TemplateLoader.h

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/* Copyright (C) 2022 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. 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.
 *
 * 0 A.D. 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 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_TEMPLATELOADER
#define INCLUDED_TEMPLATELOADER

#include "simulation2/system/ParamNode.h"

#include <string_view>
#include <unordered_map>

enum ETemplatesType
{
    ALL_TEMPLATES,
    ACTOR_TEMPLATES,
    SIMULATION_TEMPLATES
};

/**
 * Template loader: Handles the loading of entity template files for:
 * - the initialisation and deserialization of entity components in the
 *   simulation (CmpTemplateManager).
 * - access to actor templates, obstruction data, etc. in RMS/RMGEN
 * - access to various templates in the GUI, to display faction specificities
 *
 * Template names are intentionally restricted to ASCII strings for storage/serialization
 * efficiency (we have a lot of strings so this is significant);
 * they correspond to filenames so they shouldn't contain non-ASCII anyway.
 *
 *
 * TODO: Find a way to validate templates outside of the simulation.
 */
class CTemplateLoader
{
public:
    CTemplateLoader()
    {
    }

    /**
     * Provides the file data for requested template.
     */
    const CParamNode& GetTemplateFileData(const std::string& templateName);

    /**
     * Check if the template XML file exits, without trying to load it.
     */
    bool TemplateExists(const std::string& templateName) const;

    /**
     * Returns a list of strings that could be validly passed as @c templateName to LoadTemplateFile.
     * (This includes "actor|foo" etc names).
     */
    std::vector<std::string> FindTemplates(const std::string& path, bool includeSubdirectories, ETemplatesType templatesType) const;

    /**
     * Returns a list of strings that could validly be passed as @c templateName to LoadTemplateFile.
     * Not ignoring any special directories.
     */
    std::vector<std::string> FindTemplatesUnrestricted(const std::string& path, bool includeSubdirectories) const;

private:
    /**
     * (Re)loads the given template, regardless of whether it exists already,
     * and saves into m_TemplateFileData. Also loads any parents that are not yet
     * loaded. Returns false on error.
     * @param templateName - XML filename to load (may be a |-separated string)
     * @param compositing - whether this template is an intermediary layer in a |-separated string.
     * @param depth - the current recursion depth.
     */
    bool LoadTemplateFile(CParamNode& node, std::string_view templateName, bool compositing, int depth);

    /**
     * Constructs a standard static-decorative-object template for the given actor
     */
    void ConstructTemplateActor(std::string_view actorName, CParamNode& out);

    /**
     * Map from template name (XML filename or special |-separated string) to the most recently
     * loaded non-broken template data. This includes files that will fail schema validation.
     * (Failed loads won't remove existing entries under the same name, so we behave more nicely
     * when hotloading broken files)
     */
    std::unordered_map<std::string, CParamNode> m_TemplateFileData;
};

#endif // INCLUDED_TEMPLATELOADER