<?php

/**
 * PHPExcel_CachedObjectStorage_SQLite3
 *
 * Copyright (c) 2006 - 2015 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    ##VERSION##, ##DATE##
 */
class PHPExcel_CachedObjectStorage_SQLite3 extends PHPExcel_CachedObjectStorage_CacheBase implements PHPExcel_CachedObjectStorage_ICache
{

    /**
     * Database table name
     *
     * @var string
     */
    private $TableName = null;

    /**
     * Database handle
     *
     * @var resource
     */
    private $DBHandle = null;

    /**
     * Prepared statement for a SQLite3 select query
     *
     * @var SQLite3Stmt
     */
    private $selectQuery;

    /**
     * Prepared statement for a SQLite3 insert query
     *
     * @var SQLite3Stmt
     */
    private $insertQuery;

    /**
     * Prepared statement for a SQLite3 update query
     *
     * @var SQLite3Stmt
     */
    private $updateQuery;

    /**
     * Prepared statement for a SQLite3 delete query
     *
     * @var SQLite3Stmt
     */
    private $deleteQuery;

    /**
     * Store cell data in cache for the current cell object if it's "dirty",
     * and the 'nullify' the current cell object
     *
     * @return void
     * @throws PHPExcel_Exception
     */
    protected function storeData()
    {
        if ($this->currentCellIsDirty && ! empty($this->currentObjectID)) {
            $this->currentObject->detach();
            
            $this->insertQuery->bindValue('id', $this->currentObjectID, SQLITE3_TEXT);
            $this->insertQuery->bindValue('data', serialize($this->currentObject), SQLITE3_BLOB);
            $result = $this->insertQuery->execute();
            if ($result === false) {
                throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
            }
            $this->currentCellIsDirty = false;
        }
        $this->currentObjectID = $this->currentObject = null;
    }

    /**
     * Add or Update a cell in cache identified by coordinate address
     *
     * @param string $pCoord
     *            Coordinate address of the cell to update
     * @param PHPExcel_Cell $cell
     *            Cell to update
     * @return PHPExcel_Cell
     * @throws PHPExcel_Exception
     */
    public function addCacheData($pCoord, PHPExcel_Cell $cell)
    {
        if (($pCoord !== $this->currentObjectID) && ($this->currentObjectID !== null)) {
            $this->storeData();
        }
        
        $this->currentObjectID = $pCoord;
        $this->currentObject = $cell;
        $this->currentCellIsDirty = true;
        
        return $cell;
    }

    /**
     * Get cell at a specific coordinate
     *
     * @param string $pCoord
     *            Coordinate of the cell
     * @throws PHPExcel_Exception
     * @return PHPExcel_Cell Cell that was found, or null if not found
     */
    public function getCacheData($pCoord)
    {
        if ($pCoord === $this->currentObjectID) {
            return $this->currentObject;
        }
        $this->storeData();
        
        $this->selectQuery->bindValue('id', $pCoord, SQLITE3_TEXT);
        $cellResult = $this->selectQuery->execute();
        if ($cellResult === false) {
            throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
        }
        $cellData = $cellResult->fetchArray(SQLITE3_ASSOC);
        if ($cellData === false) {
            // Return null if requested entry doesn't exist in cache
            return null;
        }
        
        // Set current entry to the requested entry
        $this->currentObjectID = $pCoord;
        
        $this->currentObject = unserialize($cellData['value']);
        // Re-attach this as the cell's parent
        $this->currentObject->attach($this);
        
        // Return requested entry
        return $this->currentObject;
    }

    /**
     * Is a value set for an indexed cell?
     *
     * @param string $pCoord
     *            Coordinate address of the cell to check
     * @return boolean
     */
    public function isDataSet($pCoord)
    {
        if ($pCoord === $this->currentObjectID) {
            return true;
        }
        
        // Check if the requested entry exists in the cache
        $this->selectQuery->bindValue('id', $pCoord, SQLITE3_TEXT);
        $cellResult = $this->selectQuery->execute();
        if ($cellResult === false) {
            throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
        }
        $cellData = $cellResult->fetchArray(SQLITE3_ASSOC);
        
        return ($cellData === false) ? false : true;
    }

    /**
     * Delete a cell in cache identified by coordinate address
     *
     * @param string $pCoord
     *            Coordinate address of the cell to delete
     * @throws PHPExcel_Exception
     */
    public function deleteCacheData($pCoord)
    {
        if ($pCoord === $this->currentObjectID) {
            $this->currentObject->detach();
            $this->currentObjectID = $this->currentObject = null;
        }
        
        // Check if the requested entry exists in the cache
        $this->deleteQuery->bindValue('id', $pCoord, SQLITE3_TEXT);
        $result = $this->deleteQuery->execute();
        if ($result === false) {
            throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
        }
        
        $this->currentCellIsDirty = false;
    }

    /**
     * Move a cell object from one address to another
     *
     * @param string $fromAddress
     *            Current address of the cell to move
     * @param string $toAddress
     *            Destination address of the cell to move
     * @return boolean
     */
    public function moveCell($fromAddress, $toAddress)
    {
        if ($fromAddress === $this->currentObjectID) {
            $this->currentObjectID = $toAddress;
        }
        
        $this->deleteQuery->bindValue('id', $toAddress, SQLITE3_TEXT);
        $result = $this->deleteQuery->execute();
        if ($result === false) {
            throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
        }
        
        $this->updateQuery->bindValue('toid', $toAddress, SQLITE3_TEXT);
        $this->updateQuery->bindValue('fromid', $fromAddress, SQLITE3_TEXT);
        $result = $this->updateQuery->execute();
        if ($result === false) {
            throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
        }
        
        return true;
    }

    /**
     * Get a list of all cell addresses currently held in cache
     *
     * @return string[]
     */
    public function getCellList()
    {
        if ($this->currentObjectID !== null) {
            $this->storeData();
        }
        
        $query = "SELECT id FROM kvp_" . $this->TableName;
        $cellIdsResult = $this->DBHandle->query($query);
        if ($cellIdsResult === false) {
            throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
        }
        
        $cellKeys = array();
        while ($row = $cellIdsResult->fetchArray(SQLITE3_ASSOC)) {
            $cellKeys[] = $row['id'];
        }
        
        return $cellKeys;
    }

    /**
     * Clone the cell collection
     *
     * @param PHPExcel_Worksheet $parent
     *            The new worksheet
     * @return void
     */
    public function copyCellCollection(PHPExcel_Worksheet $parent)
    {
        $this->currentCellIsDirty;
        $this->storeData();
        
        // Get a new id for the new table name
        $tableName = str_replace('.', '_', $this->getUniqueID());
        if (! $this->DBHandle->exec('CREATE TABLE kvp_' . $tableName . ' (id VARCHAR(12) PRIMARY KEY, value BLOB)
            AS SELECT * FROM kvp_' . $this->TableName)) {
            throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
        }
        
        // Copy the existing cell cache file
        $this->TableName = $tableName;
    }

    /**
     * Clear the cell collection and disconnect from our parent
     *
     * @return void
     */
    public function unsetWorksheetCells()
    {
        if (! is_null($this->currentObject)) {
            $this->currentObject->detach();
            $this->currentObject = $this->currentObjectID = null;
        }
        // detach ourself from the worksheet, so that it can then delete this object successfully
        $this->parent = null;
        
        // Close down the temporary cache file
        $this->__destruct();
    }

    /**
     * Initialise this new cell collection
     *
     * @param PHPExcel_Worksheet $parent
     *            The worksheet for this cell collection
     */
    public function __construct(PHPExcel_Worksheet $parent)
    {
        parent::__construct($parent);
        if (is_null($this->DBHandle)) {
            $this->TableName = str_replace('.', '_', $this->getUniqueID());
            $_DBName = ':memory:';
            
            $this->DBHandle = new SQLite3($_DBName);
            if ($this->DBHandle === false) {
                throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
            }
            if (! $this->DBHandle->exec('CREATE TABLE kvp_' . $this->TableName . ' (id VARCHAR(12) PRIMARY KEY, value BLOB)')) {
                throw new PHPExcel_Exception($this->DBHandle->lastErrorMsg());
            }
        }
        
        $this->selectQuery = $this->DBHandle->prepare("SELECT value FROM kvp_" . $this->TableName . " WHERE id = :id");
        $this->insertQuery = $this->DBHandle->prepare("INSERT OR REPLACE INTO kvp_" . $this->TableName . " VALUES(:id,:data)");
        $this->updateQuery = $this->DBHandle->prepare("UPDATE kvp_" . $this->TableName . " SET id=:toId WHERE id=:fromId");
        $this->deleteQuery = $this->DBHandle->prepare("DELETE FROM kvp_" . $this->TableName . " WHERE id = :id");
    }

    /**
     * Destroy this cell collection
     */
    public function __destruct()
    {
        if (! is_null($this->DBHandle)) {
            $this->DBHandle->exec('DROP TABLE kvp_' . $this->TableName);
            $this->DBHandle->close();
        }
        $this->DBHandle = null;
    }

    /**
     * Identify whether the caching method is currently available
     * Some methods are dependent on the availability of certain extensions being enabled in the PHP build
     *
     * @return boolean
     */
    public static function cacheMethodIsAvailable()
    {
        if (! class_exists('SQLite3', false)) {
            return false;
        }
        
        return true;
    }
}
