/*
 GadgetBle.h - Library for providing sensor data via Bluetooth.
 Created by Bjoern Muntwyler, November 7, 2020.
 Released under BSD-3 licence
 */
#ifndef Sensirion_GadgetBle_Lib_h
#define Sensirion_GadgetBle_Lib_h

#include "Arduino.h"
#include <functional>

#include "esp_timer.h"

#include <BLE2902.h>
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>

// BLE Characteristics and Service Uuids

static const char* const DOWNLOAD_SERVICE_UUID =
    "00008000-b38d-4985-720e-0f993a68ee41";
static const char* const LOGGER_INTERVAL_UUID =
    "00008001-b38d-4985-720e-0f993a68ee41";
static const char* const SAMPLE_CNT_CHAR_UUID =
    "00008002-b38d-4985-720e-0f993a68ee41";
static const char* const TRANSFER_NOTIFY_UUID =
    "00008004-b38d-4985-720e-0f993a68ee41";

static const char* const GADGET_SETTINGS_SERVICE_UUID =
    "00008100-b38d-4985-720e-0f993a68ee41";
static const char* const WIFI_SSID_CHAR_UUID =
    "00008171-b38d-4985-720e-0f993a68ee41";
static const char* const WIFI_PWD_CHAR_UUID =
    "00008172-b38d-4985-720e-0f993a68ee41";

// BLE Protocol Specifics

static const char* const GADGET_NAME = "S";
static const size_t DOWNLOAD_PKT_SIZE = 20;
static const size_t MAX_SAMPLE_SIZE = 12; // TODO: Adapt depending on data type
static const size_t SAMPLE_BUFFER_SIZE_BYTES = 30000;

class GadgetBle;

typedef uint16_t (GadgetBle::*t_converter)(float);

class GadgetBle: BLECharacteristicCallbacks, BLEServerCallbacks {
  public:
    enum DataType {
        T_RH_V3,
        T_RH_V4,
        T_RH_VOC,
        T_RH_CO2,
        T_RH_CO2_ALT,
        T_RH_CO2_PM25,
        T_RH_VOC_PM25,
        T_RH_VOC_NOX,
        T_RH_VOC_NOX_PM25,
        T_RH_HCHO,
        T_RH_CO2_VOC_PM25_HCHO
    };
    enum Unit { T, RH, VOC, NOX, CO2, PM2P5, HCHO };
    struct UnitEnc {
        int offset;
        t_converter converterFct;
    };
    struct SampleType {
        DataType dataType;
        int advertisementType;
        int advSampleType;
        int dlSampleType;
        int sampleSize;
        int sampleCntPerPacket;
        std::map<Unit, UnitEnc> unitEnc;
    };
    explicit GadgetBle(DataType dataType);
    void enableWifiSetupSettings(
        std::function<void(std::string, std::string)> onWifiSettingsChanged);
    void setCurrentWifiSsid(std::string ssid);
    void begin();
    void setDataType(DataType dataType);
    void writeTemperature(float temperature);
    void writeHumidity(float humidity);
    void writeCO2(float co2);
    void writeVOC(float voc);
    void writeNOx(float nox);
    void writePM2p5(float pm2p5);
    void writeHCHO(float hcho);
    void commit();
    void handleEvents();
    String getDeviceIdString() {
        return _deviceIdString;
    }

  private:
    void _bleInit();
    int _getPositionInSample(Unit unit);
    void _writeValue(float value, Unit unit);
    void _updateAdvertising();
    void _updateConnectionState();
    bool _handleDownload();
    uint16_t _computeBufferSize();
    void _addCurrentSampleToHistory();
    uint16_t _computeRealSampleBufferSize();

    uint16_t _convertSimple(float value);
    uint16_t _convertTemperatureV1(float value);
    uint16_t _convertHumidityV1(float value);
    uint16_t _convertHumidityV2(float value);
    uint16_t _convertPM2p5V1(float value);
    uint16_t _convertPM2p5V2(float value);
    uint16_t _convertHCHOV1(float value);

    DataType _dataType;
    SampleType _sampleType;

    uint16_t _sampleBufferSize;
    uint16_t _sampleBufferCapacity;

    BLEAdvertising* _bleAdvertising;
    BLE2902* _transferDescr;
    BLECharacteristic* _transferChar;
    BLECharacteristic* _sampleCntChar;
    BLECharacteristic* _wifiSsidChar;

    String _deviceIdString;

    int64_t _lastCacheTime = 0;
    uint32_t _sampleIntervalMs = 600000; // default at 10 min
    uint32_t _sampleBufferIdx = 0;
    bool _sampleBufferWraped = false;
    std::array<uint8_t, MAX_SAMPLE_SIZE> _currentSample = {};
    std::array<uint8_t, SAMPLE_BUFFER_SIZE_BYTES> _sampleBuffer = {};
    uint16_t _downloadSeqNumber = 0;
    bool _downloading = false;
    bool _deviceConnected = false;
    bool _oldDeviceConnected = false;

    // Advertisement Data
    // Note, that the GADGET_NAME will be also attached
    // by the BLE library, so it can not be too long!
    // Byte 0: 2 bytes for BLE company identifier
    // Byte 2: advertising type
    // Byte 3: sample type
    // Byte 4: device identifier
    // Byte 6: 2 bytes for sample value
    // Byte 8: 2 bytes for sample value
    // Byte 10: 2 bytes for sample value
    // Byte 12: 2 bytes for sample value
    // Byte 14: 2 bytes for sample value
    // Byte 16: 2 bytes for sample value
    std::array<uint8_t, 18> _advertisedData = {};

    // Download Header template
    // Byte 0: 2 bytes sequcnce number
    // Byte 2: 1 byte version number
    // Byte 3: 1 byte protocol identifier
    // Byte 4: 2 bytes sample type
    // Byte 6: 4 bytes sampling interval in ms
    // Byte 10: 4 bytes age lastest sample in ms
    // Byte 14: 2 bytes sample count
    // Byte 16: 4 bytes unused
    std::array<uint8_t, DOWNLOAD_PKT_SIZE> _downloadHeader = {};

    // BLEServerCallbacks

    void onConnect(BLEServer* serverInst);
    void onDisconnect(BLEServer* serverInst);

    // BLECharacteristicCallbacks
    void onWrite(BLECharacteristic* characteristic);

    // WifiSettings change callbacks
    std::string _wifiSsidSetting = "";
    std::function<void(std::string, std::string)> _onWifiSettingsChanged;
};

#endif