#include "list_ops.h"
#include <string.h>
// constructs a new list
list_t *new_list(size_t length, list_element_t elements[]){
	list_t* list = (list_t*)malloc(sizeof(list_t) + length * sizeof(list_element_t));
	list->length = length;
	//list->elements = list + sizeof(list_t);
	memcpy(list->elements,elements, length*sizeof(list_element_t));
	return list;
}

// append entries to a list and return the new list
list_t *append_list(list_t *list1, list_t *list2){
//	list3.lenght=list1->lenght+list2->lenght;
	list_t* list3 = (list_t*)malloc(sizeof(list_t) + (list1->length+list2->length) * sizeof(list_element_t));
        list3->length = list1->length+list2->length;
        //list->elements = list + sizeof(list_t);
        memcpy(list3->elements,list1->elements, list1->length*sizeof(list_element_t));
	memcpy(list3->elements+list1->length,list2->elements, list2->length*sizeof(list_element_t));

        return list3;
}

// filter list returning only values that satisfy the filter function
list_t *filter_list(list_t *list, bool (*filter)(list_element_t)){
	for(size_t i=0; i<list->length; i++){
		if(!filter(list->elements[i])){
			for (size_t j = i; j < list->length - 1; j++) {
       				list->elements[j] = list->elements[j + 1];
			}
			list->length=list->length-1;
		}
	}
	list_t *list_new = (list_t*)malloc(sizeof(list_t) + list->length * sizeof(list_element_t));
	list_new->length=list->length;
	memcpy(list_new->elements,list->elements, list->length*sizeof(list_element_t));
//	list_t *result = (list_t*)malloc(sizeof(list_t) + 10 * sizeof(list_element_t));
  return list_new;

}

// returns the length of the list
size_t length_list(list_t *list){

  return list->length;

}

// return a list of elements whose values equal the list value transformed by
// the mapping function
list_t *map_list(list_t *list, list_element_t (*map)(list_element_t)){
	for(size_t i=0; i<list->length; i++){
		list->elements[i]=map(list->elements[i]);
	}
  list_t *list_new = (list_t*)malloc(sizeof(list_t) + list->length * sizeof(list_element_t));
        list_new->length=list->length;
        memcpy(list_new->elements,list->elements, list->length*sizeof(list_element_t));	
  return list_new;

}

// folds (reduces) the given list from the left with a function
list_element_t foldl_list(list_t *list, list_element_t initial,list_element_t (*foldl)(list_element_t,list_element_t)){
	list_element_t fold_step=initial;
	for(size_t i=0; i<list->length; i++){
		fold_step=foldl(fold_step,list->elements[i]);
	}
  return fold_step;

}

// folds (reduces) the given list from the right with a function
list_element_t foldr_list(list_t *list, list_element_t initial,list_element_t (*foldr)(list_element_t,list_element_t)){
	list_element_t fold_step=initial;
	if(list->length>0){
        	for(size_t i=list->length-1; i!=0; i--){
                	fold_step=foldr(list->elements[i],fold_step);
        	}
			fold_step=foldr(list->elements[0],fold_step);
	}
  return fold_step;

}

// reverse the elements of the list
list_t *reverse_list(list_t *list){
	list_t *list_new = (list_t*)malloc(sizeof(list_t) + list->length * sizeof(list_element_t));
        list_new->length=list->length;
	size_t i,j;
	for( i=list->length-1 , j=0 ; j<list->length; j++, i--){
		list_new->elements[i]=list->elements[j];
	}
  return list_new;

}

// destroy the entire list
// list will be a dangling pointer after calling this method on it
void delete_list(list_t *list){
	free(list);
}