#include "queue.h"

queue q_new() {
  queue q = {0};
  q.front = q.rear = Q_EMPTY_IDX;
  return q;
}

// check if q is empty
bool q_is_empty(queue *q) {
  return q->front == Q_EMPTY_IDX;
}

// check if q is full
bool q_is_full(queue *q) {
  return (q->rear + 1) % Q_MAX_SIZE == q->front;
}

// enqueue item to q
// RETURNS Q_FULL if q is full
// RETURNS Q_DONE if successful
int q_enqueue(queue *q, void *item) {
  if (q_is_full(q)) return Q_FULL;

  if (q->front == Q_EMPTY_IDX) q->front = 0;

  q->rear = (q->rear + 1) % Q_MAX_SIZE;
  q->items[q->rear] = item;
  return Q_DONE;
}

// dequeue q
// RETURNS NULL pointer if q is empty
void *q_dequeue(queue *q) {
  if (q_is_empty(q)) return Q_NULL;

  void *item = q->items[q->front];

  if (q->front == q->rear) q->front = q->rear = Q_EMPTY_IDX;
  else q->front = (q->front + 1) % Q_MAX_SIZE;

  return item;
}

// peek at q
// RETURNS NULL pointer if q is empty
void *q_peek(queue *q) {
  if (q_is_empty(q)) return Q_NULL;
  return q->items[q->front];
}

#ifdef KK_DEBUG_

#include <stdio.h>
#include "draw.h"

void q_print_type_enum(int e) {
  switch (e) {
    case DRAW:
      printf("DRAW");
      break;
    case MOVEV:
      printf("MOVEV");
      break;
    case MOVEH:
      printf("MOVEH");
      break;
    case SETL:
      printf("SETL");
      break;
    case SETX:
      printf("SETX");
      break;
    case SWITCH:
      printf("SWITCH");
      break;
    case AUTO_PAGING:
      printf("AUTO_PAGING");
      break;
    case POPULATE_W:
      printf("POPULATE_W");
      break;
  }
  printf(" ");
}

void q_debug(queue *q) {
  printf("[Q: ");
  if (q_is_empty(q)) goto end;
  int i = q->front;
  while (i != q->rear) {
    if (q->items[i] == NULL) {
      printf("NULL ");
    } else {
      int v = ((dtask *) q->items[i])->type;
      q_print_type_enum(v);
    }
    i = (i + 1) % Q_MAX_SIZE;
  }
  int v = ((dtask *) q->items[i])->type;
  q_print_type_enum(v);
end:
  printf("]");
  fflush(stdout);
}
#endif // KK_DEBUG_