main.cpp

#include "Database.h"
#include "QueryProcessor.h"

#include <iostream>
#include <fstream>
#include <exception>
#include <csignal>   // For signal handling
#include <atomic>    // For thread-safe flag
#include <cstdlib>
#include <cerrno>

#ifdef _WIN32
#include <direct.h>
#define MKDIR(path) _mkdir(path)
#else
#include <sys/stat.h>
#include <sys/types.h>
#define MKDIR(path) mkdir(path, 0777)
#endif

// Global pointer to the database so the signal handler can save it.
// (Using a global is the standard POSIX way for simple signal handlers).
static Database* g_db = nullptr;
static std::atomic<bool> g_running{true};

bool ensureDirectoryExists(const std::string& path) {
    if (MKDIR(path.c_str()) == 0 || errno == EEXIST) {
        return true;
    }
    return false;
}

void signalHandler(int signum) {
    std::cout << "\n[INFO] Interrupt signal (" << signum << ") received.\n";
    if (g_db != nullptr) {
        std::cout << "[INFO] Attempting to save database before exit...\n";
        if (g_db->saveToFile("data/graph.db")) {
            std::cout << "[INFO] Database saved successfully.\n";
        } else {
            std::cerr << "[ERROR] Failed to save database on exit.\n";
        }
    }
    g_running = false;
    exit(signum); // Exit cleanly
}

int main() {
    const std::string dataDir = "data";
    const std::string dbFile = dataDir + "/graph.db";

    // 1. Register signal handlers for Ctrl+C and terminate signals
    std::signal(SIGINT, signalHandler);  // Ctrl+C
    std::signal(SIGTERM, signalHandler); // Kill command

    // 2. Ensure data directory exists
    if (!ensureDirectoryExists(dataDir)) {
        std::cerr << "[ERROR] Failed to create data directory: " << dataDir << "\n";
        return 1;
    }

    Database db;
    g_db = &db; // Point the global to our database instance

    // 3. Load existing database if present
    std::ifstream dbFileStream(dbFile);
    if (dbFileStream.good()) {
        dbFileStream.close();
        if (db.loadFromFile(dbFile)) {
            std::cout << "[INFO] Database loaded from " << dbFile << "\n";
        } else {
            std::cerr << "[WARN] Database file exists but failed to load. Starting with empty graph.\n";
        }
    } else {
        std::cout << "[INFO] No existing database found. Starting fresh.\n";
    }

    // 4. Run interactive query loop
    try {
        QueryProcessor qp(db);
        qp.runInteractive();
    } catch (const std::exception& e) {
        std::cerr << "[ERROR] Runtime error: " << e.what() << "\n";
    }

    // 5. Save database on normal exit
    if (db.saveToFile(dbFile)) {
        std::cout << "[INFO] Database saved to " << dbFile << "\n";
    } else {
        std::cerr << "[ERROR] Failed to save database.\n";
        return 1;
    }

    g_db = nullptr; // Unregister before exit
    return 0;

}