#pragma once

#include <Arduino.h>
#include <LittleFS.h>
#include <functional> // For std::function

class RfidDB {
public:
    // The default constructor uses "/rfid.db"
    RfidDB(const String& filename = "/rfid.db");
    ~RfidDB();

    /**
     * @brief Initializes the filesystem and the database file.
     * Must be called once in setup().
     * @return true on success, otherwise false.
     */
    bool begin();

    /**
     * @brief Returns the number of stored IDs.
     */
    uint32_t count();

    /**
     * @brief Checks if an ID exists in the database.
     * @param id The ID to check.
     * @return true if the ID exists, otherwise false.
     */
    bool contains(uint32_t id);

    /**
     * @brief Adds a new ID. The ID is only added if it does not already exist.
     * @param id The ID to add.
     * @return true if the ID was successfully added, otherwise false.
     */
    bool add(uint32_t id);

    /**
     * @brief Removes an ID from the database.
     * @param id The ID to remove.
     * @return true if the ID was found and removed, otherwise false.
     */
    bool remove(uint32_t id);

    /**
     * @brief Iterates over all stored IDs and calls a callback function for each.
     * @param callback The function to be called for each ID (e.g., a lambda: `[](uint32_t id){ Serial.println(id); }`).
     */
    void iterate(std::function<void(uint32_t)> callback);

private:
    String filename_;
    String tmpFilename_;
    bool initialized_ = false;

    static constexpr size_t ENTRY_SIZE = sizeof(uint32_t);

    // Helper methods
    bool readEntryAt(File &f, uint32_t index, uint32_t &out);
    bool writeEntryAt(File &f, uint32_t index, uint32_t value);
    bool binarySearch(File &f, uint32_t &outIndex, uint32_t key, bool &found);
    uint32_t byteSwap(uint32_t x) const;
    uint32_t fileEntryCount(File &f);
};

// Global instance, kept as requested
extern RfidDB rfidDB;