#include "file.h"
#include "image.h"
#include <dirent.h>
#include <gtk-3.0/gtk/gtk.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

static char **extensions = NULL;

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

int is_file_format_supported(const char *file_name)
{
    char *file_ext = get_filename_ext(file_name);
    char **it = extensions;
    while (*it != NULL) {
        if (!strcmp(*it++, file_ext)) {
            return 1;
        }
    }
    return 0;
}

void scan_supported_formats()
{
    GSList *list, *it;
    GdkPixbufFormat *format;
    gchar **exts, **ex_it;
    int i = 0;

    list = gdk_pixbuf_get_formats();
    if (list != NULL) {
        for (it = list; it->next != NULL; it = it->next) {
            format = (GdkPixbufFormat *)it->data;
            exts = gdk_pixbuf_format_get_extensions(format);
            if (exts != NULL) {
                ex_it = exts;
                while (*ex_it != NULL) {
                    extensions = realloc(extensions, sizeof(char *) * (i + 1));
                    extensions[i++] = strdup(*ex_it);
                    g_free(*ex_it);
                    ex_it++;
                }
                g_free(exts);
            }
        }
        g_slist_free(list);
        extensions[i] = NULL;
    }
}

int image_filter(const struct dirent *dir)
{
    if (dir->d_type == DT_REG && is_file_format_supported(dir->d_name)) {
        return 1;
    }
    return 0;
}

int scan(const char *file_name)
{
    scan_supported_formats();
    struct dirent **name_list;
    char *dir_name = dirname(strdup(file_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] = g_build_filename(dir_name, name_list[i]->d_name, NULL);
        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];
}

void clean()
{
    for (int i = 0; i < file_list_count; ++i) {
        g_free(file_list[i]);
    }
    g_free(file_list);
}