import fs from "fs-extra";
import { access } from "fs/promises";
import imageThumbnail from "image-thumbnail";
import path from "path";
import gm from "gm";
import ft from "file-type";
import core from "file-type/core";
import GenerateUrl from "./MediaUrlGen";
import { FolderPaths } from "./serverInit";
import { logger } from "../server";
var Bluebird = require("bluebird");

Bluebird.promisifyAll(gm.prototype);

/** @returns {string} Returns the relative path from the file to the thumbnail on the server. This must be converted to a URL. */
export default async function GenerateThumbnail(
  file: string
  //thumbPath: string
) {
  const type: core.FileTypeResult | undefined = await ft.fromFile(file);
  let thumbnailExtension: string = GetThumbnailExtension(type);
  let thumbPath: string = path.join(
    path.dirname(file),
    FolderPaths.ThumbsSubDir,
    path.parse(path.basename(file)).name + thumbnailExtension
  );
  try {
    //Ensure the thumbs directory exists.
    await fs.ensureDir(path.dirname(thumbPath));

    try {
      await access(thumbPath);
      logger.debug("Thumbnail already exists for : " + thumbPath);
      return path.relative(path.dirname(file), thumbPath);
    } catch {}

    //Check to see if the file is an image, PDF, or video.

    if (type?.mime === "application/pdf") {
      const fileOnDisk: Buffer = await fs.readFile(file);
      await GeneratePdfThumbnail(file, thumbPath);
    } else {
      logger.debug("Thumbnail being created for : " + thumbPath);
      const thumbnail = await imageThumbnail(file, {
        responseType: "buffer",
        height: 250,
        width: 250,
      });

      await fs.writeFile(thumbPath, thumbnail);
    }
    return path.relative(path.dirname(file), thumbPath);
  } catch (err) {
    console.error("Error when genenerating thumbnail:", thumbPath);
    return path.relative(path.dirname(file), thumbPath);
  }
}

async function GeneratePdfThumbnail(file: string, thumbPath: string) {
  const fileOnDisk: Buffer = await fs.readFile(file);
  return new Promise<string>((resolve, reject) => {
    const result = gm(fileOnDisk)
      .setFormat("png")
      .resize(200) // Resize to fixed 200px width, maintaining aspect ratio
      .quality(75)
      .write(thumbPath, (error) => {
        if (error) reject(error.message);
        resolve(thumbPath);
      });
  });
}

function GetThumbnailExtension(file: core.FileTypeResult | undefined) {
  if (file === undefined) return ".png";
  return ".png";
}