<?php
/** @license MIT
 * Copyright 2017 J. King, Dustin Wilson et al.
 * See LICENSE and AUTHORS files for details */

declare(strict_types=1);
namespace JKingWeb\Arsse;

class User {
    const RIGHTS_NONE           = 0;    // normal user
    const RIGHTS_DOMAIN_MANAGER = 25;   // able to act for any normal users on same domain; cannot elevate other users
    const RIGHTS_DOMAIN_ADMIN   = 50;   // able to act for any users on same domain not above themselves; may elevate users on same domain to domain manager or domain admin
    const RIGHTS_GLOBAL_MANAGER = 75;   // able to act for any normal users on any domain; cannot elevate other users
    const RIGHTS_GLOBAL_ADMIN   = 100;  // is completely unrestricted

    public $id = null;

    /**
    * @var User\Driver
    */
    protected $u;
    protected $authz = 0;
    protected $authzSupported = 0;
    protected $actor = [];

    public static function driverList(): array {
        $sep = \DIRECTORY_SEPARATOR;
        $path = __DIR__.$sep."User".$sep;
        $classes = [];
        foreach (glob($path."*".$sep."Driver.php") as $file) {
            $name = basename(dirname($file));
            $class = NS_BASE."User\\$name\\Driver";
            $classes[$class] = $class::driverName();
        }
        return $classes;
    }

    public function __construct() {
        $driver = Arsse::$conf->userDriver;
        $this->u = new $driver();
    }

    public function __toString() {
        if ($this->id===null) {
            $this->credentials();
        }
        return (string) $this->id;
    }

    // checks whether the logged in user is authorized to act for the affected user (used especially when granting rights)
    public function authorize(string $affectedUser, string $action, int $newRightsLevel = 0): bool {
        // if authorization checks are disabled (either because we're running the installer or the background updater) just return true
        if (!$this->authorizationEnabled()) {
            return true;
        }
        // if we don't have a logged-in user, fetch credentials
        if ($this->id===null) {
            $this->credentials();
        }
        // if the affected user is the actor and the actor is not trying to grant themselves rights, accept the request
        if ($affectedUser==Arsse::$user->id && $action != "userRightsSet") {
            return true;
        }
        // if we're authorizing something other than a user function and the affected user is not the actor, make sure the affected user exists
        $this->authorizationEnabled(false);
        if (Arsse::$user->id != $affectedUser && strpos($action, "user")!==0 && !$this->exists($affectedUser)) {
            throw new User\Exception("doesNotExist", ["action" => $action, "user" => $affectedUser]);
        }
        $this->authorizationEnabled(true);
        // get properties of actor if not already available
        if (!sizeof($this->actor)) {
            $this->actor = $this->propertiesGet(Arsse::$user->id);
        }
        $rights = $this->actor["rights"];
        // if actor is a global admin, accept the request
        if ($rights==User\Driver::RIGHTS_GLOBAL_ADMIN) {
            return true;
        }
        // if actor is a common user, deny the request
        if ($rights==User\Driver::RIGHTS_NONE) {
            return false;
        }
        // if actor is not some other sort of admin, deny the request
        if (!in_array($rights, [User\Driver::RIGHTS_GLOBAL_MANAGER,User\Driver::RIGHTS_DOMAIN_MANAGER,User\Driver::RIGHTS_DOMAIN_ADMIN], true)) {
            return false;
        }
        // if actor is a domain admin/manager and domains don't match, deny the request
        if ($this->actor["domain"] && $rights != User\Driver::RIGHTS_GLOBAL_MANAGER) {
            $test = "@".$this->actor["domain"];
            if (substr($affectedUser, -1*strlen($test)) != $test) {
                return false;
            }
        }
        // certain actions shouldn't check affected user's rights
        if (in_array($action, ["userRightsGet","userExists","userList"], true)) {
            return true;
        }
        if ($action=="userRightsSet") {
            // setting rights above your own is not allowed
            if ($newRightsLevel > $rights) {
                return false;
            }
            // setting yourself to rights you already have is harmless and can be allowed
            if ($this->id==$affectedUser && $newRightsLevel==$rights) {
                return true;
            }
            // managers can only set their own rights, and only to normal user
            if (in_array($rights, [User\Driver::RIGHTS_DOMAIN_MANAGER, User\Driver::RIGHTS_GLOBAL_MANAGER])) {
                if ($this->id != $affectedUser || $newRightsLevel != User\Driver::RIGHTS_NONE) {
                    return false;
                }
                return true;
            }
        }
        $affectedRights = $this->rightsGet($affectedUser);
        // managers can only act on themselves (checked above) or regular users
        if (in_array($rights, [User\Driver::RIGHTS_GLOBAL_MANAGER,User\Driver::RIGHTS_DOMAIN_MANAGER]) && $affectedRights != User\Driver::RIGHTS_NONE) {
            return false;
        }
        // domain admins canot act above themselves
        if (!in_array($affectedRights, [User\Driver::RIGHTS_NONE,User\Driver::RIGHTS_DOMAIN_MANAGER,User\Driver::RIGHTS_DOMAIN_ADMIN])) {
            return false;
        }
        return true;
    }

    public function credentials(): array {
        if ($_SERVER['PHP_AUTH_USER']) {
            $out = ["user" => $_SERVER['PHP_AUTH_USER'], "password" => $_SERVER['PHP_AUTH_PW']];
        } elseif ($_SERVER['REMOTE_USER']) {
            $out = ["user" => $_SERVER['REMOTE_USER'], "password" => ""];
        } else {
            $out = ["user" => "", "password" => ""];
        }
        $this->id = $out["user"];
        return $out;
    }

    public function auth(string $user = null, string $password = null): bool {
        if ($user===null) {
            return $this->authHTTP();
        } else {
            $this->id = $user;
            $this->actor = [];
            switch ($this->u->driverFunctions("auth")) {
                case User\Driver::FUNC_EXTERNAL:
                    if (Arsse::$conf->userPreAuth) {
                        $out = true;
                    } else {
                        $out = $this->u->auth($user, $password);
                    }
                    if ($out && !Arsse::$db->userExists($user)) {
                        $this->autoProvision($user, $password);
                    }
                    return $out;
                case User\Driver::FUNC_INTERNAL:
                    if (Arsse::$conf->userPreAuth) {
                        if (!Arsse::$db->userExists($user)) {
                            $this->autoProvision($user, $password);
                        }
                        return true;
                    } else {
                        return $this->u->auth($user, $password);
                    }
                case User\Driver::FUNCT_NOT_IMPLEMENTED:
                    return false;
            }
        }
    }

    public function authHTTP(): bool {
        $cred = $this->credentials();
        if (!$cred["user"]) {
            return false;
        }
        return $this->auth($cred["user"], $cred["password"]);
    }

    public function driverFunctions(string $function = null) {
        return $this->u->driverFunctions($function);
    }

    public function list(string $domain = null): array {
        $func = "userList";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if ($domain===null) {
                    if (!$this->authorize("@".$domain, $func)) {
                        throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $domain]);
                    }
                } else {
                    if (!$this->authorize("", $func)) {
                        throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => "all users"]);
                    }
                }
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userList($domain);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                throw new User\ExceptionNotImplemented("notImplemented", ["action" => $func, "user" => $domain]);
        }
    }

    public function authorizationEnabled(bool $setting = null): bool {
        if (is_null($setting)) {
            return !$this->authz;
        }
        $this->authz += ($setting ? -1 : 1);
        if ($this->authz < 0) {
            $this->authz = 0;
        }
        return !$this->authz;
    }

    public function exists(string $user): bool {
        $func = "userExists";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $out = $this->u->userExists($user);
                if ($out && !Arsse::$db->userExists($user)) {
                    $this->autoProvision($user, "");
                }
                return $out;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userExists($user);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                // throwing an exception here would break all kinds of stuff; we just report that the user exists
                return true;
        }
    }

    public function add($user, $password = null): string {
        $func = "userAdd";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $newPassword = $this->u->userAdd($user, $password);
                // if there was no exception and we don't have the user in the internal database, add it
                if (!Arsse::$db->userExists($user)) {
                    $this->autoProvision($user, $newPassword);
                }
                return $newPassword;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userAdd($user, $password);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                throw new User\ExceptionNotImplemented("notImplemented", ["action" => $func, "user" => $user]);
        }
    }

    public function remove(string $user): bool {
        $func = "userRemove";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $out = $this->u->userRemove($user);
                if ($out && Arsse::$db->userExists($user)) {
                    // if the user was removed and we have it in our data, remove it there
                    if (!Arsse::$db->userExists($user)) {
                        Arsse::$db->userRemove($user);
                    }
                }
                return $out;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userRemove($user);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                throw new User\ExceptionNotImplemented("notImplemented", ["action" => $func, "user" => $user]);
        }
    }

    public function passwordSet(string $user, string $newPassword = null, $oldPassword = null): string {
        $func = "userPasswordSet";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $out = $this->u->userPasswordSet($user, $newPassword, $oldPassword);
                if (Arsse::$db->userExists($user)) {
                    // if the password change was successful and the user exists, set the internal password to the same value
                    Arsse::$db->userPasswordSet($user, $out);
                } else {
                    // if the user does not exists in the internal database, create it
                    $this->autoProvision($user, $out);
                }
                return $out;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userPasswordSet($user, $newPassword);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                throw new User\ExceptionNotImplemented("notImplemented", ["action" => $func, "user" => $user]);
        }
    }

    public function propertiesGet(string $user, bool $withAvatar = false): array {
        // prepare default values
        $domain = null;
        if (strrpos($user, "@")!==false) {
            $domain = substr($user, strrpos($user, "@")+1);
        }
        $init = [
            "id"     => $user,
            "name"   => $user,
            "rights" => User\Driver::RIGHTS_NONE,
            "domain" => $domain
        ];
        $func = "userPropertiesGet";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $out = array_merge($init, $this->u->userPropertiesGet($user));
                // remove password if it is return (not exhaustive, but...)
                if (array_key_exists('password', $out)) {
                    unset($out['password']);
                }
                // if the user does not exist in the internal database, add it
                if (!Arsse::$db->userExists($user)) {
                    $this->autoProvision($user, "", $out);
                }
                return $out;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return array_merge($init, $this->u->userPropertiesGet($user));
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                // we can return generic values if the function is not implemented
                return $init;
        }
    }

    public function propertiesSet(string $user, array $properties): array {
        // remove from the array any values which should be set specially
        foreach (['id', 'domain', 'password', 'rights'] as $key) {
            if (array_key_exists($key, $properties)) {
                unset($properties[$key]);
            }
        }
        $func = "userPropertiesSet";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $out = $this->u->userPropertiesSet($user, $properties);
                if (Arsse::$db->userExists($user)) {
                    // if the property change was successful and the user exists, set the internal properties to the same values
                    Arsse::$db->userPropertiesSet($user, $out);
                } else {
                    // if the user does not exists in the internal database, create it
                    $this->autoProvision($user, "", $out);
                }
                return $out;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userPropertiesSet($user, $properties);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                throw new User\ExceptionNotImplemented("notImplemented", ["action" => $func, "user" => $user]);
        }
    }

    public function rightsGet(string $user): int {
        $func = "userRightsGet";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $out = $this->u->userRightsGet($user);
                // if the user does not exist in the internal database, add it
                if (!Arsse::$db->userExists($user)) {
                    $this->autoProvision($user, "", null, $out);
                }
                return $out;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userRightsGet($user);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                // assume all users are unprivileged
                return User\Driver::RIGHTS_NONE;
        }
    }

    public function rightsSet(string $user, int $level): bool {
        $func = "userRightsSet";
        switch ($this->u->driverFunctions($func)) {
            case User\Driver::FUNC_EXTERNAL:
                // we handle authorization checks for external drivers
                if (!$this->authorize($user, $func)) {
                    throw new User\ExceptionAuthz("notAuthorized", ["action" => $func, "user" => $user]);
                }
                $out = $this->u->userRightsSet($user, $level);
                // if the user does not exist in the internal database, add it
                if ($out && Arsse::$db->userExists($user)) {
                    $authz = $this->authorizationEnabled();
                    $this->authorizationEnabled(false);
                    Arsse::$db->userRightsSet($user, $level);
                    $this->authorizationEnabled($authz);
                } elseif ($out) {
                    $this->autoProvision($user, "", null, $level);
                }
                return $out;
            case User\Driver::FUNC_INTERNAL:
                // internal functions handle their own authorization
                return $this->u->userRightsSet($user, $level);
            case User\Driver::FUNCT_NOT_IMPLEMENTED:
                throw new User\ExceptionNotImplemented("notImplemented", ["action" => $func, "user" => $user]);
        }
    }

    protected function autoProvision(string $user, string $password = null, array $properties = null, int $rights = 0): string {
        // temporarily disable authorization checks, to avoid potential problems
        $this->authorizationEnabled(false);
        // create the user
        $out = Arsse::$db->userAdd($user, $password);
        // set the user rights
        Arsse::$db->userRightsSet($user, $rights);
        // set the user properties...
        if ($properties===null) {
            // if nothing is provided but the driver uses an external function, try to get the current values from the external source
            try {
                if ($this->u->driverFunctions("userPropertiesGet")==User\Driver::FUNC_EXTERNAL) {
                    Arsse::$db->userPropertiesSet($user, $this->u->userPropertiesGet($user));
                }
            } catch (\Throwable $e) {
            }
        } else {
            // otherwise if values are provided, use those
            Arsse::$db->userPropertiesSet($user, $properties);
        }
        // re-enable authorization and return
        $this->authorizationEnabled(true);
        return $out;
    }
}