formatter.stdout.on("data", (data) => (stdout += data.toString()));
    formatter.stderr.on("data", (data) => (stderr += data.toString()));
    // wait for subprocess to close.
    const code = await callback(close, formatter);
    if (code >= 1) {
      stdout = cleanup_error(stdout, input_path);
      stderr = cleanup_error(stderr, input_path);
      const err_msg = [stdout, stderr].filter((x) => !!x).join("\n");
      logger.debug(`rustfmt error: ${err_msg}`);
      throw Error(err_msg);
    }

    // all fine, we read from the temp file
    const output: Buffer = await callback(readFile, input_path);
    const s: string = output.toString("utf-8");
    // logger.debug(`rust_format output s ${s}`);
    return s;
  } finally {
    unlink(input_path, () => {});
  }
}