import { createReadStream, createWriteStream, existsSync } from "node:fs";
import { tmpdir } from "node:os";
import { basename, join } from "node:path";
import { extract } from "tar-fs";
import { createBrotliDecompress, createUnzip } from "node:zlib";

class LambdaFS {
  /**
   * Decompresses a (tarballed) Brotli or Gzip compressed file and returns the path to the decompressed file/folder.
   *
   * @param filePath Path of the file to decompress.
   */
  static inflate(filePath: string): Promise<string> {
    const output = filePath.includes("swiftshader")
      ? tmpdir()
      : join(
          tmpdir(),
          basename(filePath).replace(
            /[.](?:t(?:ar(?:[.](?:br|gz))?|br|gz)|br|gz)$/i,
            ""
          )
        );

    return new Promise((resolve, reject) => {
      if (filePath.includes("swiftshader")) {
        if (existsSync(`${output}/libGLESv2.so`)) {
          return resolve(output);
        }
      } else {
        if (existsSync(output) === true) {
          return resolve(output);
        }
      }

      let source = createReadStream(filePath, { highWaterMark: 2 ** 23 });
      let target = null;

      if (/[.](?:t(?:ar(?:[.](?:br|gz))?|br|gz))$/i.test(filePath) === true) {
        target = extract(output);

        target.once("finish", () => {
          return resolve(output);
        });
      } else {
        target = createWriteStream(output, { mode: 0o700 });
      }

      source.once("error", (error: Error) => {
        return reject(error);
      });

      target.once("error", (error: Error) => {
        return reject(error);
      });

      target.once("close", () => {
        return resolve(output);
      });

      if (/(?:br|gz)$/i.test(filePath) === true) {
        source
          .pipe(
            /br$/i.test(filePath)
              ? createBrotliDecompress({ chunkSize: 2 ** 21 })
              : createUnzip({ chunkSize: 2 ** 21 })
          )
          .pipe(target);
      } else {
        source.pipe(target);
      }
    });
  }
}

export = LambdaFS;