using System;
using System.Reflection;
using System.Text;
using Mono.Cecil;
using Mono.Cecil.Cil;
using UnityEditor;
using UnityEditorInternal;
using System.Linq;
using System.IO;
using UnityEngine;
using System.Collections.Generic;
using UnityEditor.Compilation;
using Assembly = System.Reflection.Assembly;
using FieldAttributes = Mono.Cecil.FieldAttributes;
using MethodAttributes = Mono.Cecil.MethodAttributes;

namespace com.bbbirder.injection.editor
{
    public static class UnityInjectUtils
    {
        const string BACKUP_EXT = ".backup";

        [InitializeOnLoadMethod]
        static void Install()
        {
            CompilationPipeline.compilationStarted += (o) =>
            {
                var settings = GetScriptAssemblySettings();
                if (settings is null)
                {
                    Debug.LogError("cannot get BeeScriptCompilationState, Unity Version" + Application.unityVersion);
                    return;
                }
                var BuildingForEditor = (bool)settings?.GetMemberValue("BuildingForEditor", true);
                var OutputDirectory = (string)settings?.GetMemberValue("OutputDirectory", true);
                if (!BuildingForEditor)
                {
                    runtimeOutputDirectory = OutputDirectory;
                }
            };


            CompilationPipeline.assemblyCompilationFinished += (path, msg) =>
            {
                var fullPath = Path.GetFullPath(path);
                var hasError = msg.Any(m => m.type == CompilerMessageType.Error);
                if (hasError)
                {
                    var list = InjectionSettings.instance.compilationErrorAssemblies;
                    if (!list.Contains(fullPath)) list.Add(fullPath);
                }
                else
                {
                    InjectionSettings.instance.compilationErrorAssemblies.RemoveAll(p => p.Equals(fullPath));
                }
                EditorUtility.SetDirty(InjectionSettings.instance);
                AssetDatabase.SaveAssetIfDirty(InjectionSettings.instance);
            };

            CompilationPipeline.compilationFinished += (o) =>
            {
                var settings = GetScriptAssemblySettings();
                if (settings is null)
                {
                    Debug.LogError("cannot get BeeScriptCompilationState, Unity Version" + Application.unityVersion);
                    return;
                }
                var BuildingForEditor = (bool)settings.GetMemberValue("BuildingForEditor", true);
                if (!BuildingForEditor && InjectionSettings.instance.ShouldAutoInjectBuild)
                {
                    InjectRuntime();
                }
            };

            if (InjectionSettings.instance.ShouldAutoInjectEditor)
            {
                EditorApplication.delayCall += InjectEditorDelayed;
            }

            void InjectEditorDelayed()
            {
                // wait while editor is busy
                var IsEditorBusy = false;
                IsEditorBusy |= EditorApplication.isCompiling;
                IsEditorBusy |= EditorApplication.isUpdating;
                if (IsEditorBusy)
                {
                    EditorApplication.delayCall -= InjectEditorDelayed;
                    EditorApplication.delayCall += InjectEditorDelayed;
                    return;
                }

                var injectionSources = FixHelper.GetAllInjectionSources();
                var outdatedSources = new List<string>();
                // DebugHelper.Log($"injectionSources :\n {string.Join("\n",injectionSources)}");
                InjectionSettings.instance.GetOutdatedSources(injectionSources, outdatedSources);
                if (outdatedSources.Count == 0)
                {
                    return;
                }

                // filter out assemblies who has compilation error
                var injectingSources = outdatedSources.Distinct().Where(p =>
                {
                    var fullPath = Path.GetFullPath(p);
                    var hasError = InjectionSettings.instance.compilationErrorAssemblies
                        .Contains(fullPath)
                        ;
                    if (hasError)
                    {
                        Debug.LogWarning($"ignore target {p} due to compilation error");
                    }
                    return !hasError;
                }).ToList();

                var assemblies = GetAssemblies(injectingSources.ToHashSet());
                if (assemblies.Length > 0)
                {
                    InjectEditor(assemblies);
                }
                InjectionSettings.instance.SetInjectionSources(injectionSources);
            }
            static Assembly[] GetAssemblies(HashSet<string> assemblyPathes)
            {
                var hashset = assemblyPathes
                    .Select(p => p.Replace('\\', '/'))
                    .ToHashSet();
                return AppDomain.CurrentDomain.GetAssemblies()
                    .Where(a => hashset.Contains(a.GetAssemblyPath()))
                    .ToArray();
            }
        }


        public static void InjectEditor(Assembly[] assemblies)
        {
            var allInjections = FixHelper.allInjections;
            var freshInjections = FixHelper.GetAllInjections(assemblies);
            var freshAssemblies = freshInjections
                .Where(inj => inj.InjectedMethod != null)
                .Select(inj => inj.InjectedMethod.DeclaringType.Assembly)
                .Distinct().
                ToHashSet();
            var outcomeInjections = allInjections
                .Where(inj => inj.InjectedMethod != null)
                .Where(inj => freshAssemblies.Contains(inj.InjectedMethod.DeclaringType.Assembly))
                .ToArray();
            DebugHelper.Log($"auto inject {allInjections.Length} injections, {outcomeInjections.Length} to inject");

            bool isWritten = false;
            if (outcomeInjections.Length > 0)
            {
                isWritten = InjectTargetMode(outcomeInjections, true, activeBuildTarget);
            }

            var group = freshInjections
                .Where(inj => inj.DryInjectAssmemble != null)
                .GroupBy(inj => inj.DryInjectAssmemble.Assembly);
            foreach (var g in group)
            {
                isWritten |= VisitAssembly(g.Key.GetAssemblyPath(), g.ToArray(), true, activeBuildTarget);
            }

            if (isWritten)
            {
                DebugHelper.Log($"reload scripts {EditorApplication.isCompiling}");
#if UNITY_2019_3_OR_NEWER
                EditorUtility.RequestScriptReload();
#else
                UnityEditorInternal.InternalEditorUtility.RequestScriptReload();
#endif
            }
        }

        public static void InjectRuntime()
        {
            InjectTargetMode(FixHelper.allInjections, false, activeBuildTarget);
        }

        static bool InjectTargetMode(InjectionInfo[] injections, bool isEditor, BuildTarget buildTarget)
        {
            var group = injections
                .Where(inj => inj.InjectedMethod != null)
                .GroupBy(inj => inj.InjectedMethod.DeclaringType.Assembly);
            var isWritten = false;
            foreach (var g in group)
            {
                var assemblyPath = GetResolvedAssemblyPath(g.Key.GetAssemblyPath(), isEditor, buildTarget);
                isWritten |= VisitAssembly(assemblyPath, g.ToArray(), isEditor, buildTarget);
            }
            return isWritten;
        }

        static string GetResolvedAssemblyPath(string assemblyPath, bool isEditor, BuildTarget buildTarget)
        {
            var fileName = Path.GetFileName(assemblyPath);
            if (!isEditor)
            {
                var preloads = GetPreloadAssemblies(isEditor, buildTarget);
                var matchedAssembly = preloads.FirstOrDefault(path => Path.GetFileName(path) == fileName);
                if (matchedAssembly is not null)
                {
                    return matchedAssembly;
                }
                var playerAssemblyPath = Path.Join(runtimeOutputDirectory, fileName);
                if (File.Exists(playerAssemblyPath))
                {
                    return playerAssemblyPath;
                }
            }
            return assemblyPath;
        }

        static string GetEditorAssemblyPath(string assemblyPath)
            => assemblyPath;

        static bool VisitAssembly(string assemblyPath, InjectionInfo[] injections, bool isEditor, BuildTarget buildTarget)
        {
            var backPath = assemblyPath + BACKUP_EXT;
            var IsEngineAssembly = Path.GetFullPath(assemblyPath)
                .StartsWith(Path.GetFullPath(EditorApplication.applicationContentsPath));

            // engine dlls should be backed up
            if (IsEngineAssembly && !File.Exists(backPath))
            {
                if (!IsFileAvaliable(assemblyPath))
                {
                    LogError($"cannot access file: {assemblyPath}, make sure you has access rights to target");
                    return false;
                }
                File.Copy(assemblyPath, backPath, true);
            }
            else
            {
                // File.Copy(backPath, assemblyPath, true);
            }
            // var assemblySearchFolders = GetAssemblySearchFolders(isEditor, buildTarget);
            // var replaceAssemblyPath = miReplace.DeclaringType.Assembly.Location;
            try
            {
                var inputPath = IsEngineAssembly ? backPath : assemblyPath;
                var isWritten = InjectHelper.InjectAssembly(injections, inputPath, assemblyPath, isEditor, buildTarget);

                if (isWritten)
                    DebugHelper.Log($"Inject success: {assemblyPath}");
                return isWritten;
            }
            catch (Exception e)
            {
                Debug.LogException(e);
                if (IsEngineAssembly)
                {
                    File.Copy(backPath, assemblyPath, true);
                }
                throw e;
            }

        }

        static bool IsFileAvaliable(string path)
        {
            try
            {
                var fs = File.Open(path, FileMode.Open);
                fs?.Close();
                fs?.Dispose();
            }
            catch
            {
                return false;
            }
            return true;
        }
        //TODO : Restore
        //TODO : Partial restore on inject 
        // public static void RestoreEditor() {
        //     // var backPath = assemblyPath+".backup";
        //     // var existsBacked = File.Exists(backPath);
        //     RestoreTargetMode(true);
        //     RestoreTargetMode(false);
        //     void RestoreTargetMode(bool isEditor){
        //         var folders = GetAssemblySearchFolders(isEditor,activeBuildTarget);
        //         foreach(var folder in folders){
        //             var backupFiles = Directory.GetFiles(folder,"*"+BACKUP_EXT);
        //         }
        //     }
        // }
        internal static string[] GetAssemblySearchFolders(bool isEditor, BuildTarget buildTarget)
        {
            return GetPreloadAssemblies(isEditor, buildTarget)
                .Select(Path.GetDirectoryName)
                .Distinct()
                .ToArray();
        }
        internal static string[] GetPreloadAssemblies(bool isEditor, BuildTarget buildTarget)
        {
            var miGetUnityAssemblies = typeof(InternalEditorUtility).GetMethod("GetUnityAssembliesInternal", bindingFlags);
            var assemblies = (Array)miGetUnityAssemblies.Invoke(null, new object[] { isEditor, buildTarget, });
            var fiPath = miGetUnityAssemblies.ReturnType.GetElementType().GetField("Path", bindingFlags);
            return assemblies.OfType<object>()
                .Select(a => fiPath.GetValue(a))
                .OfType<string>()
                .ToArray();
        }
        static object GetScriptAssemblySettings()
        {
            var t = t_EditorCompilationInterface ??= GetType("UnityEditor.CoreModule", "EditorCompilationInterface");

            var editorCompilation = t.GetProperty("Instance", bindingFlags).GetValue(null);
            if (editorCompilation is null)
                throw new("cannot get editorCompilation,Unity:" + Application.unityVersion);

            var state = editorCompilation.GetMemberValue("activeBeeBuild")
                ?? editorCompilation.GetMemberValue("_currentBeeScriptCompilationState");
            if (state is null)
                throw new("cannot get compile state from editorCompilation,Unity:" + Application.unityVersion);

            return state.GetMemberValue("Settings", true);
        }

        static object GetMemberValue(this object obj, string name, bool IgnoreCase = false)
        {
            var flags = bindingFlags;
            if (IgnoreCase) flags |= BindingFlags.IgnoreCase;
            var memberInfo = obj.GetType().GetMember(name, flags).FirstOrDefault();
            if (memberInfo is null)
                return null;
            // {
            //     var fields = obj.GetType().GetFields(flags).Select(f=>"field:"+f.Name);
            //     var props = obj.GetType().GetProperties(flags).Select(f=>"prop:"+f.Name);
            //     DebugHelper.Log(string.Join("\n",fields)+"\n"+string.Join("\n",props));
            //     throw new($"cannot find member {name} in {obj}");
            // }
            if (memberInfo is FieldInfo fi)
                return fi.GetValue(obj);

            if (memberInfo is PropertyInfo pi)
                return pi.GetValue(obj);

            if (memberInfo is MethodInfo mi)
                return mi.Invoke(obj, null);

            return null;
        }

        static Type GetType(string moduleName, string typeName)
        {
            return System.AppDomain.CurrentDomain.GetAssemblies()
                .Where(a => a.FullName.StartsWith(moduleName + ","))
                .SelectMany(a => a.GetTypes())
                .Where(t => t.Name.Equals(typeName))
                .Single();
        }

        static Type t_EditorCompilationInterface;
        static string runtimeOutputDirectory;
        // static BuildTargetGroup activeBuildTargetGroup => EditorUserBuildSettings.selectedBuildTargetGroup;
        static BuildTarget activeBuildTarget => EditorUserBuildSettings.activeBuildTarget;
        static BindingFlags bindingFlags = 0
            | BindingFlags.Static
            | BindingFlags.Instance
            | BindingFlags.Public
            | BindingFlags.NonPublic
            ;
        static void LogError(string message)
        {
            Debug.LogError(message);
        }

    }
}