// 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:convert';
import 'dart:io';
import 'package:file/local.dart';
import 'package:intl/intl.dart';
import 'package:meta/meta.dart';

import 'package:path/path.dart' as path;
import 'package:platform/platform.dart' as platform;

import 'package:process/process.dart';

import 'utils.dart';

class CommandException implements Exception {}

Future<void> main() async {
  await postProcess();
}

/// Post-processes an APIs documentation zip file to modify the footer and version
/// strings for commits promoted to either beta or stable channels.
Future<void> postProcess() async {
  final String revision = await gitRevision(fullLength: true);
  print('Docs revision being processed: $revision');
  final Directory tmpFolder = Directory.systemTemp.createTempSync();
  final String zipDestination = path.join(tmpFolder.path, 'api_docs.zip');

  if (!Platform.environment.containsKey('SDK_CHECKOUT_PATH')) {
    print('SDK_CHECKOUT_PATH env variable is required for this script');
    exit(1);
  }
  final String checkoutPath = Platform.environment['SDK_CHECKOUT_PATH']!;
  final String docsPath = path.join(checkoutPath, 'dev', 'docs');
  await runProcessWithValidations(<String>[
    'curl',
    '-L',
    'https://storage.googleapis.com/flutter_infra_release/flutter/$revision/api_docs.zip',
    '--output',
    zipDestination,
    '--fail',
  ], docsPath);

  // Unzip to docs folder.
  await runProcessWithValidations(<String>['unzip', '-o', zipDestination], docsPath);

  // Generate versions file.
  await runProcessWithValidations(<String>['flutter', '--version'], docsPath);
  final String version;
  switch (await Version.resolveIn(const LocalFileSystem().directory(checkoutPath))) {
    case VersionError(:final String error):
      print('Could not read flutter version: $error');
      exit(1);
    case VersionOk(version: final String parsedVersion):
      version = parsedVersion;
  }

  // Recreate footer
  final String publishPath = path.join(docsPath, '..', 'docs', 'doc', 'flutter', 'footer.js');
  final File footerFile = File(publishPath)..createSync(recursive: true);
  createFooter(footerFile, version);
}

/// Gets the git revision of the current checkout. [fullLength] if true will return
/// the full commit hash, if false it will return the first 10 characters only.
Future<String> gitRevision({
  bool fullLength = false,
  @visibleForTesting platform.Platform platform = const platform.LocalPlatform(),
  @visibleForTesting ProcessManager processManager = const LocalProcessManager(),
}) async {
  const int kGitRevisionLength = 10;

  final ProcessResult gitResult = processManager.runSync(<String>['git', 'rev-parse', 'HEAD']);
  if (gitResult.exitCode != 0) {
    throw 'git rev-parse exit with non-zero exit code: ${gitResult.exitCode}';
  }
  final String gitRevision = (gitResult.stdout as String).trim();
  if (fullLength) {
    return gitRevision;
  }
  return gitRevision.length > kGitRevisionLength
      ? gitRevision.substring(0, kGitRevisionLength)
      : gitRevision;
}

/// Wrapper function to run a subprocess checking exit code and printing stderr and stdout.
/// [executable] is a string with the script/binary to execute, [args] is the list of flags/arguments
/// and [workingDirectory] is as string to the working directory where the subprocess will be run.
Future<void> runProcessWithValidations(
  List<String> command,
  String workingDirectory, {
  @visibleForTesting ProcessManager processManager = const LocalProcessManager(),
  bool verbose = true,
}) async {
  final ProcessResult result = processManager.runSync(
    command,
    stdoutEncoding: utf8,
    workingDirectory: workingDirectory,
  );
  if (result.exitCode == 0) {
    if (verbose) {
      print('stdout: ${result.stdout}');
    }
  } else {
    if (verbose) {
      print('stderr: ${result.stderr}');
    }
    throw CommandException();
  }
}

/// Get the name of the release branch.
///
/// On LUCI builds, the git HEAD is detached, so first check for the env
/// variable "LUCI_BRANCH"; if it is not set, fall back to calling git.
Future<String> getBranchName({
  @visibleForTesting platform.Platform platform = const platform.LocalPlatform(),
  @visibleForTesting ProcessManager processManager = const LocalProcessManager(),
}) async {
  final RegExp gitBranchRegexp = RegExp(r'^## (.*)');
  final String? luciBranch = platform.environment['LUCI_BRANCH'];
  if (luciBranch != null && luciBranch.trim().isNotEmpty) {
    return luciBranch.trim();
  }
  final ProcessResult gitResult = processManager.runSync(<String>[
    'git',
    'status',
    '-b',
    '--porcelain',
  ]);
  if (gitResult.exitCode != 0) {
    throw 'git status exit with non-zero exit code: ${gitResult.exitCode}';
  }
  final RegExpMatch? gitBranchMatch = gitBranchRegexp.firstMatch(
    (gitResult.stdout as String).trim().split('\n').first,
  );
  return gitBranchMatch == null ? '' : gitBranchMatch.group(1)!.split('...').first;
}

/// Updates the footer of the api documentation with the correct branch and versions.
/// [footerPath] is the path to the location of the footer js file and [version] is a
/// string with the version calculated by the flutter tool.
Future<void> createFooter(
  File footerFile,
  String version, {
  @visibleForTesting String? timestampParam,
  @visibleForTesting String? branchParam,
  @visibleForTesting String? revisionParam,
}) async {
  final String timestamp = timestampParam ?? DateFormat('yyyy-MM-dd HH:mm').format(DateTime.now());
  final String gitBranch = branchParam ?? await getBranchName();
  final String revision = revisionParam ?? await gitRevision();
  final String gitBranchOut = gitBranch.isEmpty ? '' : '• $gitBranch';
  footerFile.writeAsStringSync('''
(function() {
  var span = document.querySelector('footer>span');
  if (span) {
    span.innerText = 'Flutter $version • $timestamp • $revision $gitBranchOut';
  }
  var sourceLink = document.querySelector('a.source-link');
  if (sourceLink) {
    sourceLink.href = sourceLink.href.replace('/master/', '/$revision/');
  }
})();
''');
}