/*
 * 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 "util/list.h"
#include "services/common/event_service.h"
#include "kernel/kernel_applib_state.h"

#include "event_service_client.h"
#include "process_management/app_manager.h"
#include "util/list.h"
#include "applib/app_logging.h"
#include "process_state/app_state/app_state.h"
#include "process_state/worker_state/worker_state.h"

#include "syscall/syscall.h"
#include "system/logging.h"
#include "system/passert.h"


static EventServiceInfo *prv_get_state(void) {
  PebbleTask task = pebble_task_get_current();
  if (task == PebbleTask_App) {
    return app_state_get_event_service_state();
  } else if (task == PebbleTask_Worker) {
    return worker_state_get_event_service_state();
  } else if (task == PebbleTask_KernelMain) {
    return kernel_applib_get_event_service_state();
  } else {
    WTF;
  }
}

static int event_service_comparator(EventServiceInfo *a, EventServiceInfo *b) {
  return (b->type - a->type);
}

bool event_service_filter(ListNode *node, void *tp) {
  EventServiceInfo *info = (EventServiceInfo *)node;
  uint32_t type = (uint32_t)tp;
  return (info->type == type);
}

static void do_handle(EventServiceInfo *info, PebbleEvent *e) {
  PBL_ASSERTN(info->handler != NULL);
  info->handler(e, info->context);
}

void event_service_client_subscribe(EventServiceInfo *handler) {
  EventServiceInfo *state = prv_get_state();
  ListNode *list = &state->list_node;
  if (list_contains(list, &handler->list_node)) {
    PBL_LOG(LOG_LEVEL_DEBUG, "Event service handler already subscribed");
    return;
  }
  // Add to handlers list
  list_sorted_add(list, &handler->list_node, (Comparator)event_service_comparator, true);

  sys_event_service_client_subscribe(handler);
}

void event_service_client_unsubscribe(EventServiceInfo *handler) {
  EventServiceInfo *state = prv_get_state();
  ListNode *list = &state->list_node;
  if (!list_contains(list, &handler->list_node)) {
    PBL_LOG(LOG_LEVEL_DEBUG, "Event service handler not subscribed");
    return;
  }
  sys_event_service_client_unsubscribe(state, handler);
}

void event_service_client_handle_event(PebbleEvent *e) {
  EventServiceInfo *state = prv_get_state();
  const uintptr_t type = e->type;
  // find the first callback
  ListNode *handler = list_find(&state->list_node, event_service_filter, (void *) type);
  while (handler) {
    // find the next callback before we call the current one, because the CB may alter the list
    ListNode *next_handler = list_find_next(handler, event_service_filter, false, (void *) type);
    do_handle((EventServiceInfo *)handler, e);
    handler = next_handler;
  }

  sys_event_service_cleanup(e);
}