packages/flutter_tools/lib/src/web/content_hash.dart - mirrors/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'dart:typed_data';

 import 'package:crypto/crypto.dart' as crypto;
 import 'package:path/path.dart' as p; // flutter_ignore: package_path_import
 import 'package:standard_message_codec/standard_message_codec.dart';

 import '../base/common.dart';
 import '../base/file_system.dart';
 import '../convert.dart';

 const List<String> _kKnownHashedExtensions = <String>[
   '.js.map',
   '.wasm.map',
   '.mjs.map',
   '.js',
   '.wasm',
   '.mjs',
 ];

 const Set<String> _kManifestAssetRelativePaths = <String>{
   'AssetManifest.json',
   'AssetManifest.bin',
   'AssetManifest.bin.json',
   'FontManifest.json',
 };

 /// Result of content-hashing the files and manifests in `build/web/assets/`.
 class WebAssetHashResult {
   const WebAssetHashResult({
     required this.renamedFiles,
     this.assetManifestBinJson,
     this.fontManifestJson,
     this.extraAssets = const <String, String>{},
   });

   /// Mapping from original file paths (and normalized paths) to their renamed
   /// content-hashed [File] handles on disk.
   final Map<String, File> renamedFiles;

   /// The content-hashed filename of `AssetManifest.bin.json` (for example,
   /// `AssetManifest.bin.a1b2c3d4.json`), if present.
   final String? assetManifestBinJson;

   /// The content-hashed filename of `FontManifest.json` (for example,
   /// `FontManifest.e5f60718.json`), if present.
   final String? fontManifestJson;

   /// Non-manifest files in `build/web/assets/` (such as `NOTICES`, framework
   /// shaders not listed in `AssetManifest.bin`, `AssetManifest.bin`, and
   /// `AssetManifest.json`) mapped from their unhashed relative path to their
   /// content-hashed relative path.
   final Map<String, String> extraAssets;
 }

 String computeHashedBasename(String oldBasename, String contentHash, FileSystem fileSystem) {
   final String doubleExt = fileSystem.path.extension(oldBasename, 2);
   final String ext = _kKnownHashedExtensions.contains(doubleExt)
       ? doubleExt
       : fileSystem.path.extension(oldBasename);
   if (ext.isNotEmpty) {
     final String stem = oldBasename.substring(0, oldBasename.length - ext.length);
     return '$stem.$contentHash$ext';
   }
   return '$oldBasename.$contentHash';
 }

 WebAssetHashResult hashWebAssets(Directory assetsDir) {
   final renamedFileMap = <String, File>{};
   if (!assetsDir.existsSync()) {
     return WebAssetHashResult(renamedFiles: renamedFileMap);
   }

   final FileSystem fileSystem = assetsDir.fileSystem;
   final List<File> files = assetsDir.listSync(recursive: true).whereType<File>().toList()
     ..sort((File a, File b) => a.path.compareTo(b.path));
   final rawRenamedAssets = <String, String>{};
   final renamedAssets = <String, String>{};
   final decodedRenamedAssets = <String, String>{};

   String decodeSafe(String value) {
     try {
       return Uri.decodeFull(value);
     } on ArgumentError {
       return value;
     }
   }

   String hashAndRenameFile(File file, String posixRelativePath) {
     final String relativePath = fileSystem.path.relative(file.path, from: assetsDir.path);
     final List<String> segments = fileSystem.path.split(relativePath);
     final String basename = fileSystem.path.basename(file.path);
     final String contentHash = crypto.sha256
         .convert(file.readAsBytesSync())
         .toString()
         .substring(0, 8);
     final String newBasename = computeHashedBasename(basename, contentHash, fileSystem);

     final newSegments = <String>[...segments.sublist(0, segments.length - 1), newBasename];
     final String newRelativePath = fileSystem.path.joinAll(newSegments);
     final String posixNewPath = p.posix.joinAll(newSegments);
     final String decodedNewPath = decodeSafe(posixNewPath);

     // Rename the physical file on disk.
     final String newPath = fileSystem.path.join(assetsDir.path, newRelativePath);
     final String oldPath = file.path;
     final String normalizedOldPath = fileSystem.path.normalize(oldPath);
     file.renameSync(newPath);
     final File newFile = fileSystem.file(newPath);
     renamedFileMap[oldPath] = newFile;
     renamedFileMap[normalizedOldPath] = newFile;

     // Map POSIX paths:
     // - `renamedAssets` maps to the on-disk `%20`-encoded path (used by FontManifest.json).
     // - `decodedRenamedAssets` maps to the `Uri.decodeFull` path (used by AssetManifest.bin /
     //   AssetManifest.json, matching `_createAssetManifest` in `asset.dart`).
     rawRenamedAssets[posixRelativePath] = posixNewPath;
     renamedAssets[posixRelativePath] = posixNewPath;
     decodedRenamedAssets[posixRelativePath] = decodedNewPath;

     final String decodedOld = decodeSafe(posixRelativePath);
     renamedAssets[decodedOld] = posixNewPath;
     decodedRenamedAssets[decodedOld] = decodedNewPath;

     final String encodedOld = Uri.encodeFull(posixRelativePath);
     renamedAssets[encodedOld] = posixNewPath;
     decodedRenamedAssets[encodedOld] = decodedNewPath;

     return posixNewPath;
   }

   // Pass 1: Hash all physical asset files (including shaders and NOTICES)
   // except the manifest files themselves, whose contents depend on Pass 1 hashes.
   for (final file in files) {
     final String relativePath = fileSystem.path.relative(file.path, from: assetsDir.path);
     final List<String> segments = fileSystem.path.split(relativePath);
     final String posixRelativePath = p.posix.joinAll(segments);

     if (_kManifestAssetRelativePaths.contains(posixRelativePath)) {
       continue;
     }

     hashAndRenameFile(file, posixRelativePath);
   }

   final manifestCoveredTargets = <String>{};
   void recordManifestTarget(String target) {
     manifestCoveredTargets.add(target);
     manifestCoveredTargets.add(Uri.encodeFull(target));
     manifestCoveredTargets.add(Uri(path: Uri.encodeFull(target)).path);
     final String decoded = decodeSafe(target);
     manifestCoveredTargets.add(decoded);
     manifestCoveredTargets.add(Uri.encodeFull(decoded));
     manifestCoveredTargets.add(Uri(path: Uri.encodeFull(decoded)).path);
   }

   // Pass 2a: Rewrite FontManifest.json and hash it on disk.
   // FontManifest.json keeps the `%20`-encoded `posixNewPath` because `loadAssetFonts`
   // in `web_ui` calls `assetManager.loadAsset` directly without `PlatformAssetBundle`.
   String? hashedFontManifestJson;
   final File fontManifest = assetsDir.childFile('FontManifest.json');
   if (fontManifest.existsSync()) {
     final Object? decodedJson = json.decode(fontManifest.readAsStringSync());
     if (decodedJson is List<dynamic>) {
       for (final Object? font in decodedJson) {
         if (font is Map<String, dynamic>) {
           final Object? fonts = font['fonts'];
           if (fonts is List<dynamic>) {
             for (final Object? fontAsset in fonts) {
               if (fontAsset is Map<String, dynamic>) {
                 final Object? asset = fontAsset['asset'];
                 if (asset is String && renamedAssets.containsKey(asset)) {
                   fontAsset['asset'] = renamedAssets[asset];
                 }
               }
             }
           }
         }
       }
       fontManifest.writeAsStringSync(json.encode(decodedJson));
     }
     hashedFontManifestJson = hashAndRenameFile(fontManifest, 'FontManifest.json');
   }

   // Pass 2b: Rewrite legacy AssetManifest.json if present and hash it on disk.
   final File assetManifestJson = assetsDir.childFile('AssetManifest.json');
   if (assetManifestJson.existsSync()) {
     final Object? decodedJson = json.decode(assetManifestJson.readAsStringSync());
     if (decodedJson is Map<String, dynamic>) {
       final newManifest = <String, dynamic>{};
       for (final MapEntry<String, dynamic> entry in decodedJson.entries) {
         recordManifestTarget(entry.key);
         final Object? variants = entry.value;
         if (variants is! List<dynamic>) {
           newManifest[entry.key] = variants;
           continue;
         }
         final newVariants = <String>[];
         for (final Object? variant in variants) {
           if (variant is String) {
             recordManifestTarget(variant);
             newVariants.add(decodedRenamedAssets[variant] ?? variant);
           } else if (variant != null) {
             newVariants.add(variant.toString());
           }
         }
         newManifest[entry.key] = newVariants;
       }
       assetManifestJson.writeAsStringSync(json.encode(newManifest));
     }
     hashAndRenameFile(assetManifestJson, 'AssetManifest.json');
   }

   // Pass 2c: Rewrite AssetManifest.bin and AssetManifest.bin.json and hash both on disk.
   // Do NOT insert non-manifest SDK files (`NOTICES`, framework shaders, `FontManifest.json`,
   // `AssetManifest.bin`, etc.) into `AssetManifest.bin` or `AssetManifest.bin.json` so that
   // `AssetManifest.loadFromAssetBundle(rootBundle).listAssets()` returns the exact same keys
   // as a build without `--web-content-hash`.
   String? hashedAssetManifestBinJson;
   final File assetManifestBin = assetsDir.childFile('AssetManifest.bin');
   final File assetManifestBinJson = assetsDir.childFile('AssetManifest.bin.json');
   if (assetManifestBin.existsSync()) {
     final Uint8List rawBytes = assetManifestBin.readAsBytesSync();
     final message = ByteData.sublistView(rawBytes);
     final Object? decoded = const StandardMessageCodec().decodeMessage(message);
     if (decoded is Map<Object?, Object?>) {
       final newManifest = <String, dynamic>{};
       for (final MapEntry<Object?, Object?> entry in decoded.entries) {
         final key = entry.key.toString();
         recordManifestTarget(key);
         final Object? variantsVal = entry.value;
         if (variantsVal is! List<Object?>) {
           newManifest[key] = variantsVal;
           continue;
         }
         final newVariants = <dynamic>[];
         for (final Object? variantObj in variantsVal) {
           if (variantObj is! Map<Object?, Object?>) {
             newVariants.add(variantObj);
             continue;
           }
           final newVariantMap = <String, dynamic>{};
           for (final MapEntry<Object?, Object?> vEntry in variantObj.entries) {
             final vKey = vEntry.key.toString();
             if (vKey == 'asset') {
               final vValue = vEntry.value.toString();
               recordManifestTarget(vValue);
               newVariantMap[vKey] = decodedRenamedAssets[vValue] ?? vValue;
             } else {
               newVariantMap[vKey] = vEntry.value;
             }
           }
           newVariants.add(newVariantMap);
         }
         newManifest[key] = newVariants;
       }
       final ByteData encoded = const StandardMessageCodec().encodeMessage(newManifest)!;
       final encodedBytes = Uint8List.sublistView(encoded);
       assetManifestBin.writeAsBytesSync(encodedBytes);
       hashAndRenameFile(assetManifestBin, 'AssetManifest.bin');

       // Update AssetManifest.bin.json with the same manifest entries and hash it on disk.
       if (assetManifestBinJson.existsSync()) {
         assetManifestBinJson.writeAsStringSync(json.encode(base64.encode(encodedBytes)));
         hashedAssetManifestBinJson = hashAndRenameFile(
           assetManifestBinJson,
           'AssetManifest.bin.json',
         );
       }
     }
   }

   // Collect non-manifest files in `build/web/assets/` (such as `NOTICES`,
   // framework shaders not listed in `pubspec.yaml`, `FontManifest.json`,
   // `AssetManifest.bin`, and `AssetManifest.json`) into `extraAssets` for
   // `_flutter.buildConfig`.
   final extraAssets = <String, String>{};
   for (final MapEntry<String, String> entry in rawRenamedAssets.entries) {
     if (entry.key == 'AssetManifest.bin.json') {
       continue;
     }
     if (!manifestCoveredTargets.contains(entry.key) &&
         !manifestCoveredTargets.contains(decodeSafe(entry.key))) {
       extraAssets[decodeSafe(entry.key)] = entry.value;
     }
   }

   return WebAssetHashResult(
     renamedFiles: renamedFileMap,
     assetManifestBinJson: hashedAssetManifestBinJson,
     fontManifestJson: hashedFontManifestJson,
     extraAssets: extraAssets,
   );
 }

 final RegExp _htmlCommentRegex = RegExp(r'<!--[\s\S]*?-->');

 final RegExp _jsCommentOrStringRegex = RegExp(
   r'/\*[\s\S]*?\*/|(?<!:)//[^\r\n]*|"(?:\\.|[^"\\\r\n])*"|'
   "'"
   r'(?:\\.|[^'
   "'"
   r'\\\r\n])*'
   "'"
   r'|`(?:\\.|[^`\\])*`',
 );

 /// Strips HTML (`<!-- ... -->`) and JavaScript (`/* ... */`, `// ...`) comments
 /// from [content] while preserving single-quoted, double-quoted, and template
 /// string literals.
 String stripHtmlAndJsComments(String content) {
   final String withoutHtmlComments = content.replaceAll(_htmlCommentRegex, '');
   return withoutHtmlComments.replaceAllMapped(_jsCommentOrStringRegex, (Match match) {
     final String token = match.group(0)!;
     if (token.startsWith('/*') || token.startsWith('//')) {
       return '';
     }
     return token;
   });
 }

 final RegExp _buildConfigTokenOrCommentRegex = RegExp(
   r'<!--[\s\S]*?-->|/\*[\s\S]*?\*/|(?<!:)//[^\r\n]*|"(?:\\.|[^"\\\r\n])*"|'
   "'"
   r'(?:\\.|[^'
   "'"
   r'\\\r\n])*'
   "'"
   r'|`(?:\\.|[^`\\])*`|_flutter\.buildConfig\s*=\s*\{',
 );

 int? _findMatchingClosingBrace(String text, int openBraceIndex) {
   var depth = 0;
   int? stringQuote;
   var escaped = false;
   for (var i = openBraceIndex; i < text.length; i++) {
     final int ch = text.codeUnitAt(i);
     if (stringQuote != null) {
       if (escaped) {
         escaped = false;
       } else if (ch == 0x5C /* \ */ ) {
         escaped = true;
       } else if (ch == stringQuote) {
         stringQuote = null;
       }
       continue;
     }
     if (ch == 0x22 /* " */ || ch == 0x27 /* ' */ || ch == 0x60 /* ` */ ) {
       stringQuote = ch;
     } else if (ch == 0x7B /* { */ ) {
       depth++;
     } else if (ch == 0x7D /* } */ ) {
       depth--;
       if (depth == 0) {
         return i;
       }
     }
   }
   return null;
 }

 String _updateBuildConfigInContent(
   String content,
   WebAssetHashResult hashResult, {
   required String filePath,
 }) {
   final List<Match> matches = _buildConfigTokenOrCommentRegex
       .allMatches(content)
       .where((Match m) => m.group(0)!.startsWith('_flutter.buildConfig'))
       .toList();
   if (matches.isEmpty) {
     throwToolExit(
       'Failed to inject content-hashed asset manifest into $filePath: '
       '"_flutter.buildConfig" is not a JSON object assignment. '
       'Ensure "{{flutter_build_config}}" is used.',
     );
   }
   final buffer = StringBuffer();
   var cursor = 0;
   for (final match in matches) {
     if (match.start < cursor) {
       continue;
     }
     final int openBraceIndex = match.end - 1;
     final int? closeBraceIndex = _findMatchingClosingBrace(content, openBraceIndex);
     if (closeBraceIndex == null) {
       throwToolExit(
         'Failed to inject content-hashed asset manifest into $filePath: '
         'unterminated "_flutter.buildConfig" object.',
       );
     }
     int endIndex = closeBraceIndex + 1;
     if (endIndex < content.length && content.codeUnitAt(endIndex) == 0x3B /* ; */ ) {
       endIndex++;
     }
     final String jsonPart = content.substring(openBraceIndex, closeBraceIndex + 1);
     try {
       final Object? decoded = json.decode(jsonPart);
       if (decoded is! Map<String, Object?>) {
         throwToolExit(
           'Failed to inject content-hashed asset manifest into $filePath: '
           '"_flutter.buildConfig" is not a JSON object.',
         );
       }
       final updatedMap = <String, Object?>{
         ...decoded,
         if (hashResult.assetManifestBinJson != null)
           'assetManifest': hashResult.assetManifestBinJson,
         if (hashResult.fontManifestJson != null) 'fontManifest': hashResult.fontManifestJson,
         if (hashResult.extraAssets.isNotEmpty) 'extraAssets': hashResult.extraAssets,
       };
       buffer.write(content.substring(cursor, match.start));
       buffer.write('_flutter.buildConfig = ${json.encode(updatedMap)};');
       cursor = endIndex;
     } on FormatException catch (e) {
       throwToolExit(
         'Failed to inject content-hashed asset manifest into $filePath: '
         '"_flutter.buildConfig" is not valid JSON ($e). '
         'Ensure "{{flutter_build_config}}" is used.',
       );
     }
   }
   if (cursor == 0) {
     return content;
   }
   buffer.write(content.substring(cursor));
   return buffer.toString();
 }

 /// Injects `"assetManifest"`, `"fontManifest"`, and `"extraAssets"` into
 /// `_flutter.buildConfig` inside `flutter_bootstrap.js` and `index.html` in
 /// [outputDir].
 void injectManifestBuildConfig(Directory outputDir, WebAssetHashResult hashResult) {
   if (!outputDir.existsSync()) {
     return;
   }
   if (hashResult.assetManifestBinJson == null &&
       hashResult.fontManifestJson == null &&
       hashResult.extraAssets.isEmpty) {
     return;
   }
   for (final File file in outputDir.listSync(recursive: true).whereType<File>()) {
     final String basename = file.fileSystem.path.basename(file.path);
     if (basename != 'flutter_bootstrap.js' && basename != 'index.html') {
       continue;
     }
     final String content = file.readAsStringSync();
     if (!stripHtmlAndJsComments(content).contains('_flutter.buildConfig')) {
       continue;
     }
     final String updated = _updateBuildConfigInContent(content, hashResult, filePath: file.path);
     if (updated != content) {
       file.writeAsStringSync(updated);
     }
   }
   if (hashResult.assetManifestBinJson != null) {
     final File bootstrapFile = outputDir.childFile('flutter_bootstrap.js');
     if (!bootstrapFile.existsSync() ||
         !bootstrapFile.readAsStringSync().contains('"assetManifest"')) {
       throwToolExit(
         'Failed to inject content-hashed "assetManifest" into ${bootstrapFile.path}. '
         'Ensure web/flutter_bootstrap.js contains the "{{flutter_build_config}}" placeholder.',
       );
     }
   }
 }

 /// The filename of the precache manifest generated for web content hashing.
 const String kPrecacheManifestFile = 'precache_manifest.json';

 bool _shouldExcludeFromPrecacheManifest({
   required String posixUrl,
   required String basename,
   required List<String> segments,
   required bool useLocalCanvasKit,
 }) {
   if (basename.startsWith('.') ||
       posixUrl == kPrecacheManifestFile ||
       posixUrl == 'flutter_service_worker.js') {
     return true;
   }
   if (basename.endsWith('.map') ||
       basename.endsWith('.symbols') ||
       basename.endsWith('.info.json')) {
     return true;
   }
   if (!useLocalCanvasKit && segments.firstOrNull == 'canvaskit') {
     return true;
   }
   return false;
 }

 /// Writes `precache_manifest.json` in [outputDir] when [enabled] is true, or
 /// removes any stale manifest file when [enabled] is false.
 File? updatePrecacheManifest(
   Directory outputDir, {
   required bool enabled,
   required bool useLocalCanvasKit,
 }) {
   final File manifestFile = outputDir.childFile(kPrecacheManifestFile);
   if (!enabled) {
     if (manifestFile.existsSync()) {
       manifestFile.deleteSync();
     }
     return null;
   }

   if (!outputDir.existsSync()) {
     return null;
   }

   final FileSystem fileSystem = outputDir.fileSystem;
   final List<File> files = outputDir.listSync(recursive: true).whereType<File>().toList();

   final entries = <Map<String, Object>>[];
   for (final file in files) {
     final String relativePath = fileSystem.path.relative(file.path, from: outputDir.path);
     final List<String> segments = fileSystem.path.split(relativePath);
     final String posixUrl = p.posix.joinAll(segments);
     final String basename = segments.last;

     if (_shouldExcludeFromPrecacheManifest(
       posixUrl: posixUrl,
       basename: basename,
       segments: segments,
       useLocalCanvasKit: useLocalCanvasKit,
     )) {
       continue;
     }

     final Uint8List bytes = file.readAsBytesSync();
     final String shortHash = crypto.sha256.convert(bytes).toString().substring(0, 8);
     final bool urlHashed = basename.contains('.$shortHash.') || basename.endsWith('.$shortHash');

     entries.add(<String, Object>{
       'url': posixUrl,
       'hash': shortHash,
       'size': bytes.length,
       'urlHashed': urlHashed,
     });
   }

   entries.sort(
     (Map<String, Object> a, Map<String, Object> b) =>
         (a['url']! as String).compareTo(b['url']! as String),
   );

   manifestFile.writeAsStringSync(
     const JsonEncoder.withIndent('  ').convert(<String, Object>{'version': 1, 'entries': entries}),
   );
   return manifestFile;
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'dart:typed_data';

	import 'package:crypto/crypto.dart' as crypto;
	import 'package:path/path.dart' as p; // flutter_ignore: package_path_import
	import 'package:standard_message_codec/standard_message_codec.dart';

	import '../base/common.dart';
	import '../base/file_system.dart';
	import '../convert.dart';

	const List<String> _kKnownHashedExtensions = <String>[
	'.js.map',
	'.wasm.map',
	'.mjs.map',
	'.js',
	'.wasm',
	'.mjs',
	];

	const Set<String> _kManifestAssetRelativePaths = <String>{
	'AssetManifest.json',
	'AssetManifest.bin',
	'AssetManifest.bin.json',
	'FontManifest.json',
	};

	/// Result of content-hashing the files and manifests in `build/web/assets/`.
	class WebAssetHashResult {
	const WebAssetHashResult({
	required this.renamedFiles,
	this.assetManifestBinJson,
	this.fontManifestJson,
	this.extraAssets = const <String, String>{},
	});

	/// Mapping from original file paths (and normalized paths) to their renamed
	/// content-hashed [File] handles on disk.
	final Map<String, File> renamedFiles;

	/// The content-hashed filename of `AssetManifest.bin.json` (for example,
	/// `AssetManifest.bin.a1b2c3d4.json`), if present.
	final String? assetManifestBinJson;

	/// The content-hashed filename of `FontManifest.json` (for example,
	/// `FontManifest.e5f60718.json`), if present.
	final String? fontManifestJson;

	/// Non-manifest files in `build/web/assets/` (such as `NOTICES`, framework
	/// shaders not listed in `AssetManifest.bin`, `AssetManifest.bin`, and
	/// `AssetManifest.json`) mapped from their unhashed relative path to their
	/// content-hashed relative path.
	final Map<String, String> extraAssets;
	}

	String computeHashedBasename(String oldBasename, String contentHash, FileSystem fileSystem) {
	final String doubleExt = fileSystem.path.extension(oldBasename, 2);
	final String ext = _kKnownHashedExtensions.contains(doubleExt)
	? doubleExt
	: fileSystem.path.extension(oldBasename);
	if (ext.isNotEmpty) {
	final String stem = oldBasename.substring(0, oldBasename.length - ext.length);
	return '$stem.$contentHash$ext';
	}
	return '$oldBasename.$contentHash';
	}

	WebAssetHashResult hashWebAssets(Directory assetsDir) {
	final renamedFileMap = <String, File>{};
	if (!assetsDir.existsSync()) {
	return WebAssetHashResult(renamedFiles: renamedFileMap);
	}

	final FileSystem fileSystem = assetsDir.fileSystem;
	final List<File> files = assetsDir.listSync(recursive: true).whereType<File>().toList()
	..sort((File a, File b) => a.path.compareTo(b.path));
	final rawRenamedAssets = <String, String>{};
	final renamedAssets = <String, String>{};
	final decodedRenamedAssets = <String, String>{};

	String decodeSafe(String value) {
	try {
	return Uri.decodeFull(value);
	} on ArgumentError {
	return value;
	}
	}

	String hashAndRenameFile(File file, String posixRelativePath) {
	final String relativePath = fileSystem.path.relative(file.path, from: assetsDir.path);
	final List<String> segments = fileSystem.path.split(relativePath);
	final String basename = fileSystem.path.basename(file.path);
	final String contentHash = crypto.sha256
	.convert(file.readAsBytesSync())
	.toString()
	.substring(0, 8);
	final String newBasename = computeHashedBasename(basename, contentHash, fileSystem);

	final newSegments = <String>[...segments.sublist(0, segments.length - 1), newBasename];
	final String newRelativePath = fileSystem.path.joinAll(newSegments);
	final String posixNewPath = p.posix.joinAll(newSegments);
	final String decodedNewPath = decodeSafe(posixNewPath);

	// Rename the physical file on disk.
	final String newPath = fileSystem.path.join(assetsDir.path, newRelativePath);
	final String oldPath = file.path;
	final String normalizedOldPath = fileSystem.path.normalize(oldPath);
	file.renameSync(newPath);
	final File newFile = fileSystem.file(newPath);
	renamedFileMap[oldPath] = newFile;
	renamedFileMap[normalizedOldPath] = newFile;

	// Map POSIX paths:
	// - `renamedAssets` maps to the on-disk `%20`-encoded path (used by FontManifest.json).
	// - `decodedRenamedAssets` maps to the `Uri.decodeFull` path (used by AssetManifest.bin /
	// AssetManifest.json, matching `_createAssetManifest` in `asset.dart`).
	rawRenamedAssets[posixRelativePath] = posixNewPath;
	renamedAssets[posixRelativePath] = posixNewPath;
	decodedRenamedAssets[posixRelativePath] = decodedNewPath;

	final String decodedOld = decodeSafe(posixRelativePath);
	renamedAssets[decodedOld] = posixNewPath;
	decodedRenamedAssets[decodedOld] = decodedNewPath;

	final String encodedOld = Uri.encodeFull(posixRelativePath);
	renamedAssets[encodedOld] = posixNewPath;
	decodedRenamedAssets[encodedOld] = decodedNewPath;

	return posixNewPath;
	}

	// Pass 1: Hash all physical asset files (including shaders and NOTICES)
	// except the manifest files themselves, whose contents depend on Pass 1 hashes.
	for (final file in files) {
	final String relativePath = fileSystem.path.relative(file.path, from: assetsDir.path);
	final List<String> segments = fileSystem.path.split(relativePath);
	final String posixRelativePath = p.posix.joinAll(segments);

	if (_kManifestAssetRelativePaths.contains(posixRelativePath)) {
	continue;
	}

	hashAndRenameFile(file, posixRelativePath);
	}

	final manifestCoveredTargets = <String>{};
	void recordManifestTarget(String target) {
	manifestCoveredTargets.add(target);
	manifestCoveredTargets.add(Uri.encodeFull(target));
	manifestCoveredTargets.add(Uri(path: Uri.encodeFull(target)).path);
	final String decoded = decodeSafe(target);
	manifestCoveredTargets.add(decoded);
	manifestCoveredTargets.add(Uri.encodeFull(decoded));
	manifestCoveredTargets.add(Uri(path: Uri.encodeFull(decoded)).path);
	}

	// Pass 2a: Rewrite FontManifest.json and hash it on disk.
	// FontManifest.json keeps the `%20`-encoded `posixNewPath` because `loadAssetFonts`
	// in `web_ui` calls `assetManager.loadAsset` directly without `PlatformAssetBundle`.
	String? hashedFontManifestJson;
	final File fontManifest = assetsDir.childFile('FontManifest.json');
	if (fontManifest.existsSync()) {
	final Object? decodedJson = json.decode(fontManifest.readAsStringSync());
	if (decodedJson is List<dynamic>) {
	for (final Object? font in decodedJson) {
	if (font is Map<String, dynamic>) {
	final Object? fonts = font['fonts'];
	if (fonts is List<dynamic>) {
	for (final Object? fontAsset in fonts) {
	if (fontAsset is Map<String, dynamic>) {
	final Object? asset = fontAsset['asset'];
	if (asset is String && renamedAssets.containsKey(asset)) {
	fontAsset['asset'] = renamedAssets[asset];
	}
	}
	}
	}
	}
	}
	fontManifest.writeAsStringSync(json.encode(decodedJson));
	}
	hashedFontManifestJson = hashAndRenameFile(fontManifest, 'FontManifest.json');
	}

	// Pass 2b: Rewrite legacy AssetManifest.json if present and hash it on disk.
	final File assetManifestJson = assetsDir.childFile('AssetManifest.json');
	if (assetManifestJson.existsSync()) {
	final Object? decodedJson = json.decode(assetManifestJson.readAsStringSync());
	if (decodedJson is Map<String, dynamic>) {
	final newManifest = <String, dynamic>{};
	for (final MapEntry<String, dynamic> entry in decodedJson.entries) {
	recordManifestTarget(entry.key);
	final Object? variants = entry.value;
	if (variants is! List<dynamic>) {
	newManifest[entry.key] = variants;
	continue;
	}
	final newVariants = <String>[];
	for (final Object? variant in variants) {
	if (variant is String) {
	recordManifestTarget(variant);
	newVariants.add(decodedRenamedAssets[variant] ?? variant);
	} else if (variant != null) {
	newVariants.add(variant.toString());
	}
	}
	newManifest[entry.key] = newVariants;
	}
	assetManifestJson.writeAsStringSync(json.encode(newManifest));
	}
	hashAndRenameFile(assetManifestJson, 'AssetManifest.json');
	}

	// Pass 2c: Rewrite AssetManifest.bin and AssetManifest.bin.json and hash both on disk.
	// Do NOT insert non-manifest SDK files (`NOTICES`, framework shaders, `FontManifest.json`,
	// `AssetManifest.bin`, etc.) into `AssetManifest.bin` or `AssetManifest.bin.json` so that
	// `AssetManifest.loadFromAssetBundle(rootBundle).listAssets()` returns the exact same keys
	// as a build without `--web-content-hash`.
	String? hashedAssetManifestBinJson;
	final File assetManifestBin = assetsDir.childFile('AssetManifest.bin');
	final File assetManifestBinJson = assetsDir.childFile('AssetManifest.bin.json');
	if (assetManifestBin.existsSync()) {
	final Uint8List rawBytes = assetManifestBin.readAsBytesSync();
	final message = ByteData.sublistView(rawBytes);
	final Object? decoded = const StandardMessageCodec().decodeMessage(message);
	if (decoded is Map<Object?, Object?>) {
	final newManifest = <String, dynamic>{};
	for (final MapEntry<Object?, Object?> entry in decoded.entries) {
	final key = entry.key.toString();
	recordManifestTarget(key);
	final Object? variantsVal = entry.value;
	if (variantsVal is! List<Object?>) {
	newManifest[key] = variantsVal;
	continue;
	}
	final newVariants = <dynamic>[];
	for (final Object? variantObj in variantsVal) {
	if (variantObj is! Map<Object?, Object?>) {
	newVariants.add(variantObj);
	continue;
	}
	final newVariantMap = <String, dynamic>{};
	for (final MapEntry<Object?, Object?> vEntry in variantObj.entries) {
	final vKey = vEntry.key.toString();
	if (vKey == 'asset') {
	final vValue = vEntry.value.toString();
	recordManifestTarget(vValue);
	newVariantMap[vKey] = decodedRenamedAssets[vValue] ?? vValue;
	} else {
	newVariantMap[vKey] = vEntry.value;
	}
	}
	newVariants.add(newVariantMap);
	}
	newManifest[key] = newVariants;
	}
	final ByteData encoded = const StandardMessageCodec().encodeMessage(newManifest)!;
	final encodedBytes = Uint8List.sublistView(encoded);
	assetManifestBin.writeAsBytesSync(encodedBytes);
	hashAndRenameFile(assetManifestBin, 'AssetManifest.bin');

	// Update AssetManifest.bin.json with the same manifest entries and hash it on disk.
	if (assetManifestBinJson.existsSync()) {
	assetManifestBinJson.writeAsStringSync(json.encode(base64.encode(encodedBytes)));
	hashedAssetManifestBinJson = hashAndRenameFile(
	assetManifestBinJson,
	'AssetManifest.bin.json',
	);
	}
	}
	}

	// Collect non-manifest files in `build/web/assets/` (such as `NOTICES`,
	// framework shaders not listed in `pubspec.yaml`, `FontManifest.json`,
	// `AssetManifest.bin`, and `AssetManifest.json`) into `extraAssets` for
	// `_flutter.buildConfig`.
	final extraAssets = <String, String>{};
	for (final MapEntry<String, String> entry in rawRenamedAssets.entries) {
	if (entry.key == 'AssetManifest.bin.json') {
	continue;
	}
	if (!manifestCoveredTargets.contains(entry.key) &&
	!manifestCoveredTargets.contains(decodeSafe(entry.key))) {
	extraAssets[decodeSafe(entry.key)] = entry.value;
	}
	}

	return WebAssetHashResult(
	renamedFiles: renamedFileMap,
	assetManifestBinJson: hashedAssetManifestBinJson,
	fontManifestJson: hashedFontManifestJson,
	extraAssets: extraAssets,
	);
	}

	final RegExp _htmlCommentRegex = RegExp(r'<!--[\s\S]*?-->');

	final RegExp _jsCommentOrStringRegex = RegExp(
	r'/\[\s\S]?\/\|(?<!:)//[^\r\n]\|"(?:\\.\|[^"\\\r\n])*"\|'
	"'"
	r'(?:\\.\|[^'
	"'"
	r'\\\r\n])*'
	"'"
	r'\|`(?:\\.\|[^`\\])*`',
	);

	/// Strips HTML (`<!-- ... -->`) and JavaScript (`/* ... */`, `// ...`) comments
	/// from [content] while preserving single-quoted, double-quoted, and template
	/// string literals.
	String stripHtmlAndJsComments(String content) {
	final String withoutHtmlComments = content.replaceAll(_htmlCommentRegex, '');
	return withoutHtmlComments.replaceAllMapped(_jsCommentOrStringRegex, (Match match) {
	final String token = match.group(0)!;
	if (token.startsWith('/*') \|\| token.startsWith('//')) {
	return '';
	}
	return token;
	});
	}

	final RegExp _buildConfigTokenOrCommentRegex = RegExp(
	r'<!--[\s\S]?-->\|/\[\s\S]?\/\|(?<!:)//[^\r\n]\|"(?:\\.\|[^"\\\r\n])"\|'
	"'"
	r'(?:\\.\|[^'
	"'"
	r'\\\r\n])*'
	"'"
	r'\|`(?:\\.\|[^`\\])`\|_flutter\.buildConfig\s=\s*\{',
	);

	int? _findMatchingClosingBrace(String text, int openBraceIndex) {
	var depth = 0;
	int? stringQuote;
	var escaped = false;
	for (var i = openBraceIndex; i < text.length; i++) {
	final int ch = text.codeUnitAt(i);
	if (stringQuote != null) {
	if (escaped) {
	escaped = false;
	} else if (ch == 0x5C /* \ */ ) {
	escaped = true;
	} else if (ch == stringQuote) {
	stringQuote = null;
	}
	continue;
	}
	if (ch == 0x22 /* " / \|\| ch == 0x27 / ' / \|\| ch == 0x60 / ` */ ) {
	stringQuote = ch;
	} else if (ch == 0x7B /* { */ ) {
	depth++;
	} else if (ch == 0x7D /* } */ ) {
	depth--;
	if (depth == 0) {
	return i;
	}
	}
	}
	return null;
	}

	String _updateBuildConfigInContent(
	String content,
	WebAssetHashResult hashResult, {
	required String filePath,
	}) {
	final List<Match> matches = _buildConfigTokenOrCommentRegex
	.allMatches(content)
	.where((Match m) => m.group(0)!.startsWith('_flutter.buildConfig'))
	.toList();
	if (matches.isEmpty) {
	throwToolExit(
	'Failed to inject content-hashed asset manifest into $filePath: '
	'"_flutter.buildConfig" is not a JSON object assignment. '
	'Ensure "{{flutter_build_config}}" is used.',
	);
	}
	final buffer = StringBuffer();
	var cursor = 0;
	for (final match in matches) {
	if (match.start < cursor) {
	continue;
	}
	final int openBraceIndex = match.end - 1;
	final int? closeBraceIndex = _findMatchingClosingBrace(content, openBraceIndex);
	if (closeBraceIndex == null) {
	throwToolExit(
	'Failed to inject content-hashed asset manifest into $filePath: '
	'unterminated "_flutter.buildConfig" object.',
	);
	}
	int endIndex = closeBraceIndex + 1;
	if (endIndex < content.length && content.codeUnitAt(endIndex) == 0x3B /* ; */ ) {
	endIndex++;
	}
	final String jsonPart = content.substring(openBraceIndex, closeBraceIndex + 1);
	try {
	final Object? decoded = json.decode(jsonPart);
	if (decoded is! Map<String, Object?>) {
	throwToolExit(
	'Failed to inject content-hashed asset manifest into $filePath: '
	'"_flutter.buildConfig" is not a JSON object.',
	);
	}
	final updatedMap = <String, Object?>{
	...decoded,
	if (hashResult.assetManifestBinJson != null)
	'assetManifest': hashResult.assetManifestBinJson,
	if (hashResult.fontManifestJson != null) 'fontManifest': hashResult.fontManifestJson,
	if (hashResult.extraAssets.isNotEmpty) 'extraAssets': hashResult.extraAssets,
	};
	buffer.write(content.substring(cursor, match.start));
	buffer.write('_flutter.buildConfig = ${json.encode(updatedMap)};');
	cursor = endIndex;
	} on FormatException catch (e) {
	throwToolExit(
	'Failed to inject content-hashed asset manifest into $filePath: '
	'"_flutter.buildConfig" is not valid JSON ($e). '
	'Ensure "{{flutter_build_config}}" is used.',
	);
	}
	}
	if (cursor == 0) {
	return content;
	}
	buffer.write(content.substring(cursor));
	return buffer.toString();
	}

	/// Injects `"assetManifest"`, `"fontManifest"`, and `"extraAssets"` into
	/// `_flutter.buildConfig` inside `flutter_bootstrap.js` and `index.html` in
	/// [outputDir].
	void injectManifestBuildConfig(Directory outputDir, WebAssetHashResult hashResult) {
	if (!outputDir.existsSync()) {
	return;
	}
	if (hashResult.assetManifestBinJson == null &&
	hashResult.fontManifestJson == null &&
	hashResult.extraAssets.isEmpty) {
	return;
	}
	for (final File file in outputDir.listSync(recursive: true).whereType<File>()) {
	final String basename = file.fileSystem.path.basename(file.path);
	if (basename != 'flutter_bootstrap.js' && basename != 'index.html') {
	continue;
	}
	final String content = file.readAsStringSync();
	if (!stripHtmlAndJsComments(content).contains('_flutter.buildConfig')) {
	continue;
	}
	final String updated = _updateBuildConfigInContent(content, hashResult, filePath: file.path);
	if (updated != content) {
	file.writeAsStringSync(updated);
	}
	}
	if (hashResult.assetManifestBinJson != null) {
	final File bootstrapFile = outputDir.childFile('flutter_bootstrap.js');
	if (!bootstrapFile.existsSync() \|\|
	!bootstrapFile.readAsStringSync().contains('"assetManifest"')) {
	throwToolExit(
	'Failed to inject content-hashed "assetManifest" into ${bootstrapFile.path}. '
	'Ensure web/flutter_bootstrap.js contains the "{{flutter_build_config}}" placeholder.',
	);
	}
	}
	}

	/// The filename of the precache manifest generated for web content hashing.
	const String kPrecacheManifestFile = 'precache_manifest.json';

	bool _shouldExcludeFromPrecacheManifest({
	required String posixUrl,
	required String basename,
	required List<String> segments,
	required bool useLocalCanvasKit,
	}) {
	if (basename.startsWith('.') \|\|
	posixUrl == kPrecacheManifestFile \|\|
	posixUrl == 'flutter_service_worker.js') {
	return true;
	}
	if (basename.endsWith('.map') \|\|
	basename.endsWith('.symbols') \|\|
	basename.endsWith('.info.json')) {
	return true;
	}
	if (!useLocalCanvasKit && segments.firstOrNull == 'canvaskit') {
	return true;
	}
	return false;
	}

	/// Writes `precache_manifest.json` in [outputDir] when [enabled] is true, or
	/// removes any stale manifest file when [enabled] is false.
	File? updatePrecacheManifest(
	Directory outputDir, {
	required bool enabled,
	required bool useLocalCanvasKit,
	}) {
	final File manifestFile = outputDir.childFile(kPrecacheManifestFile);
	if (!enabled) {
	if (manifestFile.existsSync()) {
	manifestFile.deleteSync();
	}
	return null;
	}

	if (!outputDir.existsSync()) {
	return null;
	}

	final FileSystem fileSystem = outputDir.fileSystem;
	final List<File> files = outputDir.listSync(recursive: true).whereType<File>().toList();

	final entries = <Map<String, Object>>[];
	for (final file in files) {
	final String relativePath = fileSystem.path.relative(file.path, from: outputDir.path);
	final List<String> segments = fileSystem.path.split(relativePath);
	final String posixUrl = p.posix.joinAll(segments);
	final String basename = segments.last;

	if (_shouldExcludeFromPrecacheManifest(
	posixUrl: posixUrl,
	basename: basename,
	segments: segments,
	useLocalCanvasKit: useLocalCanvasKit,
	)) {
	continue;
	}

	final Uint8List bytes = file.readAsBytesSync();
	final String shortHash = crypto.sha256.convert(bytes).toString().substring(0, 8);
	final bool urlHashed = basename.contains('.$shortHash.') \|\| basename.endsWith('.$shortHash');

	entries.add(<String, Object>{
	'url': posixUrl,
	'hash': shortHash,
	'size': bytes.length,
	'urlHashed': urlHashed,
	});
	}

	entries.sort(
	(Map<String, Object> a, Map<String, Object> b) =>
	(a['url']! as String).compareTo(b['url']! as String),
	);

	manifestFile.writeAsStringSync(
	const JsonEncoder.withIndent(' ').convert(<String, Object>{'version': 1, 'entries': entries}),
	);
	return manifestFile;
	}