import { FileSystem } from 'react-native-file-access';
import filetypemime from 'magic-bytes.js';
import { lookup } from 'react-native-mime-types';
import { MEME_TYPE } from '../database';

const allowedImageMimeTypes = [
  'image/bmp',
  'image/jpg',
  'image/jpeg',
  'image/png',
  'image/webp',
];

const allowedGifMimeTypes = ['image/gif'];

const allowedVideoMimeTypes = [
  'video/av01',
  'video/3gpp',
  'video/avc',
  'video/hevc',
  'video/x-matroska',
  'video/mp2t',
  'video/mp4',
  'video/mp42',
  'video/mp43',
  'video/mp4v-es',
  'video/mpeg',
  'video/mpeg2',
  'video/x-vnd.on2.vp8',
  'video/x-vnd.on2.vp9',
  'video/webm',
];

const allowedMimeTypes = [
  ...allowedImageMimeTypes,
  ...allowedGifMimeTypes,
  ...allowedVideoMimeTypes,
];

const getMemeTypeFromMimeType = (mimeType: string): MEME_TYPE | undefined => {
  if (!allowedMimeTypes.includes(mimeType)) return undefined;

  const mimeStart = mimeType.split('/')[0];

  switch (mimeStart) {
    case 'image': {
      if (mimeType === 'image/gif') return MEME_TYPE.GIF;
      return MEME_TYPE.IMAGE;
    }
    case 'video': {
      return MEME_TYPE.VIDEO;
    }
  }
};

const guessMimeTypeFromExtension = (filename: string): string | undefined => {
  const extension = filename.split('.').pop()?.toLowerCase();
  if (!extension) return undefined;
  const guessedMimeType = lookup(extension);
  if (!guessedMimeType) return undefined;
  return guessedMimeType;
};

const guessMimeTypeFromMagicBytes = async (
  uri: string,
): Promise<string | undefined> => {
  const fileContent = await FileSystem.read(uri, 100);
  const possibleMimeTypes = filetypemime(fileContent);
  if (possibleMimeTypes.length === 0) return undefined;
  return possibleMimeTypes[0].mime;
};

const guessMimeType = async (
  uri: string,
  hint?: string | null,
): Promise<string | undefined> => {
  if (hint && allowedMimeTypes.includes(hint)) return hint;

  let guessedMimeType = guessMimeTypeFromExtension(uri);
  if (guessedMimeType && allowedMimeTypes.includes(guessedMimeType)) {
    return guessedMimeType;
  }

  guessedMimeType = await guessMimeTypeFromMagicBytes(uri);
  if (guessedMimeType && allowedMimeTypes.includes(guessedMimeType)) {
    return guessedMimeType;
  }
};

export {
  allowedImageMimeTypes,
  allowedGifMimeTypes,
  allowedMimeTypes,
  getMemeTypeFromMimeType,
  guessMimeType,
};