#include "tlbmc/sensors/fan_controller.h"

#include <sys/types.h>

#include <algorithm>
#include <array>
#include <cstdint>
#include <memory>
#include <string>
#include <string_view>
#include <unordered_map>
#include <utility>

#include "absl/log/log.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/match.h"
#include "absl/strings/numbers.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/substitute.h"
#include "g3/macros.h"
#include "tlbmc/central_config/config.h"
#include "fan_controller_config.pb.h"
#include "tlbmc/hal/sysfs/i2c.h"
#include "tlbmc/sensors/i2c_hwmon_based_sensor.h"
#include "re2/re2.h"

namespace milotic_tlbmc {

template <class TypeName>
struct TypeComparator {
  // Compared by the first element which is the type name.
  bool operator()(const std::pair<FanControllerType, TypeName>& lhs,
                  const std::pair<FanControllerType, TypeName>& rhs) const {
    return lhs.first < rhs.first;
  }
};

constexpr std::array<std::pair<FanControllerType, std::string_view>, 1>
    kSupportedFanControllerTypes = {
        // go/keep-sorted start
        {{FAN_CONTROLLER_TYPE_MAX31790, "max31790"}}
        // go/keep-sorted end
};

FanController::FanController(
    Token token, const FanControllerConfig& config,
    const std::unordered_map<uint32_t, Tachometers>& tachs,
    const std::unordered_map<uint32_t, Pwm>& pwms)
    : config_(config), index_to_tachs_(tachs), index_to_pwms_(pwms) {}

absl::StatusOr<std::string_view> FanController::GetDriverName(
    FanControllerType type) {
  const auto* it = std::lower_bound(
      kSupportedFanControllerTypes.begin(), kSupportedFanControllerTypes.end(),
      std::pair<FanControllerType, std::string_view>{type, ""},
      TypeComparator<std::string_view>());
  if (it == kSupportedFanControllerTypes.end() || it->first != type) {
    return absl::InvalidArgumentError(
        absl::Substitute("Unsupported fan controller type: $0", type));
  }
  return it->second;
}

absl::StatusOr<std::shared_ptr<FanController>> FanController::Create(
    const FanControllerConfig& config, const I2cSysfs& i2c_sysfs) {
  DLOG(INFO) << "Creating FanController for device: " << absl::StrCat(config);
  const I2cCommonConfig& i2c_common_config = config.i2c_common_config();
  ECCLESIA_ASSIGN_OR_RETURN(std::string_view driver_name,
                            GetDriverName(config.type()));

  // E.g., /sys/bus/i2c/devices/i2c-19/19-002c/hwmon/hwmon9/
  absl::StatusOr<boost::filesystem::path> hwmon_path =
      I2cHwmonBasedSensor::CreateDeviceAndReturnsHwmonPath(
          i2c_common_config, driver_name, i2c_sysfs);
  if (!hwmon_path.ok()) {
    if (!GetTlbmcConfig().allow_sensor_creation_failure) {
      return hwmon_path.status();
    }

    LOG(ERROR) << "Failed to create FanController (NONFATAL): "
               << hwmon_path.status();
    return std::make_shared<FanController>(
        Token(), config, std::unordered_map<uint32_t, Tachometers>(),
        std::unordered_map<uint32_t, Pwm>());
  }

  std::unordered_map<uint32_t, Tachometers> tachs;
  std::unordered_map<uint32_t, Pwm> pwms;

  for (const auto& entry : boost::filesystem::directory_iterator(*hwmon_path)) {
    std::string entry_path_str = entry.path().filename().string();
    std::string_view entry_path = entry_path_str;
    constexpr std::string_view kFanTachPrefix = "fan";
    constexpr std::string_view kFanTachSuffix = "_input";
    if (absl::StartsWith(entry_path, kFanTachPrefix) &&
        absl::EndsWith(entry_path, kFanTachSuffix)) {
      std::string_view index = entry_path.substr(
          kFanTachPrefix.size(),
          entry_path.size() - kFanTachPrefix.size() - kFanTachSuffix.size());
      uint32_t index_int;
      if (!absl::SimpleAtoi(index, &index_int)) {
        return absl::InternalError(absl::Substitute(
            "Failed to convert fan tach index to int: $0", index));
      }
      tachs[index_int].tach_input = entry;
    }

    constexpr std::string_view kPwmPrefix = "pwm";
    constexpr std::string_view kPwmEnableSuffix = "_enable";
    uint32_t index_int;
    if (RE2::FullMatch(entry_path, absl::StrCat(kPwmPrefix, "(\\d+)"),
                       &index_int)) {
      pwms[index_int].pwm = entry;
    }
    if (absl::StartsWith(entry_path, kPwmPrefix) &&
        absl::EndsWith(entry_path, kPwmEnableSuffix)) {
      std::string_view index = entry_path.substr(
          kPwmPrefix.size(),
          entry_path.size() - kPwmPrefix.size() - kPwmEnableSuffix.size());
      if (!absl::SimpleAtoi(index, &index_int)) {
        return absl::InternalError(absl::Substitute(
            "Failed to convert pwm enable index to int: $0", index));
      }
      pwms[index_int].pwm_enable = entry;
    }
  }

  return std::make_shared<FanController>(Token(), config, std::move(tachs),
                                         std::move(pwms));
}

}  // namespace milotic_tlbmc