<?php

/*

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * This software consists of voluntary contributions made by many individuals

 * and is licensed under the LGPL. For more information, see

 * <http://www.doctrine-project.org>.

 */

namespace Doctrine\DBAL\Schema;

use Doctrine\DBAL\Schema\Visitor\Visitor;

class Index extends AbstractAsset implements Constraint

{

    /**

     * @var array

     */

    protected $_columns;

    /**

     * @var bool

     */

    protected $_isUnique = false;

    /**

     * @var bool

     */

    protected $_isPrimary = false;

    /**

     * @param string $indexName

     * @param array $column

     * @param bool $isUnique

     * @param bool $isPrimary

     */

    public function __construct($indexName, array $columns, $isUnique=false, $isPrimary=false)

    {

        $isUnique = ($isPrimary)?true:$isUnique;

        $this->_setName($indexName);

        $this->_isUnique = $isUnique;

        $this->_isPrimary = $isPrimary;

        foreach($columns AS $column) {

            $this->_addColumn($column);

        }

    }

    /**

     * @param string $column

     */

    protected function _addColumn($column)

    {

        if(is_string($column)) {

            $this->_columns[] = $column;

        } else {

            throw new \InvalidArgumentException("Expecting a string as Index Column");

        }

    }

    /**

     * @return array

     */

    public function getColumns()

    {

        return $this->_columns;

    }

    /**

     * Is the index neither unique nor primary key?

     * 

     * @return bool

     */

    public function isSimpleIndex()

    {

        return !$this->_isPrimary && !$this->_isUnique;

    }

    /**

     * @return bool

     */

    public function isUnique()

    {

        return $this->_isUnique;

    }

    /**

     * @return bool

     */

    public function isPrimary()

    {

        return $this->_isPrimary;

    }

    /**

     * @param  string $columnName

     * @param  int $pos

     * @return bool

     */

    public function hasColumnAtPosition($columnName, $pos=0)

    {

        $columnName = strtolower($columnName);

        $indexColumns = \array_map('strtolower', $this->getColumns());

        return \array_search($columnName, $indexColumns) === $pos;

    }

    /**

     * Check if this index exactly spans the given column names in the correct order.

     *

     * @param array $columnNames

     * @return boolean

     */

    public function spansColumns(array $columnNames)

    {

        $sameColumns = true;

        for ($i = 0; $i < count($this->_columns); $i++) {

            if (!isset($columnNames[$i]) || strtolower($this->_columns[$i]) != strtolower($columnNames[$i])) {

                $sameColumns = false;

            }

        }

        return $sameColumns;

    }

    /**

     * Check if the other index already fullfills all the indexing and constraint needs of the current one.

     *

     * @param Index $other

     * @return bool

     */

    public function isFullfilledBy(Index $other)

    {

        // allow the other index to be equally large only. It being larger is an option

        // but it creates a problem with scenarios of the kind PRIMARY KEY(foo,bar) UNIQUE(foo)

        if (count($other->getColumns()) != count($this->getColumns())) {

            return false;

        }

        // Check if columns are the same, and even in the same order

        $sameColumns = $this->spansColumns($other->getColumns());

        if ($sameColumns) {

            if (!$this->isUnique() && !$this->isPrimary()) {

                // this is a special case: If the current key is neither primary or unique, any uniqe or

                // primary key will always have the same effect for the index and there cannot be any constraint

                // overlaps. This means a primary or unique index can always fullfill the requirements of just an

                // index that has no constraints.

                return true;

            } else if ($other->isPrimary() != $this->isPrimary()) {

                return false;

            } else if ($other->isUnique() != $this->isUnique()) {

                return false;

            }

            return true;

        }

        return false;

    }

    /**

     * Detect if the other index is a non-unique, non primary index that can be overwritten by this one.

     *

     * @param Index $other

     * @return bool

     */

    public function overrules(Index $other)

    {

        if ($other->isPrimary()) {

            return false;

        } else if ($this->isSimpleIndex() && $other->isUnique()) {

            return false;

        }

        if ($this->spansColumns($other->getColumns()) && ($this->isPrimary() || $this->isUnique())) {

            return true;

        }

        return false;

    }

}