import { extension, videoExtensions, imageExtensions } from "./lib";

import ffmpeg, { FfprobeData, ffprobe } from 'fluent-ffmpeg';
import ffmpegInstaller from '@ffmpeg-installer/ffmpeg';
import ffprobeInstaller from '@ffprobe-installer/ffprobe';
import which from 'which';

/**
 * Enum to represent different types of video encoding methods.
 * 
 * @enum {string}
 * @property {string} CPU - Uses the libx264 codec for CPU-based encoding
 * @property {string} NVIDIA - Uses the h264_nvenc codec for NVIDIA GPU-based encoding
 * @property {string} AMD - Uses the h264_amf codec for AMD GPU-based encoding
 * @property {string} INTEL - Uses the h264_qsv codec for Intel GPU-based encoding
 * @property {string} APPLE - Uses the h264_videotoolbox codec for Apple GPU/MediaEngine-based encoding
 */
export enum EncodingType {
  CPU = 'libx264',
  NVIDIA = 'h264_nvenc',
  AMD = 'h264_amf',
  INTEL = 'h264_qsv',
  APPLE = 'h264_videotoolbox'
}

/**
 * The current encoding type being used for video encoding. Default is CPU
 * @type {EncodingType}
 */
export let currentEncoding: EncodingType = EncodingType.CPU;

/**
 * Sets the current encoding type.
 * 
 * @param {EncodingType} type - The encoding type to set.
 */
export const setEncodingType = (type: EncodingType) => {
  currentEncoding = type;
};

/**
 * Returns the path to an executable by checking environment variables, the system path, or a default installer.
 * 
 * @param {string} envVar - The environment variable to check for the executable's path.
 * @param {string} executable - The name of the executable to search for in the system path.
 * @param {Object} installer - An object containing the default installer path.
 * @param {string} installer.path - The default path to use if the executable is not found in the environment or system path.
 * 
 * @returns {string} - The path to the executable.
 * @throws Will throw an error if the executable is not found and the installer path is not available.
 */
const getExecutablePath = (envVar: string, executable: string, installer: { path: string }) => {
  if (process.env[envVar]) {
    return process.env[envVar];
  }

  try {
    return which.sync(executable);
  } catch (error) {
    return installer.path;
  }
};

const ffmpegPath = getExecutablePath('EB_FFMPEG_PATH', 'ffmpeg', ffmpegInstaller);
const ffprobePath = getExecutablePath('EB_FFPROBE_PATH', 'ffprobe', ffprobeInstaller);

console.log(`Using ffmpeg from path: ${ffmpegPath}`);
console.log(`Using ffprobe from path: ${ffprobePath}`);

ffmpeg.setFfmpegPath(ffmpegPath!);
ffmpeg.setFfprobePath(ffprobePath!);

const checkEnvForEncoder = () => {
  const envEncoder = process.env.EB_ENCODER?.toUpperCase();

  if (envEncoder && Object.keys(EncodingType).includes(envEncoder)) {
    setEncodingType(EncodingType[envEncoder as keyof typeof EncodingType] as EncodingType);
    console.log(`Setting encoding type to ${envEncoder} based on environment variable.`);
  } else if (envEncoder) {
    console.warn(`Invalid encoder value "${envEncoder}" in environment variable, defaulting to CPU.`);
  }
};

checkEnvForEncoder();

/**
 * Downscale a video using ffmpeg with various encoding options.
 * 
 * @param {string} path - The input video file path.
 * @param {string} filename - The name of the file.
 * @param {string} extension - The file extension of the file
 * @returns {Promise<void>} - A promise that resolves when the downscaling is complete, and rejects on error.
 * 
 * @example
 * ffmpegDownscale('input.mp4').then(() => {
 *   console.log('Downscaling complete.');
 * }).catch((error) => {
 *   console.log(`Error: ${error}`);
 * });
 */
export const ffmpegDownscale = (path: string, filename: string, extension: string) => {
  const startTime = Date.now();
  const outputOptions = [
    '-vf', 'scale=-2:720',
    '-c:v', currentEncoding,
    '-c:a', 'copy',
    "-pix_fmt", "yuv420p",
  ];

  return new Promise<void>((resolve, reject) => {
    ffmpeg()
      .input(path)
      .outputOptions(outputOptions)
      .output(`uploads/720p-${filename}${extension}`)
      .on('end', () => {
        console.log(`720p copy complete using ${currentEncoding}, took ${Date.now() - startTime}ms to complete`);
        resolve();
      })
      .on('error', (e) => reject(new Error(e)))
      .run();
  });
}

/**
 * Convert a video to a gif or vice versa using ffmpeg with various encoding options.
 * 
 * @param {string} path - The input video file path.
 * @param {string} filename - The name of the file.
 * @param {string} extension - The file extension of the file
 * @returns {Promise<void>} - A promise that resolves when the conversion is complete, and rejects on error.
 * 
 * @example
 * ffmpegConvert('input.mp4').then(() => {
 *   console.log('Conversion complete.');
 * }).catch((error) => {
 *   console.log(`Error: ${error}`);
 * });
 */
export const ffmpegConvert = (path: string, filename: string, extension: string) => {
  const startTime = Date.now();
  const outputOptions = [
    '-vf', 'scale=-2:720',
    '-c:v', currentEncoding,
    '-c:a', 'copy',
    "-movflags", "+faststart",
    "-pix_fmt", "yuv420p",
  ]

  let outputFormat: string;

  if (videoExtensions.includes(extension)) {
    outputFormat = '.gif';
  } else if (extension == '.gif') {
    outputFormat = '.mp4';
  } else {
    return new Promise<void>((resolve, reject) => {
      reject(`Submitted file is neither a video nor a gif: ${path}`);
    });
  }

  return new Promise<void>((resolve, reject) => {
    ffmpeg()
      .input(path)
      .outputOptions(outputOptions)
      .output(`uploads/`)
      .outputFormat(outputFormat)
      .output(`uploads/${filename}${outputFormat}`)
      .on("end", function() {
        console.log(`Conversion complete, took ${Date.now() - startTime} to complete`);
        console.log(`uploads/${filename}${outputFormat}`);
        resolve();
      })
      .on("error", (e) => reject(e))
      .run();
  });
}

export const ffProbe = (path: string, filename: string, extension: string) => {
  return new Promise<FfprobeData>((resolve, reject) => {
    ffprobe(path, (err, data) => {
      if (err) reject (err);
      resolve(data);
    });
  });
}