<?php

/**
 * Check if a field is empty but only when specific fields have specific values
 */
class ConditionalNotEmpty extends Zend_Validate_Abstract {

    const KEY_IS_EMPTY   = 'keyIsEmpty';

    protected $_messageTemplates = array(
        self::KEY_IS_EMPTY   => 'Value is required and can\'t be empty'
    );

    protected $_fieldValues;

    /**
     * Constructs a new ConditionalNotEmpty validator.
     *
     * @param array $fieldValues - the names and expected values of the fields we're depending on;
     * E.g., if we have a field that should only be validated when two other
     * fields PARENT_1 and PARENT_2 have values of '1' and '0' respectively, then
     * $fieldValues should contain ('PARENT_1'=>'1', 'PARENT_2'=>'0')
     */
    public function __construct($fieldValues)
    {
        $this->_fieldValues = $fieldValues;
    }

    /**
     * Implements Zend_Validate_Abstract.
     * Given names and expected values of the fields we're depending on ($_fieldValues),
     * this function returns true if the expected values doesn't match the actual user input,
     * or if $value is not empty. Returns false otherwise.
     *
     * @param String $value - this field's value
     * @param array $context - names and values of the rest of the fields in this form
     * @return boolean - true if valid; false otherwise
     */
    public function isValid($value, $context = null)
    {
        if ($value != "") {
            return true;
        }

        if (is_array($context)) {
            foreach($this->_fieldValues as $fieldName=>$fieldValue) {
                if (!isset($context[$fieldName]) || $context[$fieldName] != $fieldValue) {
                    return true;
                }
            }
        } elseif (is_string($context)) {
            if (!isset($context) || $context != $fieldValue) {
                return true;
            }
        }

        $this->_error(self::KEY_IS_EMPTY);
        return false;
    }
}

?>