using System;
using System.Collections.Generic;
using System.ComponentModel;
using JD.Collections.Extensions;
using JD.Kernel.StaticHelpers;
using JD.Reflection;

namespace JD.TeaBoxAddinSystem.Addins
{
    /// <summary>
    /// An object that can convert CLR properties to/from strings.
    /// </summary>
    public class StringPropertyConverter
    {
        #region Delegates

        /// <summary>
        /// Converts a string into a custom object.
        /// </summary>
        /// <param name="targetType"></param>
        /// <param name="value"></param>
        /// <param name="convertedValue"></param>
        /// <returns></returns>
        public delegate bool CustomValueDeserializationDelegate(Type targetType, string value, out object convertedValue);

        #endregion

        #region Variables
        private readonly TypeConverterCache _typeConverter = new TypeConverterCache();

        private Action<string> m_errorLogger;
        private Action<string> m_superfluousPropertyLogger;
        private CustomValueDeserializationDelegate m_customConverter;

        private bool m_superfluousPropertiesProduceErrors;
        
        #endregion

        #region Properties

        /// <summary>
        /// Error Logger.
        /// </summary>
        public Action<string> ErrorLogger
        {
            get
            {
                return m_errorLogger;
            }
            set
            {
                m_errorLogger = value;
            }
        }

        /// <summary>
        /// Superfluous Property Logger. Used when deserializing from string dictionaries.
        /// </summary>
        public Action<string> SuperfluousPropertyLogger
        {
            get
            {
                return m_superfluousPropertyLogger;
            }
            set
            {
                m_superfluousPropertyLogger = value;
            }
        }

        /// <summary>
        /// Custom Converter.
        /// </summary>
        public CustomValueDeserializationDelegate CustomConverter
        {
            get
            {
                return m_customConverter;
            }
            set
            {
                m_customConverter = value;
            }
        }

        /// <summary>
        /// Whether to log errors about properties that do not have corresponding property descriptors.
        /// </summary>
        public bool SuperfluousPropertiesProduceErrors
        {
            get
            {
                return m_superfluousPropertiesProduceErrors;
            }
            set
            {
                m_superfluousPropertiesProduceErrors = value;
            }
        }

        #endregion

        #region Methods
        
        /// <summary>
        /// Serializes the given <paramref name="instance"/> into the given <paramref name="properties"/> using the given <paramref name="descriptors"/>.
        /// </summary>
        /// <param name="instance"></param>
        /// <param name="descriptors"></param>
        /// <param name="properties"></param>
        /// <returns></returns>
        public bool Serialize(object instance, IEnumerable<StringPropertyDescriptor> descriptors, IDictionary<string, string> properties)
        {
            Throw.IfNull(instance, "instance");
            Throw.IfNull(descriptors, "descriptors");
            Throw.IfNull(properties, "properties");
            Throw.InvalidArgumentIf(properties.IsReadOnly, "Properties are read-only.", "properties");

            bool errorEncountered = false;

            foreach (StringPropertyDescriptor propertyDescriptor in descriptors)
            {
                System.Diagnostics.Debug.Assert(propertyDescriptor.MemberInfo != null);

                string value;
                if (!GetValue(instance, propertyDescriptor, out value))
                {
                    errorEncountered = true;
                    continue;
                }
                properties[propertyDescriptor.Name] = value;
            }

            return !errorEncountered;
        }

        /// <summary>
        /// Deserializes the given <paramref name="instance"/> using the given <paramref name="properties"/>
        /// </summary>
        /// <param name="instance"></param>
        /// <param name="descriptors"></param>
        /// <param name="properties"></param>
        public bool Deserialize(object instance, IEnumerable<StringPropertyDescriptor> descriptors, IDictionary<string, string> properties)
        {
            IReadOnlyDictionary<string, string> dict = properties.AsReadOnly();
            return Deserialize(instance, descriptors, dict);
        }

        /// <summary>
        /// Deserializes the given <paramref name="instance"/> using the given <paramref name="properties"/>
        /// </summary>
        /// <param name="instance"></param>
        /// <param name="descriptors"></param>
        /// <param name="properties"></param>
        public bool Deserialize(object instance, IEnumerable<StringPropertyDescriptor> descriptors, IReadOnlyDictionary<string, string> properties)
        {
            Throw.IfNull(instance, "instance");
            Throw.IfNull(descriptors, "descriptors");
            Throw.IfNull(properties, "properties");

            bool errorEncountered = false;

            Dictionary<string, string> unusedAttributes = null;
            if (SuperfluousPropertiesProduceErrors)
            {
                unusedAttributes = CreateDictionary(properties);
            }

            foreach (StringPropertyDescriptor propertyDescriptor in descriptors)
            {
                System.Diagnostics.Debug.Assert(propertyDescriptor.MemberInfo != null);

                string name = propertyDescriptor.Name;

                string value;
                if (properties.TryGetValue(name, out value))
                {
                    errorEncountered |= !SetValue(instance, propertyDescriptor, value);
                    
                    if (unusedAttributes != null)
                    {
                        unusedAttributes.Remove(name);
                    }
                }
                else if (propertyDescriptor.Attribute.Required)
                {
                    LogError($"Attribute {name} is required by instance of type {instance.GetType().FullName}");
                    errorEncountered = true;
                }
            }

            if (unusedAttributes != null)
            {
                foreach (KeyValuePair<string, string> unusedAttribute in unusedAttributes)
                {
                    LogSuperfluousProperty(unusedAttribute.Key);
                }
            }

            return !errorEncountered;
        }

        private static Dictionary<string, string> CreateDictionary(IEnumerable<KeyValuePair<string, string>> properties)
        {
            var unusedAttributes = new Dictionary<string, string>();
            unusedAttributes.AddRange(properties);
            return unusedAttributes;
        }

        /// <summary>
        /// Gets the value of the given <paramref name="descriptor"/> for the given <paramref name="instance"/>.
        /// </summary>
        /// <param name="instance"></param>
        /// <param name="descriptor"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        public bool GetValue(object instance, StringPropertyDescriptor descriptor, out string value)
        {
            Throw.IfNull(instance, "instance");
            Throw.IfNull(descriptor, "descriptor");
            Throw.InvalidOperationIf(descriptor.MemberInfo.IsWriteOnly, "Descriptor is write-only.");
            Throw.InvalidOperationIf(descriptor.MemberInfo.InnerMemberInfo.DeclaringType.IsAssignableFrom(instance.GetType()), "Instance type is invalid.");

            try
            {
                value = ConvertValue(descriptor.MemberInfo.GetValue(instance));
                return true;
            }
            catch
            {
                LogError($"Cannot get value for property {descriptor.Name} of type {instance.GetType().FullName}");
                value = null;
                return false;
            }
        }

        /// <summary>
        /// Sets the value of the given <paramref name="descriptor"/> to the given <paramref name="value"/>, for the given <paramref name="instance"/>.
        /// </summary>
        /// <param name="instance"></param>
        /// <param name="descriptor"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        public bool SetValue(object instance, StringPropertyDescriptor descriptor, string value)
        {
            Throw.IfNull(instance, "instance");
            Throw.IfNull(descriptor, "descriptor");
            Throw.InvalidOperationIf(descriptor.MemberInfo.IsReadOnly, "Descriptor is read-only.");
            Throw.InvalidOperationIf(!descriptor.MemberInfo.InnerMemberInfo.DeclaringType.IsAssignableFrom(instance.GetType()), "Instance type is invalid.");

            Type targetType = descriptor.MemberInfo.ValueType;

            object convertedValue = null;
            try
            {
                System.Diagnostics.Debug.Assert(targetType != null);
                convertedValue = ConvertValue(targetType, value);
            }
            catch
            {
                LogError($"Cannot convert value {value} to type {targetType.FullName} for attribute {descriptor.Name} of type {instance.GetType().FullName}.");
                return false;
            }

            try
            {
                descriptor.MemberInfo.SetValue(instance, convertedValue);
            }
            catch (Exception e)
            {
                LogError($"Unexpected exception while setting value {value} to attribute {descriptor.Name} of type {instance.GetType().FullName}: {e.Message}");
                return false;
            }

            return true;
        }

        /// <summary>
        /// Converts the given <paramref name="value"/> into a string.
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public string ConvertValue(object value)
        {
            if (value != null)
            {
                TypeConverter c = _typeConverter.GetConverter(value.GetType());
                return c.ConvertToInvariantString(value);
            }
            else
            {
                return null;
            }
        }

        /// <summary>
        /// Converts the given <paramref name="value"/> into the given <paramref name="targetType"/>.
        /// </summary>
        /// <param name="targetType"></param>
        /// <param name="value"></param>
        /// <returns></returns>
        public object ConvertValue(Type targetType, string value)
        {
            Throw.IfNull(targetType, "targetType");

            // Optim: most fields are simple types
            if (targetType == typeof(string))
            {
                return value;
            }

            if (targetType.IsArray)
            {
                Type elementType = targetType.GetElementType();

                if (string.IsNullOrEmpty(value))
                {
                    return Array.CreateInstance(elementType, 0);
                }

                string[] elements = value.Split(',');
                Array array = Array.CreateInstance(elementType, elements.Length);
                for (int index = 0; index < elements.Length; index++)
                {
                    array.SetValue(ConvertValue(elementType, elements[index].Trim()), index);
                }
                return array;
            }

            object convertedValue;
            if (CustomConverter != null && CustomConverter(targetType, value, out convertedValue))
            {
                return convertedValue;
            }

            TypeConverter c = _typeConverter.GetConverter(targetType);
            return c.ConvertFromInvariantString(value);
        }

        private void LogError(string errorMessage)
        {
            if (ErrorLogger != null)
            {
                ErrorLogger(errorMessage);
            }
        }

        private void LogSuperfluousProperty(string property)
        {
            if (SuperfluousPropertyLogger != null)
            {
                SuperfluousPropertyLogger(property);
            }
        }

        #endregion
    }
}