<?php

require_once "participoLib/dbConnector.php";
require_once "participoLib/participo.php";

/** Framework for apiKeys
 */
class ApiKey
{
    /** unique identifier in the database
     *
     * @var int >0
     */
    private $id = null;
    /** Id of the user
     *
     * @var int > 0
     */
    private $userId = null;
    /** base62 coded key
     *
     * @var string
     */
    private $key = null;
    /** what you can do with this key
     *
     * @var array(string)
     */
    private $rights = null;
    /** until when the key is valid
     *
     * @var DateTime
     */
    private $endDate = null;

    /** Constructor
     *
     * sets all the members:
     * - converts the params to the internal type
     * - provides input sanitation
     *
     * @param mixed $id unique identifier of the apiKey
     * @param mixed $userId $id of the user the apiKey belongs to
     * @param mixed $key key identifier/representation
     * @param mixed $rights set of rights describing what the key is valid for
     * @param mixed $endDate the last day the key will be valid
     */
    public function __construct($id, $userId, $key, $rights, $endDate)
    {
        $this->id = filterId($id);
        $this->userId = filterId($userId);
        $this->key = self::isWellFormatted($key) ? $key : null;
        $this->rights = explode(",", $rights);
        $this->endDate = DateTime::createFromFormat("Y-m-d", $endDate);

        // @todo It would be safer to set an endDate in the past as "default" value
        if ($this->endDate == false) {
            $this->endDate = null;
        }
    }

    /** Getter for the userId
     *
     * @return int >0 representing the id of the user the apiKey is for
     */
    public function getUserId()
    {
        return $this->userId;
    }

    /** Getter for the apiKey
     *
     * @return string base62 coded string representing the apiKey
     */
    public function getKey()
    {
        return $this->key;
    }

    /** Checking if the apiKey is valid for a certain action
     *
     * @param string $action the action to test the apiKey against
     * @return boolean true if apiKey is valid for the action, false otherwise
     */
    public function isValidFor(string $action)
    {
        // @todo add as validation: does the user exist and is 'active' (?)
        $today = new DateTime();
        return $this->id != null &&
            in_array($action, $this->rights) &&
            $this->endDate->format("Y-m-d") >= $today->format("Y-m-d");
    }

    /** request a specific apiKey from the db
     *
     * @param string $key the key to request
     * @return ApiKey found in the db, null otherwise
     */
    public static function loadFromDb(string $key)
    {
        if (!self::isWellFormatted($key)) {
            return null;
        }

        $query =
            "SELECT * FROM `cwsvjudo_main`.`participo_apiKeys` WHERE apiKey = :key;";
        $params = [":key" => ["value" => $key, "data_type" => PDO::PARAM_STR]];
        $response = dbConnector::query($query, $params);

        // apiKeys are considered unique. so every other count is treated as error to prevent unprivileged access
        if (count($response) != 1) {
            return null;
        }
        return ApiKey::fromDbArray($response[0]);
    }

    /** Add a key to the DB
     *
     * @return void
     */
    public function addToDb()
    {
        $query =
            "INSERT INTO `cwsvjudo_main`.`participo_apiKeys` (userId, apiKey, rights, endDate) VALUES (:userId, :apiKey, :rights, :endDate);";
        $params = [
            ":userId" => [
                "value" => $this->userId,
                "data_type" => PDO::PARAM_INT,
            ],
            ":apiKey" => ["value" => $this->key, "data_type" => PDO::PARAM_STR],
            ":rights" => [
                "value" => implode(",", $this->rights),
                "data_type" => PDO::PARAM_STR,
            ],
            ":endDate" => [
                "value" => $this->endDate->format("Y-m-d"),
                "data_type" => PDO::PARAM_STR,
            ],
        ];
        $response = dbConnector::query($query, $params);
        // @todo use the response in an error handling/messaging
        // @todo differentiate between inserting and updating if the id is set it should only be updated (e.g. prolonging)
    }

    /** create an Api key from the return of an sql select */
    private static function fromDbArray(array $apiKey)
    {
        return new ApiKey(
            $apiKey["id"] ?? null,
            $apiKey["userId"] ?? null,
            $apiKey["apiKey"] ?? null,
            $apiKey["rights"] ?? null,
            $apiKey["endDate"] ?? null,
        );
    }

    /**
     * List of symbols that can be used for the encoding
     *
     * @var string
     */
    private static $BASE = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

    /** quick and dirty implementation of a convert_to_base62
     *
     * inspired by https://stackoverflow.com/a/4964352
     *
     * @param int $num
     * @param integer $base
     * @return void
     */
    private static function toBase(int $num, int $base = 62): string
    {
        // @todo Silent error: Replacing invalid input will lead to unexpected behaviour.
        $base = filter_var($base, FILTER_VALIDATE_INT, [
            "options" => ["default" => strlen(self::$BASE), "min_range" => 1],
        ]);
        // @todo What is with negative numbers? How are they supposed to be converted?
        $r = $num % $base;
        $res = ApiKey::$BASE[$r];
        $q = floor($num / $base);
        while ($q) {
            $r = $q % $base;
            $q = floor($q / $base);
            $res = ApiKey::$BASE[$r] . $res;
        }
        return $res;
    }

    /** simple check if a string is a well formatted apiKey
     *
     * Basically checks, if it consists only of 0-9, a-z or A-Z
     *
     * @param string $string string to check
     * @return boolean true if it is base62 encoded, false otherwise
     */
    public static function isWellFormatted(string $string)
    {
        return (bool) preg_match('/^[0-9a-zA-Z]+$/', $string);
    }

    /** provides a random api key value
     *
     * @return string a random api key value
     */
    public static function create()
    {
        // @todo What is with negative numbers? How are they supposed to be converted?
        return ApiKey::toBase(random_int(0, PHP_INT_MAX));
    }

    /** more of a backup */
    private static function createTable()
    {
        dbConnector::query(
            "CREATE TABLE `cwsvjudo_main`.`participo_apiKeys` (`id` INT NOT NULL AUTO_INCREMENT COMMENT 'unique identifier' , `userId` INT NOT NULL COMMENT 'id of the user the key belongs to' , `apiKey` VARCHAR(16) NOT NULL COMMENT 'the apiKey itself' , `rights` INT NOT NULL COMMENT 'a comma separated list of rights for the key' , `endDate` DATE NOT NULL COMMENT 'endDate for the apiKey' , PRIMARY KEY (`id`), UNIQUE (`key`)); ",
        );
    }
}