zend-blog-3-backend

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<?php
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namespace App\Utils;
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use InvalidArgumentException;
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/**
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 * Class EmojiFlagSymbol
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 *
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 * Examples:
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 * https://emojipedia.org/flags/
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 * https://apps.timwhitlock.info/unicode/inspect/hex/1F1F2/1F1E9
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 */
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class EmojiFlagSymbol
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{
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    /**
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     * The number by which to offset the character code to get the regional indicator
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     *
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     * @var int
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     */
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    private const INDICATOR_OFFSET = 127397;
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    /**
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     * @param string|null $countryCode
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     *
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     * @return string
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     */
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    public static function get(string $countryCode = null): string
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    {
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        if ($countryCode === '-') {
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            // Pirate Flag Emoji
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            return hex2bin('F09F8FB4E2808DE298A0EFB88F');
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        }
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        if (is_null($countryCode) || strlen($countryCode) !== 2) {
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            throw new InvalidArgumentException('Please provide a 2 character country code.');
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        }
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        $countryCode = strtoupper($countryCode);
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        return implode(
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            '',
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            array_map(
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                [__CLASS__, 'convertChar'],
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                str_split($countryCode)
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            )
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        );
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    }
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    private static function convertChar(string $char): string
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    {
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        $codepoint = self::INDICATOR_OFFSET + ord($char);
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        $byte0 = 0b10000000 + ($codepoint & 0b111111);
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        $byte1 = 0b10000000 + (($codepoint >> 6) & 0b111111);
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        $byte2 = 0b10000000 + (($codepoint >> 12) & 0b111111);
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        $byte3 = 0b11110000 + (($codepoint >> 18) & 0b111);
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        return chr($byte3) . chr($byte2) . chr($byte1) . chr($byte0);
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    }
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}
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