#include <modulus/log.hpp>

#include <cassert>
#include <cstdint>
#include <iostream>
#include <mutex>
#include <utility>
#include <modulus/types.hpp>


namespace {

auto is_valid_log_level(modulus::log_level level) noexcept -> std::bool_t {
  return static_cast<std::int32_t>(level) >= static_cast<std::int32_t>(modulus::log_level::TRACE) && static_cast<std::int32_t>(level) <= static_cast<std::int32_t>(modulus::log_level::OFF);
}

auto should_log(modulus::log_level record_level, modulus::log_level configured_level) noexcept -> std::bool_t {
  assert(is_valid_log_level(record_level));
  assert(is_valid_log_level(configured_level));
  return configured_level != modulus::log_level::OFF && static_cast<std::int32_t>(record_level) >= static_cast<std::int32_t>(configured_level);
}

auto format_log_record(std::ostream &stream, const modulus::log_record &record) -> void {
  assert(is_valid_log_level(record.level));
  assert(record.location.file_name() != nullptr);
  stream << '[' << modulus::to_string(record.level) << "] " << record.message << " (" << record.location.file_name() << ':' << record.location.line() << ")\n";
}

auto stderr_sink(const modulus::log_record &record) -> void {
  assert(is_valid_log_level(record.level));
  assert(record.location.file_name() != nullptr);
  static auto mutex = std::mutex{};
  auto lock = std::lock_guard{mutex};
  format_log_record(std::cerr, record);
}

}

auto modulus::to_string(modulus::log_level level) noexcept -> std::string_view {
  assert(is_valid_log_level(level));
  switch (level) {
  case modulus::log_level::TRACE:
    return "trace";
  case modulus::log_level::DEBUG:
    return "debug";
  case modulus::log_level::INFO:
    return "info";
  case modulus::log_level::WARN:
    return "warn";
  case modulus::log_level::ERROR:
    return "error";
  case modulus::log_level::CRITICAL:
    return "critical";
  case modulus::log_level::OFF:
    return "off";
  }
  return "unknown";
}

modulus::logger::logger()
    : sink_(stderr_sink) {}

auto modulus::logger::set_level(modulus::log_level level) -> void {
  assert(is_valid_log_level(level));
  auto lock = std::lock_guard{mutex_};
  level_ = level;
}

auto modulus::logger::level() const -> modulus::log_level {
  auto lock = std::lock_guard{mutex_};
  assert(is_valid_log_level(level_));
  return level_;
}

auto modulus::logger::enabled(modulus::log_level level) const -> std::bool_t {
  assert(is_valid_log_level(level));
  auto lock = std::lock_guard{mutex_};
  return should_log(level, level_) && static_cast<std::bool_t>(sink_);
}

auto modulus::logger::set_sink(std::function<void(const modulus::log_record &)> sink) -> void {
  auto lock = std::lock_guard{mutex_};
  sink_ = std::move(sink);
}

auto modulus::logger::write(modulus::log_record record) const -> void {
  assert(is_valid_log_level(record.level));
  assert(record.location.file_name() != nullptr);
  assert(record.location.function_name() != nullptr);
  auto sink = std::function<void(const modulus::log_record &)>{};
  {
    auto lock = std::lock_guard{mutex_};
    if (!should_log(record.level, level_) || !sink_) {
      return;
    }
    sink = sink_;
  }
  assert(static_cast<std::bool_t>(sink));
  auto sink_lock = std::lock_guard(sink_mutex_);
  sink(record);
}

auto modulus::logger::log(modulus::log_level level, std::string message, modulus::source_location location) const -> void {
  assert(is_valid_log_level(level));
  assert(location.file_name() != nullptr);
  assert(location.function_name() != nullptr);
  write(modulus::log_record{
    .level = level,
    .message = std::move(message),
    .location = location,
  });
}

auto modulus::default_logger() -> modulus::logger & {
  static auto instance = modulus::logger{};
  return instance;
}

auto modulus::set_default_log_level(modulus::log_level level) -> void {
  assert(is_valid_log_level(level));
  modulus::default_logger().set_level(level);
}

auto modulus::is_log_enabled(modulus::log_level level) -> std::bool_t {
  assert(is_valid_log_level(level));
  return modulus::default_logger().enabled(level);
}

auto modulus::log(modulus::log_level level, std::string message, modulus::source_location location) -> void {
  assert(is_valid_log_level(level));
  assert(location.file_name() != nullptr);
  assert(location.function_name() != nullptr);
  modulus::default_logger().log(level, std::move(message), location);
}

auto modulus::log_trace(std::string message, modulus::source_location location) -> void {
  modulus::log(modulus::log_level::TRACE, std::move(message), location);
}

auto modulus::log_debug(std::string message, modulus::source_location location) -> void {
  modulus::log(modulus::log_level::DEBUG, std::move(message), location);
}

auto modulus::log_info(std::string message, modulus::source_location location) -> void {
  modulus::log(modulus::log_level::INFO, std::move(message), location);
}

auto modulus::log_warn(std::string message, modulus::source_location location) -> void {
  modulus::log(modulus::log_level::WARN, std::move(message), location);
}

auto modulus::log_error(std::string message, modulus::source_location location) -> void {
  modulus::log(modulus::log_level::ERROR, std::move(message), location);
}

auto modulus::log_critical(std::string message, modulus::source_location location) -> void {
  modulus::log(modulus::log_level::CRITICAL, std::move(message), location);
}