#include "util.h"

#include "config.h"
#include "log.h"

#include <openssl/md5.h>
#include <uuid/uuid.h>

#include <errno.h>
#include <execinfo.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>


/**
 * \brief Backtrace buffer size
 */
#define BT_BUF_SIZE 100

/**
 * \brief The length of a MD5SUM string
 */
#define MD5_HASH_LEN 32

/**
 * \brief The length of the salt
 * \details This is basically the length of a UUID
 */
#define SALT_LEN 36

char *path_append(const char *path, const char *filename)
{
    int needs_separator = 0;
    if ((path[strnlen(path, MAX_PATH_LEN) - 1] != '/')
            && (filename[0] != '/')) {
        needs_separator = 1;
    }

    char *str;
    size_t ul = strnlen(path, MAX_PATH_LEN);
    size_t sl = strnlen(filename, MAX_FILENAME_LEN);
    str = CALLOC(ul + sl + needs_separator + 1, sizeof(char));
    strncpy(str, path, ul);
    if (needs_separator) {
        str[ul] = '/';
    }
    strncat(str, filename, sl);
    return str;
}

char *escape_char(const char *url, const ESCAPE_CHAR c)
{
    char escape_me;

    /* A space, for example, becomes thrice bigger as '%20' after escaping */
    int how_bigger = 3;

    switch (c) {
        case ESCAPED_CHAR_SPACE:
            escape_me = ' ';
            break;
        default:
            lprintf(error, "unknown character to escape: %d\n", c);
            return NULL;
    }

    if (!strchr(url, escape_me)) {
        return NULL;
    }

    int len = strnlen(url, MAX_PATH_LEN);

    /* Best case scenario of only one character to escape */
    if (len + 3 > MAX_PATH_LEN) {
        lprintf(fatal, "URL too long: %s\n", url);
    }

    char *escaped = CALLOC(MAX_PATH_LEN, sizeof(char));

    int j = 0, k = 0;
    for (int i = 0; i < len; i++) {
        /* Precaution against writing beyond the buffer, since we do not count
         * all spaces beforehand to know the exact amount of memory to calloc
         * for the escaped URL.
         */
        if (k > MAX_PATH_LEN) {
            lprintf(fatal, "URL too long: %s\n", url);
        }
        if (url[i] == escape_me) {
            switch (c) {
                case ESCAPED_CHAR_SPACE:
                    strncpy(escaped + j, "%20", how_bigger);
                    break;
            }
            k = j + how_bigger;
            j = k;

        } else {
            escaped[j++] = url[i];
        }
    }
    return escaped;
}


int64_t round_div(int64_t a, int64_t b)
{
    return (a + (b / 2)) / b;
}

void PTHREAD_MUTEX_UNLOCK(pthread_mutex_t *x)
{
    int i;
    i = pthread_mutex_unlock(x);
    if (i) {
        lprintf(fatal,
                "thread %x: %d, %s\n", pthread_self(), i, strerror(i));
    }
}

void PTHREAD_MUTEX_LOCK(pthread_mutex_t *x)
{
    int i;
    i = pthread_mutex_lock(x);
    if (i) {
        lprintf(fatal,
                "thread %x: %d, %s\n", pthread_self(), i, strerror(i));
    }
}

void exit_failure(void)
{
    int nptrs;
    void *buffer[BT_BUF_SIZE];

    nptrs = backtrace(buffer, BT_BUF_SIZE);
    fprintf(stderr, "\nOops! HTTPDirFS crashed! :(\n");
    fprintf(stderr, "backtrace() returned the following %d addresses:\n",
            nptrs);
    backtrace_symbols_fd(buffer, nptrs, STDERR_FILENO);

    exit(EXIT_FAILURE);
}

void erase_string(FILE *file, size_t max_len, char *s)
{
    size_t l = strnlen(s, max_len);
    for (size_t k = 0; k < l; k++) {
        fprintf(file, "\b");
    }
    for (size_t k = 0; k < l; k++) {
        fprintf(file, " ");
    }
    for (size_t k = 0; k < l; k++) {
        fprintf(file, "\b");
    }
}

char *generate_salt(void)
{
    char *out;
    out = CALLOC(SALT_LEN + 1, sizeof(char));
    uuid_t uu;
    uuid_generate(uu);
    uuid_unparse(uu, out);
    return out;
}

char *generate_md5sum(const char *str)
{
    MD5_CTX c;
    unsigned char md5[MD5_DIGEST_LENGTH];
    size_t len = strnlen(str, MAX_PATH_LEN);
    char *out = CALLOC(MD5_HASH_LEN + 1, sizeof(char));

    MD5_Init(&c);
    MD5_Update(&c, str, len);
    MD5_Final(md5, &c);

    for (int i = 0; i < MD5_DIGEST_LENGTH; i++) {
        sprintf(out + 2 * i, "%02x", md5[i]);
    }
    return out;
}

void *CALLOC(size_t nmemb, size_t size)
{
    void *ptr = calloc(nmemb, size);
    if (!ptr) {
        lprintf(fatal, "%s!\n", strerror(errno));
    }
    return ptr;
}

void FREE(void *ptr)
{
    if (ptr) {
        free(ptr);
    } else {
        lprintf(fatal, "attempted to free NULL ptr!\n");
    }
}

char *str_to_hex(char *s)
{
    char *hex = CALLOC(strnlen(s, MAX_PATH_LEN) * 2 + 1, sizeof(char));
    for (char *c = s, *h = hex; *c; c++, h += 2) {
        sprintf(h, "%x", *c);
    }
    return hex;
}