using System;
using System.Collections.Generic;
using System.Linq;
using global::System.Reflection;
using global::Pilz.Reflection.PluginSystem.Attributes;

namespace Pilz.Reflection.PluginSystem
{
    public class Plugin
    {

        /// <summary>
    /// A collection of Methods that contains PluginFunctions that will be called automatically when loading the Plugin, as long as the property AutoCallMainFunctions is set to True.
    /// </summary>
    /// <returns></returns>
        public IReadOnlyList<PluginFunction> MainFunctions { get; private set; }
        /// <summary>
    /// A collection of Methods with a FunctionCode (excluding all PluginFunctions from MainFunctions).
    /// </summary>
    /// <returns></returns>
        public IReadOnlyList<PluginFunction> PluginFunctions { get; private set; }
        /// <summary>
    /// Gets the assembly that contains the PluginFunctions of this Plugin
    /// </summary>
    /// <returns></returns>
        public Assembly Assembly { get; private set; }
        /// <summary>
    /// Gets the main module that contains the PluginFunctions of this Plugin
    /// </summary>
    /// <returns></returns>
        public Type MainModule { get; private set; }

        /// <summary>
    /// Load a new Plugin and its PluginFunctions.
    /// </summary>
    /// <param name="filePath"></param>
    /// <param name="autoCallMainFunction">If true, all MainMethods of a Plugin will be called as soon as a Plugin is loaded.</param>
    /// <param name="entryTypeName">The name of the type where to search for Methods when loading a new Plugin.</param>
        public Plugin(string filePath, bool autoCallMainFunction, string entryTypeName)
        {
            Assembly = Assembly.LoadFile(filePath);
            MainModule = Assembly.GetType(entryTypeName);
            if (MainModule is null)
            {
                throw new PluginLoadException("Plugin Modul not found!");
            }

            // Define the attribute types to observe
            var entryMethodType = typeof(LoadMethodAttribute);
            var implementMethodType = typeof(PluginFunctionAttribute);

            // Create the lists
            var mainMethods = new List<PluginFunction>();
            var implementMethods = new List<PluginFunction>();

            // Search for PluginFunctions
            foreach (MethodInfo mi in MainModule.GetMethods())
            {
                bool found = false;

                // Check if the method has one of the defined attributes
                foreach (Attribute attr in Attribute.GetCustomAttributes(mi))
                {
                    if (!found)
                    {
                        var t = attr.GetType();
                        switch (t)
                        {
                            case var @case when @case == entryMethodType:
                                {
                                    mainMethods.Add(new PluginFunction(mi, this));
                                    break;
                                }

                            case var case1 when case1 == implementMethodType:
                                {
                                    {
                                        var withBlock = (PluginFunctionAttribute)attr;
                                        implementMethods.Add(new PluginFunction(mi, this, withBlock.Params, withBlock.FunctionCode));
                                    }

                                    break;
                                }
                        }

                        found = true;
                    }
                }
            }

            // Set the collections
            MainFunctions = mainMethods;
            PluginFunctions = implementMethods;

            // Call all PluginFunctions in MainFunctions
            if (autoCallMainFunction)
            {
                foreach (PluginFunction func in mainMethods)
                {
                    var @params = func.Method.GetParameters();
                    if (@params.Length == 1)
                    {
                        string startupExe = Assembly.GetEntryAssembly().Location;
                        var args = new[] { startupExe, filePath };
                        func.Invoke(new[] { args });
                    }
                    else if (!@params.Any())
                    {
                        func.Invoke();
                    }
                }
            }
        }

        /// <summary>
    /// Get all PluginFunctions that have one of the given function codes.
    /// </summary>
    /// <param name="funcCodes"></param>
    /// <returns></returns>
        public IEnumerable<PluginFunction> GetFunctions(params string[] funcCodes)
        {
            var funcs = new List<PluginFunction>();
            foreach (PluginFunction func in PluginFunctions)
            {
                if (funcCodes.Contains(func.FunctionCode))
                {
                    funcs.Add(func);
                }
            }

            return funcs;
        }

        /// <summary>
    /// Get the first PluginFunction that have the one of the given function codes.
    /// </summary>
    /// <returns></returns>
        public PluginFunction GetFunction(params string[] funcCodes)
        {
            PluginFunction f = null;
            foreach (PluginFunction func in PluginFunctions)
            {
                if (f is null && funcCodes.Contains(func.FunctionCode))
                {
                    f = func;
                }
            }

            return f;
        }
    }
}