file.c


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#include "file.h"
#include <dirent.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

char *get_filename_ext(char *file_name)
{
    char *dot = strrchr(file_name, '.');
    if (!dot || dot == file_name)
        return "";
    return dot + 1;
}

int image_filter(const struct dirent *dir)
{
    char *ext = get_filename_ext(strdup(dir->d_name));
    if (dir->d_type == DT_REG && (!strcmp(ext, "png") || !strcmp(ext, "jpg"))) {
        return 1;
    }
    return 0;
}

int scan(const char *file_name)
{
    struct dirent **name_list;
    char *dir_name = dirname(strdup(file_name));
    size_t dir_name_len = strlen(dir_name);
    file_list_count = scandir(dir_name, &name_list, image_filter, alphasort);
    if (file_list_count < 0) {
        return -1;
    }

    file_list = malloc(file_list_count * sizeof(char *));
    char *file_basename = basename(strdup(file_name));
    int i = 0;
    while (i < file_list_count) {
        if (!strcmp(file_basename, name_list[i]->d_name))
            curr_file_index = i;
        file_list[i] = malloc(
            (strlen(name_list[i]->d_name) + dir_name_len + 2) * sizeof(char *));
        sprintf(file_list[i], "%s/%s", dir_name, name_list[i]->d_name);
        free(name_list[i]);
        i++;
    }
    free(name_list);

    return 0;
}

char *get_next_file()
{
    if (curr_file_index >= file_list_count - 1)
        return NULL;
    return file_list[++curr_file_index];
}

char *get_prev_file()
{
    if (curr_file_index <= 0)
        return NULL;
    return file_list[--curr_file_index];
}

char *get_first_file()
{
    if (curr_file_index == 0)
        return NULL;
    curr_file_index = 0;
    return file_list[curr_file_index];
}

char *get_last_file()
{
    if (curr_file_index == file_list_count - 1)
        return NULL;
    curr_file_index = file_list_count - 1;
    return file_list[curr_file_index];
}