#define _POSIX_C_SOURCE 200809L
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "fileQueue.h"
#include "util.h"

#define MAXNAMELEN 512

/* create a fileT file */
fileT* createFileT(char *f, int O_LOCK, int client, int open) {
    if(!f){
	errno = EINVAL;
	return NULL;
    }

    fileT *file = malloc(sizeof(fileT));

    if (file == NULL) {
	perror("createFileT: malloc");
	return NULL;
    }

    file->O_LOCK = (O_LOCK == 0)? 0 : 1;
    file->owner = client;
    file->open = (open == 0)? 0 : 1;
    file->size = 0;
    file->valid = 0;

    file->filepath = calloc(strnlen(f, MAXNAMELEN)+1, sizeof(char));
    if (file->filepath == NULL) {
	perror("createFileT: malloc");
	destroyFile(file);
	return NULL;
    }

    strncpy(file->filepath, f, strnlen(f, MAXNAMELEN));

    /* after a realloc is enough */
    if ((file->data = calloc(1, sizeof(char))) == NULL) {
	perror("createFileT: calloc");
	return NULL;
    }
    return file;
}

/* append on fileT */
int writeFileT(fileT *f, void *data, size_t size) {
    if(!f || !data || size < 0){
	errno = EINVAL;
	return -1;
    }

    if(size == 0) {
	return 0;
    }

    if ((f->data = realloc(f->data, f->valid + size)) == NULL) {
	perror("writeFileT: realloc");
	return -1;
    }

    memcpy((char*) f->data + f->valid, data, size);
    f->valid = f->valid + size;
    f->size = (f->valid>f->size)?f->valid:f->size;
    return 0;
}

/* destroy fileT */
void destroyFile(fileT *f) {
    if(!f)
	return;
    if(f->filepath)
	free(f->filepath);
    if(f->data)
	free(f->data);
    free(f);
}

// -----------------------------------------------------------------------------

/* create queue */
queueT* createQueue(size_t maxLen, size_t maxSize) {
    if(maxLen<0 || maxSize<0){
	errno = EINVAL;
	return NULL;
    }

    queueT *q = malloc(sizeof(queueT));
    if(q==NULL){
	perror("createQueue: malloc");
	return NULL;
    }

    /* create lock */
    if (pthread_mutex_init(&q->m, NULL) != 0) {
	perror("createQueue: pthread_mutex_init");
	destroyQueue(q);
	return NULL;
    }

    q->head = NULL;
    q->tail = NULL;
    q->maxLen = maxLen;
    q->len = 0;
    q->maxSize = maxSize;
    q->size = 0;

    return q;
}

/* insert into the queue */
int enqueue(queueT *q, fileT* data) {
    if(!q || !data){
	errno = EINVAL;
	return -1;
    }

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == q->maxLen) { /* too many files */
	errno = ENFILE;
	goto _end_enqueue;
    }

    if (q->size + data->size > q->maxSize) {
	errno = EFBIG;
	goto _end_enqueue;
    }

    /* insert the element at the end */
    nodeT *newNode = malloc(sizeof(nodeT));
    if (newNode == NULL) {
	perror("enqueue: malloc");
	goto _end_enqueue;
    }

    newNode->data = data;
    newNode->next = NULL;
    nodeT *tmp = q->head;

    if (q->head == NULL)
	q->head = newNode;
    else {
	while (tmp->next)
	    tmp = tmp->next;

	tmp->next = newNode;
    }

    q->tail = newNode;

    ++q->len;
    q->size += data->size;

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_enqueue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}

/* dequeue one element */
fileT* dequeue(queueT *q) {
    if(!q) {
	errno = EINVAL;
	return NULL;
    }

    LOCK_RETURN(&q->m, NULL); /* begin me */

    if (q->head == NULL || q->len == 0) { /* empty queue */
	errno = ENOENT;
	goto _end_dequeue;
    }

    fileT *data = (q->head)->data;

    /* dequeue the first in the list */
    nodeT *tmp = NULL;
    tmp = q->head;
    q->head = (q->head)->next;

    if (q->head == NULL) { /* queue becomes empty */
	q->tail = NULL;
    }

    --q->len;
    q->size -= data->size;
    free(tmp); /* free of the node */

    UNLOCK_RETURN(&q->m, NULL); /* end me */
    return data;

_end_dequeue:
    UNLOCK_RETURN(&q->m, NULL);
    return NULL;
}

/* dequeue until we have s free space and expand the file by s */
fileT ** dequeueN(queueT *q, char *filepath, size_t s) {
    if(!q) {
	errno = EINVAL;
	return NULL;
    }
    if(s<=0) {
	return NULL;
    }

    LOCK_RETURN(&q->m, NULL); /* begin me */

    fileT **returnList = NULL; /* list of removed files */

    if (q->head == NULL || q->len == 0) { /* empty queue */
	errno = ENOENT;
	goto _end_dequeueN;
    }

    if(q->maxSize < s) {
	errno = EINVAL;
	goto _end_dequeueN;
    }

    /* try to find the file */
    nodeT *tmp = q->head;
    /* if LRU keep track of previous */
#if ALGORITHM == 1
    nodeT *prev = NULL;
#endif

    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	/* if LRU keep track of previous */
#if ALGORITHM == 1
	prev = tmp;
#endif
	tmp = tmp->next;
    }

    if(!tmp) { /* not found */
	errno = ENOENT;
	goto _end_dequeueN;
    }

    nodeT* file = tmp;

    /* if LRU put the file at the end */
#if ALGORITHM == 1
    if(prev==NULL && tmp->next==NULL) {
	q->head = tmp;
	q->tail = tmp;
    } else if(prev==NULL) {
	q->head = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    } else if(tmp->next!=NULL) {
	prev->next = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    }
#endif /* ALGORITHM == 1 */

    tmp = q->head;

    returnList = calloc(1, sizeof(*returnList));
    if(!returnList) {
	perror("dequeueN: calloc");
	goto _end_dequeueN;
    }

    int purged = 0;
    int addFileAtEnd = 0;
    while(q->size + s > q->maxSize) {
	if (q->head == NULL) { /* queue becomes empty */
	    q->tail = NULL;
	    break; /* we eliminated everything so we must have enought space */
	}
	if(q->head == file) { /* dont delete the file to expand */
	    q->head = q->head->next;
	    addFileAtEnd = 1;
	}

	tmp = q->head;
	q->head = q->head->next;

	++purged;
	returnList = realloc(returnList, purged * sizeof(fileT*));
	if(!returnList) {
	    perror("dequeueN: realloc");
	    goto _end_dequeueN;
	}
	returnList[purged-1] = tmp->data;
	--q->len;
	q->size -= tmp->data->size;
	free(tmp); /* free of the node */
    }
    if(addFileAtEnd == 1) {
	/* if LRU, we know already that this code is unrechable
	 * and that q->head must be NULL if rechable */
	if(q->head == NULL) {
	    q->head = file;
	    q->head->next = NULL;
	} else {
	    file->next = q->head;
	    q->head = file;
	}
    }

    returnList = realloc(returnList, (purged+1) * sizeof(fileT*));
    if(!returnList) {
	perror("dequeueN: realloc");
	goto _end_dequeueN;
    }
    returnList[purged] = NULL; /* null terminated */

    file->data->size += s;
    q->size += s;

    UNLOCK_RETURN(&q->m, NULL); /* end me */
    return returnList;

_end_dequeueN:
    UNLOCK_RETURN(&q->m, NULL);
    if(returnList)
	free(returnList);
    return NULL;
}

void voidDequeue(queueT *q) {
    if(!q) {
	errno = EINVAL;
	return;
    }

    LOCK(&q->m); /* begin me */

    if (q->head == NULL || q->len == 0) { /* empty queue */
	errno = ENOENT;
	goto _end_void_dequeue;
    }

    nodeT *tmp = NULL;
    tmp = q->head;

    q->head = (q->head)->next;

    if (q->head == NULL) { /* queue becomes empty */
	q->tail = NULL;
    }

    --q->len;
    q->size -= (tmp->data)->size;

    destroyFile(tmp->data); /* free fileT */
    free(tmp); /* free node */

    UNLOCK(&q->m); /* end me */
    return;

_end_void_dequeue:
    UNLOCK(&q->m);
    return;
}

/* print queue */
int printQueue(FILE *stream, queueT *q) {
    if(!q || !stream) {
	errno = EINVAL;
	return -1;
    }

    LOCK_RETURN(&q->m, -1); /* begin me */

    nodeT *tmp = q->head;

    fprintf(stream, "Lista file:\n");
    fprintf(stream, "[Nome File] -> Dimensione in MB\n");
    while (tmp!=NULL) {
	float res = ((float)(tmp->data)->size)/1000000; /* in MB */
	// float res = ((float)(tmp->data)->valid)/1000000; /* in MB */
	fprintf(stream, "[%s] -> %f MB\n", (tmp->data)->filepath, res);
	tmp = tmp->next;
    }

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;
}

/* acquire lock */
int lockFileInQueue(queueT *q, char *filepath, int owner) {
    if(!q || !filepath) {
	errno = EINVAL;
	return -1;
    }

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == 0) {
	errno = ENOENT;
	goto _end_lock_file_queue;
    }

    /* find file */
    nodeT *tmp = q->head;
    /* if LRU keep track of previous */
#if ALGORITHM == 1
    nodeT *prev = NULL;
#endif

    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	/* if LRU keep track of previous */
#if ALGORITHM == 1
	prev = tmp;
#endif
	tmp = tmp->next;
    }

    if(!tmp) { /* not found */
	errno = ENOENT;
	goto _end_lock_file_queue;
    }

    /* lock already aquired by another client */
    if ((tmp->data)->O_LOCK && (tmp->data)->owner != owner) {
	errno = EPERM;
	goto _end_lock_file_queue;
    }

    /* aquire lock on the file */
    (tmp->data)->O_LOCK = 1;
    (tmp->data)->owner = owner;

    /* if LRU put the file at the end */
#if ALGORITHM == 1
    if(prev==NULL && tmp->next==NULL) {
	q->head = tmp;
	q->tail = tmp;
    } else if(prev==NULL) {
	q->head = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    } else if(tmp->next!=NULL) {
	prev->next = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    }
#endif /* ALGORITHM == 1 */


    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_lock_file_queue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}


int unlockFileInQueue(queueT *q, char *filepath, int owner) {
    if(!q || !filepath) {
	errno = EINVAL;
	return -1;
    }

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == 0) {
	errno = ENOENT;
	goto _end_unlock_file_queue;
    }

    /* find the file */
    nodeT *tmp = q->head;

    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	tmp = tmp->next;
    }

    if(!tmp) { /* not found */
	errno = ENOENT;
	goto _end_unlock_file_queue;
    }

    if((tmp->data)->O_LOCK == 0) { /* no one has the lock */
	UNLOCK_RETURN(&q->m, -1);
	return 0;
    }

    /* another client holds the lock */
    if((tmp->data)->O_LOCK == 1 && (tmp->data)->owner != owner) {
	errno = EPERM;
	goto _end_unlock_file_queue;
    }

    (tmp->data)->O_LOCK = 0;

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_unlock_file_queue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}


/* open file */
int openFileInQueue(queueT *q, char *filepath, int O_LOCK, int owner) {
    if(!q || !filepath) {
	errno = EINVAL;
	return -1;
    }

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == 0) {
	errno = ENOENT;
	goto _end_open_file_queue;
    }

    /* find the file */
    nodeT *tmp = q->head;
    /* if LRU keep track of previous */
#if ALGORITHM == 1
    nodeT *prev = NULL;
#endif

    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	/* if LRU keep track of previous */
#if ALGORITHM == 1
	prev = tmp;
#endif
	tmp = tmp->next;
    }

    if(!tmp) { /* not found */
	errno = ENOENT;
	goto _end_open_file_queue;
    }

    /* lock aquired by another client */
    if((tmp->data)->O_LOCK == 1 && (tmp->data)->owner != owner) {
	errno = EPERM;
	goto _end_open_file_queue;
    }

    (tmp->data)->open = 1;
    (tmp->data)->O_LOCK = (O_LOCK==0)?0:1;

    if(O_LOCK!=0) {
	(tmp->data)->owner = owner;
    }

    /* if LRU put the file at the end */
#if ALGORITHM == 1
    if(prev==NULL && tmp->next==NULL) {
	q->head = tmp;
	q->tail = tmp;
    } else if(prev==NULL) {
	q->head = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    } else if(tmp->next!=NULL) {
	prev->next = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    }
#endif /* ALGORITHM == 1 */

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_open_file_queue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}

/* close and relese lock */
int closeFileInQueue(queueT *q, char *filepath, int owner) {
    if(!q || !filepath) {
	errno = EINVAL;
	return -1;
    }

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == 0) {
	errno = ENOENT;
	goto _end_close_file_queue;
    }

    /* find file */
    nodeT *tmp = q->head;
    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	tmp = tmp->next;
    }

    if(!tmp) { /* not found */
	errno = ENOENT;
	goto _end_close_file_queue;
    }

    /* lock aquired by another client */
    if((tmp->data)->O_LOCK == 1 && (tmp->data)->owner != owner) {
	errno = EPERM;
	goto _end_close_file_queue;
    }

    (tmp->data)->open = 0;
    (tmp->data)->O_LOCK = 0;
    (tmp->data)->owner = owner;

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_close_file_queue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}


int writeFileInQueue(queueT *q, char *filepath, void *data, size_t size, int owner) {
    if(!q || !filepath || !data) {
	errno = EINVAL;
	return -1;
    }

    if(size == 0)
	return 0;

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == 0) { /* empty queue */
	errno = ENOENT;
	goto _end_write_file_queue;
    }

    /* find the file */
    nodeT *tmp = q->head;
    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	tmp = tmp->next;
    }

    if(!tmp) { /* not found */
	errno = ENOENT;
	goto _end_write_file_queue;
    }

    if (q->size - tmp->data->size + size > q->maxSize) { /* not enough space */
	errno = EFBIG;
	goto _end_write_file_queue;
    }

    if ((tmp->data)->open == 0 || ((tmp->data)->O_LOCK && (tmp->data)->owner != owner)) {
	/* file is closed or the client does not hold the lock */
	errno = EPERM;
	goto _end_write_file_queue;
    }

    /* write */
    if (((tmp->data)->data = realloc((tmp->data)->data, size)) == NULL) {
	perror("writeFileInQueue: realloc");
	goto _end_write_file_queue;
    }
    memcpy((tmp->data)->data, data, size);

    q->size = (q->size) - ((tmp->data)->size) + size;
    (tmp->data)->valid = size;
    (tmp->data)->size = size;

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_write_file_queue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}


int appendFileInQueue(queueT *q, char *filepath, void *data, size_t size, int owner) {
    if (!q || !filepath || !data) {
	errno = EINVAL;
	return -1;
    }
    if (size == 0)
	return 0;

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == 0) { /* empty queue */
	errno = ENOENT;
	goto _end_append_file_queue;
    }

    /* find the file */
    nodeT *tmp = q->head;
    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	tmp = tmp->next;
    }

    if(!tmp) { /* not found */
	errno = ENOENT;
	goto _end_append_file_queue;
    }

    if (q->size - tmp->data->size + size > q->maxSize) { /* not enough space */
	errno = EFBIG;
	goto _end_append_file_queue;
    }

    if ((tmp->data)->open == 0 || ((tmp->data)->O_LOCK && (tmp->data)->owner != owner)) {
	/* file is closed or the client does not hold the lock */
	errno = EPERM;
	goto _end_append_file_queue;
    }

    /* write */
    if (((tmp->data)->data = realloc((tmp->data)->data, (tmp->data)->valid + size)) == NULL) {
	perror("appendFileInQueue: realloc");
	goto _end_append_file_queue;
    }

    memcpy(((char *)(tmp->data)->data) + (tmp->data)->valid, data, size);
    /* memmove could be an alternative */
    (tmp->data)->valid += size;
    q->size -= (tmp->data)->size;
    (tmp->data)->size = ((tmp->data)->size > (tmp->data)->valid) ? (tmp->data)->size : (tmp->data)->valid;
    q->size += (tmp->data)->size;

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_append_file_queue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}


int removeFileFromQueue(queueT *q, char *filepath, int owner) {
    if(!q || !filepath) {
	errno = EINVAL;
	return -1;
    }

    LOCK_RETURN(&q->m, -1); /* begin me */

    if (q->len == 0) { /* empty queue */
	errno = ENOENT;
	goto _end_remove_file_queue;
    }

    /* find the file */
    nodeT *tmp = q->head;
    nodeT *pre = q->head;
    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	if(pre!=tmp)
	    pre = pre->next;
	tmp = tmp->next;
    }

    if (!tmp) { /* not found */
	errno = ENOENT;
	goto _end_remove_file_queue;
    }

    if (((tmp->data)->O_LOCK) && ((tmp->data)->owner != owner)) {
	/* lock not by the client */
	errno = EPERM;
	goto _end_remove_file_queue;
    }

    if (tmp == pre) { /* file is the first */
	q->head = tmp->next;

	if (tmp->next == NULL) {
	    q->tail = tmp;
	}
    } else {
	pre->next = tmp->next;

	if (pre->next == NULL) {
	    q->tail = pre;
	}
    }

    --q->len;
    q->size -= (tmp->data)->size;
    destroyFile(tmp->data); /* free file */
    free(tmp); /* free node */

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return 0;

_end_remove_file_queue:
    UNLOCK_RETURN(&q->m, -1);
    return -1;
}


// -----------------------------------------------------------------------------

/* search for file and return a copy */
fileT* find(queueT *q, char *filepath) {
    if(!q || !filepath) {
	errno = EINVAL;
	return NULL;
    }

    LOCK_RETURN(&q->m, NULL); /* begin me */

    if (q->len == 0)
	goto _end_find_in_queue;

    fileT *res = NULL;
    nodeT *tmp = q->head;
    /* if LRU keep track of previous */
#if ALGORITHM == 1
    nodeT *prev = NULL;
#endif

    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* trovato */
	    break;
	}
	/* if LRU keep track of previous */
#if ALGORITHM == 1
	prev = tmp;
#endif
	tmp = tmp->next;
    }

    if(!tmp)
	goto _end_find_in_queue;

    /* create a new instance */
    res = createFileT((tmp->data)->filepath, (tmp->data)->O_LOCK, (tmp->data)->owner, (tmp->data)->open);

    if (!res) {
	perror("find: createFileT");
	goto _end_find_in_queue;
    }

    if (writeFileT(res, (tmp->data)->data, (tmp->data)->size) == -1) {
	perror("find: writeFileT");
	destroyFile(res);
	goto _end_find_in_queue;
    }

    /* if LRU put the file at the end */
#if ALGORITHM == 1
    if(prev==NULL && tmp->next==NULL) {
	q->head = tmp;
	q->tail = tmp;
    } else if(prev==NULL) {
	q->head = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    } else if(tmp->next!=NULL) {
	prev->next = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    }
#endif /* ALGORITHM == 1 */

    UNLOCK_RETURN(&q->m, NULL); /* end me */
    return res;

_end_find_in_queue:
    UNLOCK_RETURN(&q->m, NULL);
    return NULL;
}

/* return n files */
fileT ** request(queueT *q, int n) {
    if(!q) {
	errno = EINVAL;
	return NULL;
    }
    if(n<=0) {
	return NULL;
    }

    LOCK_RETURN(&q->m, NULL); /* begin me */

    fileT **returnList = NULL; /* list of requested files */

    if (q->head == NULL || q->len == 0) { /* empty queue */
	errno = ENOENT;
	goto _end_request;
    }

    if(q->size < n) {
	errno = EINVAL;
	goto _end_request;
    }

    returnList = calloc(n+1, sizeof(*returnList));
    if(!returnList) {
	perror("dequeueN: calloc");
	goto _end_request;
    }
    returnList[n] = NULL;

    nodeT *tmp = q->head;
    for(int i=0; i<n; ++i) {
	if(tmp == NULL) {
	    errno = ENOENT;
	    goto _end_request;
	}
	returnList[i] = tmp->data;
	tmp = tmp->next;
    }

    /* if LRU put the files at the end */
#if ALGORITHM == 1
    q->tail->next = q->head;
    q->head = tmp->next;
    tmp->next = NULL;
    q->tail = tmp;
#endif /* ALGORITHM == 1 */

    UNLOCK_RETURN(&q->m, NULL); /* end me */
    return returnList;

_end_request:
    UNLOCK_RETURN(&q->m, NULL);
    if(returnList)
	free(returnList);
    return NULL;
}

/* search for file and return result of search */
int searchFile(queueT *q, char *filepath) {
    if(!q || !filepath) {
	errno = EINVAL;
	return 0;
    }

    LOCK_RETURN(&q->m, 0); /* begin me */

    if (q->len == 0)
	goto _end_search_file_in_queue;

    nodeT *tmp = q->head;
    /* if LRU keep track of previous */
#if ALGORITHM == 1
    nodeT *prev = NULL;
#endif

    while (tmp) {
	if (strcmp(filepath, (tmp->data)->filepath) == 0) { /* found */
	    break;
	}
	/* if LRU keep track of previous */
#if ALGORITHM == 1
	prev = tmp;
#endif
	tmp = tmp->next;
    }

    if(!tmp)
	goto _end_search_file_in_queue;

    /* if LRU put the file at the end */
#if ALGORITHM == 1
    if(prev==NULL && tmp->next==NULL) {
	q->head = tmp;
	q->tail = tmp;
    } else if(prev==NULL) {
	q->head = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    } else if(tmp->next!=NULL) {
	prev->next = tmp->next;
	q->tail->next = tmp;
	q->tail = tmp;
	tmp->next = NULL;
    }
#endif /* ALGORITHM == 1 */

    UNLOCK_RETURN(&q->m, 0); /* end me */
    return 1;

_end_search_file_in_queue:
    UNLOCK_RETURN(&q->m, 0);
    return 0;
}

/* number of elements in queue */
size_t getLen(queueT *q) {
    if(!q) {
	errno = EINVAL;
	return -1;
    }
    size_t len = -1;

    LOCK_RETURN(&q->m, -1); /* begin me */

    len = q->len;

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return len;
}

/* size in bytes of queue */
size_t getSize(queueT *q) {
    if(!q) {
	errno = EINVAL;
	return -1;
    }
    size_t size = -1;

    LOCK_RETURN(&q->m, -1); /* begin me */

    size = q->size;

    UNLOCK_RETURN(&q->m, -1); /* end me */
    return size;
}

void destroyQueue(queueT *q) {
    if(!q)
	return;

    /* no need for lock over queue */
    while (q->len > 0) {
	errno = 0;
	voidDequeue(q);
	if (errno) {
	    perror("destroyQueue: voidDequeue");
	}
	if(q->head == NULL) {
	    break;
	}
    }

    pthread_mutex_destroy(&q->m);

    free(q);
}