Load ten figure UK grid refs about phpcoord HOT 7 CLOSED

//Function to convert a gridref to northing and easting.
function gridref_to_ne($var_grid_ref)
{

    //Allowed prefixes.
    $var_allowed_prefixes = ['HP', 'HT', 'HU', 'HW', 'HX', 'HY', 'HZ', 'NA', 'NB', 'NC', 'ND', 'NF', 'NG', 'NH', 'NJ', 'NK', 'NL', 'NM', 'NN', 'NO', 'NR', 'NS', 'NT', 'NU', 'NW', 'NX', 'NY', 'NZ', 'OV', 'SC', 'CD', 'CE', 'SH', 'SJ', 'SK', 'SM', 'SN', 'SO', 'SP', 'SR', 'SS', 'ST', 'SU', 'SV', 'SW', 'SX', 'SY', 'SZ', 'TA', 'TF', 'TG', 'TL', 'TM', 'TQ', 'TR', 'TV'];

    //Validation. Check length, prefix letters, and that at least the next 2 characters are numeric.
    if ((strlen($var_grid_ref) >= 4) && (strlen($var_grid_ref) <= 12) && (in_array(substr($var_grid_ref, 0, 2), $var_allowed_prefixes)) && (is_numeric(substr($var_grid_ref, 2, 2)))) {

        //Clean the string.
        $var_grid_ref = strtoupper(preg_replace("/[^a-zA-Z0-9]/", "", $var_grid_ref));

        //Find the length.
        $var_grid_ref_length = strlen($var_grid_ref);

        //Chop it up.
        $var_grid_ref_prefix_1 = substr($var_grid_ref, 0, 1); //Just the first letter.
        $var_grid_ref_prefix_2 = substr($var_grid_ref, 1, 1); //Just the second letter.
        if ($var_grid_ref_length == 5) {
            //Tetrad.
            $var_grid_ref_numbers = substr($var_grid_ref, 2, 2); //2 numbers after the prefix.
            $var_grid_ref_num_1 = substr($var_grid_ref, 2, 1); //Get the first number.
            $var_grid_ref_num_2 = substr($var_grid_ref, 3, 1); //Get the second number.
            $var_tetrad = strtoupper(substr($var_grid_ref, 4, 1));
        } else {
            //Normal.
            $var_grid_ref_numbers = substr($var_grid_ref, 2, ($var_grid_ref_length - 2)); //All the numbers after the prefix.
            $var_grid_ref_num_1 = substr($var_grid_ref, 2, (($var_grid_ref_length - 2) / 2)); //Get the first N characters.
            $var_grid_ref_num_2 = substr($var_grid_ref, (2 + (($var_grid_ref_length - 2) / 2)), (($var_grid_ref_length - 2) / 2)); //Get the last N characters.
            $var_tetrad = null;
        }

        //Create variables for eastings and northing.
        $var_easting = 0;
        $var_northing = 0;

        //Handle first letters.
        if ($var_grid_ref_prefix_1 == 'S') {
            $var_easting = 0;
            $var_northing = 0;
        } else if ($var_grid_ref_prefix_1 == 'N') {
            $var_easting = 0;
            $var_northing = 500000;
        } else if ($var_grid_ref_prefix_1 == 'H') {
            $var_easting = 0;
            $var_northing = 1000000;
        } else if ($var_grid_ref_prefix_1 == 'T') {
            $var_easting = 500000;
            $var_northing = 0;
        } else if ($var_grid_ref_prefix_1 == 'O') {
            $var_easting = 500000;
            $var_northing = 500000;
        } else {
            //Unrecognised grid ref.
        }

        //Build an array for the second letter - easting.
        $var_array_second_letter_easting_array_4 = ['E', 'K', 'P', 'U', 'Z']; //400000
        $var_array_second_letter_easting_array_3 = ['D', 'J', 'O', 'T', 'Y']; //300000
        $var_array_second_letter_easting_array_2 = ['C', 'H', 'N', 'S', 'X']; //200000
        $var_array_second_letter_easting_array_1 = ['B', 'G', 'M', 'R', 'W']; //100000
        $var_array_second_letter_easting_array_0 = ['A', 'F', 'L', 'Q', 'V']; //0

        //Find the number in the array.
        $var_easting_second = 0;
        if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_easting_array_4)) {
            $var_easting_second = 400000;
        } else if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_easting_array_3)) {
            $var_easting_second = 300000;
        } else if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_easting_array_2)) {
            $var_easting_second = 200000;
        } else if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_easting_array_1)) {
            $var_easting_second = 100000;
        }

        //Build an array for the second letter - northing.
        $var_array_second_letter_northing_array_4 = ['A', 'B', 'C', 'D', 'E']; //400000
        $var_array_second_letter_northing_array_3 = ['F', 'G', 'H', 'J', 'K']; //300000
        $var_array_second_letter_northing_array_2 = ['L', 'M', 'N', 'O', 'P']; //200000
        $var_array_second_letter_northing_array_1 = ['Q', 'R', 'S', 'T', 'U']; //100000
        $var_array_second_letter_northing_array_0 = ['V', 'W', 'X', 'Y', 'Z']; //0

        //Find the number in the array.
        $var_northing_second = 0;
        if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_northing_array_4)) {
            $var_northing_second = 400000;
        } else if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_northing_array_3)) {
            $var_northing_second = 300000;
        } else if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_northing_array_2)) {
            $var_northing_second = 200000;
        } else if (in_array($var_grid_ref_prefix_2, $var_array_second_letter_northing_array_1)) {
            $var_northing_second = 100000;
        }

        //Add them together.
        $var_easting = $var_easting + $var_easting_second;
        $var_northing = $var_northing + $var_northing_second;

        /**************************************************************/

        //Deal with possible tetrad first, then everything else.
        if ($var_grid_ref_length == 5) {
            //Tetrad.
            $var_resolution = '2km';

            $var_grid_ref_num_1 = $var_grid_ref_num_1 * 10000;
            $var_grid_ref_num_2 = $var_grid_ref_num_2 * 10000;

            //Now need to add on extra for tetrad - easting.
            $var_array_tetrad_easting_array_8k = array('V', 'W', 'X', 'Y', 'Z'); //8000
            $var_array_tetrad_easting_array_6k = array('Q', 'R', 'S', 'T', 'U'); //6000
            $var_array_tetrad_easting_array_4k = array('K', 'L', 'M', 'N', 'P'); //4000
            $var_array_tetrad_easting_array_2k = array('F', 'G', 'H', 'I', 'J'); //2000
            $var_array_tetrad_easting_array_0k = array('A', 'B', 'C', 'D', 'E'); //0

            if (in_array($var_tetrad, $var_array_tetrad_easting_array_8k)) {$var_grid_ref_num_1 = $var_grid_ref_num_1 + 8000;} else if (in_array($var_tetrad, $var_array_tetrad_easting_array_6k)) {$var_grid_ref_num_1 = $var_grid_ref_num_1 + 6000;} else if (in_array($var_tetrad, $var_array_tetrad_easting_array_4k)) {$var_grid_ref_num_1 = $var_grid_ref_num_1 + 4000;} else if (in_array($var_tetrad, $var_array_tetrad_easting_array_2k)) {$var_grid_ref_num_1 = $var_grid_ref_num_1 + 2000;} else if (in_array($var_tetrad, $var_array_tetrad_easting_array_0k)) {$var_grid_ref_num_1 = $var_grid_ref_num_1 + 0;}

            //Now need to add on extra for tetrad - northing.
            $var_array_tetrad_northing_array_8k = array('E', 'J', 'P', 'U', 'Z'); //8000
            $var_array_tetrad_northing_array_6k = array('D', 'I', 'N', 'T', 'Y'); //6000
            $var_array_tetrad_northing_array_4k = array('C', 'H', 'M', 'S', 'X'); //4000
            $var_array_tetrad_northing_array_2k = array('B', 'G', 'L', 'R', 'W'); //2000
            $var_array_tetrad_northing_array_0k = array('A', 'F', 'K', 'Q', 'V'); //0
            if (in_array($var_tetrad, $var_array_tetrad_northing_array_8k)) {$var_grid_ref_num_2 = $var_grid_ref_num_2 + 8000;} else if (in_array($var_tetrad, $var_array_tetrad_northing_array_6k)) {$var_grid_ref_num_2 = $var_grid_ref_num_2 + 6000;} else if (in_array($var_tetrad, $var_array_tetrad_northing_array_4k)) {$var_grid_ref_num_2 = $var_grid_ref_num_2 + 4000;} else if (in_array($var_tetrad, $var_array_tetrad_northing_array_2k)) {$var_grid_ref_num_2 = $var_grid_ref_num_2 + 2000;} else if (in_array($var_tetrad, $var_array_tetrad_northing_array_0k)) {$var_grid_ref_num_2 = $var_grid_ref_num_2 + 0;}

        } else if ($var_grid_ref_length == 4) {
            //2 figure grid ref.
            $var_resolution = '10km';
            $var_grid_ref_num_1 = $var_grid_ref_num_1 * 10000;
            $var_grid_ref_num_2 = $var_grid_ref_num_2 * 10000;
        } else if ($var_grid_ref_length == 6) {
            //4 figure grid ref plus letters.
            $var_resolution = '1km';
            $var_grid_ref_num_1 = $var_grid_ref_num_1 * 1000;
            $var_grid_ref_num_2 = $var_grid_ref_num_2 * 1000;
        } else if ($var_grid_ref_length == 8) {
            //6 figure grid ref plus letters.
            $var_resolution = '100m';
            $var_grid_ref_num_1 = $var_grid_ref_num_1 * 100;
            $var_grid_ref_num_2 = $var_grid_ref_num_2 * 100;
        } else if ($var_grid_ref_length == 10) {
            //8 figure grid ref plus letters.
            $var_resolution = '10m';
            $var_grid_ref_num_1 = $var_grid_ref_num_1 * 10;
            $var_grid_ref_num_2 = $var_grid_ref_num_2 * 10;
        } else if ($var_grid_ref_length == 12) {
            $var_resolution = '1m';
            //10 figure grid ref plus letters. No multiplication required.
            $var_grid_ref_num_1 = $var_grid_ref_num_1 * 1;
            $var_grid_ref_num_2 = $var_grid_ref_num_2 * 1;
        } else {
            //Odd length!
            $var_resolution = 'Unknown';
        }

        //Add it all together.
        $var_easting = $var_easting + $var_grid_ref_num_1;
        $var_northing = $var_northing + $var_grid_ref_num_2;

        //Return an array of the easting and northing.
        return [
            'status' => 'success',
            'gridref' => $var_grid_ref,
            'resolution' => $var_resolution,
            'tetrad' => $var_tetrad,
            'easting' => $var_easting,
            'northing' => $var_northing,
        ];

    } else {

        return [
            'status' => 'error',
            'message' => Lang::get('geom.invalid_gridref'),
        ];

    }

}