<?php declare(strict_types=1);

namespace BradyMcD\TAATP\URI;

use InvalidArgumentException;

class Otpauth
{
    public function __construct(
        public readonly string $userid,
        public readonly string $issuer,
        public readonly string $secret,
        public readonly string $algorithm,
        public readonly int $digits,
        public readonly int $period,
    )
    {
        $this->secret = \rtrim($secret, "=");
    }

    public static function fromString(string $uri): self
    {
        // This is definitely from writing Scheme.
        $runCheck = function(array $checkArray, $target)
        {
            foreach($checkArray as $c)
            {
                ($c[0]($target))? :throw new InvalidArgumentException($c[1]);
            }
        };
        $uriChecks = [
            [ function($arr)
            { return $arr !== false; },
                $uri . " is not a valid URI."],
            [ function($arr)
            { return \array_key_exists('scheme', $arr);},
                $uri . " has no scheme."],
            [ function($arr)
            { return $arr['scheme'] === 'otpauth';},
                $uri . " is not an otpauth:// uri."],
            [ function($arr)
            { return \array_key_exists('path', $arr);},
                $uri . " isn't tagged for a user or issuer."],
            [ function($arr)
            { return \array_key_exists('query', $arr);},
                $uri . " lacks query information."]
        ];

        $parsedUri = \parse_url($uri);
        $runCheck($uriChecks, $parsedUri);

        $queryChecks = [
            [ function($que)
            { return \array_key_exists('issuer', $que);},
                $parsedUri['query'] . " has no issuer information."],
            [ function($que)
            { return \array_key_exists('secret', $que);},
                $parsedUri['query'] . "has no secret key."],
        ];
        $labelChecks = [
            [ function($lab)
            { return \count($lab) === 2;},
                $parsedUri['path'] . " doesn't have the correct number of components."]
        ];

        $label = \explode(":", $parsedUri['path']);
        $runCheck($labelChecks, $label);

        $parsedQuery = [];
        \parse_str($parsedUri['query'], $parsedQuery);

        $queryDefaults = [
            "algorithm" => "SHA1",
            "period" => "30",
            "digits" => "6",
            "issuer" => \rawurldecode(\ltrim($label[0], "/")),
        ];
        $parsedQuery = \array_merge($queryDefaults, $parsedQuery);
        $runCheck($queryChecks, $parsedQuery);

        $convertFields = function(array $conversion, array &$target) {
            foreach ($conversion as $k => $v)
            {
                $target[$k] = $v($target[$k]);
            }
        };
        $queryConversions = [
            "period" => '\intval',
            "digits" => '\intval',
            "secret" => '\rawurldecode'
        ];
        $labelConversions = [
            0 => '\rawurldecode',
        ];

        $convertFields($queryConversions, $parsedQuery);
        $convertFields($labelConversions, $label);

        // END SCHEMEING

        \ltrim($label[0], "/") === $parsedQuery['issuer']
            || throw new InvalidArgumentException($uri . " has mismatching issuer information.\n" .
                                                  \ltrim($label[0], "/") . "\n" .
                                                  $parsedQuery['issuer']);

        return new self(
            $label[1],
            $parsedQuery['issuer'],
            $parsedQuery['secret'],
            $parsedQuery['algorithm'],
            $parsedQuery['digits'],
            $parsedQuery['period']
        );
    }

    public function emitStr(): string
    {
        $encodeIssuer = \rawurlencode($this->issuer);
        $label = $encodeIssuer . ":" . $this->userid;
        $issuer = "issuer=" . $encodeIssuer;
        $algo = "algorithm=" . $this->algorithm;
        $digits = "digits=" . $this->digits;
        $period = "period=" . $this->period;
        $secret = "secret=" . \rawurlencode($this->secret);
        $query = \implode("&", [$secret, $issuer, $algo, $period, $digits]);

        return "otpauth://totp/" . $label . "?" . $query;
    }

}

?>