#include "Index.h"
#include <stdlib.h>
#include <string.h>

int initIndex(struct Index *index, int size) {
  if (index == NULL) {
    return 1;
  }
  if (size <= 0) {
    index->size = 0;
    index->bias = 0;
    index->ids = NULL;
    return 2;
  }
  index->size = size;
  index->bias = size / 2;
  index->ids = malloc(sizeof(char)*size);
  memset(index->ids, 0, sizeof(char)*size);
  return 0;
}
//
int clearIndex(struct Index *index) {
  index->bias = 0;
  index->size = 0;
  free(index->ids);
  index->ids = NULL;
  return 0;
}
/* grow adds given size to index's current size, e.g., "index + 2" */
int growIndex(struct Index *index, int size) {
  if (index == NULL) {
    return 1;
  }
  if (size <= 0) {
    return 2;
  }
  if ((index->ids = realloc(index->ids, index->size+size)) == NULL) {
    return 3;
  }
  int i;
  for(i = index->size;i < index->size+size;i++) {
    index->ids[i] = 0;
  }
  if (index->bias == 0) {
    index->bias = size/2;
  } else {
    index->bias = (index->bias + ((index->size+size)/2)) / 2; //FIXME
  }
  index->size += size;
  return 0;
}

int remIndex(struct Index *index, int id) {
  if (index == NULL) {
    return 1;
  }
  if (id < 0 || id >= index->size) {
    return 2;
  }
  index->bias += (id < index->size/2 ? -1 : 1);
  index->ids[id] = 0;
  return 0;
}

int addIndex(struct Index *index, int id) {
  if (index == NULL) {
    return 1;
  }
  if (id < 0 || id >= index->size) {
    return 2;
  }
  index->bias += (id < index->size/2 ? 1 : -1);
  index->ids[id] = 1;
  return 0;
}

int toggleIndex(struct Index *index, int id) {
  if (index == NULL) {
    return 1;
  }
  if (id < 0 || id >= index->size) {
    return 2;
  }
  int state = index->ids[id];
  if (state == 0) {
    index->bias -= (id < index->size/2 ? -1 : 1);
    index->ids[id] = 1;
  } else {
    index->bias += (id < index->size/2 ? -1 : 1);
    index->ids[id] = 0;
  }
  return 0;
}

int getIndex(struct Index *index, int id) {
  if (index == NULL) {
    return -1;
  }
  if (id < 0 || id >= index->size) {
    return -2;
  }
  return index->ids[id];
}

int acquireIndex(struct Index *index) {
  if (index == NULL) {
    return -1;
  }
  if (index->size == 0) {
    return -2;
  }
  // TODO: replace this with some magick that returns 0 or 1 from bias from center and searches towards that
  // TODO: don't start from left or right totally, but start with an offset that complements the bias
  /*int start, end, inc; // search start, end, and increment value respectively
  if (index->bias > index->size/2) {
    start = 0;
    end = index->size-1;
    inc = -1;
  } else {
    start = index->size-1;
    end = 0;
    inc = 1;
  }
  //printf("bias: %d, start: %d\n", index->bias, start);
  int i;
  for (i = start;i != end;i += inc) {
    if (index->ids[i] == 0) {
      return i;
    }
  }*/
  int i;
  for(i = 0; i < index->size; i++) {
    if (index->ids[i] == 0) {
      return i;
    }
  }
  return -2;
}