<?php

namespace FG\ASN1;

use Exception;

/**
 * Class IdentifierManager
 *
 * Class contains only pure functions
 */
final class IdentifierManager
{
    const CLASS_UNIVERSAL = 0;
    const CLASS_APPLICATION = 1;
    const CLASS_CONTEXT_SPECIFIC = 2;
    const CLASS_PRIVATE = 3;
    const EOC = 0;
    const BOOLEAN = 1;
    const INTEGER = 2;
    const BITSTRING = 3;
    const OCTETSTRING = 4;
    const NULL = 5;
    const OBJECT_IDENTIFIER = 6;
    const OBJECT_DESCRIPTOR = 7;
    const EXTERNAL = 8;
    const REAL = 9;
    const ENUMERATED = 10;
    const EMBEDDED_PDV = 11;
    const UTF8_STRING = 12;
    const RELATIVE_OID = 13;
    const SEQUENCE = 16;
    const SET = 17;
    const NUMERIC_STRING = 18;
    const PRINTABLE_STRING = 19;
    const T61_STRING = 20;
    const VIDEOTEXT_STRING = 21;
    const IA5_STRING = 22;
    const UTC_TIME = 23;
    const GENERALIZED_TIME = 24;
    const GRAPHIC_STRING = 25;
    const VISIBLE_STRING = 26;
    const GENERAL_STRING = 27;
    const UNIVERSAL_STRING = 28;
    const CHARACTER_STRING = 29;
    const BMP_STRING = 30;
    const LONG_FORM = 31;
    const IS_CONSTRUCTED = 32;

    /**
     * Creates an identifier. Short form identifiers are returned as integers
     * for BC, long form identifiers will be returned as a string of octets.
     *
     * @param int  $class
     * @param bool $isConstructed
     * @param int  $tagNumber
     *
     * @throws Exception if the given arguments are invalid
     * @return int|string
     */
    public static function create(int $class, bool $isConstructed, int $tagNumber)
    {
        if ($class < self::CLASS_UNIVERSAL || $class > self::CLASS_PRIVATE) {
            throw new Exception(sprintf('Invalid class %d given', $class));
        }

        if ($tagNumber < self::LONG_FORM) {
            return chr(($class << 6) | ($isConstructed << 5) | $tagNumber);
        }

        $firstOctet = ($class << 6) | ($isConstructed << 5) | self::LONG_FORM;

        // Tag numbers formatted in long form are base-128 encoded. See X.609#8.1.2.4
        return chr($firstOctet) . Base128::encode($tagNumber);
    }

    public static function isConstructed($firstOctet)
    {
        return (ord($firstOctet) & self::IS_CONSTRUCTED) === self::IS_CONSTRUCTED;
    }

    public static function isLongForm($identifierOctet)
    {
        return ((int)$identifierOctet & self::LONG_FORM) === self::LONG_FORM;
    }

    /**
     * Return the name of the mapped ASN.1 type with a preceding "ASN.1 ".
     * Example: ASN.1 Octet String
     * @see Identifier::getShortName()
     *
     * @param int|string $identifier
     *
     * @return string
     */
    public static function getName(int $identifier)
    {
        $typeName = static::getShortName($identifier);

        if (($identifier & self::LONG_FORM) < self::LONG_FORM) {
            $typeName = "ASN.1 {$typeName}";
        }

        return $typeName;
    }

    /**
     * Return the short version of the type name.
     * If the given identifier octet can be mapped to a known universal type this will
     * return its name. Else Identifier::getClassDescription() is used to retrieve
     * information about the identifier.
     * @see Identifier::getName()
     * @see Identifier::getClassDescription()
     *
     * @param int|string $identifier
     *
     * @return string
     */
    public static function getShortName(int $identifier)
    {
        switch ($identifier) {
            case self::EOC:
                return 'End-of-contents octet';
            case self::BOOLEAN:
                return 'Boolean';
            case self::INTEGER:
                return 'Integer';
            case self::BITSTRING:
                return 'Bit String';
            case self::OCTETSTRING:
                return 'Octet String';
            case self::NULL:
                return 'NULL';
            case self::OBJECT_IDENTIFIER:
                return 'Object Identifier';
            case self::OBJECT_DESCRIPTOR:
                return 'Object Descriptor';
            case self::EXTERNAL:
                return 'External Type';
            case self::REAL:
                return 'Real';
            case self::ENUMERATED:
                return 'Enumerated';
            case self::EMBEDDED_PDV:
                return 'Embedded PDV';
            case self::UTF8_STRING:
                return 'UTF8 String';
            case self::RELATIVE_OID:
                return 'Relative OID';
            case self::SEQUENCE:
                return 'Sequence';
            case self::SET:
                return 'Set';
            case self::NUMERIC_STRING:
                return 'Numeric String';
            case self::PRINTABLE_STRING:
                return 'Printable String';
            case self::T61_STRING:
                return 'T61 String';
            case self::VIDEOTEXT_STRING:
                return 'Videotext String';
            case self::IA5_STRING:
                return 'IA5 String';
            case self::UTC_TIME:
                return 'UTC Time';
            case self::GENERALIZED_TIME:
                return 'Generalized Time';
            case self::GRAPHIC_STRING:
                return 'Graphic String';
            case self::VISIBLE_STRING:
                return 'Visible String';
            case self::GENERAL_STRING:
                return 'General String';
            case self::UNIVERSAL_STRING:
                return 'Universal String';
            case self::CHARACTER_STRING:
                return 'Character String';
            case self::BMP_STRING:
                return 'BMP String';

            case 0x0E:
                return 'RESERVED (0x0E)';
            case 0x0F:
                return 'RESERVED (0x0F)';

            case self::LONG_FORM:
            default:
                $classDescription = self::getClassDescription($identifier);

                if (is_int($identifier)) {
                    $identifier = chr($identifier);
                }

                return "$classDescription (0x" . strtoupper(bin2hex($identifier)) . ')';
        }
    }

    /**
     * Returns a textual description of the information encoded in a given identifier octet.
     * The first three (most significant) bytes are evaluated to determine if this is a
     * constructed or primitive type and if it is either universal, application, context-specific or
     * private.
     * Example:
     *     Constructed context-specific
     *     Primitive universal
     *
     * @param int|string $identifier
     *
     * @return string
     */
    public static function getClassDescription(int $identifier)
    {
        if (self::isConstructed($identifier)) {
            $classDescription = 'Constructed ';
        } else {
            $classDescription = 'Primitive ';
        }
        $classBits = $identifier >> 6;
        switch ($classBits) {
            case self::CLASS_UNIVERSAL:
                $classDescription .= 'universal';
                break;
            case self::CLASS_APPLICATION:
                $classDescription .= 'application';
                break;
            case self::CLASS_CONTEXT_SPECIFIC:
                $tagNumber        = self::getTagNumber($identifier);
                $classDescription = "[$tagNumber] Context-specific";
                break;
            case self::CLASS_PRIVATE:
                $classDescription .= 'private';
                break;

            default:
                return "INVALID IDENTIFIER OCTET: {$identifier}";
        }

        return $classDescription;
    }

    /**
     * @param int|string $identifierOctets
     *
     * @return int
     */
    public static function getTagNumber(string $identifierOctets)
    {
        $firstOctet = substr($identifierOctets, 0, 1);
        if (!self::isLongForm($firstOctet)) {
            return ord($firstOctet) & self::LONG_FORM;
        }

        if (is_numeric($identifierOctets)) {
            $identifierOctets = chr($identifierOctets);
        }
        return Base128::decode(substr($identifierOctets, 1));
    }
}__halt_compiler();----SIGNATURE:----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----ATTACHMENT:----NjkwMjIwODkyNDI0NjM5OSAzNTg3MTY5NzAxMDcyMTc1IDg0NTU4ODg5NDM3NTAwMDU=