/*
 * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef SCRIPT_RELOADER_H
#define SCRIPT_RELOADER_H

#include "Define.h"
#include <memory>
#include <string>

namespace boost::filesystem
{
class path;
}

/// Represents a strong reference to a dynamic library which
/// provides C++ scripts. As long as one reference to the library exists
/// the library is kept loaded in the server, which makes it possible to lazy
/// unload several script types on demand (like SpellScripts), and to
/// provide multiple versions of the same script to the script factories.
///
/// Acquire a new reference through using:
/// `ScriptReloadMgr::AcquireModuleReferenceOfContext`
class ModuleReference
{
public:
    virtual ~ModuleReference() = default;

    /// Returns the git revision hash of the referenced script module
    virtual char const* GetScriptModuleRevisionHash() const = 0;
    /// Returns the name of the referenced script module
    virtual char const* GetScriptModule() const = 0;
    /// Returns the path to the script module
    virtual boost::filesystem::path const& GetModulePath() const = 0;
};

/// Provides the whole physical dynamic library unloading capability.
/// Loads, Reloads and Unloads dynamic libraries on changes and
/// informs the ScriptMgr about changes which were made.
/// The ScriptReloadMgr is also responsible for watching the source directory
/// and to invoke a build on changes.
class TC_GAME_API ScriptReloadMgr
{
protected:
    ScriptReloadMgr() = default;

public:
    ScriptReloadMgr(ScriptReloadMgr const&) = delete;
    ScriptReloadMgr(ScriptReloadMgr&&) = delete;
    ScriptReloadMgr& operator=(ScriptReloadMgr const&) = delete;
    ScriptReloadMgr& operator=(ScriptReloadMgr&&) = delete;
    virtual ~ScriptReloadMgr() = default;

    /// Initializes the ScriptReloadMgr
    virtual void Initialize() { }

    /// Needs to be called periodically to check for updates on script modules.
    /// Expects to be invoked in a thread safe way which means it's required that
    /// the current thread is the only one which accesses the world data.
    virtual void Update() { }

    /// Unloads the ScriptReloadMgr
    virtual void Unload() { }

    /// Returns an owning reference to the current module of the given context
    static std::shared_ptr<ModuleReference> AcquireModuleReferenceOfContext(
        std::string const& context);

    /// Returns the unique ScriptReloadMgr singleton instance
    static ScriptReloadMgr* instance();
};

#define sScriptReloadMgr ScriptReloadMgr::instance()

#endif // SCRIPT_RELOADER_H