#include "edgetx.h"
#include "groundstation.h"
#include "os/timer.h"
#include "tasks/mixer_task.h"

namespace {
constexpr uint8_t kMagic0 = 'G';
constexpr uint8_t kMagic1 = 'S';
constexpr uint8_t kVersion = 1;
constexpr uint8_t kTypeRCChannels = 1;
constexpr uint8_t kChannels = 16;
constexpr uint8_t kFrameSize = 10 + kChannels * 2 + 2;
constexpr uint32_t kPeriodMs = 40; // 25 Hz

const etx_serial_driver_t *driver = nullptr;
void *driverCtx = nullptr;
timer_handle_t timer = TIMER_INITIALIZER;
uint16_t sequence = 0;

uint16_t crc16(const uint8_t *data, size_t size)
{
  uint16_t crc = 0xffff;
  for (size_t i = 0; i < size; ++i) {
    crc ^= uint16_t(data[i]) << 8;
    for (uint8_t bit = 0; bit < 8; ++bit)
      crc = (crc & 0x8000) ? uint16_t((crc << 1) ^ 0x1021) : uint16_t(crc << 1);
  }
  return crc;
}

void sendRCFrame()
{
  if (!driver || !driver->sendByte || !mixerTaskRunning()) return;

  uint8_t frame[kFrameSize] = { kMagic0, kMagic1, kVersion, kTypeRCChannels };
  frame[4] = sequence & 0xff;
  frame[5] = sequence >> 8;
  const uint32_t timestamp = get_tmr10ms() * 10;
  frame[6] = timestamp & 0xff;
  frame[7] = (timestamp >> 8) & 0xff;
  frame[8] = (timestamp >> 16) & 0xff;
  frame[9] = (timestamp >> 24) & 0xff;

  for (uint8_t i = 0; i < kChannels; ++i) {
    const uint16_t value = channelOutputs[i];
    frame[10 + i * 2] = value & 0xff;
    frame[11 + i * 2] = value >> 8;
  }

  const uint16_t crc = crc16(frame, kFrameSize - 2);
  frame[kFrameSize - 2] = crc & 0xff;
  frame[kFrameSize - 1] = crc >> 8;
  for (uint8_t byte : frame) driver->sendByte(driverCtx, byte);
  ++sequence;
}

void timerCb(timer_handle_t *)
{
  // Drain input now so the future profile-control parser has a single owner.
  // The baseline intentionally does not act on received bytes yet.
  if (driver && driver->getByte) {
    uint8_t ignored;
    while (driver->getByte(driverCtx, &ignored)) {}
  }
  sendRCFrame();
}
} // namespace

void groundstationSetSerialDriver(void *ctx, const etx_serial_driver_t *drv)
{
  driverCtx = ctx;
  driver = drv;
  sequence = 0;
  if (!timer_is_created(&timer))
    timer_create(&timer, timerCb, "gstation", kPeriodMs, true);
  timer_start(&timer);
}