// Copyright (c) 2012, 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.

part of _js_helper;

class ConstantMapView<K, V> extends UnmodifiableMapView<K, V>
    implements ConstantMap<K, V> {
  ConstantMapView(Map<K, V> base) : super(base);
}

abstract class ConstantMap<K, V> implements Map<K, V> {
  // Used to create unmodifiable maps from other maps.
  factory ConstantMap.from(Map other) {
    var keys = new List<K>.from(other.keys);
    bool allStrings = true;
    for (var k in keys) {
      if (k is! String) {
        allStrings = false;
        break;
      }
    }
    if (allStrings) {
      bool containsProto = false;
      var protoValue = null;
      var object = JS('=Object', '{}');
      int length = 0;
      for (var k in keys) {
        V v = other[k];
        if (k != '__proto__') {
          if (!jsHasOwnProperty(object, k as String)) length++;
          JS('void', '#[#] = #', object, k, v);
        } else {
          containsProto = true;
          protoValue = v;
        }
      }
      if (containsProto) {
        length++;
        return new ConstantProtoMap<K, V>._(length, object, keys, protoValue);
      }
      return new ConstantStringMap<K, V>._(length, object, keys);
    }
    // TODO(lrn): Make a proper unmodifiable map implementation.
    return new ConstantMapView<K, V>(new Map.from(other));
  }

  const ConstantMap._();

  Map<RK, RV> cast<RK, RV>() => Map.castFrom<K, V, RK, RV>(this);
  bool get isEmpty => length == 0;

  bool get isNotEmpty => !isEmpty;

  String toString() => MapBase.mapToString(this);

  static Never _throwUnmodifiable() {
    throw new UnsupportedError('Cannot modify unmodifiable Map');
  }

  void operator []=(K key, V val) {
    _throwUnmodifiable();
  }

  V putIfAbsent(K key, V ifAbsent()) {
    _throwUnmodifiable();
  }

  V? remove(Object? key) {
    _throwUnmodifiable();
  }

  void clear() => _throwUnmodifiable();
  void addAll(Map<K, V> other) => _throwUnmodifiable();

  Iterable<MapEntry<K, V>> get entries sync* {
    for (var key in keys) yield new MapEntry<K, V>(key, this[key]!);
  }

  void addEntries(Iterable<MapEntry<K, V>> entries) {
    for (var entry in entries) this[entry.key] = entry.value;
  }

  Map<K2, V2> map<K2, V2>(MapEntry<K2, V2> transform(K key, V value)) {
    var result = <K2, V2>{};
    this.forEach((K key, V value) {
      var entry = transform(key, value);
      result[entry.key] = entry.value;
    });
    return result;
  }

  V update(K key, V update(V value), {V ifAbsent()?}) {
    _throwUnmodifiable();
  }

  void updateAll(V update(K key, V value)) {
    _throwUnmodifiable();
  }

  void removeWhere(bool test(K key, V value)) {
    _throwUnmodifiable();
  }
}

class ConstantStringMap<K, V> extends ConstantMap<K, V> {
  // This constructor is not used for actual compile-time constants.
  // The instantiation of constant maps is shortcut by the compiler.
  const ConstantStringMap._(this._length, this._jsObject, this._keys)
      : super._();

  // TODO(18131): Ensure type inference knows the precise types of the fields.
  final int _length;
  // A constant map is backed by a JavaScript object.
  final _jsObject;
  final List<K> _keys;

  int get length => JS('JSUInt31', '#', _length);
  List<K> get _keysArray => JS('JSUnmodifiableArray', '#', _keys);

  bool containsValue(Object? needle) {
    return values.any((V value) => value == needle);
  }

  bool containsKey(Object? key) {
    if (key is! String) return false;
    if ('__proto__' == key) return false;
    return jsHasOwnProperty(_jsObject, key);
  }

  V? operator [](Object? key) {
    if (!containsKey(key)) return null;
    return JS('', '#', _fetch(key));
  }

  // [_fetch] is the indexer for keys for which `containsKey(key)` is true.
  _fetch(key) => jsPropertyAccess(_jsObject, key);

  void forEach(void f(K key, V value)) {
    // Use a JS 'cast' to get efficient loop.  Type inference doesn't get this
    // since constant map representation is chosen after type inference and the
    // instantiation is shortcut by the compiler.
    var keys = _keysArray;
    for (int i = 0; i < keys.length; i++) {
      var key = keys[i];
      f(key, _fetch(key));
    }
  }

  Iterable<K> get keys {
    return new _ConstantMapKeyIterable<K>(this);
  }

  Iterable<V> get values {
    return new MappedIterable<K, V>(_keysArray, (key) => _fetch(key));
  }
}

class ConstantProtoMap<K, V> extends ConstantStringMap<K, V> {
  // This constructor is not used.  The instantiation is shortcut by the
  // compiler. It is here to make the uninitialized final fields legal.
  ConstantProtoMap._(length, jsObject, keys, this._protoValue)
      : super._(length, jsObject, keys);

  final V _protoValue;

  bool containsKey(Object? key) {
    if (key is! String) return false;
    if ('__proto__' == key) return true;
    return jsHasOwnProperty(_jsObject, key);
  }

  _fetch(key) =>
      '__proto__' == key ? _protoValue : jsPropertyAccess(_jsObject, key);
}

class _ConstantMapKeyIterable<K> extends Iterable<K> {
  ConstantStringMap<K, dynamic> _map;
  _ConstantMapKeyIterable(this._map);

  Iterator<K> get iterator => _map._keysArray.iterator;

  int get length => _map._keysArray.length;
}

class GeneralConstantMap<K, V> extends ConstantMap<K, V> {
  // This constructor is not used.  The instantiation is shortcut by the
  // compiler. It is here to make the uninitialized final fields legal.
  GeneralConstantMap(this._jsData) : super._();

  // [_jsData] holds a key-value pair list.
  final _jsData;

  // We cannot create the backing map on creation since hashCode interceptors
  // have not been defined when constants are created.
  Map<K, V> _getMap() {
    LinkedHashMap<K, V>? backingMap = JS('LinkedHashMap|Null', r'#.$map', this);
    if (backingMap == null) {
      backingMap = new JsLinkedHashMap<K, V>();
      fillLiteralMap(_jsData, backingMap);
      JS('', r'#.$map = #', this, backingMap);
    }
    return backingMap;
  }

  bool containsValue(Object? needle) {
    return _getMap().containsValue(needle);
  }

  bool containsKey(Object? key) {
    return _getMap().containsKey(key);
  }

  V? operator [](Object? key) {
    return _getMap()[key];
  }

  void forEach(void f(K key, V value)) {
    _getMap().forEach(f);
  }

  Iterable<K> get keys {
    return _getMap().keys;
  }

  Iterable<V> get values {
    return _getMap().values;
  }

  int get length => _getMap().length;
}