CDIXMLGenerator.hxx

/** \copyright
 * Copyright (c) 2018, Balazs Racz
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are  permitted provided that the following conditions are met:
 *
 *  - Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  - Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * \file CDIXMLGenerator.hxx
 *
 * Standalone CDI XML generation class.
 *
 * @author Balazs Racz, Mike Dunston
 * @date 24 July 2018
 */

#ifndef _CDIXMLGENERATOR_HXX_
#define _CDIXMLGENERATOR_HXX_

#include "openlcb/SimpleStack.hxx"
#include "utils/FileUtils.hxx"

/// Standalone utility class for generating the XML representation of the node
/// configuration structure. This is primarily used in Arduino environments.
class CDIXMLGenerator
{
public:
    /// Creates the XML representation of the configuration structure and saves
    /// it to a file on the filesystem. Must be called after SPIFFS.begin() but
    /// before calling the {\link create_config_file_if_needed} method. The
    /// config file will be re-written whenever there was a change in the
    /// contents. It is also necessary to declare the static compiled-in CDI to
    /// be empty:
    /// ```
    ///    namespace openlcb {
    ///    // This will stop openlcb from exporting the CDI memory space
    ///    // upon start.
    ///    extern const char CDI_DATA[] = "";
    ///    }  // namespace openlcb
    /// ```
    /// @param cfg is the global configuration instance (usually called cfg).
    /// @param filename is where the xml file can be stored on the
    /// filesystem. For example "/spiffs/cdi.xml".
    /// @return true if the configuration xml file was modified by this method,
    /// false if the file was already up-to-date.
    template <class ConfigDef>
    static bool create_config_descriptor_xml(
        const ConfigDef &config, const char *filename,
        openlcb::SimpleStackBase *stack = nullptr)
    {
        string cdi_string;
        ConfigDef cfg(config.offset());
        cfg.config_renderer().render_cdi(&cdi_string);

        cdi_string += '\0';

        bool need_write = false;
        LOG(INFO, "[CDI] Checking %s...", filename);
        FILE *ff = fopen(filename, "rb");
        if (!ff)
        {
            LOG(INFO, "[CDI] File %s does not exist", filename);
            need_write = true;
        }
        else
        {
            fclose(ff);
            string current_str = read_file_to_string(filename);
            if (current_str != cdi_string)
            {
                LOG(INFO, "[CDI] File %s is not up-to-date", filename);
                need_write = true;
            }
            else
            {
                LOG(INFO, "[CDI] File %s appears up-to-date (len %u vs %u)",
                    filename, current_str.size(), cdi_string.size());
            }
        }
        if (need_write)
        {
            LOG(INFO, "[CDI] Updating %s (len %u)", filename,
                cdi_string.size());
            write_string_to_file(filename, cdi_string);
        }

        if (stack)
        {
            LOG(INFO, "[CDI] Registering CDI with stack...");
            // Creates list of event IDs for factory reset.
            auto *v = new vector<uint16_t>();
            cfg.handle_events([v](unsigned o) { v->push_back(o); });
            v->push_back(0);
            stack->set_event_offsets(v);
            // We leak v because it has to stay alive for the entire lifetime
            // of the stack.

            // Add the file memory space to the stack.
            openlcb::MemorySpace *space =
                new openlcb::ROFileMemorySpace(filename);
            stack->memory_config_handler()->registry()->insert(
                stack->node(), openlcb::MemoryConfigDefs::SPACE_CDI, space);
        }
        return need_write;
    }
};

#endif // _CDIXMLGENERATOR_HXX_