/************************************************************************************//*!
\file           ScriptStore.cxx
\author         Tng Kah Wei, kahwei.tng, 390009620
\par            email: kahwei.tng\@digipen.edu
\date           Oct 28, 2021
\brief          Contains the definition of the functions for the ScriptStore managed
                static class.

                Note: This file is written in C++17/CLI.
 
Copyright (C) 2021 DigiPen Institute of Technology.
Reproduction or disclosure of this file or its contents without the prior written consent 
of DigiPen Institute of Technology is prohibited.
*//*************************************************************************************/
// Precompiled Headers
#include "SHpch.h"
// Primary Header
#include "ScriptStore.hxx"
// Standard Libraries
#include <sstream>
// External Dependencies
#include "ECS_Base/Managers/SHEntityManager.h"
#include "Tools/SHLog.h"
// Project Headers
#include "Utility/Debug.hxx"
#include "Utility/Convert.hxx"
#include "Script.hxx"
#include "Engine/Entity.hxx"

namespace SHADE
{
    /*---------------------------------------------------------------------------------*/
    /* Scripts Manipulation Functions                                                  */
    /*---------------------------------------------------------------------------------*/
    generic<typename T>
    T ScriptStore::AddScript(Entity entity)
    {
        // Check if entity exists
        if (!EntityUtils::IsValid(entity))
            throw gcnew System::ArgumentException("Invalid Entity provided to add a Script to.");

        System::Collections::Generic::List<Script^> ^ entityScriptList;

        // Check if storage for scripts of this entity exists
        if (!scripts.ContainsKey(entity))
        {
            // Create a new list for this set of scripts
            entityScriptList = gcnew System::Collections::Generic::List<Script^>();
            scripts.Add(entity, entityScriptList);
        }
        else
        {
            entityScriptList = scripts[entity];
        }

        // Create the script and add it in        
        array<Object^>^ params = gcnew array<Object^>{GameObject(entity)};
        Script^ script = safe_cast<Script^>(System::Activator::CreateInstance(T::typeid, params));
        entityScriptList->Add(script);
        awakeList.Add(script);
        startList.Add(script);
        script->OnAttached();

        return safe_cast<T>(script);
    }

    bool ScriptStore::AddScriptViaName(Entity entity, System::String^ scriptName)
    {
        SAFE_NATIVE_CALL_BEGIN
        Script^ script;
        return AddScriptViaNameWithRef(entity, scriptName, script);
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
        return false;
    }

    bool ScriptStore::AddScriptViaNameWithRef(Entity entity, System::String^ scriptName, Script^% createdScript)
    {
        // Check if we are set up to get scripts
        if  (addScriptMethod == nullptr)
        {
            Debug::LogError("[ScriptStore] Native AddScript<T>() was not loaded. Unable to add scripts.");
            return false;
        }

        // Get the script if it exists
        System::Type^ scriptType = getScriptType(scriptName);
        if (scriptType == nullptr)
        {
            std::ostringstream oss;
            oss << "[ScriptStore] No Script named "
                << Convert::ToNative(scriptName)
                << " found!";
            Debug::LogError(oss.str());
            return false;
        }

        // Otherwise, add the script
        System::Reflection::MethodInfo^ method = addScriptMethod->MakeGenericMethod(scriptType);
        try
        {
            array<Object^>^ params = gcnew array<Object^>{entity};
            createdScript = safe_cast<Script^>(method->Invoke(nullptr, params));
        }
        catch (System::Exception^ e)
        {
            std::ostringstream oss;
            oss << "[ScriptStore] Failed to add Script named \"" << Convert::ToNative(scriptName)
                << "\" to Entity #" << entity << "! (" << Convert::ToNative(e->GetType()->Name) << ")";
            Debug::LogError(oss.str());
            return false;
        }
        return true;
    }

    generic<typename T>
    T ScriptStore::GetScript(Entity entity)
    {
        // Check if entity exists
        if (!EntityUtils::IsValid(entity))
            throw gcnew System::ArgumentException("Invalid Entity provided to get a Script from.");
        
        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))
        {
            return T();
        }

        // Search for and obtain
        for each (Script^ script in scripts[entity])
        {
            try
            {
                T actualScript = safe_cast<T>(script);
                return actualScript;
            }
            catch (System::InvalidCastException^)
            {
                continue;
            }
        }

        return T();
    }

    generic <typename T>
    T ScriptStore::GetScriptInChildren(Entity entity)
    {
        // Check if entity exists and is a valid GameObject
        if (!EntityUtils::IsValid(entity))
            throw gcnew System::ArgumentException("Invalid Entity provided to get a Script from.");
        
        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))
        {
            return T();
        }

        // Get Entity's SceneGraphNode
        SHSceneNode* sceneGraphNode = SHSceneManager::GetCurrentSceneGraph().GetNode(entity);
        if (sceneGraphNode == nullptr)
        {
            std::ostringstream oss;
            oss << "[ECS_CLI] Failed to retrieve SceneGraphNode of entity #" << entity << ". This should not happen!";
            SHLog::Warning(oss.str());
            return T();
        }

        // Search direct children first
        for (const auto& child : sceneGraphNode->GetChildren())
        {
            T script = GetScript<T>(child->GetEntityID());
            if (script != nullptr)
                return script;
        }

        // Search their children
        for (const auto& child : sceneGraphNode->GetChildren())
        {
            T script = GetScript<T>(child->GetEntityID());
            if (script != nullptr)
                return script;
        }

        // None here
        return T();
    }

    generic <typename T>
    System::Collections::Generic::IEnumerable<T>^ ScriptStore::GetScripts(Entity entity)
    {
        // Check if entity exists and is a valid GameObject
        if (!EntityUtils::IsValid(entity))
            throw gcnew System::ArgumentException("Invalid Entity provided to get a Script from.");

        // Create a list to store entries
        System::Collections::Generic::List<T>^ foundScripts = gcnew System::Collections::Generic::List<T>();

        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))
        {
            return foundScripts;
        }

        // Search for and obtain
        for each (Script^ script in scripts[entity])
        {
            try
            {
                T actualScript = safe_cast<T>(script);
                foundScripts->Add(actualScript);
            }
            catch (System::InvalidCastException^)
            {
                continue;
            }
        }

        return foundScripts;
    }
    System::Collections::Generic::IEnumerable<Script^>^ ScriptStore::GetAllScripts(Entity entity)
    {
        // Check if entity exists
        if (!EntityUtils::IsValid(entity))
            return nullptr;

        // Check if entity exists in the script storage
        if (scripts.ContainsKey(entity))
        {
            return scripts[entity];
        }
        return nullptr;
    }
    generic<typename T>
    void ScriptStore::RemoveScript(Entity entity)
    {
        // Check if entity exists
        if (!EntityUtils::IsValid(entity))
            throw gcnew System::ArgumentException("Invalid Entity provided to remove a Script from.");
        
        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))  
        {
            Debug::LogError("[ScriptStore] Attempted to remove a Script that does not belong to the specified Entity!");
            return;
        }

        // Search for and obtain
        for each (Script^ script in scripts[entity])
        {
            try
            {
                safe_cast<T>(script);
                removeScript(script);
            }
            catch (System::InvalidCastException^)
            {
                continue;
            }
        }
    }
    bool ScriptStore::RemoveScript(Entity entity, Script^ script)
    {
        // Check if entity exists
        if (!EntityUtils::IsValid(entity))
        {
            Debug::LogError("[ScriptStore] Attempted to remove a Script from an invalid Entity!");
            return false;
        }
                
        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))  
        {
            Debug::LogError("[ScriptStore] Attempted to remove a Script that does not belong to the specified Entity!");
            return false;
        }

        // Check if the script exists to begin with
        if (!scripts[entity]->Contains(script))
        {
            Debug::LogError("[ScriptStore] Attempted to remove a Script that does not belong to the specified Entity!");
            return false;
        }

        // Script found, queue it for deletion
        removeScript(script);
        return true;
    }
    void ScriptStore::RemoveAllScripts(Entity entity)
    {
        SAFE_NATIVE_CALL_BEGIN        
        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))  
            return;

        // Search for and clear
        System::Collections::Generic::List<Script^>^ scriptList = scripts[entity];
        for each (Script^ script in scriptList)
        {
            removeScript(script);
        }
        scriptList->Clear();
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }
    void ScriptStore::RemoveAllScriptsImmediately(Entity entity, bool callOnDestroy)
    {
        SAFE_NATIVE_CALL_BEGIN
        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))  
            return;

        // Clear all
        System::Collections::Generic::List<Script^>^ scriptList = scripts[entity];
        for each (Script ^ script in scriptList)
        {
            // Call OnDestroy only if indicated and also in play mode
            if (callOnDestroy)
            {
                script->OnDestroy();
            }
            script->OnDetached();

            // Remove scripts from awakening if they were not woken up to begin with
            awakeList.Remove(script);
            startList.Remove(script);
        }
        scriptList->Clear();
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }
    
    /*---------------------------------------------------------------------------------*/
    /* Lifecycle Functions                                                             */
    /*---------------------------------------------------------------------------------*/
    void ScriptStore::Init()
    {
        // Create an enumerable list of script types
        refreshScriptTypeList();
        // Get stored methods for interop variants of functions
        getGenericMethods();
    }
    void ScriptStore::FrameSetUp()
    {
        SAFE_NATIVE_CALL_BEGIN
        // Clear the awake queue
        for each (Script^ script in awakeList)
        {
            script->Awake();
        }
        awakeList.Clear();

        // Clear the start queue
        for each (Script^ script in startList)
        {
            if (script->Owner.IsActiveInHierarchy)
            {
                script->Start();
            }
            else
            {
                inactiveStartList.Add(script);
            }
        }
        startList.Clear();
        startList.AddRange(%inactiveStartList);
        inactiveStartList.Clear();

        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }
    void ScriptStore::FrameCleanUp()
    {
        SAFE_NATIVE_CALL_BEGIN
        // Clear the queue
        while (disposalQueue.Count > 0)
        {
            Script^ script = disposalQueue.Dequeue();
            script->OnDestroy();
            auto entity = script->Owner.GetEntity();
            auto scriptList = scripts[script->Owner.GetEntity()];
            scriptList->Remove(script);
            if (scriptList->Count <= 0)
            {
                scripts.Remove(entity);
            }
        }
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }
    void ScriptStore::Exit()
    {
        SAFE_NATIVE_CALL_BEGIN
        // Run the deinit all scripts if needed
        //if (Application::IsPlaying)
        {
            Debug::Log("Running OnDestroy() for scripts.");
            for each (System::Collections::Generic::KeyValuePair<Entity, ScriptList^> entity in scripts)
            {
                for each (Script^ script in entity.Value)
                {
                    script->OnDestroy();
                }
            }
        }

        // Clear Script Storage
        scripts.Clear();
        awakeList.Clear();
        startList.Clear();
        disposalQueue.Clear();
        scriptTypeList = nullptr;
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }

    /*---------------------------------------------------------------------------------*/
    /* Script Information Functions                                                    */
    /*---------------------------------------------------------------------------------*/
    System::Collections::Generic::IEnumerable<System::Type^>^ ScriptStore::GetAvailableScriptList()
    {
        return scriptTypeList;
    }

    /*---------------------------------------------------------------------------------*/
    /* Script Execution Functions                                                      */
    /*---------------------------------------------------------------------------------*/
    void ScriptStore::ExecuteFixedUpdate()
    {
        SAFE_NATIVE_CALL_BEGIN
        for each (System::Collections::Generic::KeyValuePair<Entity, ScriptList^> entity in scripts)
        {
            // Check active state
            if (!isEntityActive(entity.Key))
                continue;

            // Update each script
            for each (Script^ script in entity.Value)
            {
                script->FixedUpdate();
            }
        }
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }
    void ScriptStore::ExecuteUpdate()
    {
        SAFE_NATIVE_CALL_BEGIN
        for each (System::Collections::Generic::KeyValuePair<Entity, ScriptList^> entity in scripts)
        {
            // Check active state
            if (!isEntityActive(entity.Key))
                continue;

            // Update each script
            for each (Script^ script in entity.Value)
            {
                script->Update();
            }
        }
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }
    void ScriptStore::ExecuteLateUpdate()
    {
        SAFE_NATIVE_CALL_BEGIN
        for each (System::Collections::Generic::KeyValuePair<Entity, ScriptList^> entity in scripts)
        {
            // Check active state
            if (!isEntityActive(entity.Key))
                continue;

            // Update each script
            for each (Script^ script in entity.Value)
            {
                script->LateUpdate();
            }
        }
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
    }
    bool ScriptStore::SerialiseScripts(Entity entity, System::Text::StringBuilder^ buffer, int bufferSize)
    {
        SAFE_NATIVE_CALL_BEGIN
        // Create a buffer that we can work with temporarily
        System::Text::StringBuilder^ jsonString = gcnew System::Text::StringBuilder();

        // Check if entity exists, otherwise nothing
        if (!EntityUtils::IsValid(entity))
            return true;
        
        // Check if entity exists in the script storage
        if (!scripts.ContainsKey(entity))  
            return true;

        // Serialise each script
        System::Collections::Generic::List<Script^>^ scriptList = scripts[entity];
        for (int i = 0; i < scriptList->Count; ++i)
        {
            throw gcnew System::NotImplementedException;
            //jsonString->Append(ReflectionUtilities::Serialise(scriptList[i]));

            // Only add separator if is not last script
            if (i != scriptList->Count - 1)
            {
                jsonString->Append(",\r\n");
            }            
        }

        // Check if the size is too big
        if (jsonString->Length > bufferSize)
            return false;

        // Otherwise we copy it over
        buffer->Clear();
        buffer->Append(jsonString->ToString());
        return true;
        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
        return false;
    }

    bool ScriptStore::DeserialiseScript(Entity entity, System::String^ yaml)
    {
        SAFE_NATIVE_CALL_BEGIN
        // Check if entity exists, otherwise nothing
        if (!EntityUtils::IsValid(entity))
            return false;

        // Get the name of the script
        const int FIRST_QUOTE  = yaml->IndexOf('\"');
        const int FIRST_COLON = yaml->IndexOf(':');
        if (FIRST_QUOTE < 0 || FIRST_COLON < 0) // No script name, it's invalid
            return false;
        const int SCRIPT_NAME_START = FIRST_QUOTE + 1;
        const int SCRIPT_NAME_END   = FIRST_COLON - 1;
        System::String^ typeName = yaml->Substring(SCRIPT_NAME_START, SCRIPT_NAME_END - SCRIPT_NAME_START);

        // Create the script
        Script^ script;
        if (AddScriptViaNameWithRef(entity, typeName, script))
        {
            // Copy the data in
            throw gcnew System::NotImplementedException;
            //ReflectionUtilities::Deserialise(json, script);
            return true;
        }

        SAFE_NATIVE_CALL_END_N("SHADE.ScriptStore")
        return false;
    }

    /*---------------------------------------------------------------------------------*/
    /* Helper Functions                                                                */
    /*---------------------------------------------------------------------------------*/
    void ScriptStore::removeScript(Script^ script)
    {
        // Prepare for disposal
        disposalQueue.Enqueue(script);

        // Also remove it fromm awake and start queues if they were created but not initialised
        awakeList.Remove(script);
        startList.Remove(script);
        script->OnDetached();
    }

    namespace
    {
        /* Select Many */
        ref struct Pair
        {
            System::Reflection::Assembly^ assembly;
            System::Type^                 type;
        };

        System::Collections::Generic::IEnumerable<System::Type^>^ selectorFunc(System::Reflection::Assembly^ assembly)
        {
            return assembly->GetExportedTypes();
        }
        Pair^ resultSelectorFunc(System::Reflection::Assembly^ assembly, System::Type^ type)
        {
            Pair^ p = gcnew Pair();
            p->assembly = assembly;
            p->type = type;
            return p;
        }

        /* Where */
        bool predicateFunc(Pair^ pair)
        {
            return pair->type->IsSubclassOf(Script::typeid) && !pair->type->IsAbstract;
        }

        /* Select */
        System::Type^ selectorFunc(Pair^ pair)
        {
            return pair->type;
        }
    }

    void ScriptStore::refreshScriptTypeList()
    {
        using namespace System;
        using namespace System::Reflection;
        using namespace System::Linq;
        using namespace System::Collections::Generic;

        /* Select Many: Types in Loaded Assemblies */
        IEnumerable<Assembly^>^ assemblies = AppDomain::CurrentDomain->GetAssemblies();
        Func<Assembly^, IEnumerable<Type^>^>^ collectionSelector = gcnew Func<Assembly^, IEnumerable<Type^>^>(selectorFunc);
        Func<Assembly^, Type^, Pair^>^ resultSelector = gcnew Func<Assembly^, Type^, Pair^>(resultSelectorFunc);
        IEnumerable<Pair^>^ selectManyResult = Enumerable::SelectMany(assemblies, collectionSelector, resultSelector);

        /* Where: Are concrete Scripts */
        Func<Pair^, bool>^ predicate = gcnew Func<Pair^, bool>(predicateFunc);
        IEnumerable<Pair^>^ whereResult = Enumerable::Where(selectManyResult, predicate);

        /* Select: Select them all */
        Func<Pair^, Type^>^ selector = gcnew Func<Pair^, Type^>(selectorFunc);
        scriptTypeList = Enumerable::Select(whereResult, selector);

        // Log
        std::ostringstream oss;
        oss << "[ScriptStore] Successfully retrieved references to " << Enumerable::Count(scriptTypeList)
            << " Script(s) from currently loaded assemblies.";
        Debug::Log(oss.str());
    }

    void ScriptStore::getGenericMethods()
    {
        addScriptMethod = ScriptStore::typeid->GetMethod("AddScript");
        if  (addScriptMethod == nullptr)
        {
            Debug::LogError("[ScriptStore] Failed to get MethodInfo of \"AddScript<T>()\". Adding of scripts from native code will fail.");
        }
    }

    System::Type^ ScriptStore::getScriptType(System::String^ scriptName)
    {
        // Remove any whitespaces just in case
        scriptName = scriptName->Trim();

        // Look for the correct script
        for each (System::Type^ type in scriptTypeList)
        {
            if (type->FullName == scriptName || type->Name == scriptName)
            {
                return type;
            }
        }

        return nullptr;
    }

    bool ScriptStore::isEntityActive(Entity entity)
    {
        // Get native Entity
        SHEntity* nativeEntity = SHEntityManager::GetEntityByID(entity);

        // Entity Validity Check
        if (nativeEntity == nullptr)
            return false;

        // Check active state
        return nativeEntity->GetActive();
    }
}