/***************************************************************************
 *   Copyright (c) 2025 Kindred Systems                                    *
 *                                                                         *
 *   This file is part of the FreeCAD CAx development system.              *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU Library General Public           *
 *   License as published by the Free Software Foundation; either          *
 *   version 2 of the License, or (at your option) any later version.      *
 *                                                                         *
 *   This library  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 Library General Public License for more details.                  *
 *                                                                         *
 *   You should have received a copy of the GNU Library General Public     *
 *   License along with this library; see the file COPYING.LIB. If not,    *
 *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
 *   Suite 330, Boston, MA  02111-1307, USA                                *
 *                                                                         *
 ***************************************************************************/

#ifndef GUI_ORIGINMANAGER_H
#define GUI_ORIGINMANAGER_H

#include <map>
#include <memory>
#include <string>
#include <vector>
#include <FCGlobal.h>
#include <fastsignals/signal.h>

namespace App {
class Document;
}

namespace Gui {

class FileOrigin;

/**
 * @brief Singleton manager for document origins
 *
 * OriginManager tracks all registered FileOrigin instances and maintains
 * the current origin selection. It provides lookup methods and signals
 * for UI updates.
 *
 * The manager always has at least one origin: the local filesystem origin,
 * which is created automatically on initialization.
 */
class GuiExport OriginManager
{
public:
    /** Get the singleton instance */
    static OriginManager* instance();
    /** Destroy the singleton instance */
    static void destruct();

    ///@name Origin Registration
    //@{
    /**
     * Register an origin with the manager.
     * The manager takes ownership of the origin.
     * @param origin The origin to register
     * @return true if successfully registered (ID not already in use)
     */
    bool registerOrigin(FileOrigin* origin);

    /**
     * Unregister and delete an origin.
     * Cannot unregister the built-in "local" origin.
     * @param id The origin ID to unregister
     * @return true if successfully unregistered
     */
    bool unregisterOrigin(const std::string& id);

    /**
     * Get all registered origin IDs.
     * @return Vector of origin ID strings
     */
    std::vector<std::string> originIds() const;

    /**
     * Get origin by ID.
     * @param id The origin ID
     * @return The origin or nullptr if not found
     */
    FileOrigin* getOrigin(const std::string& id) const;
    //@}

    ///@name Current Origin Selection
    //@{
    /**
     * Get the currently selected origin.
     * @return The current origin (never nullptr)
     */
    FileOrigin* currentOrigin() const;

    /**
     * Get the current origin ID.
     * @return The current origin's ID
     */
    std::string currentOriginId() const;

    /**
     * Set the current origin by ID.
     * @param id The origin ID to select
     * @return true if origin was found and selected
     */
    bool setCurrentOrigin(const std::string& id);
    //@}

    ///@name Document Origin Resolution
    //@{
    /**
     * Find which origin owns a document.
     * Iterates through all origins to find one that claims ownership
     * based on document properties.
     * @param doc The document to check
     * @return The owning origin or nullptr if unowned
     */
    FileOrigin* findOwningOrigin(App::Document* doc) const;

    /**
     * Get the origin associated with a document.
     * First checks explicit association, then uses findOwningOrigin().
     * @param doc The document to check
     * @return The document's origin or nullptr if unknown
     */
    FileOrigin* originForDocument(App::Document* doc) const;

    /**
     * Associate a document with an origin.
     * @param doc The document
     * @param origin The origin to associate (nullptr to clear)
     */
    void setDocumentOrigin(App::Document* doc, FileOrigin* origin);

    /**
     * Clear document origin association (called when document closes).
     * @param doc The document being closed
     */
    void clearDocumentOrigin(App::Document* doc);

    /**
     * Get the appropriate origin for a new document.
     * Returns the current origin.
     * @return The origin to use for new documents
     */
    FileOrigin* originForNewDocument() const;
    //@}

    ///@name Signals
    //@{
    /** Emitted when an origin is registered */
    fastsignals::signal<void(const std::string&)> signalOriginRegistered;
    /** Emitted when an origin is unregistered */
    fastsignals::signal<void(const std::string&)> signalOriginUnregistered;
    /** Emitted when current origin changes */
    fastsignals::signal<void(const std::string&)> signalCurrentOriginChanged;
    /** Emitted when a document's origin association changes */
    fastsignals::signal<void(App::Document*, const std::string&)> signalDocumentOriginChanged;
    //@}

protected:
    OriginManager();
    ~OriginManager();

private:
    void loadPreferences();
    void savePreferences();
    void ensureLocalOrigin();

    static OriginManager* _instance;
    std::map<std::string, std::unique_ptr<FileOrigin>> _origins;
    std::string _currentOriginId;

    // Document-to-origin associations (doc -> origin ID)
    mutable std::map<App::Document*, std::string> _documentOrigins;
};

}  // namespace Gui

#endif  // GUI_ORIGINMANAGER_H