// Copyright 2013 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:convert' show ByteConversionSink, jsonDecode, utf8;
import 'dart:io' as io;
import 'dart:typed_data';

import 'package:args/command_runner.dart';
import 'package:convert/convert.dart';
import 'package:crypto/crypto.dart' as crypto;
import 'package:http/http.dart' as http;
import 'package:path/path.dart' as path;

import 'cipd.dart';
import 'environment.dart';
import 'exceptions.dart';
import 'utils.dart';

const String expectedUrlPrefix = 'https://fonts.gstatic.com/s/';

class RollFallbackFontsCommand extends Command<bool>
    with ArgUtils<bool> {
  RollFallbackFontsCommand() {
    argParser.addOption(
      'key',
      defaultsTo: '',
      help: 'The Google Fonts API key. Used to get data about fonts hosted on '
          'Google Fonts.',
    );
    argParser.addFlag(
      'dry-run',
      help: 'Whether or not to push changes to CIPD. When --dry-run is set, the '
            'script will download everything and attempt to prepare the bundle '
            'but will stop before publishing. When not set, the bundle will be '
            'published.',
      negatable: false,
    );
  }

  @override
  final String name = 'roll-fallback-fonts';

  @override
  final String description = 'Generate fallback font data from GoogleFonts and '
                             'upload fonts to cipd.';

  String get apiKey => stringArg('key');
  bool get isDryRun => boolArg('dry-run');

  @override
  Future<bool> run() async {
    await _generateFallbackFontData();
    return true;
  }

  Future<void> _generateFallbackFontData() async {
    if (apiKey.isEmpty) {
      throw UsageException('No Google Fonts API key provided', argParser.usage);
    }
    final http.Client client = http.Client();
    final http.Response response = await client.get(Uri.parse(
        'https://www.googleapis.com/webfonts/v1/webfonts?key=$apiKey'));
    if (response.statusCode != 200) {
      throw ToolExit('Failed to download Google Fonts list.');
    }
    final Map<String, dynamic> googleFontsResult =
        jsonDecode(response.body) as Map<String, dynamic>;
    final List<Map<String, dynamic>> fontDatas =
        (googleFontsResult['items'] as List<dynamic>)
            .cast<Map<String, dynamic>>();
    final Map<String, Uri> urlForFamily = <String, Uri>{};
    for (final Map<String, dynamic> fontData in fontDatas) {
      if (fallbackFonts.contains(fontData['family'])) {
        final Uri uri = Uri.parse(fontData['files']['regular'] as String)
            .replace(scheme: 'https');
        urlForFamily[fontData['family'] as String] = uri;
      }
    }
    final Map<String, String> charsetForFamily = <String, String>{};
    final io.Directory fontDir = await io.Directory.systemTemp.createTemp('flutter_fallback_fonts');
    print('Downloading fonts into temp directory: ${fontDir.path}');
    final AccumulatorSink<crypto.Digest> hashSink = AccumulatorSink<crypto.Digest>();
    final ByteConversionSink hasher = crypto.sha256.startChunkedConversion(hashSink);
    for (final String family in fallbackFonts) {
      print('Downloading $family...');
      final Uri? uri = urlForFamily[family];
      if (uri == null) {
        throw ToolExit('Unable to determine URL to download $family. '
            'Check if it is still hosted on Google Fonts.');
      }
      final http.Response fontResponse = await client.get(uri);
      if (fontResponse.statusCode != 200) {
        throw ToolExit('Failed to download font for $family');
      }
      final String urlString = uri.toString();
      if (!urlString.startsWith(expectedUrlPrefix)) {
        throw ToolExit('Unexpected url format received from Google Fonts API: $urlString.');
      }
      final String urlSuffix = urlString.substring(expectedUrlPrefix.length);
      final io.File fontFile =
          io.File(path.join(fontDir.path, urlSuffix));

      final Uint8List bodyBytes = fontResponse.bodyBytes;
      if (!_checkForLicenseAttribution(bodyBytes)) {
        throw ToolExit('Expected license attribution not found in file: $urlString');
      }
      hasher.add(utf8.encode(urlSuffix));
      hasher.add(bodyBytes);

      await fontFile.create(recursive: true);
      await fontFile.writeAsBytes(bodyBytes, flush: true);
      final io.ProcessResult fcQueryResult =
          await io.Process.run('fc-query', <String>[
        '--format=%{charset}',
        '--',
        fontFile.path,
      ]);
      final String encodedCharset = fcQueryResult.stdout as String;
      charsetForFamily[family] = encodedCharset;
    }

    final StringBuffer sb = StringBuffer();

    sb.writeln('// Copyright 2013 The Flutter Authors. All rights reserved.');
    sb.writeln('// Use of this source code is governed by a BSD-style license '
        'that can be');
    sb.writeln('// found in the LICENSE file.');
    sb.writeln();
    sb.writeln('// DO NOT EDIT! This file is generated. See:');
    sb.writeln('// dev/roll_fallback_fonts.dart');
    sb.writeln("import 'noto_font.dart';");
    sb.writeln();
    sb.writeln('List<NotoFont> getFallbackFontData(bool useColorEmoji) => <NotoFont>[');

    for (final String family in fallbackFonts) {
      if (family == 'Noto Emoji') {
        sb.write(' if (!useColorEmoji)');
      }
      if (family == 'Noto Color Emoji') {
        sb.write(' if (useColorEmoji)');
      }
      final String urlString = urlForFamily[family]!.toString();
      if (!urlString.startsWith(expectedUrlPrefix)) {
        throw ToolExit('Unexpected url format received from Google Fonts API: $urlString.');
      }
      final String urlSuffix = urlString.substring(expectedUrlPrefix.length);
      sb.writeln(" NotoFont('$family', '$urlSuffix',");
      final List<String> starts = <String>[];
      final List<String> ends = <String>[];
      for (final String range in charsetForFamily[family]!.split(' ')) {
        final List<String> parts = range.split('-');
        if (parts.length == 1) {
          starts.add(parts[0]);
          ends.add(parts[0]);
        } else {
          starts.add(parts[0]);
          ends.add(parts[1]);
        }
      }

      // Print the unicode ranges in a readable format for easier review. This
      // shouldn't affect code size because comments are removed in release mode.
      sb.write('   // <int>[');
      for (final String start in starts) {
        sb.write('0x$start,');
      }
      sb.writeln('],');
      sb.write('   // <int>[');
      for (final String end in ends) {
        sb.write('0x$end,');
      }
      sb.writeln(']');

      sb.writeln("   '${_packFontRanges(starts, ends)}',");
      sb.writeln(' ),');
    }
    sb.writeln('];');

    final io.File fontDataFile = io.File(path.join(
      environment.webUiRootDir.path,
      'lib',
      'src',
      'engine',
      'font_fallback_data.dart',
    ));
    await fontDataFile.writeAsString(sb.toString());

    final io.File licenseFile = io.File(path.join(
      fontDir.path,
      'LICENSE.txt',
    ));
    const String licenseString = r'''
© Copyright 2015-2021 Google LLC. All Rights Reserved.

This Font Software is licensed under the SIL Open Font License, Version 1.1.
This license is copied below, and is also available with a FAQ at:
http://scripts.sil.org/OFL


-----------------------------------------------------------
SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
-----------------------------------------------------------

PREAMBLE
The goals of the Open Font License (OFL) are to stimulate worldwide
development of collaborative font projects, to support the font creation
efforts of academic and linguistic communities, and to provide a free and
open framework in which fonts may be shared and improved in partnership
with others.

The OFL allows the licensed fonts to be used, studied, modified and
redistributed freely as long as they are not sold by themselves. The
fonts, including any derivative works, can be bundled, embedded,
redistributed and/or sold with any software provided that any reserved
names are not used by derivative works. The fonts and derivatives,
however, cannot be released under any other type of license. The
requirement for fonts to remain under this license does not apply
to any document created using the fonts or their derivatives.

DEFINITIONS
"Font Software" refers to the set of files released by the Copyright
Holder(s) under this license and clearly marked as such. This may
include source files, build scripts and documentation.

"Reserved Font Name" refers to any names specified as such after the
copyright statement(s).

"Original Version" refers to the collection of Font Software components as
distributed by the Copyright Holder(s).

"Modified Version" refers to any derivative made by adding to, deleting,
or substituting -- in part or in whole -- any of the components of the
Original Version, by changing formats or by porting the Font Software to a
new environment.

"Author" refers to any designer, engineer, programmer, technical
writer or other person who contributed to the Font Software.

PERMISSION & CONDITIONS
Permission is hereby granted, free of charge, to any person obtaining
a copy of the Font Software, to use, study, copy, merge, embed, modify,
redistribute, and sell modified and unmodified copies of the Font
Software, subject to the following conditions:

1) Neither the Font Software nor any of its individual components,
in Original or Modified Versions, may be sold by itself.

2) Original or Modified Versions of the Font Software may be bundled,
redistributed and/or sold with any software, provided that each copy
contains the above copyright notice and this license. These can be
included either as stand-alone text files, human-readable headers or
in the appropriate machine-readable metadata fields within text or
binary files as long as those fields can be easily viewed by the user.

3) No Modified Version of the Font Software may use the Reserved Font
Name(s) unless explicit written permission is granted by the corresponding
Copyright Holder. This restriction only applies to the primary font name as
presented to the users.

4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
Software shall not be used to promote, endorse or advertise any
Modified Version, except to acknowledge the contribution(s) of the
Copyright Holder(s) and the Author(s) or with their explicit written
permission.

5) The Font Software, modified or unmodified, in part or in whole,
must be distributed entirely under this license, and must not be
distributed under any other license. The requirement for fonts to
remain under this license does not apply to any document created
using the Font Software.

TERMINATION
This license becomes null and void if any of the above conditions are
not met.

DISCLAIMER
THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
OTHER DEALINGS IN THE FONT SOFTWARE.
''';
    final List<int> licenseData = utf8.encode(licenseString);
    await licenseFile.create(recursive: true);
    await licenseFile.writeAsBytes(licenseData);
    hasher.add(licenseData);
    hasher.close();

    final crypto.Digest digest = hashSink.events.single;
    final String versionString = digest.toString();
    const String packageName = 'flutter/flutter_font_fallbacks';
    if (await cipdKnowsPackageVersion(
      package: packageName,
      versionTag: versionString)) {
        print('Package already exists with hash $versionString. Skipping upload');
    } else {
      print('Uploading fallback fonts to CIPD with hash $versionString');
      await uploadDirectoryToCipd(
        directory: fontDir,
        packageName: packageName,
        configFileName: 'cipd.flutter_font_fallbacks.yaml',
        description: 'A set of Noto fonts to fall back to for use in testing.',
        root: fontDir.path,
        version: versionString,
        buildId: versionString,
        isDryRun: isDryRun,
      );
    }

    print('Setting new fallback fonts deps version to $versionString');
    final String depFilePath = path.join(
      environment.engineSrcDir.path,
      'flutter',
      'DEPS',
    );
    await runProcess('gclient', <String>[
      'setdep',
      '--revision=src/third_party/google_fonts_for_unit_tests:$packageName@$versionString',
      '--deps-file=$depFilePath'
    ]);
  }
}

const List<String> fallbackFonts = <String>[
  'Noto Sans',
  'Noto Color Emoji',
  'Noto Emoji',
  'Noto Sans Symbols',
  'Noto Sans Symbols 2',
  'Noto Sans Adlam',
  'Noto Sans Anatolian Hieroglyphs',
  'Noto Sans Arabic',
  'Noto Sans Armenian',
  'Noto Sans Avestan',
  'Noto Sans Balinese',
  'Noto Sans Bamum',
  'Noto Sans Bassa Vah',
  'Noto Sans Batak',
  'Noto Sans Bengali',
  'Noto Sans Bhaiksuki',
  'Noto Sans Brahmi',
  'Noto Sans Buginese',
  'Noto Sans Buhid',
  'Noto Sans Canadian Aboriginal',
  'Noto Sans Carian',
  'Noto Sans Caucasian Albanian',
  'Noto Sans Chakma',
  'Noto Sans Cham',
  'Noto Sans Cherokee',
  'Noto Sans Coptic',
  'Noto Sans Cuneiform',
  'Noto Sans Cypriot',
  'Noto Sans Deseret',
  'Noto Sans Devanagari',
  'Noto Sans Duployan',
  'Noto Sans Egyptian Hieroglyphs',
  'Noto Sans Elbasan',
  'Noto Sans Elymaic',
  'Noto Sans Georgian',
  'Noto Sans Glagolitic',
  'Noto Sans Gothic',
  'Noto Sans Grantha',
  'Noto Sans Gujarati',
  'Noto Sans Gunjala Gondi',
  'Noto Sans Gurmukhi',
  'Noto Sans HK',
  'Noto Sans Hanunoo',
  'Noto Sans Hatran',
  'Noto Sans Hebrew',
  'Noto Sans Imperial Aramaic',
  'Noto Sans Indic Siyaq Numbers',
  'Noto Sans Inscriptional Pahlavi',
  'Noto Sans Inscriptional Parthian',
  'Noto Sans JP',
  'Noto Sans Javanese',
  'Noto Sans KR',
  'Noto Sans Kaithi',
  'Noto Sans Kannada',
  'Noto Sans Kayah Li',
  'Noto Sans Kharoshthi',
  'Noto Sans Khmer',
  'Noto Sans Khojki',
  'Noto Sans Khudawadi',
  'Noto Sans Lao',
  'Noto Sans Lepcha',
  'Noto Sans Limbu',
  'Noto Sans Linear A',
  'Noto Sans Linear B',
  'Noto Sans Lisu',
  'Noto Sans Lycian',
  'Noto Sans Lydian',
  'Noto Sans Mahajani',
  'Noto Sans Malayalam',
  'Noto Sans Mandaic',
  'Noto Sans Manichaean',
  'Noto Sans Marchen',
  'Noto Sans Masaram Gondi',
  'Noto Sans Math',
  'Noto Sans Mayan Numerals',
  'Noto Sans Medefaidrin',
  'Noto Sans Meetei Mayek',
  'Noto Sans Meroitic',
  'Noto Sans Miao',
  'Noto Sans Modi',
  'Noto Sans Mongolian',
  'Noto Sans Mro',
  'Noto Sans Multani',
  'Noto Sans Myanmar',
  'Noto Sans NKo',
  'Noto Sans Nabataean',
  'Noto Sans New Tai Lue',
  'Noto Sans Newa',
  'Noto Sans Nushu',
  'Noto Sans Ogham',
  'Noto Sans Ol Chiki',
  'Noto Sans Old Hungarian',
  'Noto Sans Old Italic',
  'Noto Sans Old North Arabian',
  'Noto Sans Old Permic',
  'Noto Sans Old Persian',
  'Noto Sans Old Sogdian',
  'Noto Sans Old South Arabian',
  'Noto Sans Old Turkic',
  'Noto Sans Oriya',
  'Noto Sans Osage',
  'Noto Sans Osmanya',
  'Noto Sans Pahawh Hmong',
  'Noto Sans Palmyrene',
  'Noto Sans Pau Cin Hau',
  'Noto Sans Phags Pa',
  'Noto Sans Phoenician',
  'Noto Sans Psalter Pahlavi',
  'Noto Sans Rejang',
  'Noto Sans Runic',
  'Noto Sans SC',
  'Noto Sans Saurashtra',
  'Noto Sans Sharada',
  'Noto Sans Shavian',
  'Noto Sans Siddham',
  'Noto Sans Sinhala',
  'Noto Sans Sogdian',
  'Noto Sans Sora Sompeng',
  'Noto Sans Soyombo',
  'Noto Sans Sundanese',
  'Noto Sans Syloti Nagri',
  'Noto Sans Syriac',
  'Noto Sans TC',
  'Noto Sans Tagalog',
  'Noto Sans Tagbanwa',
  'Noto Sans Tai Le',
  'Noto Sans Tai Tham',
  'Noto Sans Tai Viet',
  'Noto Sans Takri',
  'Noto Sans Tamil',
  'Noto Sans Tamil Supplement',
  'Noto Sans Telugu',
  'Noto Sans Thaana',
  'Noto Sans Thai',
  'Noto Sans Tifinagh',
  'Noto Sans Tirhuta',
  'Noto Sans Ugaritic',
  'Noto Sans Vai',
  'Noto Sans Wancho',
  'Noto Sans Warang Citi',
  'Noto Sans Yi',
  'Noto Sans Zanabazar Square',
];

String _packFontRanges(List<String> starts, List<String> ends) {
  assert(starts.length == ends.length);

  final StringBuffer sb = StringBuffer();

  for (int i = 0; i < starts.length; i++) {
    final int start = int.parse(starts[i], radix: 16);
    final int end = int.parse(ends[i], radix: 16);

    sb.write(start.toRadixString(36));
    sb.write('|');
    if (start != end) {
      sb.write((end - start).toRadixString(36));
    }
    sb.write(';');
  }

  return sb.toString();
}

bool _checkForLicenseAttribution(Uint8List fontBytes) {
  final ByteData fontData = fontBytes.buffer.asByteData();
  final int codePointCount = fontData.lengthInBytes ~/ 2;
  const String attributionString = 'This Font Software is licensed under the SIL Open Font License, Version 1.1.';
  for (int i = 0; i < codePointCount - attributionString.length; i++) {
    bool match = true;
    for (int j = 0; j < attributionString.length; j++) {
      if (fontData.getUint16((i + j) * 2) != attributionString.codeUnitAt(j)) {
        match = false;
        break;
      }
    }
    if (match) {
      return true;
    }
  }
  return false;
}