/*
 * Copyright (c) 2019 Samsung Electronics Co., Ltd All Rights Reserved
 *
 * Licensed under the Apache License, Version 2.0 (the License);
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;
using System.IO;
using System.Reflection;
using System.Runtime.Loader;
using System.Globalization;
using System.Runtime.CompilerServices;

namespace Tizen.Runtime
{
    public class Preloader
    {
        const string preloadPath = "/usr/share/dotnet.tizen/preload/";

        // If current culture's casing for ASCII is the same as invariant, it can take a fast path
        // than calling out to the OS for culture-aware casing.
        // However, in certain languages, the following function may be significantly slowed down.
        // To avoid that kind situation, call it in advance on the candidate process.
        [MethodImpl(MethodImplOptions.NoOptimization | MethodImplOptions.NoInlining)]
        private static void CheckAsciiCasing()
        {
            _ = CultureInfo.CurrentCulture.CompareInfo.Compare("abcdefghijklmnopqrstuvwxyz", "ABCDEFGHIJKLMNOPQRSTUVWXYZ", CompareOptions.IgnoreCase);
            _ = "abc".ToUpper().ToLower();
        }

        public static void Preload()
        {
            CheckAsciiCasing();

            if (!Directory.Exists(preloadPath))
                return;

            string[] paths = Directory.GetFiles(preloadPath, "*.preload");
            Array.Sort(paths);
            foreach (string path in paths)
            {
                string fileName = Path.GetFileName(path);

                // GetFileName() can return NULL
                if (fileName == null)
                    continue;

                // ex) Tizen.preload / 0A.Tizen.preload / A0.Tizen.preload / .0.Tizen.preload / .00.Tizen.preload
                if (!char.IsNumber(fileName, 0) || !char.IsNumber(fileName, 1))
                    continue;

                // ex) 000.Tizen.preload / 0.Tizen.preload
                if (fileName.IndexOf('.') != 2)
                    continue;

                string value = System.Environment.GetEnvironmentVariable("TIZEN_UIFW");
                // if TIZEN_UIFW is not set, do not preload UI related dll
                if (value == null && (fileName.Contains("NUI") || fileName.Contains("ElmSharp") || fileName.Contains("XSF") ))
                    continue;
                else if (value == "ElmSharp" && fileName.Contains("NUI"))
                    continue;
                else if (value == "NUI" && (fileName.Contains("ElmSharp") || fileName.Contains("XSF")))
                    continue;

                try
                {
                    Console.WriteLine("Start preload : " + fileName);
                    BindingFlags bindingFlag = BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic;
                    foreach (string line in File.ReadLines(path))
                    {
                        if (line.StartsWith('#') || !line.Contains(".dll") || !line.Contains(' '))
                            continue;

                        string[] getWord = line.Split(' ');
                        if (getWord.Length != 2)
                            continue;

                        string assemblyStr = getWord[0].Replace(".dll", "");
                        string typenameStr = getWord[1];
                        string methodStr = "";
                        string parenthesis = "()";

                        if (line.Contains(parenthesis))
                        {
                            string[] getMethod = typenameStr.Split('.');
                            methodStr = getMethod[getMethod.Length - 1].Replace(parenthesis, "");
                            typenameStr = typenameStr.Replace("." + methodStr + parenthesis, "");
                        }

                        if (assemblyStr == "")
                        {
                            Console.WriteLine("[Warning] Skip the '" + line + "' in " + fileName);
                            continue;
                        }

                        try
                        {
                            Assembly asm = AssemblyLoadContext.Default.LoadFromAssemblyName(new AssemblyName(assemblyStr));
                            if (asm == null)
                            {
                                Console.WriteLine("[Warning] Check the '" + line + "' in " + fileName);
                                continue;
                            }

                            if (typenameStr != "" && !typenameStr.Contains(parenthesis))
                            {
                                Type type = asm.GetType(typenameStr);
                                if (type == null)
                                {
                                    Console.WriteLine("[Warning] Check the '" + line + "' in " + fileName);
                                    continue;
                                }

                                if (methodStr != "")
                                {
                                    MethodInfo method = type.GetMethod(methodStr, bindingFlag);
                                    if (method == null)
                                    {
                                        Console.WriteLine("[Warning] Check the '" + line + "' in " + fileName);
                                        continue;
                                    }
                                    method.Invoke(null, null);
                                }
                            }
                        }
                        catch
                        {
                            Console.WriteLine("[Error] Fail the '" + line + "' in " + fileName);
                        }
                    }
                }
                catch (IOException e)
                {
                    Console.WriteLine(e.ToString());
                    Console.WriteLine("[Error] Failed to open file : " + fileName);
                }
            }

            GC.Collect();
            GC.WaitForPendingFinalizers();

            Profiler.SetCandidateProcessProfile();
        }
    }
}