#include "tlbmc/hal/gpio/gpio_monitor.h"

#include <gpiod.h>

#include <memory>
#include <utility>

#include "absl/log/log.h"
#include "absl/memory/memory.h"
#include "boost/asio/io_context.hpp"  // NOLINT: boost is commonly used in BMC codebase
#include "boost/asio/posix/stream_descriptor.hpp"  // NOLINT: boost is commonly used in BMC codebase
#include "g3/macros.h"
#include "gpio_config.pb.h"
#include "tlbmc/hal/gpio/gpio.h"

namespace milotic_tlbmc {

GpioMonitor::GpioMonitor(
    std::unique_ptr<Gpio> gpio, bool is_one_time_request,
    std::unique_ptr<boost::asio::posix::stream_descriptor> event_descriptor)
    : gpio_(std::move(gpio)),
      is_one_time_request_(is_one_time_request),
      event_descriptor_(std::move(event_descriptor)) {
  ScheduleEventHandler();
}

GpioMonitor::~GpioMonitor() {
  if (event_descriptor_->is_open()) {
    event_descriptor_->close();
  }
}

void GpioMonitor::ScheduleEventHandler() {
  event_descriptor_->async_wait(
      boost::asio::posix::stream_descriptor::wait_read,
      [this](const boost::system::error_code& ec) {
        if (ec) {
          LOG(ERROR) << "GPIO event handler error: " << ec.message();
          return;
        }
        EventHandler();
      });
}

void GpioMonitor::EventHandler() {
  // Need to consume the event. Otherwise, the event will be stuck in the queue
  // and the descriptor will always be ready for read.
  gpiod_line_event gpio_line_event;
  if (gpiod_line_event_read_fd(event_descriptor_->native_handle(),
                               &gpio_line_event) < 0) {
    LOG(ERROR) << ("Failed to read from GPIO event descriptor");
    return;
  }

  // TODO(alexlai): Implement generic event handler for other modules and
  // functions.

  if (is_one_time_request_) {
    event_descriptor_->close();
  } else {
    ScheduleEventHandler();
  }
}

absl::StatusOr<std::unique_ptr<GpioMonitor>> GpioMonitor::Create(
    const GpioConfig& gpio_config,
    std::shared_ptr<boost::asio::io_context> io_context) {
  ECCLESIA_ASSIGN_OR_RETURN(std::unique_ptr<Gpio> gpio,
                            Gpio::Create(gpio_config));
  auto event_descriptor =
      std::make_unique<boost::asio::posix::stream_descriptor>(*io_context);
  event_descriptor->assign(gpio->GetGpioLineEventFd());

  return absl::WrapUnique(new GpioMonitor(
      std::move(gpio), gpio_config.gpio_event_config().one_time_request(),
      std::move(event_descriptor)));
}

}  // namespace milotic_tlbmc