#pragma once

#include <LittleFS.h>
#include <esp_random.h>

// Persistent 32-byte AES-256-GCM key for BLE payload encryption.
// Generated on first boot, stored at /ble.keyfile, pulled to the host
// during every profile upload via the get_ble_key serial command.
class BLEKeyStore {
public:
    static constexpr size_t KEY_LEN = 32;
    static constexpr const char* KEY_PATH = "/ble.keyfile";

    // Loads the key from LittleFS, or generates and persists a new one
    // if no key exists. Assumes LittleFS is already mounted.
    bool begin() {
        if (LittleFS.exists(KEY_PATH)) {
            File f = LittleFS.open(KEY_PATH, "r");
            if (f && f.size() == KEY_LEN && f.read(_key, KEY_LEN) == KEY_LEN) {
                f.close();
                _loaded = true;
                Serial.println("[BLE] Key loaded");
                return true;
            }
            if (f) f.close();
            // Corrupt or wrong-size file — regenerate.
        }

        esp_fill_random(_key, KEY_LEN);
        File f = LittleFS.open(KEY_PATH, "w");
        if (!f) {
            Serial.println("[BLE] Failed to open key file for write");
            return false;
        }
        size_t wrote = f.write(_key, KEY_LEN);
        f.close();
        if (wrote != KEY_LEN) {
            Serial.println("[BLE] Failed to write full key");
            return false;
        }
        _loaded = true;
        Serial.println("[BLE] Generated new key");
        return true;
    }

    bool hasKey() const { return _loaded; }
    const uint8_t* key() const { return _key; }

private:
    uint8_t _key[KEY_LEN] = {0};
    bool _loaded = false;
};