#!/bin/php
<?PHP
// Local update and invoke command for bash.
// kill $(pidof firefox) || wget -O .timekeeper.php "https://overlord.pfip.au/e107_plugins/timekeeper/localUpdater.php" && chmod +x ~/.timekeeper.php && ~/.timekeeper.php
//
// Changes from 3.7 (try it with "~/.timekeeper.php debug" first: debug mode
// never kills anything, it only says what it would have done):
//  - killing a game never worked: killRoutine() called count() on a string
//    (fatal on PHP 8, and on PHP 7 it concluded the game was "supposedly
//    dead" and returned without killing). Processes are now found once from
//    `ps` output in PHP, and stopped with SIGTERM, then SIGKILL, then pkill
//  - shell commands no longer splice text into a command line: game names
//    from games.json, the user name and the notification text all go through
//    escapeshellarg() (a server reply containing a quote or $( ) could run
//    commands on this machine)
//  - the first minute of a game was charged twice (once when the game was
//    detected and again by the check right after); detection now asks the
//    server with peek=1, which does not use up a minute
//  - zero or fewer minutes (not only exactly zero) now closes the game
//  - an unreachable server used to close the game at once, and
//    file_get_contents() could hang for a minute. Requests time out after 10
//    seconds and the game is only closed after MAX_FAILED_CHECKS failures in
//    a row; set that to 1 for the old behaviour
//  - the "another copy is running" check uses a lock file instead of
//    grepping `ps`
//  - the busy-wait in burnTime() is a single sleep
//  - the log is capped at 1 MB and written next to the script

class timekeeperLocal {

    const VERSION = '3.8';
    const BASE_URL = 'https://overlord.pfip.au/e107_plugins/timekeeper/timekeeperClientServices/';
    const HTTP_TIMEOUT = 10;     // seconds to wait for the server
    const MAX_FAILED_CHECKS = 5; // unreachable-server checks in a row before the game is closed
    const MAX_LOG_BYTES = 1048576;

    public $lastActiveGame = '';
    public $user = '';
    public $debug = false;
    private $failedChecks = 0;

    public function __construct() {
        $this->user = trim(exec('whoami'));
    }

    public function test() {
        $this->message('test title', 'test message', '');
    }

    /**
     * Send a message to the user.
     *
     * Example usage:
     * $this->message('Alert','this is an important message.',1);
     *
     * @param string $title The title to be displayed for the message.
     * @param string $messageText The body text of the message to be displayed.
     * @param int $urgency 1 = High, 2 = Medium, 3 = Low
     *
     * @return void
     */
    public function message($title, $messageText, $urgency = '') {
        switch ($urgency) {
            case 1:
                $urgencyText = ' --urgency=critical';
                break;
            case 2:
                $urgencyText = ' --urgency=normal';
                break;
            case 3:
                $urgencyText = ' --urgency=low';
                break;
            default:
                $urgencyText = '';
                break;
        }
        exec('notify-send' . $urgencyText . ' ' . escapeshellarg((string) $title) . ' ' . escapeshellarg(substr((string) $messageText, 0, 300)));
    }

    /**
     * Ask the server. Returns the trimmed reply, or null if it can't be reached.
     */
    private function fetch($path) {
        $context = stream_context_create(['http' => ['timeout' => self::HTTP_TIMEOUT]]);
        $reply = @file_get_contents(self::BASE_URL . $path, false, $context);
        return ($reply === false) ? null : trim($reply);
    }

    private function timerUrl($game, $peek = false) {
        return 'timer.php?user=' . rawurlencode($this->user) . '&game=' . rawurlencode($game) . ($peek ? '&peek=1' : '');
    }

    /**
     * The list of game process names. Waits until the server answers.
     */
    public function loadGames() {
        while (true) {
            $json = $this->fetch('games.json');
            $games = ($json === null) ? null : json_decode($json, true);
            if (is_array($games)) {
                return $games;
            }
            $this->Logging('Could not load games.json, trying again in 30 seconds.');
            sleep(30);
        }
    }

    /**
     * All of this user's processes as [pid => command line], without this script.
     */
    private function processList() {
        $lines = [];
        exec('ps -u ' . escapeshellarg($this->user) . ' -o pid=,args=', $lines);

        $self = getmypid();
        $processes = [];
        foreach ($lines as $line) {
            if (!preg_match('/^\s*(\d+)\s+(.*)$/', $line, $match)) {
                continue;
            }
            if ((int) $match[1] === $self) {
                continue;
            }
            $processes[(int) $match[1]] = $match[2];
        }
        return $processes;
    }

    /**
     * Pids of the processes that belong to $game.
     */
    private function gamePids($game, $processes) {
        $pids = [];
        foreach ($processes as $pid => $commandLine) {
            if (strpos($commandLine, $game) !== false && $this->cmdExceptions($commandLine)) {
                $pids[] = $pid;
            }
        }
        return $pids;
    }

    public function burnTime($startupTime, $burnTimeDuration) {
        if ($this->lastActiveGame == "") {
            sleep(20);
            return;
        }

        $remaining = ($startupTime + $burnTimeDuration) - microtime(true);
        if ($remaining > 0) {
            usleep((int) ($remaining * 1000000));
        }
    }

    public function CheckForGames($listOfKnownGames) {
        $processes = $this->processList();

        foreach ($listOfKnownGames as $gameName) {
            if (!is_string($gameName) || $gameName === '') {
                continue;
            }
            if (count($this->gamePids($gameName, $processes)) > 0) {
                $this->AnounceGameDetected($gameName);
                return;
            }
        }
        $this->AnounceGameNotDetected();
    }

    private function cmdExceptions($cmdLineReturn) {
        if (strpos($cmdLineReturn, 'grep') !== false) {
            return false;
        } elseif (strpos($cmdLineReturn, 'kiosk') !== false) {
            return false;
        } elseif (strpos($cmdLineReturn, 'contentproc') !== false) {
            return false;
        } elseif (strpos($cmdLineReturn, 'new-window') !== false) { //opera helper exception
            return false;
        } elseif (strpos($cmdLineReturn, 'type=gpu-process') !== false) { // opera helper exception
            return false;
        }
        return true;
    }

    private function AnounceGameDetected($game) {
        if ($this->lastActiveGame == "") {
            $this->lastActiveGame = $game;
            $this->failedChecks = 0;

            // peek=1: report the minutes remaining without using one up.
            $reply = $this->fetch($this->timerUrl($game, true));

            if ($reply !== null && is_numeric($reply)) {
                $text = ucfirst($game) . " detected running." . PHP_EOL . "You have " . $reply . " minutes remaining.";
            } elseif ($reply !== null) {
                $text = ucfirst($game) . " detected running." . PHP_EOL . $reply;
            } else {
                $text = ucfirst($game) . " detected running." . PHP_EOL . "The Timekeeper server could not be reached.";
            }

            $this->message("Timekeeper", $text);
            $this->Logging(ucfirst($game) . " detected running. " . ($reply === null ? 'No reply from server.' : $reply . ' minutes remaining.'));
        }
    }

    private function AnounceGameNotDetected() {
        if ($this->lastActiveGame != "") {
            $this->lastActiveGame = "";
            $this->failedChecks = 0;
            $this->message("Timekeeper", "No games detected running.");
            $this->Logging("No games detected running.");
        }
    }

    public function CheckTimeRemaining() {
        if ($this->lastActiveGame == "") {
            return;
        }

        $reply = $this->fetch($this->timerUrl($this->lastActiveGame));

        if ($reply === null) {
            $this->failedChecks++;
            $this->Logging('Could not reach the Timekeeper server (' . $this->failedChecks . ' in a row).');
            if ($this->failedChecks >= self::MAX_FAILED_CHECKS) {
                $this->message("Timekeeper", "The Timekeeper server can not be reached, so the game will be closed.", 1);
                $this->KillGame();
            }
            return;
        }

        $this->failedChecks = 0;
        $this->TimeLimitWarning($reply);
    }

    private function TimeLimitWarning($reply) {
        if (!is_numeric($reply)) {
            // Anything that is not a number is the reason play is not allowed.
            $this->message("Timekeeper", $reply);
            $this->KillGame();
            return;
        }

        $minutes = (int) $reply;

        if ($minutes <= 0) {
            $this->message("Timekeeper", "Your play time has expired.");
            $this->KillGame();
        } elseif ($minutes == 5) {
            $this->message("Timekeeper", "You only have 5 minutes remaining.");
        } elseif ($minutes == 1) {
            $this->message("Timekeeper", "You only have 1 minute remaining.");
        }
    }

    private function KillGame() {
        $game = $this->lastActiveGame;
        if ($game == "") {
            return;
        }

        $pids = $this->gamePids($game, $this->processList());

        if (count($pids) == 0) {
            $this->Logging('Game is supposedly dead, bailing out now.');
            return;
        }

        if ($this->debug) {
            $this->message("Timekeeper", "Game PID-" . implode(',', $pids) . " should\nhave just been killed.");
            return;
        }

        foreach ([15, 9] as $signal) {
            $this->Logging('Killing ' . $game . ' (pid ' . implode(',', $pids) . ') with signal ' . $signal . '.');
            foreach ($pids as $pid) {
                $this->signal($pid, $signal);
            }
            sleep($signal === 15 ? 10 : 3);

            $pids = $this->gamePids($game, $this->processList());
            if (count($pids) == 0) {
                return;
            }
        }

        // Last resort.
        $this->Logging('Still running, using pkill on ' . $game . '.');
        exec('pkill -9 -u ' . escapeshellarg($this->user) . ' -f ' . escapeshellarg($game));
    }

    private function signal($pid, $signal) {
        if (function_exists('posix_kill')) {
            @posix_kill((int) $pid, (int) $signal);
        } else {
            exec('kill -' . (int) $signal . ' ' . (int) $pid);
        }
    }

    /**
     * Write to the common log file (next to this script, capped at 1 MB).
     *
     * @param string $message The message to be written into the log file.
     * @param bool $append Set to false to overwrite the log file.
     *
     * @return void
     */
    public function Logging($message, $append = true) {
        $filename = __DIR__ . '/timekeeper.log';

        if (is_file($filename) && filesize($filename) > self::MAX_LOG_BYTES) {
            @rename($filename, $filename . '.1');
        }

        if (@file_put_contents($filename, $message . PHP_EOL, $append ? FILE_APPEND : 0) === false) {
            $this->message("Error", "Logging can not be initialised.", 1);
        }
    }

}

$TKL = new timekeeperLocal();

if (isset($argv[1]) && $argv[1] == 'debug') {
    echo "Debug mode active.";
    $TKL->debug = true;
    $TKL->message("Timekeeper " . timekeeperLocal::VERSION, "Timekeeper is running. (In debug mode)");
} else {
    $TKL->message("Timekeeper " . timekeeperLocal::VERSION, "Timekeeper is running.");
}

// Only one copy per user: the lock goes away by itself when this script ends.
$lock = fopen(sys_get_temp_dir() . '/timekeeper-' . preg_replace('/\W/', '_', $TKL->user) . '.lock', 'c');
if (!$lock || !flock($lock, LOCK_EX | LOCK_NB)) {
    die("Found another instance." . PHP_EOL);
}

set_time_limit(0);

$gamesList = $TKL->loadGames();
$TKL->Logging("Timekeeper " . timekeeperLocal::VERSION . " initialised for " . $TKL->user, false);

while (true) {
    $startupTime = microtime(true);
    $TKL->CheckForGames($gamesList);
    $TKL->CheckTimeRemaining();
    $TKL->burnTime($startupTime, 60);
}