<?php
class Config {
	private const _ENVVAR_PREFIX = "TTRSS_";

	// override defaults, defined below in _DEFAULTS[], via environment: DB_TYPE becomes TTRSS_DB_TYPE, etc

	const DB_TYPE = "DB_TYPE";
	const DB_HOST = "DB_HOST";
	const DB_USER = "DB_USER";
	const DB_NAME = "DB_NAME";
	const DB_PASS = "DB_PASS";
	const DB_PORT = "DB_PORT";
	const MYSQL_CHARSET = "MYSQL_CHARSET";
	const SELF_URL_PATH = "SELF_URL_PATH";
	const SINGLE_USER_MODE = "SINGLE_USER_MODE";
	const SIMPLE_UPDATE_MODE = "SIMPLE_UPDATE_MODE";
	const PHP_EXECUTABLE = "PHP_EXECUTABLE";
	const LOCK_DIRECTORY = "LOCK_DIRECTORY";
	const CACHE_DIR = "CACHE_DIR";
	const ICONS_DIR = "ICONS_DIR";
	const ICONS_URL = "ICONS_URL";
	const AUTH_AUTO_CREATE = "AUTH_AUTO_CREATE";
	const AUTH_AUTO_LOGIN = "AUTH_AUTO_LOGIN";
	const FORCE_ARTICLE_PURGE = "FORCE_ARTICLE_PURGE";
	const ENABLE_REGISTRATION = "ENABLE_REGISTRATION";
	const SESSION_COOKIE_LIFETIME = "SESSION_COOKIE_LIFETIME";
	const SMTP_FROM_NAME = "SMTP_FROM_NAME";
	const SMTP_FROM_ADDRESS = "SMTP_FROM_ADDRESS";
	const DIGEST_SUBJECT = "DIGEST_SUBJECT";
	const CHECK_FOR_UPDATES = "CHECK_FOR_UPDATES";
	const PLUGINS = "PLUGINS";
	const LOG_DESTINATION = "LOG_DESTINATION";
	const LOCAL_OVERRIDE_STYLESHEET = "LOCAL_OVERRIDE_STYLESHEET";
	const DAEMON_MAX_CHILD_RUNTIME = "DAEMON_MAX_CHILD_RUNTIME";
	const DAEMON_MAX_JOBS = "DAEMON_MAX_JOBS";
	const FEED_FETCH_TIMEOUT = "FEED_FETCH_TIMEOUT";
	const FEED_FETCH_NO_CACHE_TIMEOUT = "FEED_FETCH_NO_CACHE_TIMEOUT";
	const FILE_FETCH_TIMEOUT = "FILE_FETCH_TIMEOUT";
	const FILE_FETCH_CONNECT_TIMEOUT = "FILE_FETCH_CONNECT_TIMEOUT";
	const DAEMON_UPDATE_LOGIN_LIMIT = "DAEMON_UPDATE_LOGIN_LIMIT";
	const DAEMON_FEED_LIMIT = "DAEMON_FEED_LIMIT";
	const DAEMON_SLEEP_INTERVAL = "DAEMON_SLEEP_INTERVAL";
	const MAX_CACHE_FILE_SIZE = "MAX_CACHE_FILE_SIZE";
	const MAX_DOWNLOAD_FILE_SIZE = "MAX_DOWNLOAD_FILE_SIZE";
	const MAX_FAVICON_FILE_SIZE = "MAX_FAVICON_FILE_SIZE";
	const CACHE_MAX_DAYS = "CACHE_MAX_DAYS";
	const MAX_CONDITIONAL_INTERVAL = "MAX_CONDITIONAL_INTERVAL";
	const DAEMON_UNSUCCESSFUL_DAYS_LIMIT = "DAEMON_UNSUCCESSFUL_DAYS_LIMIT";
	const LOG_SENT_MAIL = "LOG_SENT_MAIL";
	const HTTP_PROXY = "HTTP_PROXY";
	const FORBID_PASSWORD_CHANGES = "FORBID_PASSWORD_CHANGES";
	const TTRSS_SESSION_NAME = "TTRSS_SESSION_NAME";

	private const _DEFAULTS = [
		Config::DB_TYPE => "pgsql",
		Config::DB_HOST => "db",
		Config::DB_USER => "",
		Config::DB_NAME => "",
		Config::DB_PASS => "",
		Config::DB_PORT => "5432",
		Config::MYSQL_CHARSET => "UTF8",
		Config::SELF_URL_PATH => "",
		Config::SINGLE_USER_MODE => "",
		Config::SIMPLE_UPDATE_MODE => "",
		Config::PHP_EXECUTABLE => "/usr/bin/php",
		Config::LOCK_DIRECTORY => "lock",
		Config::CACHE_DIR => "cache",
		Config::ICONS_DIR => "feed-icons",
		Config::ICONS_URL => "feed-icons",
		Config::AUTH_AUTO_CREATE => "true",
		Config::AUTH_AUTO_LOGIN => "true",
		Config::FORCE_ARTICLE_PURGE => 0,
		Config::ENABLE_REGISTRATION => "",
		Config::SESSION_COOKIE_LIFETIME => 86400,
		Config::SMTP_FROM_NAME => "Tiny Tiny RSS",
		Config::SMTP_FROM_ADDRESS => "noreply@localhost",
		Config::DIGEST_SUBJECT => "[tt-rss] New headlines for last 24 hours",
		Config::CHECK_FOR_UPDATES => "true",
		Config::PLUGINS => "auth_internal",
		Config::LOG_DESTINATION => "sql",
		Config::LOCAL_OVERRIDE_STYLESHEET => "local-overrides.css",
		Config::DAEMON_MAX_CHILD_RUNTIME => 1800,
		Config::DAEMON_MAX_JOBS => 2,
		Config::FEED_FETCH_TIMEOUT => 45,
		Config::FEED_FETCH_NO_CACHE_TIMEOUT => 15,
		Config::FILE_FETCH_TIMEOUT => 45,
		Config::FILE_FETCH_CONNECT_TIMEOUT => 15,
		Config::DAEMON_UPDATE_LOGIN_LIMIT => 30,
		Config::DAEMON_FEED_LIMIT => 500,
		Config::DAEMON_SLEEP_INTERVAL => 120,
		Config::MAX_CACHE_FILE_SIZE => 64*1024*1024,
		Config::MAX_DOWNLOAD_FILE_SIZE => 16*1024*1024,
		Config::MAX_FAVICON_FILE_SIZE => 1*1024*1024,
		Config::CACHE_MAX_DAYS => 7,
		Config::MAX_CONDITIONAL_INTERVAL => 3600*12,
		Config::DAEMON_UNSUCCESSFUL_DAYS_LIMIT => 30,
		Config::LOG_SENT_MAIL => "",
		Config::HTTP_PROXY => "",
		Config::FORBID_PASSWORD_CHANGES => "",
		Config::TTRSS_SESSION_NAME => "ttrss_sid",
	];

	private static $instance;

	private $params = [];

	public static function get_instance() {
		if (self::$instance == null)
			self::$instance = new self();

		return self::$instance;
	}

	function __construct() {
		$ref = new ReflectionClass(get_class($this));

		foreach ($ref->getConstants() as $const => $cvalue) {
			if (strpos($const, "_") !== 0) {
				$override = getenv($this::_ENVVAR_PREFIX . $const);

				$this->params[$cvalue] = !empty($override) ? $override : $this::_DEFAULTS[$const];
			}
		}
	}

	private function _get(string $param) {
		return $this->params[$param];
	}

	private function _add(string $param, string $default) {
		$override = getenv($this::_ENVVAR_PREFIX . $param);

		$this->params[$param] = !empty($override) ? $override : $default;
	}

	static function add(string $param, string $default) {
		$instance = self::get_instance();

		return $instance->_add($param, $default);
	}

	static function get(string $param) {
		$instance = self::get_instance();

		return $instance->_get($param);
	}

}