using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace JD.Serialization
{
    /// <summary>
    /// Holds the curves of a clip.
    /// </summary>
    /// <remarks>
    /// Initialize itself using the reflection. Parses all the properties declared with a <see cref="BezierCurveTypeAttribute"/> and adds them to the editable list.
    /// </remarks>
    public class CurveCollection : UAFList<BezierCurveFloat>
    {
        private readonly Clip _clip;
        
        public CurveCollection(Clip clip)
        {
            _clip = clip;
            _clip.PropertyChanged += clip_PropertyChanged;
            InitializeCurves();
        }

        public BezierCurveFloat this[BezierCurveType curveType]
        {
            get
            {
                return Items.FirstOrDefault(x => x.Type == curveType);
            }
        }

        #region Curve Initialization With Reflection

        /// <summary>
        /// Cache the curve properties, calling the reflection can be long.
        /// </summary>
        private static readonly ConcurrentDictionary<Type, List<PropertyInfo>> _curvesProperties = new ConcurrentDictionary<Type, List<PropertyInfo>>();

        private void InitializeCurves()
        {
            foreach (var property in GetCurveProperties())
            {
                var curve = (BezierCurveFloat)property.GetValue(_clip, null);
                curve.Type = GetCurveType(property).Value;
                curve.Clip = _clip;
                Add(curve);
            }
        }

        private IEnumerable<PropertyInfo> GetCurveProperties()
        {
            return _curvesProperties.GetOrAdd(_clip.GetType(), x =>
            {
                return _clip.GetType().GetProperties().Where(property => GetCurveType(property) != null).ToList();
            });
        }

        private BezierCurveType? GetCurveType(PropertyInfo property)
        {
            var attributes = property.GetCustomAttributes(typeof(BezierCurveTypeAttribute), true);
            return attributes.Length > 0 ? ((BezierCurveTypeAttribute)attributes[0]).Type : (BezierCurveType?)null;
        }

        /// <summary>
        /// When a curve is reassigned, update the curve collection.
        /// </summary>
        void clip_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            if (!string.IsNullOrEmpty(e.PropertyName) && GetCurveProperties().Any(property => property.Name == e.PropertyName))
            {
                Clear();
                InitializeCurves();
            }
        }

        #endregion
    }
}