silverstripe-framework/src/Forms/CreditCardField.php

<?php

namespace SilverStripe\Forms;

/**
 * Allows input of credit card numbers via four separate form fields,
 * including generic validation of its numeric values.
 *
 * @todo Validate
 */
class CreditCardField extends TextField
{

    /**
     * Add default attributes for use on all inputs.
     *
     * @return array List of attributes
     */
    public function getAttributes()
    {
        return array_merge(
            parent::getAttributes(),
            array(
                'autocomplete' => 'off',
                'maxlength' => 4,
                'size' => 4
            )
        );
    }

    public function Field($properties = array())
    {
        $parts = $this->arrayValue();

        $properties['ValueOne'] = $parts[0];
        $properties['ValueTwo'] = $parts[1];
        $properties['ValueThree'] = $parts[2];
        $properties['ValueFour'] = $parts[3];

        return parent::Field($properties);
    }

    /**
     * Get tabindex HTML string
     *
     * @param int $increment Increase current tabindex by this value
     * @return string
     */
    public function getTabIndexHTML($increment = 0)
    {
        // we can't add a tabindex if there hasn't been one set yet.
        if ($this->getAttribute('tabindex') === null) {
            return false;
        }

        $tabIndex = (int)$this->getAttribute('tabindex') + (int)$increment;
        return (is_numeric($tabIndex)) ? ' tabindex = "' . $tabIndex . '"' : '';
    }

    public function dataValue()
    {
        if (is_array($this->value)) {
            return implode("", $this->value);
        } else {
            return $this->value;
        }
    }

    /**
     * Get either list of values, or null
     *
     * @return array
     */
    public function arrayValue()
    {
        if (is_array($this->value)) {
            return $this->value;
        }

        $value = $this->dataValue();
        return $this->parseCreditCard($value);
    }

    /**
     * Parse credit card value into list of four four-digit values
     *
     * @param string $value
     * @return array|null
     */
    protected function parseCreditCard($value)
    {
        if (preg_match("/([0-9]{4})([0-9]{4})([0-9]{4})([0-9]{4})/", $value, $parts)) {
            return [ $parts[1], $parts[2], $parts[3], $parts[4] ];
        }
        return null;
    }

    public function validate($validator)
    {
        $value = $this->dataValue();
        if (empty($value)) {
            return true;
        }

        // Check if format is valid
        if ($this->parseCreditCard($value)) {
            return true;
        }

        // Format is invalid
        $validator->validationError(
            $this->name,
            _t(
                'Form.VALIDATIONCREDIT',
                "Please ensure you have entered the credit card number correctly"
            ),
            "validation"
        );
        return false;
    }
}