/**************************************************************************
* Tint2 : .desktop file handling
*
* Copyright (C) 2015       (mrovi9000@gmail.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
**************************************************************************/

/* http://standards.freedesktop.org/desktop-entry-spec/ */

#include "apps-common.h"
#include "common.h"
#include "strnatcmp.h"

#include <glib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static gint compare_strings(gconstpointer a, gconstpointer b)
{
	return strnatcasecmp((const char *)a, (const char *)b);
}

int parse_dektop_line(char *line, char **key, char **value)
{
	char *p;
	int found = 0;
	*key = line;
	for (p = line; *p; p++) {
		if (*p == '=') {
			*value = p + 1;
			*p = 0;
			found = 1;
			break;
		}
	}
	if (!found)
		return 0;
	if (found && (strlen(*key) == 0 || strlen(*value) == 0))
		return 0;
	return 1;
}

void expand_exec(DesktopEntry *entry, const char *path)
{
	// Expand % in exec
	// %i -> --icon Icon
	// %c -> Name
	// %k -> path
	if (entry->exec) {
		char *exec2 = calloc(strlen(entry->exec) + (entry->name ? strlen(entry->name) : 1) +
		                         (entry->icon ? strlen(entry->icon) : 1) + 100,
		                     1);
		char *p, *q;
		// p will never point to an escaped char
		for (p = entry->exec, q = exec2; *p; p++, q++) {
			*q = *p; // Copy
			if (*p == '\\') {
				p++, q++;
				// Copy the escaped char
				if (*p == '%') // For % we delete the backslash, i.e. write % over it
					q--;
				*q = *p;
				if (!*p)
					break;
				continue;
			}
			if (*p == '%') {
				p++;
				if (!*p)
					break;
				if (*p == 'i' && entry->icon != NULL) {
					sprintf(q, "--icon '%s'", entry->icon);
					q += strlen("--icon ''");
					q += strlen(entry->icon);
					q--; // To balance the q++ in the for
				} else if (*p == 'c' && entry->name != NULL) {
					sprintf(q, "'%s'", entry->name);
					q += strlen("''");
					q += strlen(entry->name);
					q--; // To balance the q++ in the for
				} else if (*p == 'c') {
					sprintf(q, "'%s'", path);
					q += strlen("''");
					q += strlen(path);
					q--; // To balance the q++ in the for
				} else {
					// We don't care about other expansions
					q--; // Delete the last % from q
				}
				continue;
			}
		}
		*q = '\0';
		free(entry->exec);
		entry->exec = exec2;
	}
}

gboolean read_desktop_file_full_path(const char *path, DesktopEntry *entry)
{
	entry->name = entry->generic_name = entry->icon = entry->exec = NULL;
	entry->hidden_from_menus = FALSE;

	FILE *fp = fopen(path, "rt");
	if (fp == NULL) {
		fprintf(stderr, "Could not open file %s\n", path);
		return FALSE;
	}

	const gchar **languages = (const gchar **)g_get_language_names();
	// lang_index is the index of the language for the best Name key in the language vector
	// lang_index_default is a constant that encodes the Name key without a language
	int lang_index_default = 1;
#define LANG_DBG 0
	if (LANG_DBG)
		printf("Languages:");
	for (int i = 0; languages[i]; i++) {
		lang_index_default = i + 1;
		if (LANG_DBG)
			printf(" %s", languages[i]);
	}
	if (LANG_DBG)
		printf("\n");
	// we currently do not know about any Name key at all, so use an invalid index
	int lang_index_name = lang_index_default + 1;
	int lang_index_generic_name = lang_index_default + 1;

	gboolean inside_desktop_entry = 0;
	char *line = NULL;
	size_t line_size;
	while (getline(&line, &line_size, fp) >= 0) {
		int len = strlen(line);
		if (len == 0)
			continue;
		if (line[len - 1] == '\n')
			line[len - 1] = '\0';
		if (line[0] == '[') {
			inside_desktop_entry = (strcmp(line, "[Desktop Entry]") == 0);
		}
		char *key, *value;
		if (inside_desktop_entry && parse_dektop_line(line, &key, &value)) {
			if (strstr(key, "Name") == key) {
				if (strcmp(key, "Name") == 0 && lang_index_name > lang_index_default) {
					entry->name = strdup(value);
					lang_index_name = lang_index_default;
				} else {
					for (int i = 0; languages[i] && i < lang_index_name; i++) {
						gchar *localized_key = g_strdup_printf("Name[%s]", languages[i]);
						if (strcmp(key, localized_key) == 0) {
							if (entry->name)
								free(entry->name);
							entry->name = strdup(value);
							lang_index_name = i;
						}
						g_free(localized_key);
					}
				}
			} else if (strstr(key, "GenericName") == key) {
				if (strcmp(key, "GenericName") == 0 && lang_index_generic_name > lang_index_default) {
					entry->generic_name = strdup(value);
					lang_index_generic_name = lang_index_default;
				} else {
					for (int i = 0; languages[i] && i < lang_index_generic_name; i++) {
						gchar *localized_key = g_strdup_printf("GenericName[%s]", languages[i]);
						if (strcmp(key, localized_key) == 0) {
							if (entry->generic_name)
								free(entry->generic_name);
							entry->generic_name = strdup(value);
							lang_index_generic_name = i;
						}
						g_free(localized_key);
					}
				}
			} else if (!entry->exec && strcmp(key, "Exec") == 0) {
				entry->exec = strdup(value);
			} else if (!entry->icon && strcmp(key, "Icon") == 0) {
				entry->icon = strdup(value);
			} else if (strcmp(key, "NoDisplay") == 0) {
				entry->hidden_from_menus = strcasecmp(value, "true") == 0;
			}
		}
	}
	fclose(fp);
	// From this point:
	// entry->name, entry->generic_name, entry->icon, entry->exec will never be empty strings (can be NULL though)

	expand_exec(entry, entry->path);

	free(line);
	return entry->exec != NULL;
}

gboolean read_desktop_file_from_dir(const char *path, const char *file_name, DesktopEntry *entry)
{
	gchar *full_path = g_build_filename(path, file_name, NULL);
	if (read_desktop_file_full_path(full_path, entry)) {
		g_free(full_path);
		return TRUE;
	}
	free(entry->name);
	free(entry->generic_name);
	free(entry->icon);
	free(entry->exec);
	entry->name = entry->generic_name = entry->icon = entry->exec = NULL;

	GList *subdirs = NULL;

	GDir *d = g_dir_open(path, 0, NULL);
	if (d) {
		const gchar *name;
		while ((name = g_dir_read_name(d))) {
			gchar *child = g_build_filename(path, name, NULL);
			if (g_file_test(child, G_FILE_TEST_IS_DIR)) {
				subdirs = g_list_append(subdirs, child);
			} else {
				g_free(child);
			}
		}
		g_dir_close(d);
	}

	subdirs = g_list_sort(subdirs, compare_strings);
	gboolean found = FALSE;
	for (GList *l = subdirs; l; l = g_list_next(l)) {
		if (read_desktop_file_from_dir(l->data, file_name, entry)) {
			found = TRUE;
			break;
		}
	}

	for (GList *l = subdirs; l; l = g_list_next(l)) {
		g_free(l->data);
	}
	g_list_free(subdirs);
	g_free(full_path);

	return found;
}

gboolean read_desktop_file(const char *path, DesktopEntry *entry)
{
	entry->path = strdup(path);
	entry->name = entry->generic_name = entry->icon = entry->exec = NULL;

	if (strchr(path, '/'))
		return read_desktop_file_full_path(path, entry);
	for (const GSList *location = get_apps_locations(); location; location = g_slist_next(location)) {
		if (read_desktop_file_from_dir(location->data, path, entry))
			return TRUE;
	}
	return FALSE;
}

void free_desktop_entry(DesktopEntry *entry)
{
	free(entry->name);
	free(entry->generic_name);
	free(entry->icon);
	free(entry->exec);
	free(entry->path);
	entry->name = entry->generic_name = entry->icon = entry->exec = entry->path = NULL;
}

void test_read_desktop_file()
{
	fprintf(stdout, "\033[1;33m");
	DesktopEntry entry;
	read_desktop_file("/usr/share/applications/firefox.desktop", &entry);
	printf("Name:%s GenericName:%s Icon:%s Exec:%s\n", entry.name, entry.generic_name, entry.icon, entry.exec);
	fprintf(stdout, "\033[0m");
}

GSList *apps_locations = NULL;
// Do not free the result.
const GSList *get_apps_locations()
{
	if (apps_locations)
		return apps_locations;

	apps_locations = load_locations_from_env(apps_locations, "XDG_DATA_HOME", "applications", NULL);

	apps_locations =
	    g_slist_append(apps_locations, g_build_filename(g_get_home_dir(), ".local/share/applications", NULL));

	apps_locations = load_locations_from_env(apps_locations, "XDG_DATA_DIRS", "applications", NULL);

	apps_locations = g_slist_append(apps_locations, g_strdup("/usr/local/share/applications"));
	apps_locations = g_slist_append(apps_locations, g_strdup("/usr/share/applications"));
	apps_locations = g_slist_append(apps_locations, g_strdup("/opt/share/applications"));

	apps_locations = slist_remove_duplicates(apps_locations, g_str_equal, g_free);

	return apps_locations;
}