#include "bacnet_bridge.hpp"
#include "bridge.hpp"
#include "bridge_model.hpp"
#include "bridge_provisioning.hpp"
#include "dali_comm.hpp"
#include "modbus_bridge.hpp"

#include <cstring>
#include <vector>

extern "C" {
#include "esp_log.h"
#include "nvs_flash.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "lwip/inet.h"
#include "lwip/sockets.h"
}

namespace {

constexpr const char* kTag = "dali_bridge_example";
constexpr int kModbusTaskStack = 6144;
constexpr int kDefaultModbusListenPort = 1502;

struct ExampleContext {
  DaliModbusBridge* modbus = nullptr;
  uint16_t listenPort = kDefaultModbusListenPort;
};

ExampleContext gExampleContext;

bool writeGateway(const uint8_t* data, size_t len) {
  ESP_LOGI(kTag, "placeholder DALI gateway write len=%u first=0x%02X",
           static_cast<unsigned>(len), len > 0 ? data[0] : 0U);
  (void)data;
  return false;
}

std::vector<uint8_t> readGateway(size_t len, uint32_t timeoutMs) {
  ESP_LOGI(kTag, "placeholder DALI gateway read len=%u timeout=%u",
           static_cast<unsigned>(len), static_cast<unsigned>(timeoutMs));
  return {};
}

std::vector<uint8_t> transactGateway(const uint8_t* data, size_t len) {
  ESP_LOGI(kTag, "placeholder DALI gateway transact len=%u first=0x%02X",
           static_cast<unsigned>(len), len > 0 ? data[0] : 0U);
  (void)data;
  return {};
}

uint16_t readBe16(const uint8_t* data) {
  return static_cast<uint16_t>((static_cast<uint16_t>(data[0]) << 8) | data[1]);
}

void writeBe16(uint8_t* data, uint16_t value) {
  data[0] = static_cast<uint8_t>((value >> 8) & 0xFF);
  data[1] = static_cast<uint8_t>(value & 0xFF);
}

bool recvAll(int sock, uint8_t* buffer, size_t len) {
  size_t received = 0;
  while (received < len) {
    const int ret = recv(sock, buffer + received, len - received, 0);
    if (ret <= 0) {
      return false;
    }
    received += static_cast<size_t>(ret);
  }
  return true;
}

bool sendAll(int sock, const uint8_t* buffer, size_t len) {
  size_t sent = 0;
  while (sent < len) {
    const int ret = send(sock, buffer + sent, len - sent, 0);
    if (ret <= 0) {
      return false;
    }
    sent += static_cast<size_t>(ret);
  }
  return true;
}

int normalizeHoldingRegister(uint16_t zeroBasedAddress) {
  return 40001 + static_cast<int>(zeroBasedAddress);
}

bool sendModbusFrame(int sock, const uint8_t* mbap, const std::vector<uint8_t>& pdu) {
  std::vector<uint8_t> frame(7 + pdu.size());
  std::memcpy(frame.data(), mbap, 7);
  writeBe16(&frame[4], static_cast<uint16_t>(pdu.size() + 1));
  std::memcpy(frame.data() + 7, pdu.data(), pdu.size());
  return sendAll(sock, frame.data(), frame.size());
}

bool sendModbusException(int sock, const uint8_t* mbap, uint8_t functionCode, uint8_t exceptionCode) {
  const std::vector<uint8_t> pdu{static_cast<uint8_t>(functionCode | 0x80), exceptionCode};
  return sendModbusFrame(sock, mbap, pdu);
}

BridgeModel makeModbusBrightnessModel() {
  BridgeModel model;
  model.id = "modbus-light-1";
  model.name = "Modbus line 1 brightness";
  model.protocol = BridgeProtocolKind::modbus;
  model.external.network = "line-a";
  model.external.device = "plc-1";
  model.external.objectType = BridgeObjectType::holdingRegister;
  model.external.registerAddress = 40001;
  model.dali.shortAddress = 1;
  model.operation = BridgeOperation::setBrightness;
  model.valueEncoding = BridgeValueEncoding::integer;
  model.valueTransform.clampMin = 0;
  model.valueTransform.clampMax = 254;
  return model;
}

BridgeModel makeBacnetBrightnessModel() {
  BridgeModel model;
  model.id = "bacnet-zone-2";
  model.name = "BACnet zone 2 level";
  model.protocol = BridgeProtocolKind::bacnet;
  model.external.network = "floor-2";
  model.external.device = "bacnet-controller";
  model.external.objectType = BridgeObjectType::analogOutput;
  model.external.objectInstance = 2;
  model.external.property = "presentValue";
  model.dali.shortAddress = 2;
  model.operation = BridgeOperation::setBrightnessPercent;
  model.valueEncoding = BridgeValueEncoding::percentage;
  return model;
}

BridgeModel makeStatusQueryModel() {
  BridgeModel model;
  model.id = "modbus-light-1-status";
  model.name = "Modbus line 1 status";
  model.protocol = BridgeProtocolKind::modbus;
  model.external.network = "line-a";
  model.external.device = "plc-1";
  model.external.objectType = BridgeObjectType::holdingRegister;
  model.external.registerAddress = 40002;
  model.dali.shortAddress = 1;
  model.operation = BridgeOperation::getStatus;
  return model;
}

BridgeRuntimeConfig makeDefaultRuntimeConfig() {
  BridgeRuntimeConfig config;
  config.models.push_back(makeModbusBrightnessModel());
  config.models.push_back(makeBacnetBrightnessModel());
  config.models.push_back(makeStatusQueryModel());

  ModbusBridgeConfig modbus;
  modbus.transport = "tcp-server";
  modbus.port = kDefaultModbusListenPort;
  modbus.unitID = 7;
  config.modbus = modbus;

  BacnetBridgeConfig bacnet;
  bacnet.deviceInstance = 1001;
  bacnet.localAddress = "192.168.10.20";
  config.bacnet = bacnet;

  config.metadata["example"] = "esp32s3_bridge";
  return config;
}

void logResult(const char* label, const DaliBridgeResult& result) {
  ESP_LOGI(kTag, "%s ok=%d op=%s data=%d error=%s", label, result.ok,
           bridgeOperationToString(result.operation), result.data.value_or(-1),
           result.error.empty() ? "<none>" : result.error.c_str());
}

void handleModbusClient(int clientSock, const ExampleContext& context) {
  uint8_t header[7];
  while (recvAll(clientSock, header, sizeof(header))) {
    const uint16_t protocolID = readBe16(&header[2]);
    const uint16_t length = readBe16(&header[4]);
    if (protocolID != 0 || length < 2) {
      break;
    }

    std::vector<uint8_t> pdu(length - 1);
    if (!recvAll(clientSock, pdu.data(), pdu.size()) || pdu.empty()) {
      break;
    }

    const uint8_t functionCode = pdu[0];
    if (functionCode == 0x06 && pdu.size() == 5) {
      const uint16_t registerAddress = readBe16(&pdu[1]);
      const uint16_t value = readBe16(&pdu[3]);
      const int holdingRegister = normalizeHoldingRegister(registerAddress);
      const DaliBridgeResult result = context.modbus->handleHoldingRegisterWrite(holdingRegister, value);
      logResult("modbus tcp write single", result);
      if (!result.ok) {
        sendModbusException(clientSock, header, functionCode, 0x04);
        continue;
      }
      sendModbusFrame(clientSock, header, pdu);
      continue;
    }

    if (functionCode == 0x10 && pdu.size() >= 6) {
      const uint16_t startAddress = readBe16(&pdu[1]);
      const uint16_t quantity = readBe16(&pdu[3]);
      const uint8_t byteCount = pdu[5];
      if (pdu.size() != static_cast<size_t>(6 + byteCount) || byteCount != quantity * 2) {
        sendModbusException(clientSock, header, functionCode, 0x03);
        continue;
      }

      bool ok = true;
      for (uint16_t index = 0; index < quantity; ++index) {
        const size_t offset = 6 + (index * 2);
        const uint16_t value = readBe16(&pdu[offset]);
        const int holdingRegister = normalizeHoldingRegister(static_cast<uint16_t>(startAddress + index));
        const DaliBridgeResult result = context.modbus->handleHoldingRegisterWrite(holdingRegister, value);
        logResult("modbus tcp write multiple", result);
        if (!result.ok) {
          ok = false;
          break;
        }
      }

      if (!ok) {
        sendModbusException(clientSock, header, functionCode, 0x04);
        continue;
      }

      std::vector<uint8_t> response(5);
      response[0] = functionCode;
      writeBe16(&response[1], startAddress);
      writeBe16(&response[3], quantity);
      sendModbusFrame(clientSock, header, response);
      continue;
    }

    sendModbusException(clientSock, header, functionCode, 0x01);
  }
}

void modbusServerTask(void* arg) {
  auto* context = static_cast<ExampleContext*>(arg);
  const int listenSock = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
  if (listenSock < 0) {
    ESP_LOGE(kTag, "failed to create Modbus listen socket");
    vTaskDelete(nullptr);
    return;
  }

  int reuse = 1;
  setsockopt(listenSock, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));

  sockaddr_in address = {};
  address.sin_family = AF_INET;
  address.sin_addr.s_addr = htonl(INADDR_ANY);
  address.sin_port = htons(context->listenPort);

  if (bind(listenSock, reinterpret_cast<sockaddr*>(&address), sizeof(address)) != 0 ||
      listen(listenSock, 2) != 0) {
    ESP_LOGE(kTag, "failed to bind/listen Modbus TCP on port %u", context->listenPort);
    close(listenSock);
    vTaskDelete(nullptr);
    return;
  }

  ESP_LOGI(kTag, "Modbus TCP listener ready on port %u", context->listenPort);
  while (true) {
    sockaddr_in clientAddress = {};
    socklen_t clientLen = sizeof(clientAddress);
    const int clientSock = accept(listenSock, reinterpret_cast<sockaddr*>(&clientAddress), &clientLen);
    if (clientSock < 0) {
      continue;
    }
    ESP_LOGI(kTag, "Modbus client connected");
    handleModbusClient(clientSock, *context);
    close(clientSock);
    ESP_LOGI(kTag, "Modbus client disconnected");
  }
}

}  // namespace

extern "C" void app_main(void) {
  esp_err_t nvsErr = nvs_flash_init();
  if (nvsErr != ESP_OK) {
    ESP_LOGW(kTag, "nvs_flash_init failed: %s", esp_err_to_name(nvsErr));
  }

  BridgeProvisioningStore provisioningStore;
  BridgeRuntimeConfig runtimeConfig;
  if (provisioningStore.load(&runtimeConfig) != ESP_OK || runtimeConfig.models.empty()) {
    runtimeConfig = makeDefaultRuntimeConfig();
    provisioningStore.save(runtimeConfig);
  }

  static DaliComm comm(writeGateway, readGateway, transactGateway);
  static DaliBridgeEngine engine(comm);

  for (const auto& model : runtimeConfig.models) {
    engine.upsertModel(model);
  }

  static DaliModbusBridge modbus(engine);
  ModbusBridgeConfig modbusConfig = runtimeConfig.modbus.value_or(ModbusBridgeConfig{});
  modbus.setConfig(modbusConfig);

  static DaliBacnetBridge bacnet(engine);
  BacnetBridgeConfig bacnetConfig = runtimeConfig.bacnet.value_or(BacnetBridgeConfig{});
  bacnet.setConfig(bacnetConfig);

  gExampleContext.modbus = &modbus;
  gExampleContext.listenPort = modbus.config().port == 0 ? kDefaultModbusListenPort : modbus.config().port;

  for (const auto& binding : modbus.describeHoldingRegisters()) {
    ESP_LOGI(kTag, "modbus binding model=%s register=%d", binding.modelID.c_str(),
             binding.registerAddress);
  }

  for (const auto& binding : bacnet.describeObjects()) {
    ESP_LOGI(kTag, "bacnet binding model=%s object=%s:%d property=%s",
             binding.modelID.c_str(), bridgeObjectTypeToString(binding.objectType),
             binding.objectInstance, binding.property.c_str());
  }

  const DaliBridgeResult modbusResult = modbus.handleHoldingRegisterWrite(40001, 180);
  logResult("modbus write", modbusResult);

  const DaliBridgeResult bacnetResult =
      bacnet.handlePropertyWrite(BridgeObjectType::analogOutput, 2, "presentValue", 75.0);
  logResult("bacnet write", bacnetResult);

    DaliBridgeRequest statusRequest;
    statusRequest.sequence = "startup-status";
    statusRequest.modelID = "modbus-light-1-status";
    const DaliBridgeResult statusResult = engine.execute(statusRequest);
  logResult("status query", statusResult);

  xTaskCreate(modbusServerTask, "modbus_tcp", kModbusTaskStack, &gExampleContext, 5, nullptr);
}