using System.Reflection;
using LinFu.AOP.Cecil.Interfaces;
using LinFu.AOP.Interfaces;
using Mono.Cecil;
using Mono.Cecil.Cil;

namespace LinFu.AOP.Cecil.Extensions
{
    /// <summary>
    ///     Adds helper methods classes that implement the <see cref="IInvocationInfo" />
    ///     interface.
    /// </summary>
    public static class InvocationInfoExtensions
    {
        /// <summary>
        ///     Emits the IL instructions that will store information about the method
        ///     <paramref name="targetMethod">currently being executed</paramref>
        ///     and stores the results into the <paramref name="invocationInfo">variable.</paramref>
        /// </summary>
        /// <param name="emitter">The <see cref="IEmitInvocationInfo" /> instance.</param>
        /// <param name="method">The method whose implementation will be intercepted.</param>
        /// <param name="targetMethod">The actual method that will contain the resulting instructions.</param>
        /// <param name="invocationInfo">
        ///     The <see cref="VariableDefinition">local variable</see> that will store the current
        ///     <see cref="IInvocationInfo" /> instance.
        /// </param>
        public static void Emit(this IEmitInvocationInfo emitter, MethodInfo method, MethodDefinition targetMethod,
            VariableDefinition invocationInfo)
        {
            var module = targetMethod.DeclaringType.Module;
            var interceptedMethod = module.Import(method);
            emitter.Emit(targetMethod, interceptedMethod, invocationInfo);
        }

        /// <summary>
        ///     Invokes the currently executing method by using the <see cref="IInvocationInfo.Target" />
        ///     as the target instance, the <see cref="IInvocationInfo.TargetMethod" /> as the method,
        ///     and uses the <see cref="IInvocationInfo.Arguments" /> for the method
        ///     arguments.
        /// </summary>
        /// <param name="info">The <see cref="IInvocationInfo" /> instance that contains information about the method call itself.</param>
        /// <returns>The return value of the method call.</returns>
        public static object Proceed(this IInvocationInfo info)
        {
            var targetMethod = info.TargetMethod;
            var target = info.Target;
            var arguments = info.Arguments;

            return targetMethod.Invoke(target, arguments);
        }

        /// <summary>
        ///     Invokes the currently executing method by using the <paramref name="target" />
        ///     as the target instance, the <see cref="IInvocationInfo.TargetMethod" /> as the method,
        ///     and uses the <see cref="IInvocationInfo.Arguments" /> for the method
        ///     arguments.
        /// </summary>
        /// <param name="info">The <see cref="IInvocationInfo" /> instance that contains information about the method call itself.</param>
        /// <param name="target">The target instance that will handle the method call.</param>
        /// <returns>The return value of the method call.</returns>
        public static object Proceed(this IInvocationInfo info, object target)
        {
            var targetMethod = info.TargetMethod;
            var arguments = info.Arguments;

            return targetMethod.Invoke(target, arguments);
        }

        /// <summary>
        ///     Invokes the currently executing method by using the <paramref name="target" />
        ///     as the target instance, the <see cref="IInvocationInfo.TargetMethod" /> as the method,
        ///     and uses the <paramref name="arguments" /> for the method
        ///     arguments.
        /// </summary>
        /// <param name="info">The <see cref="IInvocationInfo" /> instance that contains information about the method call itself.</param>
        /// <param name="target">The target instance that will handle the method call.</param>
        /// <param name="arguments">The arguments that will be used for the actual method call.</param>
        /// <returns>The return value of the method call.</returns>
        public static object Proceed(this IInvocationInfo info, object target,
            params object[] arguments)
        {
            var targetMethod = info.TargetMethod;
            return targetMethod.Invoke(target, arguments);
        }
    }
}