
#include "bmc/scheduler_bmc.h"

#include <chrono>  // NOLINT(build/c++11)
#include <iostream>
#include <memory>
#include <optional>
#include <ostream>
#include <string>
#include <string_view>
#include <utility>

#include "absl/base/attributes.h"
#include "absl/base/thread_annotations.h"
#include "absl/functional/any_invocable.h"
#include "absl/log/log.h"
#include "absl/status/status.h"
#include "absl/synchronization/mutex.h"
#include "absl/time/time.h"

// NOLINTBEGIN(readability/boost): This file is only used for test in google3
#include "boost/asio/io_context.hpp"
#include "boost/asio/io_service.hpp"
#include "boost/bind/bind.hpp"
#include "boost/date_time/posix_time/posix_time.hpp"
#include "boost/system/detail/errc.hpp"
#include "boost/system/detail/error_code.hpp"
// NOLINTEND(readability/boost)

namespace safepower_agent {

SchedulerBMC::SchedulerBMC(
    boost::asio::io_context& io_in ABSL_ATTRIBUTE_LIFETIME_BOUND)
    : io_(io_in),
      work_guard_(boost::asio::executor_work_guard<
                  boost::asio::io_context::executor_type>(io_.get_executor())),
      shutdown_called_(false) {}

SchedulerBMC::~SchedulerBMC() {
  if (!shutdown_called_) {
    (void)Shutdown();  // the error has already been logged
  }
  while (!timer_by_name_.empty()) {
    io_.poll();
  }
}

absl::Status SchedulerBMC::Shutdown() {
  // No new task in the event loop
  absl::Status errc = CancelAll();
  if (!errc.ok()) {
    LOG(WARNING) << "~Scheduler, unable to cancel all current timers"
                 << "error message:" << errc;
  }
  absl::MutexLock lock(&lock_);

  // allow the event loop function to return (io_->run())
  work_guard_.reset();
  shutdown_called_ = true;
  return errc;
}

void SchedulerBMC::Print() {
  LOG(INFO) << "printing all names and timers";
  for (const auto& [name, timer] : timer_by_name_) {
    LOG(INFO) << " name: " << name << " Addr:" << timer;
  }
}

// only SchedulerBMC->Run Task  will run the following code
void SchedulerBMC::CallbackPeriodic(
    std::string task_name, std::unique_ptr<boost::asio::steady_timer> timer,
    std::chrono::milliseconds wait_duration,
    std::shared_ptr<absl::AnyInvocable<void()>> fn) {
  timer->expires_at(timer->expiry() + wait_duration);
  timer->async_wait([captured_this = this, captured_name = std::move(task_name),
                     captured_timer = std::move(timer), wait_duration,
                     lambda_fn = fn](const boost::system::error_code& ec)
                        ABSL_LOCKS_EXCLUDED(lock_) mutable {
                          if (ec == boost::asio::error::operation_aborted) {
                            // this code path happens when the task is canceled
                            LOG(WARNING) << "CallBack lambda operation_aborted "
                                         << captured_name;
                            absl::MutexLock lock(&captured_this->lock_);
                            captured_this->timer_by_name_.erase(captured_name);
                            return;
                          }
                          if (ec != boost::system::errc::errc_t::success) {
                            LOG(ERROR)
                                << "boost timer error value: " << ec.value()
                                << "name:" << ec.category().name();
                            absl::MutexLock lock(&captured_this->lock_);
                            captured_this->timer_by_name_.erase(captured_name);
                            return;
                          }
                          captured_this->CallbackPeriodic(
                              captured_name, std::move(captured_timer),
                              wait_duration, std::move(lambda_fn));
                        });
  (*fn)();  // running the task after async_wait allows the self cancel
}

// API callers run this function
absl::Status SchedulerBMC::CancelAll() {
  absl::MutexLock lock(&lock_);
  for (auto it : timer_by_name_) {
    it.second->cancel();
    std::cerr << "canceling timer named :" << it.first << std::endl;
  }
  return absl::OkStatus();
}

// API callers run this function
absl::Status SchedulerBMC::CancelCall(const std::string_view name) {
  absl::MutexLock lock(&lock_);
  // TODO when map is switched to absl flat_hash_map
  // do not convert to string_view to string (heterogeneous-lookup)
  std::string name_str(name);
  auto it = timer_by_name_.find(name_str);
  if (it == timer_by_name_.end()) {
    LOG(ERROR) << "Task name not found " << name_str << " tasks_by_name_: ";
    Print();
    return absl::NotFoundError("Task name not found");
  }
  it->second->cancel();
  return absl::OkStatus();
}

// API callers run this function, the lambda function is run in the event loop
absl::Status SchedulerBMC::PeriodicCall(absl::AnyInvocable<void()> fn,
                                        const absl::Duration interval,
                                        const std::string_view name) {
  if (shutdown_called_) {
    return absl::FailedPreconditionError("Scheduler is shutting down");
  }
  std::string name_str(name);
  // create timer using io
  auto timer_ptr = std::make_unique<boost::asio::steady_timer>(io_);
  {
    absl::MutexLock lock(&lock_);

    auto it = timer_by_name_.find(name_str);
    if (it != timer_by_name_.end()) {
      return absl::AlreadyExistsError("Task already exists");
    }
    // add task to tasks_by_name_
    timer_by_name_[name_str] = timer_ptr.get();
  }
  auto shared_fn = std::make_shared<absl::AnyInvocable<void()>>(std::move(fn));
  auto interval_chrono = absl::ToChronoMilliseconds(interval);
  timer_ptr->expires_after(interval_chrono);
  timer_ptr->async_wait([captured_name = std::move(name_str),
                         captured_timer = std::move(timer_ptr), interval_chrono,
                         lambda_fn = shared_fn, captured_this = this](
                            const boost::system::error_code&
                                ec) ABSL_LOCKS_EXCLUDED(lock_) mutable {
    if (ec != boost::system::errc::errc_t::success) {
      LOG(WARNING)
          << "PeriodicCall lambda operation_aborted or error before first call "
          << ec.value() << "name:" << ec.category().name();
      absl::MutexLock lock(&captured_this->lock_);
      captured_this->timer_by_name_.erase(captured_name);
      return;
    }
    captured_this->CallbackPeriodic(captured_name, std::move(captured_timer),
                                    interval_chrono, std::move(lambda_fn));
  });
  return absl::OkStatus();
}

// API callers run this function, the lambda function is run in the event loop
absl::Status SchedulerBMC::DelayCall(absl::AnyInvocable<void() &&> fn,
                                     const absl::Duration delay,
                                     const std::string_view name) {
  if (shutdown_called_) {
    return absl::FailedPreconditionError("Scheduler is shutting down");
  }
  std::string name_str(name);
  // create timer using io
  auto timer_ptr = std::make_unique<boost::asio::steady_timer>(io_);
  {
    absl::MutexLock lock(&lock_);

    auto it = timer_by_name_.find(name_str);
    // allow the running task to reschedule itself
    if (it != timer_by_name_.end() && !(current_task_ == name_str)) {
      return absl::AlreadyExistsError("Task already exists");
    }
    // add task to tasks_by_name_
    timer_by_name_[name_str] = timer_ptr.get();
  }
  timer_ptr->expires_after(absl::ToChronoMilliseconds(delay));
  timer_ptr->async_wait([captured_name = std::move(name_str),
                         lambda_fn = std::move(fn), captured_this = this](
                            const boost::system::error_code&
                                ec) ABSL_LOCKS_EXCLUDED(lock_) mutable {
    if (ec != boost::system::errc::errc_t::success) {
      LOG(WARNING)
          << "DelayCall lambda operation_aborted or error before first call "
          << ec.value() << "name:" << ec.category().name();
    }
    captured_this->current_task_ = captured_name;
    std::move(lambda_fn)();
    captured_this->current_task_ = std::nullopt;
    absl::MutexLock lock(&captured_this->lock_);
    captured_this->timer_by_name_.erase(captured_name);
  });

  return absl::OkStatus();
}
}  // namespace safepower_agent