#include <Arduino.h>
#include <NimBLEDevice.h>

#include <mbedtls/md.h>
#include <Preferences.h>

#define RELAY1_PIN  1
#define RELAY2_PIN  2
#define TOUCH1_PIN  8
#define TOUCH2_PIN  6
#define BUTTON_PIN  41
#define LED_PIN     46

#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361f26d8"
#define UUID_CHAR_UUID      "beb5483e-36e1-4688-b7f5-ea07361f26d9"

#define HMAC_PKT_SIZE 37   // 1 cmd + 4 seq + 32 hmac
#define HMAC_KEY_LEN  32
#define ESP_UUID_LEN  16
#define NVS_NAMESPACE "hmac"
#define NVS_KEY_NAME  "key"
#define NVS_UUID_NAME "uuid"

NimBLECharacteristic *pCharacteristic;
bool deviceConnected = false;
bool bleRelay1 = false;
bool bleRelay2 = false;
bool relay1State = false;
bool relay2State = false;
uint32_t lastSeq = 0;

uint8_t hmacKey[HMAC_KEY_LEN];
uint8_t deviceUuid[ESP_UUID_LEN];
bool keyProvisioned = false;
bool uuidProvisioned = false;
Preferences preferences;

class MyServerCallbacks : public NimBLEServerCallbacks {
    void onConnect(NimBLEServer *pServer, NimBLEConnInfo &connInfo) override {
        deviceConnected = true;
        lastSeq = 0;
        Serial.println("BLE: device connected");
    }
    void onDisconnect(NimBLEServer *pServer, NimBLEConnInfo &connInfo, int reason) override {
        deviceConnected = false;
        bleRelay1 = false;
        bleRelay2 = false;
        lastSeq = 0;
        Serial.println("BLE: device disconnected");
        NimBLEDevice::startAdvertising();
    }
};

static bool verifyHmac(const uint8_t *packet) {
    uint8_t cmd = packet[0];
    uint32_t seq = ((uint32_t)packet[1] << 24) |
                   ((uint32_t)packet[2] << 16) |
                   ((uint32_t)packet[3] << 8)  |
                   (uint32_t)packet[4];

    if (seq <= lastSeq) {
        Serial.printf("BLE: replay rejected (seq=%lu, last=%lu)\n", seq, lastSeq);
        return false;
    }

    uint8_t hmacData[5];
    hmacData[0] = cmd;
    hmacData[1] = (seq >> 24) & 0xFF;
    hmacData[2] = (seq >> 16) & 0xFF;
    hmacData[3] = (seq >> 8)  & 0xFF;
    hmacData[4] = seq & 0xFF;

    uint8_t computed[32];
    const mbedtls_md_info_t *mdInfo = mbedtls_md_info_from_type(MBEDTLS_MD_SHA256);
    mbedtls_md_hmac(mdInfo, hmacKey, HMAC_KEY_LEN, hmacData, 5, computed);

    if (memcmp(computed, packet + 5, 32) != 0) {
        Serial.println("BLE: HMAC mismatch");
        return false;
    }

    lastSeq = seq;
    return true;
}

static bool isHexKey(const String &hex) {
    for (int i = 0; i < hex.length(); i++) {
        char c = hex.charAt(i);
        if (!((c >= '0' && c <= '9') || (c >= 'A' && c <= 'F'))) return false;
    }
    return true;
}

static void parseHexKey(const String &hex, uint8_t *out) {
    for (int i = 0; i < HMAC_KEY_LEN; i++) {
        out[i] = (uint8_t)strtoul(hex.substring(i * 2, i * 2 + 2).c_str(), nullptr, 16);
    }
}

class MyCharacteristicCallbacks : public NimBLECharacteristicCallbacks {
    void onWrite(NimBLECharacteristic *pChar, NimBLEConnInfo &connInfo) override {
        std::string value = pChar->getValue();
        if (value.length() != HMAC_PKT_SIZE) {
            Serial.printf("BLE: bad packet length %d (expected %d)\n",
                          (int)value.length(), HMAC_PKT_SIZE);
            return;
        }

        const uint8_t *pkt = (const uint8_t *)value.data();

        if (!verifyHmac(pkt)) {
            return;
        }

        uint8_t cmd = pkt[0];
        uint32_t seq = lastSeq;

        if (cmd == 0x01) {
            bleRelay1 = true;
            Serial.printf("BLE: relay1 ON (seq=%lu)\n", seq);
        } else if (cmd == 0x00) {
            bleRelay1 = false;
            Serial.printf("BLE: relay1 OFF (seq=%lu)\n", seq);
        } else if (cmd == 0x02) {
            bleRelay2 = true;
            Serial.printf("BLE: relay2 ON (seq=%lu)\n", seq);
        } else if (cmd == 0x03) {
            bleRelay2 = false;
            Serial.printf("BLE: relay2 OFF (seq=%lu)\n", seq);
        }
    }
};

void setup() {
    Serial.begin(115200);
    delay(2000);
    Serial.println("=== Atom VoiceS3R BLE Relay ===");

    preferences.begin(NVS_NAMESPACE, true);
    size_t len = preferences.getBytes(NVS_KEY_NAME, hmacKey, HMAC_KEY_LEN);
    size_t uuidLen = preferences.getBytes(NVS_UUID_NAME, deviceUuid, ESP_UUID_LEN);
    preferences.end();

    if (len == HMAC_KEY_LEN) {
        keyProvisioned = true;
        Serial.println("HMAC key loaded from NVS");
    } else {
        keyProvisioned = false;
        Serial.println("No HMAC key provisioned — connect USB and run SET_KEY");
    }

    if (uuidLen == ESP_UUID_LEN) {
        uuidProvisioned = true;
        Serial.print("UUID loaded from NVS: ");
        for (int i = 0; i < ESP_UUID_LEN; i++) Serial.printf("%02X", deviceUuid[i]);
        Serial.println();
    } else {
        uuidProvisioned = false;
        for (int i = 0; i < ESP_UUID_LEN; i++) deviceUuid[i] = (uint8_t)(esp_random() & 0xFF);
        preferences.begin(NVS_NAMESPACE, false);
        preferences.putBytes(NVS_UUID_NAME, deviceUuid, ESP_UUID_LEN);
        preferences.end();
        uuidProvisioned = true;
        Serial.print("Generated new UUID: ");
        for (int i = 0; i < ESP_UUID_LEN; i++) Serial.printf("%02X", deviceUuid[i]);
        Serial.println();
    }

    pinMode(TOUCH1_PIN, INPUT_PULLUP);
    pinMode(TOUCH2_PIN, INPUT_PULLUP);
    pinMode(BUTTON_PIN, INPUT);
    pinMode(RELAY1_PIN, OUTPUT);
    pinMode(RELAY2_PIN, OUTPUT);
    pinMode(LED_PIN, OUTPUT);

    for (int i = 0; i < 3; i++) {
        digitalWrite(LED_PIN, HIGH);
        delay(200);
        digitalWrite(LED_PIN, LOW);
        delay(200);
    }
    Serial.println("LED blink done, starting BLE...");

    NimBLEDevice::init("SylDa_Server");

    NimBLEServer *pServer = NimBLEDevice::createServer();
    pServer->setCallbacks(new MyServerCallbacks());

    NimBLEService *pService = pServer->createService(SERVICE_UUID);
    pCharacteristic = pService->createCharacteristic(
        CHARACTERISTIC_UUID,
        NIMBLE_PROPERTY::WRITE_NR | NIMBLE_PROPERTY::NOTIFY
    );
    pCharacteristic->setCallbacks(new MyCharacteristicCallbacks());
    pCharacteristic->setValue("0");

    NimBLECharacteristic *pUuidChar = pService->createCharacteristic(
        UUID_CHAR_UUID,
        NIMBLE_PROPERTY::READ
    );
    pUuidChar->setValue(deviceUuid, ESP_UUID_LEN);

    NimBLEAdvertising *pAdvertising = NimBLEDevice::getAdvertising();
    pAdvertising->addServiceUUID(SERVICE_UUID);
    pAdvertising->enableScanResponse(true);
    pAdvertising->setMinInterval(32);
    pAdvertising->setMaxInterval(64);
    NimBLEDevice::startAdvertising();

    Serial.println("BLE: advertising started as 'SylDa_Server'");

    if (keyProvisioned) {
        Serial.print("HMAC Key: ");
        for (int i = 0; i < HMAC_KEY_LEN; i++) {
            Serial.printf("%02X", hmacKey[i]);
        }
        Serial.println();
    } else {
        Serial.println("No HMAC key — use USB SET_KEY to provision");
    }

    Serial.println("Setup done.");
}

void loop() {
    if (Serial.available()) {
        static String serialBuf;
        char c = Serial.read();
        serialBuf += c;
        if (c == '\n') {
            serialBuf.trim();
            if (serialBuf == "KEY?") {
                if (keyProvisioned && uuidProvisioned) {
                    Serial.print("DEVICE_ID:");
                    for (int i = 0; i < ESP_UUID_LEN; i++) Serial.printf("%02X", deviceUuid[i]);
                    Serial.println();
                    Serial.print("HMAC_KEY:");
                    for (int i = 0; i < HMAC_KEY_LEN; i++) {
                        Serial.printf("%02X", hmacKey[i]);
                    }
                    Serial.println();
                } else {
                    Serial.println("NO_KEY");
                }
            } else if (serialBuf.startsWith("SET_KEY:")) {
                String hex = serialBuf.substring(8);
                hex.toUpperCase();
                if (hex.length() == 64 && isHexKey(hex)) {
                    parseHexKey(hex, hmacKey);
                    preferences.begin(NVS_NAMESPACE, false);
                    preferences.putBytes(NVS_KEY_NAME, hmacKey, HMAC_KEY_LEN);
                    preferences.end();
                    keyProvisioned = true;
                    Serial.println("OK");
                    Serial.println("HMAC key stored in NVS");
                } else {
                    Serial.println("ERROR: invalid key format");
                }
            } else if (serialBuf.startsWith("SET_ID:")) {
                String hex = serialBuf.substring(7);
                hex.toUpperCase();
                if (hex.length() == 32 && isHexKey(hex)) {
                    for (int i = 0; i < ESP_UUID_LEN; i++) {
                        deviceUuid[i] = (uint8_t)strtoul(hex.substring(i * 2, i * 2 + 2).c_str(), nullptr, 16);
                    }
                    preferences.begin(NVS_NAMESPACE, false);
                    preferences.putBytes(NVS_UUID_NAME, deviceUuid, ESP_UUID_LEN);
                    preferences.end();
                    uuidProvisioned = true;
                    Serial.println("OK");
                    Serial.println("UUID stored in NVS");
                } else {
                    Serial.println("ERROR: invalid UUID format");
                }
            }
            serialBuf = "";
        }
    }

    static bool t1Stable = false;
    static bool t2Stable = false;
    static bool btnStable = false;
    static uint32_t t1Change = 0;
    static uint32_t t2Change = 0;
    static uint32_t btnChange = 0;
    #define DEBOUNCE_MS 50
    bool t1Raw = (digitalRead(TOUCH1_PIN) == LOW);
    bool t2Raw = (digitalRead(TOUCH2_PIN) == LOW);
    bool btnRaw = (digitalRead(BUTTON_PIN) == LOW);
    if (t1Raw != t1Stable) { t1Change = millis(); t1Stable = t1Raw; }
    if (t2Raw != t2Stable) { t2Change = millis(); t2Stable = t2Raw; }
    if (btnRaw != btnStable) { btnChange = millis(); btnStable = btnRaw; }
    bool t1Active = (millis() - t1Change > DEBOUNCE_MS) && t1Stable;
    bool t2Active = (millis() - t2Change > DEBOUNCE_MS) && t2Stable;
    bool btnActive = (millis() - btnChange > DEBOUNCE_MS) && btnStable;

    relay1State = t1Active || btnActive || (deviceConnected && bleRelay1);
    relay2State = t2Active || (deviceConnected && bleRelay2);

    digitalWrite(RELAY1_PIN, relay1State ? HIGH : LOW);
    digitalWrite(RELAY2_PIN, relay2State ? HIGH : LOW);

    digitalWrite(LED_PIN, (relay1State || relay2State) ? HIGH : LOW);

    static bool lastRelay1 = false;
    static bool lastRelay2 = false;
    if (relay1State != lastRelay1 || relay2State != lastRelay2) {
        Serial.printf("Relays: R1=%s R2=%s (t1=%s t2=%s btn=%s ble1=%s ble2=%s)\n",
            relay1State ? "ON" : "OFF",
            relay2State ? "ON" : "OFF",
            t1Active ? "YES" : "no",
            t2Active ? "YES" : "no",
            btnActive ? "YES" : "no",
            bleRelay1 ? "ON" : "OFF",
            bleRelay2 ? "ON" : "OFF");
        lastRelay1 = relay1State;
        lastRelay2 = relay2State;
    }

    static uint32_t heartbeat = 0;
    if (millis() - heartbeat > 5000) {
        Serial.printf("[heartbeat] R1=%s R2=%s t1=%s t2=%s btn=%s ble1=%s ble2=%s\n",
            relay1State ? "ON" : "OFF",
            relay2State ? "ON" : "OFF",
            t1Active ? "YES" : "no",
            t2Active ? "YES" : "no",
            btnActive ? "YES" : "no",
            bleRelay1 ? "ON" : "OFF",
            bleRelay2 ? "ON" : "OFF");
        heartbeat = millis();
    }

    delay(50);
}