/*****************************************************************************
 * Copyright (c) 2014-2018 OpenRCT2 developers
 *
 * For a complete list of all authors, please refer to contributors.md
 * Interested in contributing? Visit https://github.com/OpenRCT2/OpenRCT2
 *
 * OpenRCT2 is licensed under the GNU General Public License version 3.
 *****************************************************************************/

#include "ScriptEngine.h"

#include "../PlatformEnvironment.h"
#include "../core/FileScanner.h"
#include "../core/Path.hpp"
#include "../interface/InteractiveConsole.h"
#include "../platform/Platform2.h"
#include "Duktape.hpp"
#include "ScConsole.hpp"
#include "ScContext.hpp"
#include "ScDisposable.hpp"
#include "ScMap.hpp"
#include "ScNetwork.hpp"
#include "ScPark.hpp"
#include "ScThing.hpp"
#include "ScTile.hpp"

#include <iostream>
#include <stdexcept>

using namespace OpenRCT2;
using namespace OpenRCT2::Scripting;

static std::string Stringify(duk_context* ctx, duk_idx_t idx);

static constexpr int32_t OPENRCT2_PLUGIN_API_VERSION = 1;

DukContext::DukContext()
{
    _context = duk_create_heap_default();
    if (_context == nullptr)
    {
        throw std::runtime_error("Unable to initialise duktape context.");
    }
}

DukContext::~DukContext()
{
    duk_destroy_heap(_context);
}

ScriptEngine::ScriptEngine(InteractiveConsole& console, IPlatformEnvironment& env)
    : _console(console)
    , _env(env)
    , _hookEngine(_execInfo)
{
}

void ScriptEngine::Initialise()
{
    auto ctx = (duk_context*)_context;
    ScConsole::Register(ctx);
    ScContext::Register(ctx);
    ScDisposable::Register(ctx);
    ScMap::Register(ctx);
    ScNetwork::Register(ctx);
    ScPark::Register(ctx);
    ScPlayer::Register(ctx);
    ScPlayerGroup::Register(ctx);
    ScTile::Register(ctx);
    ScTileElement::Register(ctx);
    ScThing::Register(ctx);

    dukglue_register_global(ctx, std::make_shared<ScConsole>(_console), "console");
    dukglue_register_global(ctx, std::make_shared<ScContext>(_execInfo, _hookEngine), "context");
    dukglue_register_global(ctx, std::make_shared<ScMap>(ctx), "map");
    dukglue_register_global(ctx, std::make_shared<ScNetwork>(ctx), "network");
    dukglue_register_global(ctx, std::make_shared<ScPark>(), "park");

    _initialised = true;
    _pluginsLoaded = false;
    _pluginsStarted = false;
}

void ScriptEngine::LoadPlugins()
{
    auto base = _env.GetDirectoryPath(DIRBASE::USER, DIRID::PLUGIN);
    auto pattern = Path::Combine(base, "*.js");
    auto scanner = std::unique_ptr<IFileScanner>(Path::ScanDirectory(pattern, true));
    while (scanner->Next())
    {
        auto path = std::string(scanner->GetPath());
        if (ShouldLoadScript(path))
        {
            try
            {
                auto plugin = std::make_shared<Plugin>(_context, path);
                ScriptExecutionInfo::PluginScope scope(_execInfo, plugin);
                plugin->Load();

                auto metadata = plugin->GetMetadata();
                if (metadata.MinApiVersion <= OPENRCT2_PLUGIN_API_VERSION)
                {
                    LogPluginInfo(plugin, "Loaded");
                    _plugins.push_back(std::move(plugin));
                }
                else
                {
                    LogPluginInfo(plugin, "Requires newer API version: v" + std::to_string(metadata.MinApiVersion));
                }
            }
            catch (const std::exception& e)
            {
                _console.WriteLineError(e.what());
            }
        }
    }

    try
    {
        // Enable hot reloading
        _pluginFileWatcher = std::make_unique<FileWatcher>(base);
        _pluginFileWatcher->OnFileChanged = [this](const std::string& path) {
            std::lock_guard<std::mutex> guard(_changedPluginFilesMutex);
            _changedPluginFiles.push_back(path);
        };
    }
    catch (const std::exception& e)
    {
        std::printf("Unable to enable hot reloading of plugins: %s\n", e.what());
    }

    _pluginsLoaded = true;
}

bool ScriptEngine::ShouldLoadScript(const std::string& path)
{
    // A lot of JavaScript is often found in a node_modules directory tree and is most likely unwanted, so ignore it
    return path.find("/node_modules/") == std::string::npos && path.find("\\node_modules\\") == std::string::npos;
}

void ScriptEngine::AutoReloadPlugins()
{
    if (_changedPluginFiles.size() > 0)
    {
        std::lock_guard<std::mutex> guard(_changedPluginFilesMutex);
        for (auto& path : _changedPluginFiles)
        {
            auto findResult = std::find_if(_plugins.begin(), _plugins.end(), [&path](const std::shared_ptr<Plugin>& plugin) {
                return Path::Equals(path, plugin->GetPath());
            });
            if (findResult != _plugins.end())
            {
                auto& plugin = *findResult;
                try
                {
                    _hookEngine.UnsubscribeAll(plugin);

                    ScriptExecutionInfo::PluginScope scope(_execInfo, plugin);
                    plugin->Load();
                    LogPluginInfo(plugin, "Reloaded");
                    plugin->Start();
                }
                catch (const std::exception& e)
                {
                    _console.WriteLineError(e.what());
                }
            }
        }
        _changedPluginFiles.clear();
    }
}

void ScriptEngine::UnloadPlugins()
{
    StopPlugins();
    for (auto& plugin : _plugins)
    {
        LogPluginInfo(plugin, "Unloaded");
    }
    _plugins.clear();
    _pluginsLoaded = false;
    _pluginsStarted = false;
}

void ScriptEngine::StartPlugins()
{
    for (auto& plugin : _plugins)
    {
        if (!plugin->HasStarted())
        {
            ScriptExecutionInfo::PluginScope scope(_execInfo, plugin);
            try
            {
                plugin->Start();
            }
            catch (const std::exception& e)
            {
                _console.WriteLineError(e.what());
            }
        }
    }
    _pluginsStarted = true;
}

void ScriptEngine::StopPlugins()
{
    _hookEngine.UnsubscribeAll();
    for (auto& plugin : _plugins)
    {
        if (plugin->HasStarted())
        {
            ScriptExecutionInfo::PluginScope scope(_execInfo, plugin);
            try
            {
                plugin->Stop();
            }
            catch (const std::exception& e)
            {
                _console.WriteLineError(e.what());
            }
        }
    }
    _pluginsStarted = false;
}

void ScriptEngine::Update()
{
    if (!_initialised)
    {
        Initialise();
    }

    if (_pluginsLoaded)
    {
        if (!_pluginsStarted)
        {
            StartPlugins();
        }
        else
        {
            auto tick = Platform::GetTicks();
            if (tick - _lastHotReloadCheckTick > 1000)
            {
                AutoReloadPlugins();
                _lastHotReloadCheckTick = tick;
            }
        }
    }

    ProcessREPL();
}

void ScriptEngine::ProcessREPL()
{
    while (_evalQueue.size() > 0)
    {
        auto item = std::move(_evalQueue.front());
        _evalQueue.pop();
        auto promise = std::move(std::get<0>(item));
        auto command = std::move(std::get<1>(item));
        if (duk_peval_string(_context, command.c_str()) != 0)
        {
            std::string result = std::string(duk_safe_to_string(_context, -1));
            _console.WriteLineError(result);
        }
        else if (duk_get_type(_context, -1) != DUK_TYPE_UNDEFINED)
        {
            std::string result = Stringify(_context, -1);
            _console.WriteLine(result);
        }
        duk_pop(_context);
        // Signal the promise so caller can continue
        promise.set_value();
    }
}

std::future<void> ScriptEngine::Eval(const std::string& s)
{
    std::promise<void> barrier;
    auto future = barrier.get_future();
    _evalQueue.emplace(std::move(barrier), s);
    return future;
}

void ScriptEngine::LogPluginInfo(const std::shared_ptr<Plugin>& plugin, const std::string_view& message)
{
    const auto& pluginName = plugin->GetMetadata().Name;
    _console.WriteLine("[" + pluginName + "] " + std::string(message));
}

static std::string Stringify(duk_context* ctx, duk_idx_t idx)
{
    auto type = duk_get_type(ctx, idx);
    if (type == DUK_TYPE_OBJECT && !duk_is_function(ctx, idx))
    {
        return duk_json_encode(ctx, idx);
    }
    else
    {
        return duk_safe_to_string(ctx, idx);
    }
}