using Python.Runtime;
using System;
using static System.Net.Mime.MediaTypeNames;
using System.IO;
using System.Reflection;

namespace doptPlugin
{
    public class Plugin
    {
        internal const string relPathToPyDll = @".\python\python311.dll";
        internal const string relPathToExtensionDlls = @".\python\DLLs";
        internal const string relPathToVirtualEnv = @".\python\.venv";
        internal const string relPathToPythonInit = @".\python\";
        internal const string langMainBaseFolderName = "bin";
        internal const string langMainStopSearchFolderName = "python";
        internal const string doptTOMPluginLibraryUsage = "1";
        private IntPtr _threadState;
        private bool _prepared = false;
        private bool _initialised = false;

        public Plugin() 
        {
            PrepareEnv();
        }

        internal void PrepareEnv()
        {
            Type t = typeof(Plugin);
            Assembly assembly = t.Assembly;
            Console.WriteLine($"Location:\n{assembly.Location}\n---\nCodeBase:\n{assembly.CodeBase}");
            string assemPath = assembly.CodeBase;
            if (assemPath.StartsWith("file:///"))
            {
                assemPath = assemPath.Replace("file:///", "");
            }
            string dllDir = System.IO.Path.GetDirectoryName(assemPath);
            Console.WriteLine($"Current DLL Dir: {dllDir}");

            string pathToPyDll = Path.Combine(dllDir, relPathToPyDll);
            string pathToExtensionDlls = Path.Combine(dllDir, relPathToExtensionDlls);
            string pathToVirtualEnv = Path.Combine(dllDir, relPathToVirtualEnv);
            string pathToPythonInit = Path.Combine(dllDir, relPathToPythonInit);

            if (!File.Exists(pathToPyDll))
            {
                throw new FileNotFoundException($"Python DLL not found at: {pathToPyDll}");
            }
            else if (!Directory.Exists(pathToExtensionDlls))
            {
                throw new DirectoryNotFoundException($"Python Extension Dlls not found at: {pathToExtensionDlls}");
            }
            else if (!Directory.Exists(pathToVirtualEnv))
            {
                throw new DirectoryNotFoundException($"Python Virtual Env not found at: {pathToVirtualEnv}");
            }
            else if (!Directory.Exists(pathToPythonInit))
            {
                throw new DirectoryNotFoundException($"Python base directory not found at: {pathToPythonInit}");
            }
            // environment preparation
            Environment.SetEnvironmentVariable("PYTHONNET_PYDLL", pathToPyDll, EnvironmentVariableTarget.Process);
            Environment.SetEnvironmentVariable("LANG_MAIN_BASE_FOLDERNAME", langMainBaseFolderName, EnvironmentVariableTarget.Process);
            Environment.SetEnvironmentVariable("LANG_MAIN_STOP_SEARCH_FOLDERNAME", langMainStopSearchFolderName, EnvironmentVariableTarget.Process);
            Environment.SetEnvironmentVariable("DOPT_TOM_PLUGIN_LIBRARY_USAGE", doptTOMPluginLibraryUsage, EnvironmentVariableTarget.Process);
            var path = Environment.GetEnvironmentVariable("PATH").TrimEnd(';');
            path = string.IsNullOrEmpty(path) ? pathToVirtualEnv : path + ";" + pathToVirtualEnv;
            Environment.SetEnvironmentVariable("PATH", path, EnvironmentVariableTarget.Process);
            Environment.SetEnvironmentVariable("PYTHONHOME", pathToVirtualEnv, EnvironmentVariableTarget.Process);
            Environment.SetEnvironmentVariable("PYTHONPATH", $@"{pathToPythonInit}\Lib;{pathToVirtualEnv}\Lib\site-packages;{pathToVirtualEnv}\Lib;{pathToExtensionDlls}", EnvironmentVariableTarget.Process);

            PythonEngine.PythonHome = pathToVirtualEnv;
            PythonEngine.PythonPath = Environment.GetEnvironmentVariable("PYTHONPATH", EnvironmentVariableTarget.Process);

            _prepared = true;
        }

        internal void Initialise()
        {
            if (!_prepared) PrepareEnv();

            PythonEngine.Initialize();
            _threadState = PythonEngine.BeginAllowThreads(); // release GIL for use in other threads

            _initialised = true;
        }

            internal void Finalise()
        {
            PythonEngine.EndAllowThreads(_threadState);
            /*
             * The shutdown method leads to a Exception because the unsafe BinaryFormatter is used.
             * Therefore the unsafe formatter option can be allowed temporarily. A fix is already applied,
             * but not yet published.
             * see: https://github.com/pythonnet/pythonnet/issues/2282
            */
            AppContext.SetSwitch("System.Runtime.Serialization.EnableUnsafeBinaryFormatterSerialization", true);
            PythonEngine.Shutdown();
            AppContext.SetSwitch("System.Runtime.Serialization.EnableUnsafeBinaryFormatterSerialization", false);

            _initialised = false;
        }

        private void Run() // for testing purposes
        {
            if (!_initialised) Initialise();

            using (Py.GIL())
            {
                dynamic np = Py.Import("numpy");
                Console.WriteLine(np.cos(np.pi * 2));
                dynamic rand = Py.Import("random");
                Console.WriteLine(rand.randint(1, 2));
                dynamic pathlib = Py.Import("pathlib");
                dynamic ret = pathlib.Path.cwd();
                Console.WriteLine(ret);
            }

            Finalise();
        }
        public void RunOnCSV(string identifier, string filename)
        {
            if (!_initialised) Initialise();

            using (Py.GIL())
            {
                dynamic tomWrapperPipeline = Py.Import("tom_plugin.pipeline");
                tomWrapperPipeline.run_on_csv_data(identifier, filename);
            }

            Finalise();
        }
    }
}