/*
 * Copyright 2024 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "workout_service.h"

#include "activity_algorithm.h"
#include "activity_calculators.h"
#include "activity_insights.h"
#include "activity_private.h"
#include "hr_util.h"

#include "apps/system_apps/workout/workout_utils.h"
#include "applib/app.h"
#include "applib/health_service.h"
#include "kernel/events.h"
#include "kernel/pbl_malloc.h"
#include "services/common/evented_timer.h"
#include "services/common/regular_timer.h"
#include "system/passert.h"
#include "util/time/time.h"
#include "util/units.h"

#include <os/mutex.h>

#define WORKOUT_HR_READING_TS_EXPIRE (SECONDS_PER_MINUTE)
#define WORKOUT_ENDED_HR_SUBSCRIPTION_TS_EXPIRE (10 * SECONDS_PER_MINUTE)
#define WORKOUT_ACTIVE_HR_SUBSCRIPTION_TS_EXPIRE (SECONDS_PER_HOUR)
#define WORKOUT_ABANDONED_NOTIFICATION_TIMEOUT_MS (55 * MS_PER_MINUTE)
#define WORKOUT_ABANDON_WORKOUT_TIMEOUT_MS (5 * MS_PER_MINUTE)

//! Allocated when a Workout is started
typedef struct CurrentWorkoutData {
  ActivitySessionType type;

  time_t start_utc;
  time_t last_paused_utc;
  time_t duration_completed_pauses_s;

  int32_t duration_s;
  int32_t steps;
  int32_t distance_m;
  // Pace
  int32_t active_calories;
  int32_t current_bpm;
  time_t current_bpm_timestamp_ts; // Time since boot
  HRZone current_hr_zone;
  int32_t hr_zone_time_s[HRZoneCount];
  int32_t hr_samples_sum;
  int32_t hr_samples_count;

  // Step count total from the last HealthEventMovementUpdate
  int32_t last_event_step_count;
  time_t last_movement_event_time_ts;

  // Whether or not the current workout is paused
  bool paused;

  EventedTimerID workout_abandoned_timer;
} CurrentWorkoutData;

//! Persisted statically in RAM
typedef struct WorkoutServiceData {
  PebbleRecursiveMutex *s_workout_mutex;
  RegularTimerInfo second_timer;
  time_t last_workout_end_ts;
  time_t frontend_last_opened_ts;
  HRMSessionRef hrm_session;

  CurrentWorkoutData *current_workout;
} WorkoutServiceData;

static WorkoutServiceData s_workout_data;

static void prv_lock(void) {
  mutex_lock_recursive(s_workout_data.s_workout_mutex);
}

static void prv_unlock(void) {
  mutex_unlock_recursive(s_workout_data.s_workout_mutex);
}

static void prv_put_event(PebbleWorkoutEventType e_type) {
  PebbleEvent event = {
    .type = PEBBLE_WORKOUT_EVENT,
    .workout = {
      .type = e_type,
    }
  };
  event_put(&event);
}

static int32_t prv_get_avg_hr(void) {
  if (!s_workout_data.current_workout->hr_samples_count) {
    return 0;
  }

  return ROUND(s_workout_data.current_workout->hr_samples_sum,
               s_workout_data.current_workout->hr_samples_count);
}

static void prv_update_duration(void) {
  // We can't just increment the time on a second callback because of the inaccuracy of our timer
  // system. PBL-32523
  // Instead, we keep track of a start_utc, paused_time, and last_paused_utc. With these
  // we can accurately keep track of the total duration of the workout.
  if (!workout_service_is_workout_ongoing()) {
    return;
  }

  time_t now_utc = rtc_get_time();

  time_t total_paused_time_s = s_workout_data.current_workout->duration_completed_pauses_s;
  if (workout_service_is_paused()) {
    const time_t duration_current_pause = now_utc - s_workout_data.current_workout->last_paused_utc;
    total_paused_time_s += duration_current_pause;
  }

  s_workout_data.current_workout->duration_s =
      now_utc - s_workout_data.current_workout->start_utc - total_paused_time_s;
}

static void prv_reset_hr_data(void) {
  const time_t now_ts = time_get_uptime_seconds();
  s_workout_data.current_workout->current_bpm = 0;
  s_workout_data.current_workout->current_hr_zone = HRZone_Zone0;
  s_workout_data.current_workout->current_bpm_timestamp_ts = now_ts;
}

// ---------------------------------------------------------------------------------------
static void prv_handle_movement_update(HealthEventMovementUpdateData *event) {
  CurrentWorkoutData *wrkt_data = s_workout_data.current_workout;

  const int32_t new_event_steps = event->steps;
  const time_t now_ts = time_get_uptime_seconds();
  if (new_event_steps < wrkt_data->last_event_step_count) {
    PBL_LOG(LOG_LEVEL_WARNING, "Working out through midnight, resetting last_event_step_count");
    wrkt_data->last_event_step_count = 0;
  }

  if (!workout_service_is_paused()) {
    // Calculate the step delta
    const uint32_t delta_steps = new_event_steps - wrkt_data->last_event_step_count;
    wrkt_data->steps += delta_steps;

    // Calculate the distance delta
    const time_t delta_ms = (now_ts - wrkt_data->last_movement_event_time_ts) * MS_PER_SECOND;
    const int32_t delta_distance_mm = activity_private_compute_distance_mm(delta_steps, delta_ms);
    wrkt_data->distance_m += (delta_distance_mm / MM_PER_METER);

    // Calculate active calories
    const int32_t active_calories = activity_private_compute_active_calories(delta_distance_mm,
                                                                             delta_ms);
    wrkt_data->active_calories += active_calories;
  }

  // Reset the last event count regardless of whether we are paused
  wrkt_data->last_event_step_count = new_event_steps;
  wrkt_data->last_movement_event_time_ts = now_ts;
}

static void prv_handle_heart_rate_update(HealthEventHeartRateUpdateData *event) {
  CurrentWorkoutData *wrkt_data = s_workout_data.current_workout;

  if (event->is_filtered) {
    // We don't care about median heart rate updates
    return;
  }

  if (event->quality == HRMQuality_OffWrist) {
    // Reset to zero for OffWrist readings
    prv_reset_hr_data();
  } else if (event->quality >= HRMQuality_Worst) {
    const int prev_bpm_timestamp_ts = wrkt_data->current_bpm_timestamp_ts;

    wrkt_data->current_bpm = event->current_bpm;
    wrkt_data->current_hr_zone = hr_util_get_hr_zone(wrkt_data->current_bpm);
    wrkt_data->current_bpm_timestamp_ts = time_get_uptime_seconds();

    if (!workout_service_is_paused()) {
      // TODO: Maybe apply smoothing
      wrkt_data->hr_zone_time_s[wrkt_data->current_hr_zone] +=
          wrkt_data->current_bpm_timestamp_ts - prev_bpm_timestamp_ts;
      wrkt_data->hr_samples_count++;
      wrkt_data->hr_samples_sum += event->current_bpm;
    }
  }
  return;
}

// ---------------------------------------------------------------------------------------
bool workout_service_is_workout_type_supported(ActivitySessionType type) {
  return type == ActivitySessionType_Walk ||
         type == ActivitySessionType_Run ||
         type == ActivitySessionType_Open;
}

// ---------------------------------------------------------------------------------------
T_STATIC void prv_abandon_workout_timer_callback(void *unused) {
  workout_service_stop_workout();
}

// ---------------------------------------------------------------------------------------
T_STATIC void prv_abandoned_notification_timer_callback(void *unused) {
  workout_utils_send_abandoned_workout_notification();

  s_workout_data.current_workout->workout_abandoned_timer =
      evented_timer_register(WORKOUT_ABANDON_WORKOUT_TIMEOUT_MS, false,
                             prv_abandon_workout_timer_callback, NULL);
}

// ---------------------------------------------------------------------------------------
T_STATIC void prv_workout_timer_cb(void *unused) {
  if (!workout_service_is_workout_ongoing()) {
    return;
  }

  prv_lock();
  {
    // Update the duration
    prv_update_duration();

    // Check to make sure our HR sample is still valid
    const time_t now_ts = time_get_uptime_seconds();
    const time_t age_hr_s = now_ts - s_workout_data.current_workout->current_bpm_timestamp_ts;
    if (s_workout_data.current_workout->current_bpm != 0 &&
        age_hr_s >= WORKOUT_HR_READING_TS_EXPIRE) {
      // Reset HR reading. It has expired
      prv_reset_hr_data();
    }
  }
  prv_unlock();
}

// ---------------------------------------------------------------------------------------
void workout_service_health_event_handler(PebbleHealthEvent *event) {
  if (!workout_service_is_workout_ongoing()) {
    return;
  }

  prv_lock();
  {
    if (event->type == HealthEventMovementUpdate) {
      prv_handle_movement_update(&event->data.movement_update);
    } else if (event->type == HealthEventHeartRateUpdate) {
      prv_handle_heart_rate_update(&event->data.heart_rate_update);
    }
  }
  prv_unlock();
}

// ---------------------------------------------------------------------------------------
void workout_service_activity_event_handler(PebbleActivityEvent *event) {
  if (!workout_service_is_workout_ongoing()) {
    return;
  }

  if (event->type == PebbleActivityEvent_TrackingStopped) {
    workout_service_pause_workout(true);
  }
}

// ---------------------------------------------------------------------------------------
void workout_service_workout_event_handler(PebbleWorkoutEvent *event) {
  if (!workout_service_is_workout_ongoing()) {
    return;
  }

  // Handling this with an event because the timer needs to be called from KernelMain
  if (event->type == PebbleWorkoutEvent_FrontendOpened) {
    evented_timer_cancel(s_workout_data.current_workout->workout_abandoned_timer);
  } else if (event->type == PebbleWorkoutEvent_FrontendClosed) {
    s_workout_data.current_workout->workout_abandoned_timer =
        evented_timer_register(WORKOUT_ABANDONED_NOTIFICATION_TIMEOUT_MS, false,
                               prv_abandoned_notification_timer_callback, NULL);
  }
}

// ---------------------------------------------------------------------------------------
void workout_service_init(void) {
  s_workout_data.s_workout_mutex = mutex_create_recursive();
}

// ---------------------------------------------------------------------------------------
// FIXME: We should probably handle this on KernelBG and not use the official app subscription
void workout_service_frontend_opened(void) {
  PBL_ASSERT_TASK(PebbleTask_App);
  prv_lock();
  {
#if CAPABILITY_HAS_BUILTIN_HRM
    s_workout_data.hrm_session =
        sys_hrm_manager_app_subscribe(app_get_app_id(), 1, 0, HRMFeature_BPM);
#endif // CAPABILITY_HAS_BUILTIN_HRM
    s_workout_data.frontend_last_opened_ts = time_get_uptime_seconds();
    prv_put_event(PebbleWorkoutEvent_FrontendOpened);
  }
  prv_unlock();
}


// ---------------------------------------------------------------------------------------
// FIXME: We should probably handle this on KernelBG and not use the official app subscription
void workout_service_frontend_closed(void) {
  PBL_ASSERT_TASK(PebbleTask_App);
  prv_lock();
  {
    int32_t hr_time_left;

    if (workout_service_is_workout_ongoing()) {
      // The workout app can be closed without stopping the workout. In this scenario keep
      // collecting HR data until so much time has passed that it is assumed the user has forgotten
      // about the workout
      hr_time_left = WORKOUT_ACTIVE_HR_SUBSCRIPTION_TS_EXPIRE;
    } else if (s_workout_data.frontend_last_opened_ts >= s_workout_data.last_workout_end_ts) {
      // If the app was opened and closed without starting a workout, turn the HR sensor off
      hr_time_left = 0;
    } else {
      // We have ended a workout while the app was open. Make sure to keep the HR sensor on for at
      // least a little bit after the workout is finished
      const time_t now_ts = time_get_uptime_seconds();
      const time_t time_since_workout = (now_ts - s_workout_data.last_workout_end_ts);

      // After a workout has finished, keep the HR sensor on for a bit to capture the user's HR
      // returning to a normal level.
      hr_time_left = WORKOUT_ENDED_HR_SUBSCRIPTION_TS_EXPIRE - time_since_workout;
    }

#if CAPABILITY_HAS_BUILTIN_HRM
    if (hr_time_left > 0) {
      // Still some time left. Set a subscription with an expiration
      s_workout_data.hrm_session =
          sys_hrm_manager_app_subscribe(app_get_app_id(), 1, hr_time_left, HRMFeature_BPM);
    } else {
      // No time left. Kill the subscription
      sys_hrm_manager_unsubscribe(s_workout_data.hrm_session);
    }
#endif // CAPABILITY_HAS_BUILTIN_HRM

    prv_put_event(PebbleWorkoutEvent_FrontendClosed);
  }
  prv_unlock();
}


// ---------------------------------------------------------------------------------------
bool workout_service_start_workout(ActivitySessionType type) {
  bool rv = true;
  prv_lock();
  {
    if (!workout_service_is_workout_type_supported(type)) {
      rv = false;
      goto unlock;
    }

    if (workout_service_is_workout_ongoing()) {
      PBL_LOG(LOG_LEVEL_WARNING, "Only 1 workout at a time is supported");
      rv = false;
      goto unlock;
    }

    // Before starting this new session we need to deal with any in progress sessions
    uint32_t num_sessions = 0;
    ActivitySession *sessions = kernel_zalloc_check(sizeof(ActivitySession) *
                                                    ACTIVITY_MAX_ACTIVITY_SESSIONS_COUNT);
    activity_get_sessions(&num_sessions, sessions);
    for (unsigned i = 0; i < num_sessions; i++) {
      // End and save any automatically detected ongoing sessions
      if (sessions[i].ongoing) {
        sessions[i].ongoing = false;
        activity_sessions_prv_add_activity_session(&sessions[i]);
      }
    }
    kernel_free(sessions);

    s_workout_data.current_workout = kernel_zalloc_check(sizeof(CurrentWorkoutData));
    s_workout_data.current_workout->type = type;
    s_workout_data.current_workout->start_utc = rtc_get_time();
    s_workout_data.current_workout->current_bpm_timestamp_ts = time_get_uptime_seconds();
    // FIXME: This probably doesn't need to be on a timer. We can just flush out a new time on each
    // API function call
    s_workout_data.second_timer = (RegularTimerInfo) {
      .cb = prv_workout_timer_cb,
    };

    // Initialize all of our initial values for keeping track of metrics
    activity_get_metric(ActivityMetricStepCount, 1,
                        &s_workout_data.current_workout->last_event_step_count);
    s_workout_data.current_workout->last_movement_event_time_ts = time_get_uptime_seconds();

    regular_timer_add_seconds_callback(&s_workout_data.second_timer);

    // Finally tell our algorithm it should stop automatically tracking activities
    activity_algorithm_enable_activity_tracking(false /* disable */);

    PBL_LOG(LOG_LEVEL_INFO, "Starting a workout with type: %d", type);
    prv_put_event(PebbleWorkoutEvent_Started);
  }
unlock:
  prv_unlock();
  return rv;
}

// ---------------------------------------------------------------------------------------
bool workout_service_pause_workout(bool should_be_paused) {
  if (workout_service_is_paused() == should_be_paused) {
    // If no change in state, return early and successful
    return true;
  }

  if (!workout_service_is_workout_ongoing()) {
    PBL_LOG(LOG_LEVEL_WARNING, "Workout (un)pause requested but no workout in progress");
    return false;
  }

  prv_lock();
  {
    CurrentWorkoutData *wrkt_data = s_workout_data.current_workout;

    if (workout_service_is_paused()) {
      // We are paused and want to unpause. Add the in progress pause time to the total
      wrkt_data->duration_completed_pauses_s += (rtc_get_time() - wrkt_data->last_paused_utc);
    } else {
      // We are unpaused and want to pause. Set the last_paused_utc timestamp
      wrkt_data->last_paused_utc = rtc_get_time();
    }

    s_workout_data.current_workout->paused = should_be_paused;

    // Update the global duration since we have changed the pause state
    prv_update_duration();
    PBL_LOG(LOG_LEVEL_INFO, "Paused a workout with type: %d", wrkt_data->type);
    prv_put_event(PebbleWorkoutEvent_Paused);
  }
  prv_unlock();
  return true;
}

// ---------------------------------------------------------------------------------------
bool workout_service_stop_workout(void) {
  bool rv = true;
  prv_lock();
  {
    if (!workout_service_is_workout_ongoing()) {
      PBL_LOG(LOG_LEVEL_WARNING, "No workout in progress");
      rv = false;
      goto unlock;
    }

    // Create an activity session for this workout if it was long enough
    if (s_workout_data.current_workout->duration_s >= SECONDS_PER_MINUTE) {
      const time_t len_min =
          MIN(ACTIVITY_SESSION_MAX_LENGTH_MIN,
              s_workout_data.current_workout->duration_s / SECONDS_PER_MINUTE);

      ActivitySession session = {
        .type = s_workout_data.current_workout->type,
        .start_utc = s_workout_data.current_workout->start_utc,
        .length_min = len_min,
        .ongoing = false,
        .manual = true,
        .step_data.steps = s_workout_data.current_workout->steps,
        .step_data.distance_meters = s_workout_data.current_workout->distance_m,
        .step_data.active_kcalories = ROUND(s_workout_data.current_workout->active_calories,
                                            ACTIVITY_CALORIES_PER_KCAL),
        .step_data.resting_kcalories = ROUND(activity_private_compute_resting_calories(len_min),
                                             ACTIVITY_CALORIES_PER_KCAL),
      };
      activity_sessions_prv_add_activity_session(&session);

      activity_insights_push_activity_session_notification(rtc_get_time(), &session,
          prv_get_avg_hr(), s_workout_data.current_workout->hr_zone_time_s);

      s_workout_data.last_workout_end_ts = time_get_uptime_seconds();
    }

    regular_timer_remove_callback(&s_workout_data.second_timer);

    // Re-enable automatic activity tracking
    activity_algorithm_enable_activity_tracking(true /* enable */);

    PBL_LOG(LOG_LEVEL_INFO, "Stopping a workout with type: %d",
            s_workout_data.current_workout->type);
    prv_put_event(PebbleWorkoutEvent_Stopped);

    kernel_free(s_workout_data.current_workout);
    s_workout_data.current_workout = NULL;
  }
unlock:
  prv_unlock();
  return rv;
}

// ---------------------------------------------------------------------------------------
bool workout_service_is_workout_ongoing(void) {
  prv_lock();
  bool rv = (s_workout_data.current_workout != NULL);
  prv_unlock();
  return rv;
}

// ---------------------------------------------------------------------------------------
bool workout_service_takeover_activity_session(ActivitySession *session) {
  bool rv = true;
  prv_lock();
  {
    if (!workout_service_is_workout_type_supported(session->type)) {
      rv = false;
      goto unlock;
    }

    ActivitySession session_copy = *session;

    // Remove the session from out list of sessions so it doesn't get counted twice
    activity_sessions_prv_delete_activity_session(session);

    // Start a new workout
    if (!workout_service_start_workout(session_copy.type)) {
      rv = false;
      goto unlock;
    }

    // Update the new workout to mirror the session we took over
    s_workout_data.current_workout->start_utc = session_copy.start_utc;
    s_workout_data.current_workout->duration_s = session_copy.length_min * SECONDS_PER_MINUTE;
    s_workout_data.current_workout->steps = session_copy.step_data.steps;
    s_workout_data.current_workout->distance_m = session_copy.step_data.distance_meters;
    s_workout_data.current_workout->active_calories =
        session_copy.step_data.active_kcalories * ACTIVITY_CALORIES_PER_KCAL;
  }
unlock:
  prv_unlock();
  return rv;
}

// ---------------------------------------------------------------------------------------
bool workout_service_is_paused(void) {
  prv_lock();
  bool rv = (workout_service_is_workout_ongoing() && s_workout_data.current_workout->paused);
  prv_unlock();
  return rv;
}


// ---------------------------------------------------------------------------------------
bool workout_service_get_current_workout_type(ActivitySessionType *type_out) {
  bool rv = true;
  prv_lock();
  if (!type_out || !workout_service_is_workout_ongoing()) {
    rv = false;
  } else {
    if (type_out) {
      *type_out = s_workout_data.current_workout->type;
    }
  }
  prv_unlock();
  return rv;
}

// ---------------------------------------------------------------------------------------
bool workout_service_get_current_workout_info(int32_t *steps_out, int32_t *duration_s_out,
                                              int32_t *distance_m_out, int32_t *current_bpm_out,
                                              HRZone *current_hr_zone_out) {
  bool rv = true;
  prv_lock();
  {
    if (!workout_service_is_workout_ongoing()) {
      rv = false;
    } else {
      if (steps_out) {
        *steps_out = s_workout_data.current_workout->steps;
      }
      if (duration_s_out) {
        *duration_s_out = s_workout_data.current_workout->duration_s;
      }
      if (distance_m_out) {
        *distance_m_out = s_workout_data.current_workout->distance_m;
      }
      if (current_bpm_out) {
        *current_bpm_out = s_workout_data.current_workout->current_bpm;
      }
      if (current_hr_zone_out) {
        *current_hr_zone_out = s_workout_data.current_workout->current_hr_zone;
      }
    }
  }
  prv_unlock();
  return rv;
}

#if UNITTEST
bool workout_service_get_avg_hr(int32_t *avg_hr_out) {
  if (!avg_hr_out || !workout_service_is_workout_ongoing()) {
    return false;
  }

  *avg_hr_out = prv_get_avg_hr();
  return true;
}

bool workout_service_get_current_workout_hr_zone_time(int32_t *hr_zone_time_s_out) {
  if (!hr_zone_time_s_out || !workout_service_is_workout_ongoing()) {
    return false;
  }

  prv_lock();
  {
    hr_zone_time_s_out[HRZone_Zone0] = s_workout_data.current_workout->hr_zone_time_s[HRZone_Zone0];
    hr_zone_time_s_out[HRZone_Zone1] = s_workout_data.current_workout->hr_zone_time_s[HRZone_Zone1];
    hr_zone_time_s_out[HRZone_Zone2] = s_workout_data.current_workout->hr_zone_time_s[HRZone_Zone2];
    hr_zone_time_s_out[HRZone_Zone3] = s_workout_data.current_workout->hr_zone_time_s[HRZone_Zone3];
  }
  prv_unlock();
  return true;
}

void workout_service_get_active_kcalories(int32_t *active) {
  if (workout_service_is_workout_ongoing()) {
    *active = ROUND(s_workout_data.current_workout->active_calories, ACTIVITY_CALORIES_PER_KCAL);
  }
}

void workout_service_reset(void) {
  if (s_workout_data.current_workout) {
    kernel_free(s_workout_data.current_workout);
  }
  s_workout_data = (WorkoutServiceData) {};
}
#endif