using IPA.Config.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace IPA.Config.Stores
{
    /// <summary>
    /// The base interface for a value converter for use by objects generated by
    /// <see cref="GeneratedExtension.Generated{T}(Config, bool)"/>.
    /// </summary>
    /// <remarks>
    /// The object returned from <see cref="FromValue(Value)"/>, if fed into <see cref="ToValue(object)"/>,
    /// should return equivalent <see cref="Value"/> structures. Similarly, if the result of <see cref="ToValue(object)"/>
    /// is fed into <see cref="FromValue(Value)"/>, the resulting object should be equivalent to the one passed to 
    /// <see cref="ToValue(object)"/>.
    /// </remarks>
    public interface IValueConverter
    {
        /// <summary>
        /// Converts the given object to a <see cref="Value"/>.
        /// </summary>
        /// <param name="obj">the object to convert</param>
        /// <returns>a representation of <paramref name="obj"/> as a <see cref="Value"/> structure</returns>
        Value ToValue(object obj);
        /// <summary>
        /// Converts the given <see cref="Value"/> to the object type handled by this converter.
        /// </summary>
        /// <param name="value">the <see cref="Value"/> to deserialize</param>
        /// <returns>the deserialized object</returns>
        object FromValue(Value value);
        /// <summary>
        /// Gets the type that this <see cref="IValueConverter"/> handles.
        /// </summary>
        Type Type { get; }
    }

    /// <summary>
    /// A strongly-typed <see cref="IValueConverter"/>.
    /// </summary>
    /// <typeparam name="T">the type of object to handle</typeparam>
    /// <seealso cref="IValueConverter"/>
    public abstract class ValueConverter<T> : IValueConverter
    {
        /// <summary>
        /// Converts the given object to a <see cref="Value"/>.
        /// </summary>
        /// <param name="obj">the object to convert</param>
        /// <returns>a representation of <paramref name="obj"/> as a <see cref="Value"/> structure</returns>
        /// <seealso cref="IValueConverter.ToValue(object)"/>
        public abstract Value ToValue(T obj);
        /// <summary>
        /// Converts the given <see cref="Value"/> to the object type handled by this converter.
        /// </summary>
        /// <param name="value">the <see cref="Value"/> to deserialize</param>
        /// <returns>the deserialized object</returns>
        /// <seealso cref="IValueConverter.FromValue(Value)"/>
        public abstract T FromValue(Value value);

        Value IValueConverter.ToValue(object obj) => ToValue((T)obj);
        object IValueConverter.FromValue(Value value) => FromValue(value);
        Type IValueConverter.Type => typeof(T);
    }
}