using System;
using System.Reflection;

namespace LinFu.Reflection.Plugins
{
    /// <summary>
    ///     A plugin class that provides the basic implementation
    ///     for plugins that work with <see cref="IAssemblyTargetLoader{TTarget}" /> instances.
    /// </summary>
    /// <typeparam name="TTarget">The target type being configured.</typeparam>
    /// <typeparam name="TAssembly">The assembly type.</typeparam>
    /// <typeparam name="TType">The input type.</typeparam>
    public abstract class BaseTargetLoaderPlugin<TTarget, TAssembly, TType> : BaseLoaderPlugin<TTarget>,
        IInitialize<ILoader<TTarget>>
    {
        private readonly IAssemblyTargetLoader<TTarget, TAssembly, TType> _assemblyLoader;
        private readonly ITypeExtractor<TAssembly, TType> _typeExtractor;

        /// <summary>
        ///     Initializes a new instance of the <see cref="BaseTargetLoaderPlugin{TTarget,TAssembly,TType}" /> class.
        /// </summary>
        /// <param name="typeExtractor">The type extractor that will pull the types out of the current assembly.</param>
        /// <param name="assemblyLoader">The assembly loader that will load the current assembly into memory.</param>
        protected BaseTargetLoaderPlugin(ITypeExtractor<TAssembly, TType> typeExtractor,
            IAssemblyTargetLoader<TTarget, TAssembly, TType> assemblyLoader)
        {
            _typeExtractor = typeExtractor;
            _assemblyLoader = assemblyLoader;
        }


        /// <summary>
        ///     Searches the loader for an <see cref="IAssemblyTargetLoader{T}" />
        ///     instance and uses its derived classes to initialize
        ///     the assembly target loader.
        /// </summary>
        /// <param name="source">The <see cref="ILoader{TTarget}" /> instance that will hold the plugin.</param>
        public void Initialize(ILoader<TTarget> source)
        {
            Initialize(source, _assemblyLoader);
        }


        /// <summary>
        ///     Initializes the <paramref name="loader" /> instance
        ///     with the given <paramref name="assemblyLoader" /> instance.
        /// </summary>
        /// <param name="loader">The loader being configured.</param>
        /// <param name="assemblyLoader">The assembly loader that will load the types into the loader itself.</param>
        protected abstract void Initialize(ILoader<TTarget> loader,
            IAssemblyTargetLoader<TTarget, TAssembly, TType> assemblyLoader);
    }

    /// <summary>
    ///     A plugin class that provides the basic implementation
    ///     for plugins that work with <see cref="IAssemblyTargetLoader{TTarget}" /> instances.
    /// </summary>
    public abstract class BaseTargetLoaderPlugin<TTarget> : BaseTargetLoaderPlugin<TTarget, Assembly, Type>
    {
        /// <summary>
        ///     Initializes a new instance of the <see cref="BaseTargetLoaderPlugin{TTarget,TAssembly,TType}" /> class.
        /// </summary>
        protected BaseTargetLoaderPlugin() : this(new TypeExtractor())
        {
        }

        /// <summary>
        ///     Initializes a new instance of the <see cref="BaseTargetLoaderPlugin{TTarget,TAssembly,TType}" /> class.
        /// </summary>
        /// <param name="typeExtractor">The type extractor that will pull the types out of the current assembly.</param>
        protected BaseTargetLoaderPlugin(ITypeExtractor<Assembly, Type> typeExtractor) :
            base(typeExtractor, new AssemblyTargetLoader<TTarget, Assembly, Type>(typeExtractor, new AssemblyLoader()))
        {
        }
    }
}