// 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 'package:pub_semver/pub_semver.dart';

import 'build_info.dart';
import 'cmake_project.dart';
import 'globals.dart' as globals;

/// Extracts the `BINARY_NAME` from a project's CMake file.
///
/// Returns `null` if it cannot be found.
String? getCmakeExecutableName(CmakeBasedProject project) {
  if (!project.cmakeFile.existsSync()) {
    return null;
  }
  final RegExp nameSetPattern = RegExp(r'^\s*set\(BINARY_NAME\s*"(.*)"\s*\)\s*$');
  for (final String line in project.cmakeFile.readAsLinesSync()) {
    final RegExpMatch? match = nameSetPattern.firstMatch(line);
    if (match != null) {
      return match.group(1);
    }
  }
  return null;
}

String _escapeBackslashes(String s) {
  return s.replaceAll(r'\', r'\\');
}

String _determineVersionString(CmakeBasedProject project, BuildInfo buildInfo) {
  // Prefer the build arguments for version information.
  final String buildName = buildInfo.buildName ?? project.parent.manifest.buildName ?? '1.0.0';
  final String? buildNumber = buildInfo.buildName != null
    ? buildInfo.buildNumber
    : (buildInfo.buildNumber ?? project.parent.manifest.buildNumber);

  return buildNumber != null
    ? '$buildName+$buildNumber'
    : buildName;
}

Version _determineVersion(CmakeBasedProject project, BuildInfo buildInfo) {
  final String version = _determineVersionString(project, buildInfo);
  try {
    return Version.parse(version);
  } on FormatException {
    globals.printWarning('Warning: could not parse version $version, defaulting to 1.0.0.');

    return Version(1, 0, 0);
  }
}

/// Attempts to map a Dart version's build identifier (the part after a +) into
/// a single integer. Returns null for complex build identifiers like `foo` or `1.2`.
int? _tryDetermineBuildVersion(Version version) {
  if (version.build.isEmpty) {
    return 0;
  }

  if (version.build.length != 1) {
    return null;
  }

  final Object buildIdentifier = version.build.first as Object;
  return buildIdentifier is int ? buildIdentifier : null;
}

/// Writes a generated CMake configuration file for [project], including
/// variables expected by the build template and an environment variable list
/// for calling back into Flutter.
void writeGeneratedCmakeConfig(
  String flutterRoot,
  CmakeBasedProject project,
  BuildInfo buildInfo,
  Map<String, String> environment) {
  // Only a limited set of variables are needed by the CMake files themselves,
  // the rest are put into a list to pass to the re-entrant build step.
  final String escapedFlutterRoot = _escapeBackslashes(flutterRoot);
  final String escapedProjectDir = _escapeBackslashes(project.parent.directory.path);

  final Version version = _determineVersion(project, buildInfo);
  final int? buildVersion = _tryDetermineBuildVersion(version);

  // Since complex Dart build identifiers cannot be converted into integers,
  // different Dart versions may be converted into the same Windows numeric version.
  // Warn the user as some Windows installers, like MSI, don't update files if their versions are equal.
  if (buildVersion == null && project is WindowsProject) {
      final String buildIdentifier = version.build.join('.');
      globals.printWarning(
        'Warning: build identifier $buildIdentifier in version $version is not numeric '
        'and cannot be converted into a Windows build version number. Defaulting to 0.\n'
        'This may cause issues with Windows installers.'
      );
  }

  final StringBuffer buffer = StringBuffer('''
# Generated code do not commit.
file(TO_CMAKE_PATH "$escapedFlutterRoot" FLUTTER_ROOT)
file(TO_CMAKE_PATH "$escapedProjectDir" PROJECT_DIR)

set(FLUTTER_VERSION "$version" PARENT_SCOPE)
set(FLUTTER_VERSION_MAJOR ${version.major} PARENT_SCOPE)
set(FLUTTER_VERSION_MINOR ${version.minor} PARENT_SCOPE)
set(FLUTTER_VERSION_PATCH ${version.patch} PARENT_SCOPE)
set(FLUTTER_VERSION_BUILD ${buildVersion ?? 0} PARENT_SCOPE)

# Environment variables to pass to tool_backend.sh
list(APPEND FLUTTER_TOOL_ENVIRONMENT
  "FLUTTER_ROOT=$escapedFlutterRoot"
  "PROJECT_DIR=$escapedProjectDir"
''');
  environment.forEach((String key, String value) {
    final String configValue = _escapeBackslashes(value);
    buffer.writeln('  "$key=$configValue"');
  });
  buffer.writeln(')');

  project.generatedCmakeConfigFile
    ..createSync(recursive: true)
    ..writeAsStringSync(buffer.toString());
}