// Copyright (c) 2019, 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:math' as math;

import 'package:analysis_server/plugin/edit/fix/fix_core.dart';
import 'package:analysis_server/src/services/correction/fix.dart';
import 'package:analysis_server/src/services/correction/strings.dart';
import 'package:analyzer/error/error.dart';
import 'package:analyzer/source/line_info.dart';
import 'package:analyzer/source/source_range.dart';
import 'package:analyzer/src/analysis_options/error/option_codes.dart';
import 'package:analyzer/src/generated/java_core.dart';
import 'package:analyzer/src/generated/source.dart';
import 'package:analyzer_plugin/protocol/protocol_common.dart'
    show SourceChange;
import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
import 'package:meta/meta.dart';
import 'package:source_span/src/span.dart';
import 'package:yaml/yaml.dart';

/// The generator used to generate fixes in analysis options files.
class AnalysisOptionsFixGenerator {
  final AnalysisError error;

  final int errorOffset;

  final int errorLength;

  final String content;

  final YamlMap options;

  final LineInfo lineInfo;

  final List<Fix> fixes = <Fix>[];

  List<YamlNode> coveringNodePath;

  AnalysisOptionsFixGenerator(this.error, this.content, this.options)
      : errorOffset = error.offset,
        errorLength = error.length,
        lineInfo = new LineInfo.fromContent(content);

  /// Return the absolute, normalized path to the file in which the error was
  /// reported.
  String get file => error.source.fullName;

  /// Return the list of fixes that apply to the error being fixed.
  Future<List<Fix>> computeFixes() async {
    YamlNodeLocator locator = new YamlNodeLocator(
        start: errorOffset, end: errorOffset + errorLength - 1);
    coveringNodePath = locator.searchWithin(options);
    if (coveringNodePath.isEmpty) {
      return fixes;
    }

    ErrorCode errorCode = error.errorCode;
//    if (errorCode == AnalysisOptionsErrorCode.INCLUDED_FILE_PARSE_ERROR) {
//    } else if (errorCode == AnalysisOptionsErrorCode.PARSE_ERROR) {
//    } else if (errorCode ==
//        AnalysisOptionsHintCode.DEPRECATED_ANALYSIS_OPTIONS_FILE_NAME) {
//    } else if (errorCode ==
//        AnalysisOptionsHintCode.PREVIEW_DART_2_SETTING_DEPRECATED) {
//    } else if (errorCode ==
//        AnalysisOptionsHintCode.STRONG_MODE_SETTING_DEPRECATED) {
//    } else
    if (errorCode == AnalysisOptionsHintCode.SUPER_MIXINS_SETTING_DEPRECATED) {
      await _addFix_removeSetting();
//    } else if (errorCode ==
//        AnalysisOptionsWarningCode.ANALYSIS_OPTION_DEPRECATED) {
//    } else if (errorCode == AnalysisOptionsWarningCode.INCLUDED_FILE_WARNING) {
//    } else if (errorCode == AnalysisOptionsWarningCode.INCLUDE_FILE_NOT_FOUND) {
//    } else if (errorCode == AnalysisOptionsWarningCode.INVALID_OPTION) {
//    } else if (errorCode == AnalysisOptionsWarningCode.INVALID_SECTION_FORMAT) {
//    } else if (errorCode == AnalysisOptionsWarningCode.SPEC_MODE_REMOVED) {
//    } else if (errorCode ==
//        AnalysisOptionsWarningCode.UNRECOGNIZED_ERROR_CODE) {
    } else if (errorCode ==
        AnalysisOptionsWarningCode.UNSUPPORTED_OPTION_WITHOUT_VALUES) {
      await _addFix_removeSetting();
//    } else if (errorCode ==
//        AnalysisOptionsWarningCode.UNSUPPORTED_OPTION_WITH_LEGAL_VALUE) {
//    } else if (errorCode ==
//        AnalysisOptionsWarningCode.UNSUPPORTED_OPTION_WITH_LEGAL_VALUES) {
//    } else if (errorCode == AnalysisOptionsWarningCode.UNSUPPORTED_VALUE) {
    }
    return fixes;
  }

  void _addFix_removeSetting() async {
    if (coveringNodePath[0] is YamlScalar) {
      SourceRange deletionRange;
      int index = 1;
      while (index < coveringNodePath.length) {
        YamlNode parent = coveringNodePath[index];
        if (parent is YamlList) {
          if (parent.nodes.length > 1) {
            YamlNode nodeToDelete = coveringNodePath[index - 1];
            deletionRange = _lines(
                nodeToDelete.span.start.offset, nodeToDelete.span.end.offset);
            break;
          }
        } else if (parent is YamlMap) {
          Map<dynamic, YamlNode> nodes = parent.nodes;
          if (nodes.length > 1) {
            YamlNode key;
            YamlNode value;
            YamlNode child = coveringNodePath[index - 1];
            if (nodes.containsKey(child)) {
              key = child;
              value = nodes[child];
            } else if (nodes.containsValue(child)) {
              for (var entry in nodes.entries) {
                if (child == entry.value) {
                  key = entry.key;
                  value = child;
                  break;
                }
              }
            }
            if (key == null || value == null) {
              throw StateError(
                  'Child is neither a key nor a value in the parent');
            }
            deletionRange = _lines(key.span.start.offset,
                _firstNonWhitespaceBefore(value.span.end.offset));
            break;
          }
        } else if (parent is YamlDocument) {
          break;
        }
        index++;
      }
      YamlNode nodeToDelete = coveringNodePath[index - 1];
      deletionRange ??=
          _lines(nodeToDelete.span.start.offset, nodeToDelete.span.end.offset);
      ChangeBuilder builder = new ChangeBuilder();
      await builder.addFileEdit(file, (builder) {
        builder.addDeletion(deletionRange);
      });
      _addFixFromBuilder(builder, AnalysisOptionsFixKind.REMOVE_SETTING,
          args: [coveringNodePath[0].toString()]);
    }
  }

  /// Add a fix whose edits were built by the [builder] that has the given
  /// [kind]. If [args] are provided, they will be used to fill in the message
  /// for the fix.
  void _addFixFromBuilder(ChangeBuilder builder, FixKind kind,
      {List args: null}) {
    SourceChange change = builder.sourceChange;
    if (change.edits.isEmpty) {
      return;
    }
    change.message = formatList(kind.message, args);
    fixes.add(new Fix(kind, change));
  }

  int _firstNonWhitespaceBefore(int offset) {
    while (offset > 0 && isWhitespace(content.codeUnitAt(offset - 1))) {
      offset--;
    }
    return offset;
  }

  SourceRange _lines(int start, int end) {
    CharacterLocation startLocation = lineInfo.getLocation(start);
    int startOffset = lineInfo.getOffsetOfLine(startLocation.lineNumber - 1);
    CharacterLocation endLocation = lineInfo.getLocation(end);
    int endOffset = lineInfo.getOffsetOfLine(
        math.min(endLocation.lineNumber, lineInfo.lineCount - 1));
    return new SourceRange(startOffset, endOffset - startOffset);
  }
}

/// An object used to locate the [YamlNode] associated with a source range.
/// More specifically, it will return the deepest [YamlNode] which completely
/// encompasses the specified range.
class YamlNodeLocator {
  /// The inclusive start offset of the range used to identify the node.
  int _startOffset = 0;

  /// The inclusive end offset of the range used to identify the node.
  int _endOffset = 0;

  /// Initialize a newly created locator to locate the deepest [YamlNode] for
  /// which `node.offset <= [start]` and `[end] < node.end`.
  ///
  /// If the [end] offset is not provided, then it is considered the same as the
  /// [start] offset.
  YamlNodeLocator({@required int start, int end})
      : this._startOffset = start,
        this._endOffset = end ?? start;

  /// Search within the given Yaml [node] and return the path to the most deeply
  /// nested node that includes the whole target range, or an empty list if no
  /// node was found. The path is represented by all of the elements from the
  /// starting [node] to the most deeply nested node, in reverse order.
  List<YamlNode> searchWithin(YamlNode node) {
    List<YamlNode> path = [];
    _searchWithin(path, node);
    return path;
  }

  void _searchWithin(List<YamlNode> path, YamlNode node) {
    SourceSpan span = node.span;
    if (span.start.offset > _endOffset || span.end.offset < _startOffset) {
      return;
    }
    if (node is YamlList) {
      for (YamlNode element in node.nodes) {
        _searchWithin(path, element);
        if (path.isNotEmpty) {
          path.add(node);
          return;
        }
      }
    } else if (node is YamlMap) {
      Map<dynamic, YamlNode> nodeMap = node.nodes;
      for (YamlNode key in nodeMap.keys) {
        _searchWithin(path, key);
        if (path.isNotEmpty) {
          path.add(node);
          return;
        }
        _searchWithin(path, nodeMap[key]);
        if (path.isNotEmpty) {
          path.add(node);
          return;
        }
      }
    }
    path.add(node);
  }
}