using System.Collections.Generic;
using System.Linq;
using LeanCloud.Utilities;

namespace LeanCloud.Storage.Internal {
  /// <summary>
  /// Provides a Dictionary implementation that can delegate to any other
  /// dictionary, regardless of its value type. Used for coercion of
  /// dictionaries when returning them to users.
  /// </summary>
  /// <typeparam name="TOut">The resulting type of value in the dictionary.</typeparam>
  /// <typeparam name="TIn">The original type of value in the dictionary.</typeparam>
  [Preserve(AllMembers = true, Conditional = false)]
  public class FlexibleDictionaryWrapper<TOut, TIn> : IDictionary<string, TOut> {
    private readonly IDictionary<string, TIn> toWrap;
    public FlexibleDictionaryWrapper(IDictionary<string, TIn> toWrap) {
      this.toWrap = toWrap;
    }

    public void Add(string key, TOut value) {
      toWrap.Add(key, (TIn)Conversion.ConvertTo<TIn>(value));
    }

    public bool ContainsKey(string key) {
      return toWrap.ContainsKey(key);
    }

    public ICollection<string> Keys {
      get { return toWrap.Keys; }
    }

    public bool Remove(string key) {
      return toWrap.Remove(key);
    }

    public bool TryGetValue(string key, out TOut value) {
      TIn outValue;
      bool result = toWrap.TryGetValue(key, out outValue);
      value = (TOut)Conversion.ConvertTo<TOut>(outValue);
      return result;
    }

    public ICollection<TOut> Values {
      get {
        return toWrap.Values
            .Select(item => (TOut)Conversion.ConvertTo<TOut>(item)).ToList();
      }
    }

    public TOut this[string key] {
      get {
        return (TOut)Conversion.ConvertTo<TOut>(toWrap[key]);
      }
      set {
        toWrap[key] = (TIn)Conversion.ConvertTo<TIn>(value);
      }
    }

    public void Add(KeyValuePair<string, TOut> item) {
      toWrap.Add(new KeyValuePair<string, TIn>(item.Key,
          (TIn)Conversion.ConvertTo<TIn>(item.Value)));
    }

    public void Clear() {
      toWrap.Clear();
    }

    public bool Contains(KeyValuePair<string, TOut> item) {
      return toWrap.Contains(new KeyValuePair<string, TIn>(item.Key,
          (TIn)Conversion.ConvertTo<TIn>(item.Value)));
    }

    public void CopyTo(KeyValuePair<string, TOut>[] array, int arrayIndex) {
      var converted = from pair in toWrap
                      select new KeyValuePair<string, TOut>(pair.Key,
                          (TOut)Conversion.ConvertTo<TOut>(pair.Value));
      converted.ToList().CopyTo(array, arrayIndex);
    }

    public int Count {
      get { return toWrap.Count; }
    }

    public bool IsReadOnly {
      get { return toWrap.IsReadOnly; }
    }

    public bool Remove(KeyValuePair<string, TOut> item) {
      return toWrap.Remove(new KeyValuePair<string, TIn>(item.Key,
          (TIn)Conversion.ConvertTo<TIn>(item.Value)));
    }

    public IEnumerator<KeyValuePair<string, TOut>> GetEnumerator() {
      foreach (var pair in toWrap) {
        yield return new KeyValuePair<string, TOut>(pair.Key,
            (TOut)Conversion.ConvertTo<TOut>(pair.Value));
      }
    }

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
      return this.GetEnumerator();
    }
  }
}