93 lines
2.4 KiB
Dart
93 lines
2.4 KiB
Dart
import 'dart:async';
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import 'dart:convert';
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import 'dart:io';
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import 'dart:math';
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enum FileKind { image, svg, pdf, text, video, audio, unknown }
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const Set<String> _imageExtensions = {
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'png',
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'jpg',
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'jpeg',
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'webp',
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'gif',
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'bmp',
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'wbmp',
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};
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const Set<String> _videoExtensions = {
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'mp4',
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'm4v',
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'mov',
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'webm',
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'mkv',
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'3gp',
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};
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/// ogg/opus/flac are Android-only; iOS init errors fall through to the
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/// "format not supported" message.
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const Set<String> _audioExtensions = {
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'mp3',
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'm4a',
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'aac',
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'wav',
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'flac',
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'ogg',
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'oga',
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'opus',
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};
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/// Unknown extensions still get a content sniff via [_looksLikeText].
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const Set<String> _textExtensions = {
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'txt', 'md', 'markdown', 'rst', 'log',
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'json', 'json5', 'xml', 'yaml', 'yml', 'toml',
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'csv', 'tsv', 'tab',
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'ini', 'conf', 'cfg', 'env', 'properties',
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'html', 'htm', 'xhtml',
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'css', 'scss', 'sass', 'less',
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'js', 'mjs', 'cjs', 'ts', 'jsx', 'tsx',
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'dart', 'java', 'kt', 'kts', 'groovy', 'scala', 'swift',
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'py', 'rb', 'pl', 'lua', 'r',
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'go', 'rs', 'zig',
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'c', 'cpp', 'cc', 'cxx', 'h', 'hpp', 'cs', 'm', 'mm',
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'php', 'sh', 'bash', 'zsh', 'fish', 'ps1', 'bat', 'cmd',
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'sql', 'graphql', 'gql',
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'gitignore', 'gitattributes', 'editorconfig', 'dockerignore',
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'dockerfile', 'makefile', 'cmake',
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'tex', 'bib',
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'srt', 'vtt',
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};
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/// Detects the [FileKind] of the file at [path] from its extension, falling
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/// back to an 8 KB content sniff ([_looksLikeText]) for unknown extensions.
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Future<FileKind> detectFileKind(String path) async {
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final ext = path.split('.').last.toLowerCase();
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if (_imageExtensions.contains(ext)) return FileKind.image;
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if (ext == 'svg') return FileKind.svg;
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if (ext == 'pdf') return FileKind.pdf;
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if (_videoExtensions.contains(ext)) return FileKind.video;
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if (_audioExtensions.contains(ext)) return FileKind.audio;
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if (_textExtensions.contains(ext)) return FileKind.text;
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if (await _looksLikeText(path)) return FileKind.text;
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return FileKind.unknown;
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}
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/// 8 KB sniff: NUL bytes or non-UTF-8 sequences disqualify.
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Future<bool> _looksLikeText(String path) async {
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final file = File(path);
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RandomAccessFile? raf;
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try {
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final length = await file.length();
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if (length == 0) return true;
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raf = await file.open();
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final sample = await raf.read(min(length, 8192));
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if (sample.contains(0)) return false;
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utf8.decode(sample);
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return true;
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} on Object {
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return false;
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} finally {
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await raf?.close();
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}
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}
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