<?php

require __DIR__ . '/vendor/autoload.php';

require_once('config.inc.php');

$route = explode('/', trim(substr(explode('?', $_SERVER['REDIRECT_URL'])[0], strrpos($_SERVER['SCRIPT_NAME'], '/')), '/'));
$meth = $_SERVER['REQUEST_METHOD'];

$DOMAIN_NAME_REGEX = '[a-zA-Z0-9\p{L}][a-zA-Z0-9\p{L}-\.]{1,61}[a-zA-Z0-9\p{L}]\.[a-zA-Z0-9\p{L}][a-zA-Z\p{L}-]*[a-zA-Z0-9\p{L}]+'; // From http://stackoverflow.com/a/38477788/2766106
$SSH_KEY_REGEX = '/^(ssh-(rsa|ed25519|dss)|ecdsa-sha2-nistp256) [a-zA-Z0-9+=\/]+/';

$machineArgs = array(
    'name' => array(
        'type' => 'string',
        'pattern' => '/^[a-zA-Z0-9\-_]+$/',
        'repeatable' => false,
        'optional' => false
    ),
    'host' => array(
        'type' => 'string',
        'pattern' => '/^'.$DOMAIN_NAME_REGEX.'(:\d+)?$/',
        'repeatable' => true,
        'optional' => true
    ),
    'user' => array(
        'type' => 'string',
        'pattern' => '/^[a-zA-Z0-9\-_]+$/',
        'repeatable' => false,
        'optional' => false
    ),
    'network' => array(
        'type' => 'string',
        'oneof' => 'network',
        'repeatable' => false,
        'optional' => true
    ),
    'userkey' => array(
        'type' => 'string',
        'pattern' => $SSH_KEY_REGEX,
        'repeatable' => false,
        'optional' => true
    ),
    'hostkey' => array(
        'type' => 'string',
        'pattern' => $SSH_KEY_REGEX,
        'repeatable' => false,
        'optional' => true
    )
);

$networkArgs = array(
    'name' => array(
        'type' => 'string',
        'pattern' => '/^[a-zA-Z0-9]+$/',
        'repeatable' => false,
        'optional' => false
    ),
    'allowed' => array(
        'type' => 'string',
        'oneof' => 'network',
        'repeatable' => true,
        'optional' => true
    ),
    'secure' => array(
        'type' => 'boolean',
        'repeatable' => false,
        'optional' => false
    )
);

// Compute a diff between two arrays
// From http://stackoverflow.com/a/22021254/2766106
function computeDiff($from, $to)
{
    $diffValues = array();
    $diffMask = array();

    $dm = array();
    $n1 = count($from);
    $n2 = count($to);

    for ($j = -1; $j < $n2; $j++) $dm[-1][$j] = 0;
    for ($i = -1; $i < $n1; $i++) $dm[$i][-1] = 0;
    for ($i = 0; $i < $n1; $i++)
    {
        for ($j = 0; $j < $n2; $j++)
        {
            if ($from[$i] == $to[$j])
            {
                $ad = $dm[$i - 1][$j - 1];
                $dm[$i][$j] = $ad + 1;
            }
            else
            {
                $a1 = $dm[$i - 1][$j];
                $a2 = $dm[$i][$j - 1];
                $dm[$i][$j] = max($a1, $a2);
            }
        }
    }

    $i = $n1 - 1;
    $j = $n2 - 1;
    while (($i > -1) || ($j > -1))
    {
        if ($j > -1)
        {
            if ($dm[$i][$j - 1] == $dm[$i][$j])
            {
                $diffValues[] = $to[$j];
                $diffMask[] = 1;
                $j--;
                continue;
            }
        }
        if ($i > -1)
        {
            if ($dm[$i - 1][$j] == $dm[$i][$j])
            {
                $diffValues[] = $from[$i];
                $diffMask[] = -1;
                $i--;
                continue;
            }
        }
        {
            $diffValues[] = $from[$i];
            $diffMask[] = 0;
            $i--;
            $j--;
        }
    }

    $diffValues = array_reverse($diffValues);
    $diffMask = array_reverse($diffMask);

    return array('values' => $diffValues, 'mask' => $diffMask);
}

function requireToken() {
    global $TOTP;
    if (isset($_SERVER['HTTP_X_TOTP']) && $_SERVER['HTTP_X_TOTP']) {
        if (!$TOTP->verify($_SERVER['HTTP_X_TOTP'], null, 1)) {
            http_response_code(403);
            die("Invalid token\n");
        }
    } else {
        http_response_code(401);
        die("Authorization required\n");
    }

}

function requireSigned() {
    if ($_SERVER['SSL_CLIENT_VERIFY'] == 'NONE') {
        http_response_code(401);
        die("Authorization required\n");
    } elseif ($_SERVER['SSL_CLIENT_VERIFY'] != 'SUCCESS') {
        http_response_code(403);
        die("Wrong certificate\n");
    }
}

function logActivity($text) {
    $ex = explode("\n", $text);
    $t = '';
    foreach ($ex as $line) {
        if ($line == '') {
            continue;
        }
        $t .= strval(time()).'|'.$line."\n";
    }
    file_put_contents('machines.log', $t, FILE_APPEND);
}

function save($elname, $elements) {
    file_put_contents($elname.'.ser.db', serialize($elements));
}

function load($elname) {
    if (!file_exists($elname.'.ser.db')) {
        save($elname, []);
    }
    return unserialize(file_get_contents($elname.'.ser.db'));
}

function getKeys($network) {
    global $SSH_KEY_REGEX;
    global $DOMAIN;
    $machines = load('machine');
    $networks = load('network');
    $t = '';
    foreach ($machines as $machineName => $machine) {
        if (
            (
                isset($machine['network'])
                && isset($networks[$machine['network']])
            ) && (
                (
                    $networks[$machine['network']]['secure'] == 'true'
                ) || (
                    $network
                    && isset($network['allowed'])
                    && in_array($machine['network'], $network['allowed'])
                )
            )
        ) {
            if (isset($machine['userkey']) && preg_match($SSH_KEY_REGEX, $machine['userkey'], $matches)) {
                $t .= $matches[0].' '.$machineName.'@'.($machine['network'] ? $machine['network'].'.' : '').$DOMAIN."\n";
            }
        }
    }
    return $t;
}

// Display an element in a simple, easily-editable,
// easily-diffable, plain text format
function displayElement($element, $elementArgs) {
    $t = '';
    ksort($element);
    foreach ($element as $arg => $value) {
        if ($arg == 'name') {
            continue;
        }
        if (array_key_exists($arg, $elementArgs)) {
            if ($value) {
                $argData = $elementArgs[$arg];
                if ($argData['repeatable']) {
                    sort($value);
                    foreach ($value as $arrValue) {
                        $t .= $arg.'[]='.$arrValue."\n";
                    }
                } else {
                    $t .= $arg.'='.$value."\n";
                }
            }
        }
    }
    return $t;
}

// Verifiy if one argument is valid
// return false if valid, string with
// description if not
function argAssertOne($argData, $data) {
    // Type casting
    switch ($argData['type']) {
    case 'boolean':
        switch ($data) {
        case 'true':
            $data = true;
            break;
        case 'false':
            $data = false;
            break;
        }
        break;
    }

    // Type validation
    if (gettype($data) != $argData['type']) {
        return "should be of type ".$argData['type'];
    }

    // Pattern validation
    if (isset($argData['pattern']) && !preg_match($argData['pattern'], $data)) {
        return "should match pattern ".$argData['pattern'];
    }

    // OneOf validation
    if (isset($argData['oneof'])) {
        $elname = $argData['oneof'];
        $elements = load($elname);
        if (!isset($elements[$data])) {
            return "should be an existing $elname";
        }
    }

    return false;
}

function argAssert($arg, $data, $args) {
    $argData = $args[$arg];
    # TODO oneof

    if (!$data) {
        if ($argData['optional']) {
            return false;
        } else {
                return "Argument $arg is required";
        }

    }

    if ($argData['repeatable']) {
        if (gettype($data) == 'array') {
            foreach ($data as $key => $dat) {
                if ($err = argAssertOne($argData, $dat)) {
                    return "Argument $arg"."[$key] $err";
                }
            }
        } else {
            return "Argument $arg should be an array";
        }
    } else {
        if ($err = argAssertOne($argData, $data)) {
            return "Argument $arg ".$err;
        }
    }
    return false;
}

switch ($route[0]) {
case 'machine':
case 'network':
    switch ($elname = $route[0]) {
    case 'machine':
        $elementArgs = $machineArgs;
        break;
    case 'network':
        $elementArgs = $networkArgs;
        break;
    }

    // GET /element
    if (count($route) == 1 && $meth == 'GET') {
        requireSigned();
        $elements = load($elname);
        foreach ($elements as $key => $value) {
            echo $key."\n";
        }

    // GET /element/{name}
    } elseif (count($route) == 2 && $meth == 'GET') {
        if ($elname != 'machine') {
            requireSigned();
        }
        $elements = load($elname);
        if (isset($elements[$route[1]])) {
            $element = $elements[$route[1]];
            echo displayElement($element, $elementArgs);
        } else {
            http_response_code(404);
            die("Unknown $elname\n");
        }

    // POST /element
    } elseif (count($route) == 1 && $meth == 'POST') {
        if (isset($_SERVER['HTTP_X_TOTP']) && $elname == 'machine') {
            $restrained = true;
            requireToken();
        } else {
            $restrained = false;
            requireSigned();
        }
        foreach ($_POST as $arg => $value) {
            if ($restrained && $arg == 'network') {
                http_response_code(403);
                die("You can't add a network authenticated like that\n");
            }

            if (!array_key_exists($arg, $elementArgs)) {
                die("Unknown argument $arg\n");
            }
        }
        $elements = load($elname);
        $element = array();
        foreach ($elementArgs as $arg => $argData) {
            if (!isset($_POST[$arg])) {
                $_POST[$arg] = null;
            }
            if ($err = argAssert($arg, $_POST[$arg], $elementArgs)) {
                http_response_code(400);
                die("$err\n");
            }

            if ($arg == 'name') {
                $name = $_POST[$arg];
            } else {
                $element[$arg] = $_POST[$arg];
            }
        }
        if (isset($elements[$name])) {
            http_response_code(409);
            die("$elname with the same name already exists\n");
        } else {
            $elements[$name] = $element;
            save($elname, $elements);
            http_response_code(201);
            logActivity("Created $elname \"$name\"\n".displayElement($element, $elementArgs));
        }

    // POST /element/{name}
    } elseif (count($route) == 2 && $meth == 'POST') {
        requireSigned();
        foreach ($_POST as $arg => $value) {
            if (!array_key_exists($arg, $elementArgs)) {
                die("Unknown argument $arg\n");
            }
        }
        $elements = load($elname);
        if (isset($elements[$route[1]])) {
            $element = $elements[$route[1]];
            foreach ($elementArgs as $arg => $typ) {
                if (isset($_POST[$arg])) {
                    if ($arg == 'name') {
                        http_response_code(501);
                        die("Can't change name\n");
                    }
                    if ($err = argAssert($arg, $_POST[$arg], $elementArgs)) {
                        http_response_code(400);
                        die("$err\n");
                    }
                    $element[$arg] = $_POST[$arg];
                }
            }
            $oldEls = explode("\n", displayElement($elements[$route[1]], $elementArgs));

            $elements[$route[1]] = $element;
            save($elname, $elements);
            http_response_code(204);

            $newEls = explode("\n", displayElement($elements[$route[1]], $elementArgs));
            $diff = computeDiff($oldEls, $newEls);
            $t = '';
            foreach ($diff['values'] as $i => $line) {
                switch ($diff['mask'][$i]) {
                case -1:
                    $t .= '- '.$line."\n";
                    break;
                case 1:
                    $t .= '+ '.$line."\n";
                    break;
                }

            }
            logActivity("Modified $elname \"$route[1]\"\n".$t);
        } else {
            http_response_code(404);
            die("Unknown $elname\n");
        }

    // DELETE /element/{name}
    } elseif (count($route) == 2 && $meth == 'DELETE') {
        requireSigned();
        $elements = load($elname);
        if (isset($elements[$route[1]])) {
            unset($elements[$route[1]]);
            save($elname, $elements);
            http_response_code(204);
            logActivity("Removed $elname \"$name\"");
        } else {
            http_response_code(404);
            die("Unknown $elname\n");
        }

    } else {
        http_response_code(501);
        die("Unkown route\n");
    }
    break;

// Authorized keys for networks
case 'akey':

    // GET /akey/{network}
    if ((count($route) == 1 || count($route) == 2) && $meth == 'GET') {
        if (count($route) == 2) {
            $networkName = $route[1];
        } else {
            $networkName = '';
        }
        $networks = load('network');
        if (!$networkName || isset($networks[$networkName])) {
            if ($networkName) {
                $network = $networks[$networkName];
            }

            // GET /akey/{network}?signature
            if (isset($_GET['signature'])) {
                echo file_get_contents('akey/'.$networkName.'.authorized_keys.sha256');

            // GET /akey/{network}?unsigned
            } elseif (isset($_GET['unsigned'])) {
                requireSigned();
                echo getKeys($networkName ? $network : null);

            // GET /akey/{network}
            } else {
                echo file_get_contents('akey/'.$networkName.'.authorized_keys');
            }
        } else {
            http_response_code(404);
            die("Unknown network\n");
        }

    // PUT /akey/{network}
    } elseif ((count($route) == 1 || count($route) == 2) && $meth == 'PUT') {
        requireSigned();
        if (count($route) == 2) {
            $networkName = $route[1];
        } else {
            $networkName = '';
        }
        $networks = load('network');
        if (!$networkName || isset($networks[$networkName])) {
            if ($networkName) {
                $network = $networks[$networkName];
            }

            $sign = file_get_contents('php://input');
            file_put_contents('akey/'.$networkName.'.authorized_keys', getKeys($networkName ? $network : null));
            file_put_contents('akey/'.$networkName.'.authorized_keys.sha256', $sign);

            http_response_code(201);
            logActivity('Updated key '.$networkName);
        } else {
            http_response_code(404);
            die("Unknown network\n");
        }
    } else {
        http_response_code(501);
        die("Unkown route\n");
    }
    break;

// Activity log
case 'log':
    if  (count($route) == 1 && $meth == 'GET') {
        requireSigned();
        if (!isset($_GET['from']) || !$from = intval($_GET['from'])) {
            $from = 0;
        }
        $file = fopen('machines.log', 'r');
        while (!feof($file)) {
            $line = fgets($file);
            if ($line == '') {
                continue;
            }
            preg_match('/^(\d+)\|(.+)$/', $line, $matches);
            if (intval($matches[1]) > $from) {
                echo $matches[2]."\n";
            }
        }
        fclose($file);
    }
    break;
case 'totp':
    global $TOTP;
    if  (count($route) == 1 && $meth == 'GET') {
        requireSigned();
        echo $TOTP->getProvisioningUri();
    }
    break;
case 'cert':
    if  (count($route) == 1 && $meth == 'GET') {
        echo file_get_contents('machines.crt');
    }
    break;
default:
    http_response_code(501);
    die("Unkown route\n");
}


?>