<?php
/**
 * @package framework
 * @subpackage search
 */

/**
 * Matches textual content with a substring match from the beginning
 * of the string.
 * 
 * <code>
 *  "abcdefg" => "defg" # false
 *  "abcdefg" => "abcd" # true
 * </code>
 * 
 * @package framework
 * @subpackage search
 */
class StartsWithFilter extends SearchFilter {
	protected function comparison($exclude = false) {
		$modifiers = $this->getModifiers();
		if(($extras = array_diff($modifiers, array('not', 'nocase', 'case'))) != array()) {
			throw new InvalidArgumentException(
				get_class($this) . ' does not accept ' . implode(', ', $extras) . ' as modifiers');
		}
		if(DB::getConn() instanceof PostgreSQLDatabase) {
			if(in_array('case', $modifiers)) {
				$comparison = 'LIKE';
			} else {
				$comparison = 'ILIKE';
			}
		} elseif(in_array('case', $modifiers)) {
			$comparison = 'LIKE BINARY';
		} else {
			$comparison = 'LIKE';
		}
		if($exclude) {
			$comparison = 'NOT ' . $comparison;
		}
		return $comparison;
	}
	
	/**
	 * Applies a match on the starting characters of a field value.
	 *
	 * @return DataQuery
	 */
	protected function applyOne(DataQuery $query) {
		$this->model = $query->applyRelation($this->relation);
		return $query->where(sprintf(
			"%s %s '%s%%'",
			$this->getDbName(),
			$this->comparison(false),
			Convert::raw2sql($this->getValue())
		));
	}

	/**
	 * Applies a match on the starting characters of a field value.
	 * Matches against one of the many values.
	 *
	 * @return DataQuery
	 */
	protected function applyMany(DataQuery $query) {
		$this->model = $query->applyRelation($this->relation);
		$connectives = array();
		foreach($this->getValue() as $value) {
			$connectives[] = sprintf(
				"%s %s '%s%%'",
				$this->getDbName(),
				$this->comparison(false),
				Convert::raw2sql($value)
			);
		}
		$whereClause = implode(' OR ', $connectives);
		return $query->where($whereClause);
	}

	/**
	 * Excludes a match on the starting characters of a field value.
	 *
	 * @return DataQuery
	 */
	protected function excludeOne(DataQuery $query) {
		$this->model = $query->applyRelation($this->relation);
		return $query->where(sprintf(
			"%s %s '%s%%'",
			$this->getDbName(),
			$this->comparison(true),
			Convert::raw2sql($this->getValue())
		));
	}

	/**
	 * Excludes a match on the starting characters of a field value.
	 * Excludes a field if it matches any of the values.
	 *
	 * @return DataQuery
	 */
	protected function excludeMany(DataQuery $query) {
		$this->model = $query->applyRelation($this->relation);
		$connectives = array();
		foreach($this->getValue() as $value) {
			$connectives[] = sprintf(
				"%s %s '%s%%'",
				$this->getDbName(),
				$this->comparison(true),
				Convert::raw2sql($value)
			);
		}
		$whereClause = implode(' AND ', $connectives);
		return $query->where($whereClause);
	}
	
	public function isEmpty() {
		return $this->getValue() === array() || $this->getValue() === null || $this->getValue() === '';
	}
}