// 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.

import 'dart:convert';

/// Decodes a YAML object (obtained from `pkg/front_end/messages.yaml`) into a
/// map from error name to [ErrorCodeInfo].
Map<String, ErrorCodeInfo> decodeCfeMessagesYaml(Map<Object?, Object?> yaml) {
  var result = <String, ErrorCodeInfo>{};
  for (var entry in yaml.entries) {
    result[entry.key as String] =
        ErrorCodeInfo.fromYaml(entry.value as Map<Object?, Object?>);
  }
  return result;
}

/// In-memory representation of error code information obtained from a
/// `messages.yaml` file.
class ErrorCodeInfo {
  /// Pattern used by the front end to identify placeholders in error message
  /// strings.  TODO(paulberry): share this regexp (and the code for interpreting
  /// it) between the CFE and analyzer.
  static final RegExp _placeholderPattern =
      RegExp("#\([-a-zA-Z0-9_]+\)(?:%\([0-9]*\)\.\([0-9]+\))?");

  /// For error code information obtained from the CFE, the set of analyzer
  /// error codes that corresponds to this error code, if any.
  final List<String> analyzerCode;

  /// `true` if diagnostics with this code have documentation for them that has
  /// been published.
  final bool hasPublishedDocs;

  /// For error code information obtained from the CFE, the index of the error
  /// in the analyzer's `fastaAnalyzerErrorCodes` table.
  final int? index;

  /// The template for the error message.
  final String template;

  /// If the error code has an associated tip/correction message, the template
  /// for it.
  final String? tip;

  ErrorCodeInfo(
      {this.analyzerCode = const [],
      this.hasPublishedDocs = false,
      this.index,
      required this.template,
      this.tip});

  /// Decodes an [ErrorCodeInfo] object from its YAML representation.
  ErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
      : this(
            analyzerCode: _decodeAnalyzerCode(yaml['analyzerCode']),
            hasPublishedDocs: yaml['hasPublishedDocs'] as bool? ?? false,
            index: yaml['index'] as int?,
            template: yaml['template'] as String,
            tip: yaml['tip'] as String?);

  /// Generates a dart declaration for this error code, suitable for inclusion
  /// in the error class [className].  [errorCode] is the name of the error code
  /// to be generated.
  String toAnalyzerCode(String className, String errorCode) {
    var out = StringBuffer();
    out.writeln('$className(');
    out.writeln("'$errorCode',");
    final placeholderToIndexMap = _computePlaceholderToIndexMap();
    out.writeln(json.encode(_convertTemplate(placeholderToIndexMap, template)));
    final tip = this.tip;
    if (tip is String) {
      out.write(',correction: ');
      out.writeln(json.encode(_convertTemplate(placeholderToIndexMap, tip)));
    }
    if (hasPublishedDocs) {
      out.writeln(',hasPublishedDocs:true');
    }
    out.write(');');
    return out.toString();
  }

  /// Given a messages.yaml entry, come up with a mapping from placeholder
  /// patterns in its message and tip strings to their corresponding indices.
  Map<String, int> _computePlaceholderToIndexMap() {
    var mapping = <String, int>{};
    for (var value in [template, tip]) {
      if (value is! String) continue;
      for (Match match in _placeholderPattern.allMatches(value)) {
        // CFE supports a bunch of formatting options that we don't; make sure
        // none of those are used.
        if (match.group(0) != '#${match.group(1)}') {
          throw 'Template string ${json.encode(value)} contains unsupported '
              'placeholder pattern ${json.encode(match.group(0))}';
        }

        mapping[match.group(0)!] ??= mapping.length;
      }
    }
    return mapping;
  }

  /// Convert a CFE template string (which uses placeholders like `#string`) to
  /// an analyzer template string (which uses placeholders like `{0}`).
  static String _convertTemplate(
      Map<String, int> placeholderToIndexMap, String entry) {
    return entry.replaceAllMapped(_placeholderPattern,
        (match) => '{${placeholderToIndexMap[match.group(0)!]}}');
  }

  static List<String> _decodeAnalyzerCode(Object? value) {
    if (value == null) {
      return const [];
    } else if (value is String) {
      return [value];
    } else if (value is List) {
      return [for (var s in value) s as String];
    } else {
      throw 'Unrecognized analyzer code: $value';
    }
  }
}