#region License

/*

    Copyright (c) 2010, Paweł Hofman (CodeTitans)

    All Rights Reserved.



    Licensed under the Apache License version 2.0.

    For more information please visit:



    http://codetitans.codeplex.com/license

        or

    http://www.apache.org/licenses/





    For latest source code, documentation, samples

    and more information please visit:



    http://codetitans.codeplex.com/

*/

#endregion



using System;

using System.Reflection;

using System.Collections;



namespace CodeTitans.JSon.Objects

{

    /// <summary>

    /// Class that converts IJSonObject to given type.

    /// </summary>

    internal static class JSonObjectConverter

    {

        /// <summary>

        /// Gets the object value from given <see cref="IJSonObject"/>.

        /// It is capable of converting most of the FCL types and also all custom classes/structures marked with JSonSerializable attribute.

        /// It can also detect if a collection of objects should be returned.

        /// </summary>

        public static object ToObject(IJSonObject source, Type oType)

        {

            if (oType == typeof(Single))

                return source.SingleValue;

            if (oType == typeof(Double))

                return source.DoubleValue;

            if (oType == typeof(DateTime))

                return source.DateTimeValue;

            if (oType == typeof(TimeSpan))

                return source.TimeSpanValue;

            if (oType == typeof(Boolean))

                return source.BooleanValue;

            if (source.IsNull || oType == typeof(DBNull))

                return null;

            if (oType == typeof(string))

                return source.StringValue;

            if (oType == typeof(char))

                return string.IsNullOrEmpty(source.StringValue) ? '\0' : source.StringValue[0];

            if (oType == typeof(Guid))

                return source.GuidValue;

            if (oType == typeof(Byte))

                return (Byte)source.UInt32Value;

            if (oType == typeof(SByte))

                return (SByte)source.Int32Value;

            if (oType == typeof(UInt16))

                return (UInt16)source.UInt32Value;

            if (oType == typeof(Int16))

                return (Int16)source.Int32Value;

            if (oType == typeof(Int32))

                return source.Int32Value;

            if (oType == typeof(UInt32))

                return source.UInt32Value;

            if (oType == typeof(Int64))

                return source.Int64Value;

            if (oType == typeof(object))

                return source.ObjectValue;

            if (oType == typeof(IJSonObject))

                return source;



            // if a collection should be parsed:

            if (oType.IsGenericType && (oType.Namespace.StartsWith("System.Collections", StringComparison.OrdinalIgnoreCase) || oType.IsArray))

            {

                if (!source.IsEnumerable || source.Names != null)

                    throw new JSonException("Expected source is not a collection.");



                Type resultType = oType.GetGenericArguments()[0];

                Array result = Array.CreateInstance(resultType, source.Count);

                int i = 0;



                foreach (IJSonObject data in source.ArrayItems)

                {

                    result.SetValue(ToObject(data, Activator.CreateInstance(resultType), resultType), i++);

                }



                return result;

            }



            return ToObject(source, Activator.CreateInstance(oType), oType);

        }



        /// <summary>

        /// Gets the object value from given IJSonObject.

        /// It is capable of converting most of the FCL types and also all custom classes/structures marked with JSonSerializable attribute.

        /// It can also detect if a collection of objects should be returned.

        /// </summary>

        public static T ToObject<T>(IJSonObject source) where T : new()

        {

            return (T)ToObject(source, new T(), typeof(T));

        }



        private static object ToObject(IJSonObject source, object destination, Type oType)

        {

            if (source == null)

                throw new ArgumentNullException("source");

            if (destination == null)

                throw new ArgumentNullException("destination");



            if (!source.IsEnumerable || source.Names == null)

                throw new ArgumentException("Source is not a JSON Object");



            JSonSerializableAttribute jsonAttribute = (JSonSerializableAttribute)Attribute.GetCustomAttribute(oType, typeof(JSonSerializableAttribute));



            if (jsonAttribute == null)

                throw new JSonException("Object doesn't marked with JSonSerializable attribute");



            // get members that will be serialized:

            FieldInfo[] fieldMembers = oType.GetFields(jsonAttribute.Flags);

            PropertyInfo[] propertyMembers = oType.GetProperties(jsonAttribute.Flags);



            // deserialize all fields:

            foreach (FieldInfo fieldInfo in fieldMembers)

            {

                ToObjectSetField(source, destination, oType, jsonAttribute, fieldInfo);

            }



            // deserialize all properties:

            foreach (PropertyInfo propertyInfo in propertyMembers)

            {

                ToObjectSetProperty(source, destination, oType, jsonAttribute, propertyInfo);

            }



            return destination;

        }



        private static void ToObjectSetField(IJSonObject source, object destination, Type oType, JSonSerializableAttribute jsonAttribute, FieldInfo fieldInfo)

        {

            if (fieldInfo.IsLiteral)

                return;



            JSonIgnoreAttribute ignore = (JSonIgnoreAttribute)Attribute.GetCustomAttribute(fieldInfo, typeof(JSonIgnoreAttribute));



            if (ignore != null)

                return;



            JSonMemberAttribute attr = (JSonMemberAttribute)Attribute.GetCustomAttribute(fieldInfo, typeof(JSonMemberAttribute));



            if (attr == null && !jsonAttribute.AllowAllFields)

                return;



            string name = attr != null && !string.IsNullOrEmpty(attr.Name) ? attr.Name : fieldInfo.Name;

            Type type = attr != null && attr.ReadAs != null ? attr.ReadAs : fieldInfo.FieldType;



            if (source.Contains(name))

                fieldInfo.SetValue(destination, ToObject(source[name], type));

            else

                if (attr != null)

                {

                    if (attr.DefaultValue != null)

                        fieldInfo.SetValue(destination, ToObject(attr.DefaultValue, type));

                    else

                        if (!attr.SuppressThrowWhenMissing && !attr.SkipWhenNull)

                            throw new JSonMemberMissingException("Missing required field", oType, name);

                }

                else

                    if (!jsonAttribute.SuppressThrowWhenMissing)

                        throw new JSonMemberMissingException("Field value not provided", oType, name);

        }



        private static void ToObjectSetProperty(IJSonObject source, object destination, Type oType, JSonSerializableAttribute jsonAttribute, PropertyInfo propertyInfo)

        {

            // there must be a getter defined:

            if (!propertyInfo.CanWrite)

                return;



            JSonIgnoreAttribute ignore = (JSonIgnoreAttribute)Attribute.GetCustomAttribute(propertyInfo, typeof(JSonIgnoreAttribute));



            if (ignore != null)

                return;



            JSonMemberAttribute attr = (JSonMemberAttribute)Attribute.GetCustomAttribute(propertyInfo, typeof(JSonMemberAttribute));

            if (attr == null && !jsonAttribute.AllowAllProperties)

                return;



            string name = attr != null && !string.IsNullOrEmpty(attr.Name) ? attr.Name : propertyInfo.Name;

            Type type = attr != null && attr.ReadAs != null ? attr.ReadAs : propertyInfo.PropertyType;



            if (source.Contains(name))

                propertyInfo.SetValue(destination, ToObject(source[name], type), null);

            else

                if (attr != null)

                {

                    if (attr.DefaultValue != null)

                        propertyInfo.SetValue(destination, ToObject(attr.DefaultValue, type), null);

                    else

                        if (!attr.SuppressThrowWhenMissing && !attr.SkipWhenNull)

                            throw new JSonMemberMissingException("Missing required property", oType, name);

                }

                else

                    if (!jsonAttribute.SuppressThrowWhenMissing)

                        throw new JSonMemberMissingException("Property value not provided", oType, name);

        }

    }

}