<?php
header("Content-type:application/json;charset=utf-8");
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
$action = strtolower($_GET["action"]);
if ($action === "register") {
    $username = strtolower($_GET["username"]);
    $password = $_GET["password"];
    if (empty($username)) {
        $error[] = "EMPTY_USERNAME";
    }
    if (empty($password)) {
        $error[] = "EMPTY_PASSWORD";
    }
    if (strlen($username) > 15) {
        $error[] = "USERNAME_TOOLONG";
    }
    if (!ctype_alnum($username)) {
        $error[] = "INVALID_USERNAME";
    }
    if (file_exists("accounts/$username.json")) {
        $error[] = "USERNAME_TAKEN";
    }
    if (isset($error)) {
        $array = array(
            "error" => $error
        );
    } else {
        $passwordHash  = password_hash($password, PASSWORD_DEFAULT);
        $registerArray = array(
            "passwordHash" => $passwordHash
        );
        if (!file_exists("accounts")) {
            mkdir("accounts", 0777, true);
        }
        $memberFile = fopen("accounts/$username.json", "w");
        $data       = json_encode($registerArray, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
        fwrite($memberFile, $data);
        fclose($memberFile);
        $array = array(
            "error" => false
        );
    }
} elseif ($action === "login") {
    $username = strtolower($_GET["username"]);
    $password = $_GET["password"];
    if (file_exists("accounts/$username.json")) {
        $memberFile   = file_get_contents("accounts/$username.json");
        $json         = json_decode($memberFile, TRUE);
        $passwordHash = $json["passwordHash"];
    }
    if (empty($username)) {
        $error[] = "EMPTY_USERNAME";
    }
    if (empty($password)) {
        $error[] = "EMPTY_PASSWORD";
    }
    if (!file_exists("accounts/$username.json")) {
        $error[] = "NONEXISTANT_USERNAME";
    }
    if (!password_verify($password, $passwordHash)) {
        $error[] = "INVALID_LOGIN";
    }
    if (isset($error)) {
        $array = array(
            "error" => $error
        );
    } else {
        $array = array(
            "error" => false
        );
    }
} else {
    $array = array(
        "error" => "INVALID_ACTION"
    );
}
echo json_encode($array, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
?>