// This file is part of YamlDotNet - A .NET library for YAML.
// Copyright (c) Antoine Aubry and contributors
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
// of the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

using System;
using System.Collections;
using YamlDotNet.Core;
using YamlDotNet.Core.Events;

namespace YamlDotNet.Serialization.NodeDeserializers
{
    public abstract class DictionaryDeserializer
    {
        private readonly bool duplicateKeyChecking;

        public DictionaryDeserializer(bool duplicateKeyChecking)
        {
            this.duplicateKeyChecking = duplicateKeyChecking;
        }

        private void TryAssign(IDictionary result, object key, object value, MappingStart propertyName)
        {
            if (duplicateKeyChecking && result.Contains(key))
            {
                throw new YamlException(propertyName.Start, propertyName.End, $"Encountered duplicate key {key}");
            }
            result[key] = value!;
        }

        protected virtual void Deserialize(Type tKey, Type tValue, IParser parser, Func<IParser, Type, object?> nestedObjectDeserializer, IDictionary result, ObjectDeserializer rootDeserializer)
        {
            var property = parser.Consume<MappingStart>();
            while (!parser.TryConsume<MappingEnd>(out var _))
            {
                var key = nestedObjectDeserializer(parser, tKey);
                var value = nestedObjectDeserializer(parser, tValue);
                var valuePromise = value as IValuePromise;

                if (key is IValuePromise keyPromise)
                {
                    if (valuePromise == null)
                    {
                        // Key is pending, value is known
                        keyPromise.ValueAvailable += v => result[v!] = value!;
                    }
                    else
                    {
                        // Both key and value are pending. We need to wait until both of them become available.
                        var hasFirstPart = false;

                        keyPromise.ValueAvailable += v =>
                        {
                            if (hasFirstPart)
                            {
                                TryAssign(result, v!, value!, property);
                            }
                            else
                            {
                                key = v!;
                                hasFirstPart = true;
                            }
                        };

                        valuePromise.ValueAvailable += v =>
                        {
                            if (hasFirstPart)
                            {
                                TryAssign(result, key, v!, property);
                            }
                            else
                            {
                                value = v;
                                hasFirstPart = true;
                            }
                        };
                    }
                }
                else
                {
                    if (key == null)
                    {
                        throw new ArgumentException("Empty key names are not supported yet.", nameof(tKey));
                    }

                    if (valuePromise == null)
                    {
                        // Happy path: both key and value are known
                        TryAssign(result, key, value!, property);
                    }
                    else
                    {
                        // Key is known, value is pending
                        valuePromise.ValueAvailable += v => result[key!] = v!;
                    }
                }
            }
        }
    }
}