#pragma once

#include "database.h"
#include <nlohmann/json.hpp>
#include <string>

using json = nlohmann::json;

/**
 * @class JsonLoader
 * @brief Loads world geographic data from JSON file into SQLite database
 *
 * Handles parsing and population of world cities, states, and countries from
 * a structured JSON source file. The loader uses parallel threads to chunk
 * the city records and maximize database insertion throughput.
 *
 * Input Format (JSON Structure):
 * @code
 * {
 *   "countries": [
 *     {"id": 1, "name": "Canada", "iso2": "CA", "iso3": "CAN"},
 *     ...
 *   ],
 *   "states": [
 *     {"id": 1, "country_id": 1, "name": "Ontario", "iso2": "ON"},
 *     ...
 *   ],
 *   "cities": [
 *     {"id": 1, "state_id": 1, "country_id": 1, "name": "Toronto",
 *      "latitude": 43.6532, "longitude": -79.3832},
 *     ...
 *   ]
 * }
 * @endcode
 *
 * Performance Characteristics:
 * - Reads entire JSON file into memory (nlohmann/json parser)
 * - Iterates through countries: typically 200+ records
 * - Iterates through states: typically 3000+ records
 * - Iterates through cities: typically 50,000+ records (MAJOR DATASET)
 * - Uses multithreading to chunk city insertion across threads
 * - Thread pool size defaults to number of CPU cores
 *
 * Multithreading Strategy:
 * - Divides cities into N chunks (N = CPU core count)
 * - Each thread processes one chunk sequentially
 * - Database has mutex protection for thread-safe concurrent access
 * - Allows safe parallel writing to same SQLite database
 *
 * Example Usage:
 * @code
 *   SqliteDatabase db;
 *   db.Initialize();
 *   JsonLoader::LoadWorldCities("../data/world_city_data.json", db);
 *   // Database now contains all countries, states, and cities
 * @endcode
 */
class JsonLoader {
public:
  /// @brief Loads world geographic data from JSON and populates database
  ///
  /// Process:
  /// 1. Reads and parses entire JSON file
  /// 2. Inserts all countries into database (typically 200-250 records)
  /// 3. Inserts all states/provinces (typically 3000+ records)
  /// 4. Spawns worker threads to insert cities (typically 50,000+ records)
  /// 5. Waits for all threads to complete
  /// 6. Prints statistics about loaded data
  ///
  /// @param jsonPath Filesystem path to world_city_data.json
  /// @param db Reference to initialized SqliteDatabase to populate
  ///
  /// @throws std::runtime_error if JSON file cannot be read or parsed
  /// @throws std::runtime_error if database insertion fails
  ///
  /// Output Examples:
  /// @code
  ///   Loading JSON: ../data/world_city_data.json
  ///   Loaded countries: 250
  ///   Loaded states: 3500
  ///   Loaded cities: 52000
  ///   ✓ World city data loaded successfully
  /// @endcode
  static void LoadWorldCities(const std::string &jsonPath, SqliteDatabase &db);
};