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

namespace Quadarax.Foundation.Core.Object.Dynamic
{
    /// <summary>
    /// Provides a dynamic object implementation that allows for runtime definition and manipulation of properties.
    /// </summary>
    /// <remarks>
    /// The Dyna class offers a flexible way to create objects with dynamic property sets that can be
    /// defined at runtime. It supports property access control, value comparison, and cloning capabilities.
    /// </remarks>
    public class Dyna : IDyna
    {
        #region *** Private Fields ***
        /// <summary>
        /// Thread-safe dictionary storing the dynamic properties and their values.
        /// </summary>
        private IDictionary<string, DynaPropertyWithValue> _properties = new ConcurrentDictionary<string, DynaPropertyWithValue>();

        private IList<string> _changedPropertes = new List<string>();
        private IList<Tuple<string, object?>> _defaultValues = new List<Tuple<string, object?>>();
        #endregion

        #region *** Properties ***
        /// <summary>
        /// Gets an array of all property definitions contained in this Dyna instance.
        /// </summary>
        /// <returns>An array of <see cref="IDynaProperty"/> objects representing the properties.</returns>
        public IDynaProperty[] Properties => _properties.Values.Select(x => x.Property).ToArray();

        /// <summary>
        /// Gets an array of all property names changed after calling TrackChanges.
        /// </summary>
        /// <returns>An array of <see cref="string"/> contains property names.</returns>
        public string[] ChangedProperties => _changedPropertes.ToArray();

        /// <summary>
        /// Gets or sets the value of a property by its name.
        /// </summary>
        /// <param name="propertyName">The name of the property to access.</param>
        /// <returns>The value of the specified property.</returns>
        /// <exception cref="ArgumentOutOfRangeException">Thrown when the property does not exist.</exception>
        public object? this[string propertyName]
        {
            get => GetValue<object>(propertyName);
            set => SetValue(propertyName, value);
        }
        #endregion

        #region *** Constructors ***
        /// <summary>
        /// Initializes a new instance of the <see cref="Dyna"/> class with no properties.
        /// </summary>
        public Dyna()
        {
            TrackChanges();
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="Dyna"/> class with properties derived from the specified type.
        /// </summary>
        /// <param name="templateType">The type whose properties should be reflected into this Dyna instance.</param>
        /// <exception cref="ArgumentException">Thrown when the template type does not have a valid FullName.</exception>
        public Dyna(Type templateType)
        {
            AnalyzeType(templateType);
            TrackChanges();
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="Dyna"/> class with the specified properties.
        /// </summary>
        /// <param name="properties">A collection of <see cref="DynaProperty"/> objects defining the properties for this instance.</param>
        public Dyna(IEnumerable<DynaProperty> properties) : this()
        {
            AnalyzeProperties(properties);
            TrackChanges();
        }
        #endregion

        #region *** Public Operations ***
        /// <summary>
        /// Gets the value of a property as a specified type.
        /// </summary>
        /// <typeparam name="TValue">The type to convert the property value to.</typeparam>
        /// <param name="propertyName">The name of the property to get the value from.</param>
        /// <returns>The value of the property cast to the specified type, or null if the property value is null.</returns>
        /// <exception cref="ArgumentOutOfRangeException">Thrown when the property does not exist.</exception>
        public TValue? GetValue<TValue>(string propertyName)
        {
            if (_properties.TryGetValue(propertyName, out var property))
            {
                if (property.Value == null) return default;
                return (TValue)property.Value;
            }

            throw new ArgumentOutOfRangeException(nameof(propertyName), $"Property '{propertyName}' not found in Dyna collection.");
        }

        /// <summary>
        /// Sets the value of a property.
        /// </summary>
        /// <typeparam name="TValue">The type of the value being set.</typeparam>
        /// <param name="propertyName">The name of the property to set.</param>
        /// <param name="value">The value to set the property to.</param>
        /// <exception cref="ArgumentOutOfRangeException">Thrown when the property does not exist.</exception>
        public void SetValue<TValue>(string propertyName, TValue? value)
        {
            if (_properties.TryGetValue(propertyName, out var property))
            {
                if (!object.Equals(property.Value, value))
                {
                    // check if new value is the same as the default value, then discard the change
                    if (object.Equals(value, _defaultValues.First(x=>x.Item1 == propertyName).Item2))
                    {
                        property.Value = value;
                        _changedPropertes.Remove(propertyName);
                        return;
                    }
                     
                    if (OnChangingProperty(propertyName, property.Value, value))
                    {        
                        property.Value = value;

                        // track changes
                        if (!_changedPropertes.Contains(propertyName))
                            _changedPropertes.Add(propertyName);
                    }
                }
            }
            else
                throw new ArgumentOutOfRangeException(nameof(propertyName), $"Property '{propertyName}' not found in Dyna collection.");
        }

        /// <summary>
        /// Clears all property values, setting them to null.
        /// </summary>
        public void Clear()
        {
            foreach (var property in _properties)
                property.Value.Value = null;

            OnClear();

            TrackChanges();
        }

        /// <summary>
        /// Tracks all property changes after calling this method.
        /// </summary>
        public void TrackChanges()
        {
            _changedPropertes.Clear();
            _defaultValues.Clear();

            // create new snapshot of default values
            foreach (var property in _properties)
                _defaultValues.Add(new Tuple<string, object?>(property.Key, property.Value.Value));
        }

        /// <summary>
        /// Determines whether this Dyna instance has the same property structure as another Dyna instance.
        /// </summary>
        /// <param name="target">The Dyna instance to compare with.</param>
        /// <returns>
        /// <c>true</c> if both instances have the same property names and types; otherwise, <c>false</c>.
        /// </returns>
        public bool IsSame(Dyna target)
        {
            if (_properties.Count != target._properties.Count)
                return false;
            foreach (var property in _properties)
            {
                if (!target._properties.TryGetValue(property.Key, out var targetProperty))
                    return false;
            }
            return true;
        }

        /// <summary>
        /// Determines whether this Dyna instance has the same properties and values as another Dyna instance.
        /// </summary>
        /// <param name="target">The Dyna instance to compare with.</param>
        /// <returns>
        /// <c>true</c> if both instances have the same properties and values; otherwise, <c>false</c>.
        /// </returns>
        public bool IsEquals(Dyna target)
        {
            if (_properties.Count != target._properties.Count)
                return false;
            foreach (var property in _properties)
            {
                if (!target._properties.TryGetValue(property.Key, out var targetProperty))
                    return false;
                if (!Equals(property.Value.Value, targetProperty.Value))
                    return false;
            }
            return true;
        }

        /// <summary>
        /// Determines whether this Dyna instance contains a property with the specified name.
        /// </summary>
        /// <param name="propertyName">The name of the property to check for.</param>
        /// <returns><c>true</c> if the property exists; otherwise, <c>false</c>.</returns>
        public bool ContainsProperty(string propertyName)
        {
            return _properties.ContainsKey(propertyName);
        }

        /// <summary>
        /// Copies all property values from this Dyna instance to a target Dyna instance.
        /// </summary>
        /// <param name="target">The target Dyna instance to copy values to.</param>
        /// <remarks>
        /// This method only copies values for properties that exist in both instances.
        /// It does not create new properties in the target instance.
        /// </remarks>
        public void CopyTo(IDyna target)
        {
            foreach (var property in _properties)
                target.SetValue(property.Key, property.Value.Value);
        }

        /// <summary>
        /// Creates a deep clone of this Dyna instance.
        /// </summary>
        /// <returns>A new Dyna instance with the same properties and values.</returns>
        public object Clone()
        {
            var clone = new Dyna(_properties.Values.Select(x => x.Property));
            foreach (var property in _properties)
                clone.SetValue(property.Key, property.Value.Value);

            clone.TrackChanges();
            return clone;
        }
        #endregion

        #region *** Virtual Operations ***
        public virtual bool OnChangingProperty(string propertyName, object? oldValue, object? newValue)
        {
            return true;
        }

        public virtual void OnClear()
        {

        }

        #endregion

        #region *** Private Operations ***
        /// <summary>
        /// Analyzes a type using reflection and creates corresponding dynamic properties.
        /// </summary>
        /// <param name="templateType">The type to analyze.</param>
        /// <exception cref="ArgumentException">Thrown when the template type does not have a valid FullName.</exception>
        private void AnalyzeType(Type templateType)
        {
            if (templateType.FullName == null)
                throw new ArgumentException("Type must have a FullName", nameof(templateType));

            foreach (var property in templateType.GetProperties())
                _properties.Add(property.Name, new DynaPropertyWithValue(new DynaProperty(property.Name, property.PropertyType, DynaPropertyAccessability.Public, DynaPropertyAccessability.Public), null));
        }

        /// <summary>
        /// Creates dynamic properties from a collection of property definitions.
        /// </summary>
        /// <param name="properties">The collection of property definitions to use.</param>
        private void AnalyzeProperties(IEnumerable<DynaProperty> properties)
        {
            foreach (var property in properties)
                _properties.Add(property.Name, new DynaPropertyWithValue(property, null));
        }
        #endregion

        #region *** Nested Classes ***
        /// <summary>
        /// Represents a dynamic property with its metadata.
        /// </summary>
        public sealed class DynaProperty : IDynaProperty
        {
            #region *** Properties ***
            /// <summary>
            /// Gets the name of the property.
            /// </summary>
            public string Name { get; private set; }

            /// <summary>
            /// Gets the type of the property.
            /// </summary>
            public Type ValueType { get; private set; }

            /// <summary>
            /// Gets the accessibility level for reading the property.
            /// </summary>
            public DynaPropertyAccessability GetAccessability { get; private set; }

            /// <summary>
            /// Gets the accessibility level for writing to the property.
            /// </summary>
            public DynaPropertyAccessability SetAccessability { get; private set; }

            #endregion

            #region *** Constructors ***
            /// <summary>
            /// Initializes a new instance of the <see cref="DynaProperty"/> class.
            /// </summary>
            /// <param name="name">The name of the property.</param>
            /// <param name="valueType">The type of the property.</param>
            /// <param name="getAccessability">The accessibility level for reading the property.</param>
            /// <param name="setAccessability">The accessibility level for writing to the property.</param>
            public DynaProperty(string name, Type valueType, DynaPropertyAccessability getAccessability, DynaPropertyAccessability setAccessability)
            {
                Name = name;
                ValueType = valueType;
                GetAccessability = getAccessability;
                SetAccessability = setAccessability;
            }
            #endregion
        }

        /// <summary>
        /// Internal class that pairs a property definition with its value.
        /// </summary>
        private sealed class DynaPropertyWithValue
        {
            /// <summary>
            /// Gets the property definition.
            /// </summary>
            public DynaProperty Property { get; private set; }

            /// <summary>
            /// Gets or sets the current value of the property.
            /// </summary>
            public object? Value { get; set; }

            /// <summary>
            /// Initializes a new instance of the <see cref="DynaPropertyWithValue"/> class.
            /// </summary>
            /// <param name="property">The property definition.</param>
            /// <param name="value">The initial value of the property.</param>
            public DynaPropertyWithValue(DynaProperty property, object? value)
            {
                Property = property;
                Value = value;
            }
        }
        #endregion
    }
}