<?php

namespace SilverStripe\Dev;

use SilverStripe\Control\Director;
use SilverStripe\Core\Manifest\ClassLoader;
use SilverStripe\Core\Manifest\Module;
use SilverStripe\Core\Manifest\ModuleLoader;

/**
 * Handles raising an notice when accessing a deprecated method
 *
 * A pattern used in SilverStripe when deprecating a method is to add something like
 *   user_error('This method is deprecated', E_USER_NOTICE);
 * to the method
 *
 * However sometimes we want to mark that a method will be deprecated in some future version and shouldn't be used in
 * new code, but not forbid in the current version - for instance when that method is still heavily used in framework
 * or cms.
 *
 * This class abstracts the above pattern and adds a way to do that.
 *
 * Each call to notice passes a version that the notice will be valid from. Additionally this class has a notion of the
 * version it should use when deciding whether to raise the notice. If that version is equal to or greater than the
 * notices version (and SilverStripe is in dev mode) a deprecation message will be raised.
 *
 * Normally the checking version will be the release version of SilverStripe, but a developer can choose to set it to a
 * future version, to see how their code will behave in future versions.
 *
 * Modules can also set the version for calls they make - either setting it to a future version in order to ensure
 * forwards compatibility or setting it backwards if a module has not yet removed references to deprecated methods.
 *
 * When set per-module, only direct calls to deprecated methods from those modules are considered - if the module
 * calls a non-module method which then calls a deprecated method, that call will use the global check version, not
 * the module specific check version.
 */
class Deprecation
{

    const SCOPE_METHOD = 1;
    const SCOPE_CLASS = 2;
    const SCOPE_GLOBAL = 4;

    /**
     *
     * @var string
     */
    protected static $version;

    /**
     * Override whether deprecation is enabled. If null, then fallback to
     * SS_DEPRECATION_ENABLED, and then true if not defined.
     *
     * Deprecation is only available on dev.
     *
     * Must be configured outside of the config API, as deprecation API
     * must be available before this to avoid infinite loops.
     *
     * @var boolean|null
     */
    protected static $enabled = null;

    /**
     *
     * @var array
     */
    protected static $module_version_overrides = array();

    /**
     * @var int - the notice level to raise on a deprecation notice. Defaults to E_USER_DEPRECATED if that exists,
     * E_USER_NOTICE if not
     */
    public static $notice_level = null;

    /**
     * Set the version that is used to check against the version passed to notice. If the ::notice version is
     * greater than or equal to this version, a message will be raised
     *
     * @static
     * @param $ver string -
     *     A php standard version string, see http://php.net/manual/en/function.version-compare.php for details.
     * @param null $forModule string -
     *    The name of a module. The passed version will be used as the check value for
     *    calls directly from this module rather than the global value
     * @return void
     */
    public static function notification_version($ver, $forModule = null)
    {
        if ($forModule) {
            self::$module_version_overrides[$forModule] = $ver;
        } else {
            self::$version = $ver;
        }
    }

    /**
     * Given a backtrace, get the module name from the caller two removed (the caller of the method that called
     * #notice)
     *
     * @param array $backtrace A backtrace as returned from debug_backtrace
     * @return Module The module being called
     */
    protected static function get_calling_module_from_trace($backtrace)
    {
        if (!isset($backtrace[1]['file'])) {
            return null;
        }

        $callingfile = realpath($backtrace[1]['file']);

        $modules = ModuleLoader::instance()->getManifest()->getModules();
        foreach ($modules as $module) {
            if (strpos($callingfile, realpath($module->getPath())) === 0) {
                return $module;
            }
        }
        return null;
    }

    /**
     * Given a backtrace, get the method name from the immediate parent caller (the caller of #notice)
     *
     * @static
     * @param $backtrace array - a backtrace as returned from debug_backtrace
     * @param $level - 1 (default) will return immediate caller, 2 will return caller's caller, etc.
     * @return string - the name of the method
     */
    protected static function get_called_method_from_trace($backtrace, $level = 1)
    {
        $level = (int)$level;
        if (!$level) {
            $level = 1;
        }
        $called = $backtrace[$level];

        if (isset($called['class'])) {
            return $called['class'] . $called['type'] . $called['function'];
        } else {
            return $called['function'];
        }
    }

    /**
     * Determine if deprecation notices should be displayed
     *
     * @return bool
     */
    public static function get_enabled()
    {
        // Deprecation is only available on dev
        if (!Director::isDev()) {
            return false;
        }
        if (isset(self::$enabled)) {
            return self::$enabled;
        }
        return getenv('SS_DEPRECATION_ENABLED') ?: true;
    }

    /**
     * Toggle on or off deprecation notices. Will be ignored in live.
     *
     * @param bool $enabled
     */
    public static function set_enabled($enabled)
    {
        self::$enabled = $enabled;
    }

    /**
     * Raise a notice indicating the method is deprecated if the version passed as the second argument is greater
     * than or equal to the check version set via ::notification_version
     *
     * @param string $atVersion The version at which this notice should start being raised
     * @param string $string The notice to raise
     * @param int $scope Notice relates to the method or class context its called in.
     */
    public static function notice($atVersion, $string = '', $scope = Deprecation::SCOPE_METHOD)
    {
        if (!static::get_enabled()) {
            return;
        }

        $checkVersion = self::$version;
        // Getting a backtrace is slow, so we only do it if we need it
        $backtrace = null;

        // If you pass #.#, assume #.#.0
        if (preg_match('/^[0-9]+\.[0-9]+$/', $atVersion)) {
            $atVersion .= '.0';
        }
        if (preg_match('/^[0-9]+\.[0-9]+$/', $checkVersion)) {
            $checkVersion .= '.0';
        }

        if (self::$module_version_overrides) {
            $module = self::get_calling_module_from_trace($backtrace = debug_backtrace(0));
            if ($module) {
                if (($name = $module->getComposerName())
                    && isset(self::$module_version_overrides[$name])
                ) {
                    $checkVersion = self::$module_version_overrides[$name];
                } elseif (($name = $module->getShortName())
                    && isset(self::$module_version_overrides[$name])
                ) {
                    $checkVersion = self::$module_version_overrides[$name];
                }
            }
        }

        // Check the version against the notice version
        if ($checkVersion && version_compare($checkVersion, $atVersion, '>=')) {
            // Get the calling scope
            if ($scope == Deprecation::SCOPE_METHOD) {
                if (!$backtrace) {
                    $backtrace = debug_backtrace(0);
                }
                $caller = self::get_called_method_from_trace($backtrace);
            } elseif ($scope == Deprecation::SCOPE_CLASS) {
                if (!$backtrace) {
                    $backtrace = debug_backtrace(0);
                }
                $caller = isset($backtrace[1]['class']) ? $backtrace[1]['class'] : '(unknown)';
            } else {
                $caller = false;
            }

            // Get the level to raise the notice as
            $level = self::$notice_level;
            if (!$level) {
                $level = E_USER_DEPRECATED;
            }

            // Then raise the notice
            if (substr($string, -1) != '.') {
                $string .= ".";
            }

            $string .= " Called from " . self::get_called_method_from_trace($backtrace, 2) . '.';

            if ($caller) {
                user_error($caller.' is deprecated.'.($string ? ' '.$string : ''), $level);
            } else {
                user_error($string, $level);
            }
        }
    }

    /**
     * Method for when testing. Dump all the current version settings to a variable for later passing to restore
     *
     * @return array Opaque array that should only be used to pass to {@see Deprecation::restore_settings()}
     */
    public static function dump_settings()
    {
        return array(
            'level' => self::$notice_level,
            'version' => self::$version,
            'moduleVersions' => self::$module_version_overrides,
            'enabled' => self::$enabled,
        );
    }

    /**
     * Method for when testing. Restore all the current version settings from a variable
     *
     * @param $settings array An array as returned by {@see Deprecation::dump_settings()}
     */
    public static function restore_settings($settings)
    {
        self::$notice_level = $settings['level'];
        self::$version = $settings['version'];
        self::$module_version_overrides = $settings['moduleVersions'];
        self::$enabled = $settings['enabled'];
    }
}