mqtt::lib::JsonMappingReader Class Reference

#include <JsonMappingReader.h>

Collaboration diagram for mqtt::lib::JsonMappingReader:

Classes
struct	VersionEntry

Public Member Functions
	JsonMappingReader ()=delete

Static Public Member Functions
static nlohmann::json	readMappingFromFile (const std::string &mapFilePath)
static void	saveDraft (const std::string &mapFilePath, const nlohmann::json &content)
static nlohmann::json	readDraftOrActive (const std::string &mapFilePath)
static nlohmann::json	deployDraft (const std::string &mapFilePath)
static void	discardDraft (const std::string &mapFilePath)
static std::string	getDraftPath (const std::string &mapFilePath)
static std::vector< VersionEntry >	getHistory (const std::string &mapFilePath)
static nlohmann::json	rollbackTo (const std::string &mapFilePath, const std::string &versionId)

Static Private Member Functions
static nlohmann::json	getDefaultPatch (const nlohmann::json &inputJson)

Detailed Description

Definition at line 57 of file JsonMappingReader.h.

Constructor & Destructor Documentation

JsonMappingReader()

mqtt::lib::JsonMappingReader::JsonMappingReader ( )

delete

Member Function Documentation

deployDraft()

nlohmann::json mqtt::lib::JsonMappingReader::deployDraft ( const std::string & mapFilePath )

static

Definition at line 129 of file JsonMappingReader.cpp.

                                                                            {
        std::string draftPath = getDraftPath(mapFilePath);
        if (!fs::exists(draftPath))
            return nlohmann::json();
 
        nlohmann::json j;
 
        // 1. Inject creation timestamp into draft
        try {
            std::ifstream f(draftPath);
            f >> j;
            f.close();
 
            auto now = std::chrono::system_clock::now();
            std::time_t now_c = std::chrono::system_clock::to_time_t(now);
            std::stringstream ss;
            ss << std::put_time(std::gmtime(&now_c), "%Y-%m-%dT%H:%M:%SZ");
 
            if (!j.contains("meta"))
                j["meta"] = nlohmann::json::object();
            j["meta"]["created"] = ss.str();
            j["meta"]["version"] = std::to_string(std::chrono::duration_cast<std::chrono::seconds>(now.time_since_epoch()).count());
 
            std::ofstream out(draftPath, std::ios::trunc);
            out << j.dump(2);
            out.close();
        } catch (const std::exception& e) {
            VLOG(1) << "Failed to inject metadata into draft: " << e.what();
        }
 
        // 2. Backup current active file
        if (fs::exists(mapFilePath)) {
            fs::path versionDir = fs::path(mapFilePath).parent_path() / "versions";
            if (!fs::exists(versionDir)) {
                fs::create_directories(versionDir);
            }
 
            auto now = std::chrono::system_clock::now();
            auto timestamp = std::chrono::duration_cast<std::chrono::seconds>(now.time_since_epoch()).count();
            std::string filename = fs::path(mapFilePath).filename().string();
            std::string backupPath = versionDir / (filename + "." + std::to_string(timestamp));
 
            fs::copy_file(mapFilePath, backupPath, fs::copy_options::overwrite_existing);
 
            // 3. Prune old versions (Keep last 50)
            try {
                std::vector<fs::path> versions;
                for (const auto& entry : fs::directory_iterator(versionDir)) {
                    if (entry.path().filename().string().starts_with(filename + ".")) {
                        versions.push_back(entry.path());
                    }
                }
                if (versions.size() > 50) {
                    std::sort(versions.begin(), versions.end(), [](const fs::path& a, const fs::path& b) {
                        return fs::last_write_time(a) < fs::last_write_time(b); // Oldest first
                    });
                    for (size_t i = 0; i < versions.size() - 50; ++i) {
                        fs::remove(versions[i]);
                    }
                }
            } catch (...) {
            }
 
            // 4. Promote draft to active
            fs::rename(draftPath, mapFilePath);
        } else {
            fs::remove(draftPath);
        }
 
        return j;
    }

References getDraftPath().

Referenced by mqtt::lib::admin::makeMappingAdminRouter().

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discardDraft()

void mqtt::lib::JsonMappingReader::discardDraft ( const std::string & mapFilePath )

static

Definition at line 201 of file JsonMappingReader.cpp.

                                                                     {
        std::string draftPath = getDraftPath(mapFilePath);
        if (fs::exists(draftPath)) {
            fs::remove(draftPath);
        }
    }

References getDraftPath().

Referenced by rollbackTo().

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getDefaultPatch()

nlohmann::json mqtt::lib::JsonMappingReader::getDefaultPatch ( const nlohmann::json & inputJson )

staticprivate

getDraftPath()

std::string mqtt::lib::JsonMappingReader::getDraftPath ( const std::string & mapFilePath )

static

Definition at line 98 of file JsonMappingReader.cpp.

                                                                          {
        return mapFilePath + ".draft";
    }

Referenced by deployDraft(), discardDraft(), mqtt::lib::admin::makeMappingAdminRouter(), readDraftOrActive(), and saveDraft().

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getHistory()

std::vector< JsonMappingReader::VersionEntry > mqtt::lib::JsonMappingReader::getHistory ( const std::string & mapFilePath )

static

Definition at line 208 of file JsonMappingReader.cpp.

                                                                                                       {
        std::vector<VersionEntry> history;
        fs::path versionDir = fs::path(mapFilePath).parent_path() / "versions";
        std::string baseName = fs::path(mapFilePath).filename().string();
 
        if (!fs::exists(versionDir))
            return history;
 
        for (const auto& entry : fs::directory_iterator(versionDir)) {
            if (entry.path().filename().string().starts_with(baseName + ".")) {
                VersionEntry v;
                v.filename = entry.path().string();
                // Extract ID (timestamp) from filename extension
                v.id = entry.path().extension().string().substr(1);
 
                // Peek inside JSON to get the comment
                try {
                    std::ifstream f(v.filename);
                    nlohmann::json j;
                    f >> j;
                    if (j.contains("meta")) {
                        if (j["meta"].contains("comment"))
                            v.comment = j["meta"]["comment"];
                        if (j["meta"].contains("created"))
                            v.date = j["meta"]["created"];
                    }
                } catch (...) {
                }
 
                // Fallback date if not in meta
                if (v.date.empty()) {
                    try {
                        long long ts = std::stoll(v.id);
                        std::time_t t = static_cast<std::time_t>(ts);
                        std::stringstream ss;
                        ss << std::put_time(std::gmtime(&t), "%Y-%m-%dT%H:%M:%SZ");
                        v.date = ss.str();
                    } catch (...) {
                        v.date = "Unknown";
                    }
                }
 
                history.push_back(v);
            }
        }
        // Sort by ID (descending)
        std::sort(history.begin(), history.end(), [](const VersionEntry& a, const VersionEntry& b) {
            // String comparison of timestamps works if they are same length, but better to be safe
            try {
                return std::stoll(a.id) > std::stoll(b.id);
            } catch (...) {
                return a.id > b.id;
            }
        });
        return history;
    }

References mqtt::lib::JsonMappingReader::VersionEntry::comment, mqtt::lib::JsonMappingReader::VersionEntry::date, mqtt::lib::JsonMappingReader::VersionEntry::filename, and mqtt::lib::JsonMappingReader::VersionEntry::id.

Referenced by mqtt::lib::admin::makeMappingAdminRouter().

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readDraftOrActive()

nlohmann::json mqtt::lib::JsonMappingReader::readDraftOrActive ( const std::string & mapFilePath )

static

Definition at line 110 of file JsonMappingReader.cpp.

                                                                                  {
        std::string draftPath = getDraftPath(mapFilePath);
        if (fs::exists(draftPath)) {
            std::ifstream f(draftPath);
            if (f) {
                nlohmann::json j;
                f >> j;
                return j;
            }
        }
        // Fallback to active file
        std::ifstream f(mapFilePath);
        if (!f)
            throw std::runtime_error("Cannot open mapping file: " + mapFilePath);
        nlohmann::json j;
        f >> j;
        return j;
    }

References getDraftPath().

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readMappingFromFile()

nlohmann::json mqtt::lib::JsonMappingReader::readMappingFromFile ( const std::string & mapFilePath )

static

Definition at line 71 of file JsonMappingReader.cpp.

                                                                                    {
        nlohmann::json mapFileJson;
 
        if (!mapFilePath.empty()) {
            std::ifstream mapFile(mapFilePath);
 
            if (mapFile.is_open()) {
                VLOG(1) << "MappingFilePath: " << mapFilePath;
 
                try {
                    mapFile >> mapFileJson;
                } catch (const std::exception& e) {
                    mapFile.close();
 
                    VLOG(1) << "JSON map file parsing failed: " << e.what() << " at " << mapFile.tellg();
                    throw std::runtime_error("JSON map file parsing faile at: " + std::to_string(mapFile.tellg()) + "\nWhat: " + e.what());
                }
 
                mapFile.close();
            } else {
                VLOG(1) << "MappingFile: " << mapFilePath << " not found";
            }
        }
 
        return mapFileJson;
    }

Referenced by mqtt::lib::ConfigApplication::ConfigApplication(), and mqtt::lib::ConfigApplication::setMappingFile().

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rollbackTo()

nlohmann::json mqtt::lib::JsonMappingReader::rollbackTo ( const std::string & mapFilePath, const std::string & versionId )

static

Definition at line 265 of file JsonMappingReader.cpp.

                                                                                                       {
        nlohmann::json j;
 
        fs::path versionDir = fs::path(mapFilePath).parent_path() / "versions";
        std::string baseName = fs::path(mapFilePath).filename().string();
        fs::path backupPath = versionDir / (baseName + "." + versionId);
 
        if (!fs::exists(backupPath)) {
            throw std::runtime_error("Version not found: " + versionId);
        }
 
        // Validate before rollback
        try {
            std::ifstream f(backupPath);
            f >> j;
            MqttMapper::validate(j);
        } catch (const std::exception& e) {
            throw std::runtime_error(std::string("Cannot rollback: Version is invalid against current schema: ") + e.what());
        }
 
        // Overwrite active file
        fs::copy_file(backupPath, mapFilePath, fs::copy_options::overwrite_existing);
 
        // Delete any existing draft to avoid confusion
        discardDraft(mapFilePath);
 
        return j;
    }

References discardDraft(), and mqtt::lib::MqttMapper::validate().

Referenced by mqtt::lib::admin::makeMappingAdminRouter().

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saveDraft()

void mqtt::lib::JsonMappingReader::saveDraft ( const std::string & mapFilePath, const nlohmann::json & content )

static

Definition at line 102 of file JsonMappingReader.cpp.

                                                                                               {
        std::ofstream out(getDraftPath(mapFilePath), std::ios::trunc);
        if (!out) {
            throw std::runtime_error("Cannot open draft file for writing: " + getDraftPath(mapFilePath));
        }
        out << content.dump(2) << std::endl;
    }

References getDraftPath().

Referenced by mqtt::lib::admin::makeMappingAdminRouter().

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The documentation for this class was generated from the following files:

• lib/JsonMappingReader.h
• lib/JsonMappingReader.cpp