config.cpp

#include <jansson.h>
#include <fstream>
#include <iostream>
#include <sstream>
#include "config.h"
#include <unistd.h>
#include <pwd.h>
#include <grp.h>

using std::string;

string ssid = "*";
string password = "";
string mqttBrokerIP = "1.2.3.4";
string brokerusername;
string brokerpassword;
string publishTopic = "kmpub";
string responseTopic = "kmcmd";
string locationTopic = "Solaranlage";
string deviceTopic = "Pylontech Akku Monitor";

bool mqtt_changed = false;

string getMQTTtopic() 
{
    // update from config
    readConfigFromJson();
    return publishTopic + "/" + locationTopic + "/" + deviceTopic;
}
 
bool saveDefaultConfigToJson() 
{
    // Create a new JSON object
    json_t *root = json_object();
    
    // Insert data into the JSON object
    json_object_set_new(root, "ssid", json_string(ssid.c_str()));
    json_object_set_new(root, "password", json_string(password.c_str()));
    json_object_set_new(root, "mqttBrokerIP", json_string(mqttBrokerIP.c_str()));
    json_object_set_new(root, "brokerusername", json_string(brokerusername.c_str()));
    json_object_set_new(root, "brokerpassword", json_string(brokerpassword.c_str()));
    json_object_set_new(root, "publishTopic", json_string(publishTopic.c_str()));
    json_object_set_new(root, "responseTopic", json_string(responseTopic.c_str()));
    json_object_set_new(root, "locationTopic", json_string(locationTopic.c_str()));
    json_object_set_new(root, "deviceTopic", json_string(deviceTopic.c_str()));
    
    // Dump the JSON object to a string
    char *jsonString = json_dumps(root, JSON_INDENT(4));
    if (!jsonString) {
        // Cleanup
        json_decref(root);
        return false; // Failed to dump JSON string
    }
    
    // Write the JSON string to a file
    // Check if the file already exists
    if (access("/var/www/html/wxdata/configData.json", F_OK) != -1) {
        std::cerr << "File already exists.\n";
        // Cleanup
        json_decref(root);
        free(jsonString);
        return false; // Do not overwrite the file
    } else {
        // File does not exist, proceed to create it
        std::ofstream outFile("/var/www/html/wxdata/configData.json");
        if (!outFile.is_open()) {
            std::cerr << "Failed to open file for writing.\n";
            // Cleanup
            json_decref(root);
            free(jsonString);
            return false;
        }
        
        outFile << jsonString;
        outFile.close();
        
        // Get the UID and GID for www-data
        struct passwd *pwd = getpwnam("www-data");
        struct group *grp = getgrnam("www-data");
        if (!pwd || !grp) {
            std::cerr << "Failed to get UID or GID for www-data.\n";
            // Cleanup
            json_decref(root);
            free(jsonString);
            return false;
        }

        // Change file ownership to www-data:www-data
        if (chown("/var/www/html/wxdata/configData.json", pwd->pw_uid, grp->gr_gid) == -1) {
            std::cerr << "Failed to change file ownership.\n";
            // Cleanup, although not critical to return false here since the file was written successfully
        }
    }

    // Cleanup JSON resources
    json_decref(root);
    free(jsonString);

    return true; // Indicate success
}

bool readConfigFromJson() 
{
    // Open the JSON file
    std::ifstream inFile("/var/www/html/wxdata/configData.json");
    if (!inFile.is_open()) {
        std::cerr << "Failed to open file for reading.\n";
        return false; // Failed to open file
    }

    // Read file into a string
    std::stringstream strStream;
    strStream << inFile.rdbuf(); // Read the file
    std::string jsonString = strStream.str(); // str holds the content of the file
    inFile.close();

    // Parse the JSON string
    json_error_t error;
    json_t *root = json_loads(jsonString.c_str(), 0, &error);
    if (!root) {
        std::cerr << "Error parsing JSON: " << error.text << "\n";
        return false; // Failed to parse JSON
    }

    static string last_brokerIP;
    static string last_brokerusername;
    static string last_brokerpassword;

    // Extract values
    mqttBrokerIP = json_string_value(json_object_get(root, "mqttBrokerIP"));
    brokerusername = json_string_value(json_object_get(root, "brokerusername"));
    brokerpassword = json_string_value(json_object_get(root, "brokerpassword"));
    publishTopic = json_string_value(json_object_get(root, "publishTopic"));
    responseTopic = json_string_value(json_object_get(root, "responseTopic"));
    locationTopic = json_string_value(json_object_get(root, "locationTopic"));
    deviceTopic = json_string_value(json_object_get(root, "deviceTopic"));

    if( last_brokerIP != mqttBrokerIP ||
        last_brokerusername != brokerusername ||
        last_brokerpassword != brokerpassword) {

        printf("Broker Config has changed\n");        
        last_brokerIP = mqttBrokerIP;
        last_brokerusername = brokerusername;
        last_brokerpassword = brokerpassword;
        mqtt_changed = true;
    }

    // Cleanup
    json_decref(root);

    return true; // Success
}