/* config-ini.c -- INI config file parser
   This file is part of Redshift.

   Redshift is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   Redshift 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 Redshift.  If not, see <http://www.gnu.org/licenses/>.

   Copyright (c) 2010-2018  Jon Lund Steffensen <jonlst@gmail.com>
   Copyright (c) 2025       Mattias Andrée <m@maandree.se>
*/
#include "common.h"

#define MAX_CONFIG_PATH  4096
#define MAX_LINE_LENGTH   512


static FILE *
open_config_file(const char *filepath)
{
	FILE *f = NULL;

	/* If a path is not specified (filepath is NULL) then
	   the configuration file is searched for in the directories
	   specified by the XDG Base Directory Specification
	   <http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html>.

	   If HOME is not set, getpwuid() is consulted for the home directory. On
	   windows platforms the %localappdata% is used in place of XDG_CONFIG_HOME.
	*/

	if (filepath == NULL) {
		char cp[MAX_CONFIG_PATH];
		char *env;

		if (f == NULL && (env = getenv("XDG_CONFIG_HOME")) != NULL &&
		    env[0] != '\0') {
			snprintf(cp, sizeof(cp), "%s/redshift/redshift.conf", env);
			f = fopen(cp, "r");
			if (f == NULL) {
				/* Fall back to formerly used path. */
				snprintf(cp, sizeof(cp), "%s/redshift.conf", env);
				f = fopen(cp, "r");
			}
		}

#ifdef WINDOWS
		if (f == NULL && (env = getenv("localappdata")) != NULL &&
		    env[0] != '\0') {
			snprintf(cp, sizeof(cp), "%s\\redshift.conf", env);
			f = fopen(cp, "r");
		}
#endif
		if (f == NULL && (env = getenv("HOME")) != NULL &&
		    env[0] != '\0') {
			snprintf(cp, sizeof(cp), "%s/.config/redshift/redshift.conf", env);
			f = fopen(cp, "r");
			if (f == NULL) {
				/* Fall back to formerly used path. */
				snprintf(cp, sizeof(cp), "%s/.config/redshift.conf", env);
				f = fopen(cp, "r");
			}
		}
#ifndef WINDOWS

		if (f == NULL) {
			struct passwd *pwd = getpwuid(getuid());
			if (pwd != NULL) {
				char *home = pwd->pw_dir;
				if ((home != NULL) && (*home != '\0')) {
					snprintf(cp, sizeof(cp), "%s/.config/redshift/redshift.conf", home);
					f = fopen(cp, "r");
					if (!f) {
						/* Fall back to formerly used path. */
						snprintf(cp, sizeof(cp), "%s/.config/redshift.conf", home);
						f = fopen(cp, "r");
					}
				} else {
					weprintf(_("Cannot determine your home directory,"
					           " it is from the system's user table."));
				}
			} else if (errno) {
				weprintf("getpwuid:");
			} else {
				weprintf(_("Cannot determine your home directory, your"
				           " user ID is missing from the system's user table."));
				/* errno can either be set to any number of error codes,
				   or be zero if the user does not have a passwd entry. */
			}
		}

		if (f == NULL && (env = getenv("XDG_CONFIG_DIRS")) != NULL && *env) {
			char *begin = env;
			char *end;
			int len;
			for (;;) {
				end = strchr(begin, ':');
				if (end == NULL) end = strchr(begin, '\0');

				len = (int)(end - begin);
				if (len > 0) {
					snprintf(cp, sizeof(cp), "%.*s/redshift/redshift.conf", len, begin);
					f = fopen(cp, "r");
					if (f == NULL) {
						/* Fall back to formerly used path. */
						snprintf(cp, sizeof(cp), "%.*s/redshift.conf", len, begin);
						f = fopen(cp, "r");
					}
					if (f != NULL)
						break;
				}

				if (*end)
					break;
				begin = &end[1];
			}
		}

		if (f == NULL) {
			snprintf(cp, sizeof(cp), "%s/redshift.conf", "/etc");
			f = fopen(cp, "r");
		}
#endif
	} else {
		f = fopen(filepath, "r");
		if (f == NULL) {
			weprintf("fopen:");
			return NULL;
		}
	}

	return f;
}

int
config_ini_init(struct config_ini_state *state, const char *filepath)
{
	struct config_ini_section *section = NULL;
	char line[MAX_LINE_LENGTH];
	char *s;
	FILE *f;

	state->sections = NULL;

	f = open_config_file(filepath);
	if (f == NULL) {
		/* Only a serious error if a file was explicitly requested. */
		return filepath ? 0 : -1;
	}

	for (;;) {
		/* Handle the file input linewise. */
		char *r = fgets(line, sizeof(line), f);
		if (!r)
			break;

		/* Strip leading blanks and trailing newline. */
		s = line + strspn(line, " \t");
		s[strcspn(s, "\r\n")] = '\0';

		/* Skip comments and empty lines. */
		if (s[0] == ';' || s[0] == '#' || s[0] == '\0')
			continue;

		if (s[0] == '[') {
			/* Read name of section. */
			const char *name = &s[1];
			char *end = strchr(s, ']');
			if (end == NULL || end[1] != '\0' || end == name) {
				weprintf(_("Malformed section header in config file."));
				fclose(f);
				config_ini_free(state);
				return -1;
			}

			*end = '\0';

			/* Create section. */
			section = emalloc(sizeof(*section));

			/* Insert into section list. */
			section->name = NULL;
			section->settings = NULL;
			section->next = state->sections;
			state->sections = section;

			/* Copy section name. */
			section->name = malloc(end - name + 1);
			if (section->name == NULL) {
				fclose(f);
				config_ini_free(state);
				return -1;
			}

			memcpy(section->name, name, end - name + 1);
		} else {
			char *value, *end;
			size_t value_len;
			struct config_ini_setting *setting;

			/* Split assignment at equals character. */
			end = strchr(s, '=');
			if (!end || end == s) {
				weprintf(_("Malformed assignment in config file."));
				fclose(f);
				config_ini_free(state);
				return -1;
			}

			*end++ = '\0';
			value = end;

			if (!section) {
				weprintf(_("Assignment outside section in config file."));
				fclose(f);
				config_ini_free(state);
				return -1;
			}

			/* Create section. */
			setting = emalloc(sizeof(*setting));

			/* Insert into section list. */
			setting->name = NULL;
			setting->value = NULL;
			setting->next = section->settings;
			section->settings = setting;

			/* Copy name of setting. */
			setting->name = emalloc(end - s);

			memcpy(setting->name, s, end - s);

			/* Copy setting value. */
			value_len = strlen(value) + 1;
			setting->value = emalloc(value_len);

			memcpy(setting->value, value, value_len);
		}
	}

	fclose(f);

	return 0;
}

void
config_ini_free(struct config_ini_state *state)
{
	struct config_ini_section *section, *section_next;
	struct config_ini_setting *setting, *setting_next;
	for (section = state->sections; section; section = section_next) {
		section_next = section->next;
		for (setting = section->settings; setting; setting = setting_next) {
			setting_next = setting->next;
			free(setting->name);
			free(setting->value);
			free(setting);
		}
		free(section->name);
		free(section);
	}
}

struct config_ini_section *
config_ini_get_section(struct config_ini_state *state, const char *name)
{
	struct config_ini_section *section;
	for (section = state->sections; section; section = section->next)
		if (!strcasecmp(section->name, name))
			return section;
	return NULL;
}