// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/// This implements support for dependency-bot style automated upgrades.
/// It is still work in progress - do not rely on the current output.
import 'dart:convert';
import 'dart:io';

import 'package:collection/collection.dart';
import 'package:path/path.dart';
import 'package:pub_semver/pub_semver.dart';
import 'package:yaml/yaml.dart';
import 'package:yaml_edit/yaml_edit.dart';

import '../command.dart';
import '../exceptions.dart';
import '../io.dart';
import '../lock_file.dart';
import '../log.dart' as log;
import '../package.dart';
import '../package_name.dart';
import '../pubspec.dart';
import '../pubspec_utils.dart';
import '../solver.dart';
import '../source/git.dart';
import '../source/hosted.dart';
import '../system_cache.dart';
import '../utils.dart';

class DependencyServicesReportCommand extends PubCommand {
  @override
  String get name => 'report';
  @override
  String get description =>
      'Output a machine-digestible report of the upgrade options for each dependency.';
  @override
  String get argumentsDescription => '[options]';

  @override
  bool get takesArguments => false;

  DependencyServicesReportCommand() {
    argParser.addOption(
      'directory',
      abbr: 'C',
      help: 'Run this in the directory<dir>.',
      valueHelp: 'dir',
    );
  }

  @override
  Future<void> runProtected() async {
    final compatiblePubspec = stripDependencyOverrides(entrypoint.root.pubspec);

    final breakingPubspec = stripVersionUpperBounds(compatiblePubspec);

    final compatiblePackagesResult =
        await _tryResolve(compatiblePubspec, cache);

    final breakingPackagesResult = await _tryResolve(breakingPubspec, cache);

    // The packages in the current lockfile or resolved from current pubspec.yaml.
    late Map<String, PackageId> currentPackages;

    if (fileExists(entrypoint.lockFilePath)) {
      currentPackages =
          Map<String, PackageId>.from(entrypoint.lockFile.packages);
    } else {
      final resolution = await _tryResolve(entrypoint.root.pubspec, cache) ??
          (throw DataException('Failed to resolve pubspec'));
      currentPackages =
          Map<String, PackageId>.fromIterable(resolution, key: (e) => e.name);
    }
    currentPackages.remove(entrypoint.root.name);

    final dependencies = <Object>[];
    final result = <String, Object>{'dependencies': dependencies};

    Future<List<Object>> computeUpgradeSet(
      Pubspec rootPubspec,
      PackageId? package, {
      required _UpgradeType upgradeType,
    }) async {
      if (package == null) return [];
      final lockFile = entrypoint.lockFile;
      final pubspec = upgradeType == _UpgradeType.multiBreaking
          ? stripVersionUpperBounds(rootPubspec)
          : Pubspec(
              rootPubspec.name,
              dependencies: rootPubspec.dependencies.values,
              devDependencies: rootPubspec.devDependencies.values,
              sdkConstraints: rootPubspec.sdkConstraints,
            );

      final dependencySet = _dependencySetOfPackage(pubspec, package);
      if (dependencySet != null) {
        // Force the version to be the new version.
        dependencySet[package.name] =
            package.toRef().withConstraint(package.toRange().constraint);
      }

      final resolution = await tryResolveVersions(
        SolveType.get,
        cache,
        Package.inMemory(pubspec),
        lockFile: lockFile,
      );

      // TODO(sigurdm): improve error messages.
      if (resolution == null) {
        throw DataException('Failed resolving');
      }

      return [
        ...resolution.packages.where((r) {
          if (r.name == rootPubspec.name) return false;
          final originalVersion = currentPackages[r.name];
          return originalVersion == null || r != originalVersion;
        }).map((p) {
          final depset = _dependencySetOfPackage(rootPubspec, p);
          final originalConstraint = depset?[p.name]?.constraint;
          final currentPackage = currentPackages[p.name];
          return {
            'name': p.name,
            'version': p.versionOrHash(),
            'kind': _kindString(pubspec, p.name),
            'source': _source(p, containingDir: directory),
            'constraintBumped': originalConstraint == null
                ? null
                : upgradeType == _UpgradeType.compatible
                    ? originalConstraint.toString()
                    : VersionConstraint.compatibleWith(p.version).toString(),
            'constraintWidened': originalConstraint == null
                ? null
                : upgradeType == _UpgradeType.compatible
                    ? originalConstraint.toString()
                    : _widenConstraint(originalConstraint, p.version)
                        .toString(),
            'constraintBumpedIfNeeded': originalConstraint == null
                ? null
                : upgradeType == _UpgradeType.compatible
                    ? originalConstraint.toString()
                    : originalConstraint.allows(p.version)
                        ? originalConstraint.toString()
                        : VersionConstraint.compatibleWith(p.version)
                            .toString(),
            'previousVersion': currentPackage?.versionOrHash(),
            'previousConstraint': originalConstraint?.toString(),
            'previousSource': currentPackage == null
                ? null
                : _source(currentPackage, containingDir: directory),
          };
        }),
        // Find packages that were removed by the resolution
        for (final oldPackageName in lockFile.packages.keys)
          if (!resolution.packages
              .any((newPackage) => newPackage.name == oldPackageName))
            {
              'name': oldPackageName,
              'version': null,
              'kind':
                  'transitive', // Only transitive constraints can be removed.
              'constraintBumped': null,
              'constraintWidened': null,
              'constraintBumpedIfNeeded': null,
              'previousVersion':
                  currentPackages[oldPackageName]?.versionOrHash(),
              'previousConstraint': null,
              'previous': _source(
                currentPackages[oldPackageName]!,
                containingDir: directory,
              )
            },
      ];
    }

    for (final package in currentPackages.values) {
      final compatibleVersion = compatiblePackagesResult
          ?.firstWhereOrNull((element) => element.name == package.name);
      final multiBreakingVersion = breakingPackagesResult
          ?.firstWhereOrNull((element) => element.name == package.name);
      final singleBreakingPubspec = Pubspec(
        compatiblePubspec.name,
        version: compatiblePubspec.version,
        sdkConstraints: compatiblePubspec.sdkConstraints,
        dependencies: compatiblePubspec.dependencies.values,
        devDependencies: compatiblePubspec.devDependencies.values,
      );
      final dependencySet =
          _dependencySetOfPackage(singleBreakingPubspec, package);
      final kind = _kindString(compatiblePubspec, package.name);
      PackageId? singleBreakingVersion;
      if (dependencySet != null) {
        dependencySet[package.name] = package
            .toRef()
            .withConstraint(stripUpperBound(package.toRange().constraint));
        final singleBreakingPackagesResult =
            await _tryResolve(singleBreakingPubspec, cache);
        singleBreakingVersion = singleBreakingPackagesResult
            ?.firstWhereOrNull((element) => element.name == package.name);
      }
      dependencies.add({
        'name': package.name,
        'version': package.versionOrHash(),
        'kind': kind,
        'source': _source(package, containingDir: directory),
        'latest':
            (await cache.getLatest(package.toRef(), version: package.version))
                ?.versionOrHash(),
        'constraint':
            _constraintOf(compatiblePubspec, package.name)?.toString(),
        'compatible': await computeUpgradeSet(
          compatiblePubspec,
          compatibleVersion,
          upgradeType: _UpgradeType.compatible,
        ),
        'singleBreaking': kind != 'transitive' && singleBreakingVersion == null
            ? []
            : await computeUpgradeSet(
                compatiblePubspec,
                singleBreakingVersion,
                upgradeType: _UpgradeType.singleBreaking,
              ),
        'multiBreaking': kind != 'transitive' && multiBreakingVersion != null
            ? await computeUpgradeSet(
                compatiblePubspec,
                multiBreakingVersion,
                upgradeType: _UpgradeType.multiBreaking,
              )
            : [],
      });
    }
    log.message(JsonEncoder.withIndent('  ').convert(result));
  }
}

VersionConstraint? _constraintOf(Pubspec pubspec, String packageName) {
  return (pubspec.dependencies[packageName] ??
          pubspec.devDependencies[packageName])
      ?.constraint;
}

String _kindString(Pubspec pubspec, String packageName) {
  return pubspec.dependencies.containsKey(packageName)
      ? 'direct'
      : pubspec.devDependencies.containsKey(packageName)
          ? 'dev'
          : 'transitive';
}

Map<String, Object?> _source(PackageId id, {required String containingDir}) {
  return {
    'type': id.source.name,
    'description':
        id.description.serializeForLockfile(containingDir: containingDir),
  };
}

/// Try to solve [pubspec] return [PackageId]s in the resolution or `null` if no
/// resolution was found.
Future<List<PackageId>?> _tryResolve(Pubspec pubspec, SystemCache cache) async {
  final solveResult = await tryResolveVersions(
    SolveType.upgrade,
    cache,
    Package.inMemory(pubspec),
  );

  return solveResult?.packages;
}

class DependencyServicesListCommand extends PubCommand {
  @override
  String get name => 'list';

  @override
  String get description =>
      'Output a machine digestible listing of all dependencies';

  @override
  bool get takesArguments => false;

  DependencyServicesListCommand() {
    argParser.addOption(
      'directory',
      abbr: 'C',
      help: 'Run this in the directory<dir>.',
      valueHelp: 'dir',
    );
  }

  @override
  Future<void> runProtected() async {
    final pubspec = entrypoint.root.pubspec;

    final currentPackages = fileExists(entrypoint.lockFilePath)
        ? entrypoint.lockFile.packages.values.toList()
        : (await _tryResolve(pubspec, cache) ?? <PackageId>[]);

    final dependencies = <Object>[];
    final result = <String, Object>{'dependencies': dependencies};

    for (final package in currentPackages.where((p) => !p.isRoot)) {
      dependencies.add({
        'name': package.name,
        'version': package.versionOrHash(),
        'kind': _kindString(pubspec, package.name),
        'constraint': _constraintOf(pubspec, package.name).toString(),
        'source': _source(package, containingDir: directory),
      });
    }
    log.message(JsonEncoder.withIndent('  ').convert(result));
  }
}

extension on PackageId {
  String versionOrHash() {
    final description = this.description;
    if (description is GitResolvedDescription) {
      return description.resolvedRef;
    } else {
      return version.toString();
    }
  }
}

enum _UpgradeType {
  /// Only upgrade pubspec.lock.
  compatible,

  /// Unlock at most one dependency in pubspec.yaml.
  singleBreaking,

  /// Unlock any dependencies in pubspec.yaml needed for getting the
  /// latest resolvable version.
  multiBreaking,
}

class DependencyServicesApplyCommand extends PubCommand {
  @override
  String get name => 'apply';

  @override
  String get description =>
      'Updates pubspec.yaml and pubspec.lock according to input.';

  @override
  bool get takesArguments => true;

  DependencyServicesApplyCommand() {
    argParser.addOption(
      'directory',
      abbr: 'C',
      help: 'Run this in the directory <dir>.',
      valueHelp: 'dir',
    );
  }

  @override
  Future<void> runProtected() async {
    YamlEditor(readTextFile(entrypoint.pubspecPath));
    final toApply = <_PackageVersion>[];
    final input = json.decode(await utf8.decodeStream(stdin));
    for (final change in input['dependencyChanges']) {
      toApply.add(
        _PackageVersion(
          change['name'],
          change['version'],
          change['constraint'] != null
              ? VersionConstraint.parse(change['constraint'])
              : null,
        ),
      );
    }

    final pubspec = entrypoint.root.pubspec;
    final pubspecEditor = YamlEditor(readTextFile(entrypoint.pubspecPath));
    final lockFile = fileExists(entrypoint.lockFilePath)
        ? readTextFile(entrypoint.lockFilePath)
        : null;
    final lockFileYaml = lockFile == null ? null : loadYaml(lockFile);
    final lockFileEditor = lockFile == null ? null : YamlEditor(lockFile);
    final hasContentHashes = _lockFileHasContentHashes(lockFileYaml);
    for (final p in toApply) {
      final targetPackage = p.name;
      final targetVersion = p.version;
      final targetConstraint = p.constraint;
      final targetRevision = p.gitRevision;

      if (targetConstraint != null) {
        final section = pubspec.dependencies[targetPackage] != null
            ? 'dependencies'
            : 'dev_dependencies';
        final packageConfig =
            pubspecEditor.parseAt([section, targetPackage]).value;
        if (packageConfig == null || packageConfig is String) {
          pubspecEditor
              .update([section, targetPackage], targetConstraint.toString());
        } else if (packageConfig is Map) {
          pubspecEditor.update(
            [section, targetPackage, 'version'],
            targetConstraint.toString(),
          );
        } else {
          fail(
            'The dependency $targetPackage does not have a map or string as a description',
          );
        }
      } else if (targetVersion != null) {
        final constraint = _constraintOf(pubspec, targetPackage);
        if (constraint != null && !constraint.allows(targetVersion)) {
          final section = pubspec.dependencies[targetPackage] != null
              ? 'dependencies'
              : 'dev_dependencies';
          pubspecEditor.update(
            [section, targetPackage],
            VersionConstraint.compatibleWith(targetVersion).toString(),
          );
        }
      }
      if (lockFileEditor != null) {
        if (targetVersion != null &&
            lockFileYaml['packages'].containsKey(targetPackage)) {
          lockFileEditor.update(
            ['packages', targetPackage, 'version'],
            targetVersion.toString(),
          );
          // Remove the now outdated content-hash - it will be restored below
          // after resolution.
          if (lockFileEditor
              .parseAt(['packages', targetPackage, 'description'])
              .value
              .containsKey('sha256')) {
            lockFileEditor.remove(
              ['packages', targetPackage, 'description', 'sha256'],
            );
          }
        } else if (targetRevision != null &&
            lockFileYaml['packages'].containsKey(targetPackage)) {
          final ref = entrypoint.lockFile.packages[targetPackage]!.toRef();
          final currentDescription = ref.description as GitDescription;
          final updatedRef = PackageRef(
            targetPackage,
            GitDescription(
              url: currentDescription.url,
              path: currentDescription.path,
              ref: targetRevision,
              containingDir: directory,
            ),
          );
          final versions = await cache.getVersions(updatedRef);
          if (versions.isEmpty) {
            dataError(
              'Found no versions of $targetPackage with git revision `$targetRevision`.',
            );
          }
          // GitSource can only return a single version.
          assert(versions.length == 1);

          lockFileEditor.update(
            ['packages', targetPackage, 'version'],
            versions.single.version.toString(),
          );
          lockFileEditor.update(
            ['packages', targetPackage, 'description', 'resolved-ref'],
            targetRevision,
          );
        } else if (targetVersion == null &&
            targetRevision == null &&
            !lockFileYaml['packages'].containsKey(targetPackage)) {
          dataError(
            'Trying to remove non-existing transitive dependency $targetPackage.',
          );
        }
      }
    }

    final updatedLockfile = lockFileEditor == null
        ? null
        : LockFile.parse(
            lockFileEditor.toString(),
            cache.sources,
            filePath: entrypoint.lockFilePath,
          );
    await log.errorsOnlyUnlessTerminal(
      () async {
        final updatedPubspec = pubspecEditor.toString();
        // Resolve versions, this will update transitive dependencies that were
        // not passed in the input. And also counts as a validation of the input
        // by ensuring the resolution is valid.
        //
        // We don't use `acquireDependencies` as that downloads all the archives
        // to cache.
        // TODO: Handle HTTP exceptions gracefully!
        final solveResult = await resolveVersions(
          SolveType.get,
          cache,
          Package.inMemory(
            Pubspec.parse(
              updatedPubspec,
              cache.sources,
              location: toUri(entrypoint.pubspecPath),
            ),
          ),
          lockFile: updatedLockfile,
        );
        if (pubspecEditor.edits.isNotEmpty) {
          writeTextFile(entrypoint.pubspecPath, updatedPubspec);
        }
        // Only if we originally had a lock-file we write the resulting lockfile back.
        if (updatedLockfile != null) {
          final updatedPackages = <PackageId>[];
          for (var package in solveResult.packages) {
            if (package.isRoot) continue;
            final description = package.description;

            // Handle content-hashes of hosted dependencies.
            if (description is ResolvedHostedDescription) {
              // Ensure we get content-hashes if the original lock-file had
              // them.
              if (hasContentHashes) {
                if (description.sha256 == null) {
                  // We removed the hash above before resolution - as we get the
                  // locked id back we need to find the content-hash from the
                  // version listing.
                  //
                  // `pub get` gets this version-listing from the downloaded
                  // archive but we don't want to download all archives - so we
                  // copy it from the version listing.
                  package = (await cache.getVersions(package.toRef()))
                      .firstWhere((id) => id == package, orElse: () => package);
                  if ((package.description as ResolvedHostedDescription)
                          .sha256 ==
                      null) {
                    // This happens when we resolved a package from a legacy
                    // server not providing archive_sha256. As a side-effect of
                    // downloading the package we compute and store the sha256.
                    package = await cache.downloadPackage(package);
                  }
                }
              } else {
                // The original pubspec.lock did not have content-hashes. Remove
                // any content hash, so we don't start adding them.
                package = PackageId(
                  package.name,
                  package.version,
                  description.withSha256(null),
                );
              }
            }
            updatedPackages.add(package);
          }

          final newLockFile = LockFile(
            updatedPackages,
            sdkConstraints: updatedLockfile.sdkConstraints,
            mainDependencies: pubspec.dependencies.keys.toSet(),
            devDependencies: pubspec.devDependencies.keys.toSet(),
            overriddenDependencies: pubspec.dependencyOverrides.keys.toSet(),
          );

          newLockFile.writeToFile(entrypoint.lockFilePath, cache);
        }
      },
    );
    // Dummy message.
    log.message(json.encode({'dependencies': []}));
  }
}

class _PackageVersion {
  String name;
  Version? version;
  String? gitRevision;
  VersionConstraint? constraint;
  _PackageVersion(this.name, String? versionOrHash, this.constraint)
      : version =
            versionOrHash == null ? null : _tryParseVersion(versionOrHash),
        gitRevision =
            versionOrHash == null ? null : _tryParseHash(versionOrHash);
}

Version? _tryParseVersion(String v) {
  try {
    return Version.parse(v);
  } on FormatException {
    return null;
  }
}

String? _tryParseHash(String v) {
  if (RegExp(r'^[a-fA-F0-9]+$').hasMatch(v)) {
    return v;
  }
  return null;
}

Map<String, PackageRange>? _dependencySetOfPackage(
  Pubspec pubspec,
  PackageId package,
) {
  return pubspec.dependencies.containsKey(package.name)
      ? pubspec.dependencies
      : pubspec.devDependencies.containsKey(package.name)
          ? pubspec.devDependencies
          : null;
}

VersionConstraint _widenConstraint(
  VersionConstraint original,
  Version newVersion,
) {
  if (original.allows(newVersion)) return original;
  if (original is VersionRange) {
    final min = original.min;
    final max = original.max;
    if (max != null && newVersion >= max) {
      return _compatibleWithIfPossible(
        VersionRange(
          min: min,
          includeMin: original.includeMin,
          max: newVersion.nextBreaking.firstPreRelease,
        ),
      );
    }
    if (min != null && newVersion <= min) {
      return _compatibleWithIfPossible(
        VersionRange(
          min: newVersion,
          includeMin: true,
          max: max,
          includeMax: original.includeMax,
        ),
      );
    }
  }

  if (original.isEmpty) return newVersion;
  throw ArgumentError.value(
    original,
    'original',
    'Must be a Version range or empty',
  );
}

VersionConstraint _compatibleWithIfPossible(VersionRange versionRange) {
  final min = versionRange.min;
  if (min != null && min.nextBreaking.firstPreRelease == versionRange.max) {
    return VersionConstraint.compatibleWith(min);
  }
  return versionRange;
}

/// `true` iff any of the packages described by the [lockfile] has a
/// content-hash.
///
/// Undefined for invalid lock files, but mostly `true`.
bool _lockFileHasContentHashes(dynamic lockfile) {
  if (lockfile is! Map) return true;
  final packages = lockfile['packages'];
  if (packages is! Map) return true;

  /// We consider an empty lockfile ready to get content-hashes.
  if (packages.isEmpty) return true;
  for (final package in packages.values) {
    if (package is! Map) return true;
    final descriptor = package['description'];
    if (descriptor is! Map) return true;
    if (descriptor['sha256'] != null) return true;
  }
  return false;
}