<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\sphinx;

use yii\base\Object;
use yii\caching\Cache;
use Yii;
use yii\caching\TagDependency;
use yii\db\Exception;

/**
 * Schema represents the Sphinx schema information.
 *
 * @property string[] $indexNames All index names in the Sphinx. This property is read-only.
 * @property IndexSchema[] $indexSchemas The metadata for all indexes in the Sphinx. Each array element is an
 * instance of [[IndexSchema]] or its child class. This property is read-only.
 * @property array $indexTypes All index types in the Sphinx in format: index name => index type. This
 * property is read-only.
 * @property QueryBuilder $queryBuilder The query builder for this connection. This property is read-only.
 *
 * @author Paul Klimov <klimov.paul@gmail.com>
 * @since 2.0
 */
class Schema extends Object
{
    /**
     * The followings are the supported abstract column data types.
     */
    const TYPE_PK = 'pk';
    const TYPE_STRING = 'string';
    const TYPE_INTEGER = 'integer';
    const TYPE_BIGINT = 'bigint';
    const TYPE_FLOAT = 'float';
    const TYPE_TIMESTAMP = 'timestamp';
    const TYPE_BOOLEAN = 'boolean';

    /**
     * @var Connection the Sphinx connection
     */
    public $db;
    /**
     * @var array list of ALL index names in the Sphinx
     */
    private $_indexNames;
    /**
     * @var array list of ALL index types in the Sphinx (index name => index type)
     */
    private $_indexTypes;
    /**
     * @var array list of loaded index metadata (index name => IndexSchema)
     */
    private $_indexes = [];
    /**
     * @var QueryBuilder the query builder for this Sphinx connection
     */
    private $_builder;


    /**
     * @var array mapping from physical column types (keys) to abstract column types (values)
     */
    public $typeMap = [
        'field' => self::TYPE_STRING,
        'string' => self::TYPE_STRING,
        'ordinal' => self::TYPE_STRING,
        'integer' => self::TYPE_INTEGER,
        'int' => self::TYPE_INTEGER,
        'uint' => self::TYPE_INTEGER,
        'bigint' => self::TYPE_BIGINT,
        'timestamp' => self::TYPE_TIMESTAMP,
        'bool' => self::TYPE_BOOLEAN,
        'float' => self::TYPE_FLOAT,
        'mva' => self::TYPE_INTEGER,
    ];

    /**
     * Loads the metadata for the specified index.
     * @param string $name index name
     * @return IndexSchema driver dependent index metadata. Null if the index does not exist.
     */
    protected function loadIndexSchema($name)
    {
        $index = new IndexSchema;
        $this->resolveIndexNames($index, $name);
        $this->resolveIndexType($index);

        if ($this->findColumns($index)) {
            return $index;
        } else {
            return null;
        }
    }

    /**
     * Resolves the index name.
     * @param IndexSchema $index the index metadata object
     * @param string $name the index name
     */
    protected function resolveIndexNames($index, $name)
    {
        $index->name = str_replace('`', '', $name);
    }

    /**
     * Resolves the index name.
     * @param IndexSchema $index the index metadata object
     */
    protected function resolveIndexType($index)
    {
        $indexTypes = $this->getIndexTypes();
        $index->type = array_key_exists($index->name, $indexTypes) ? $indexTypes[$index->name] : 'unknown';
        $index->isRuntime = ($index->type == 'rt');
    }

    /**
     * Obtains the metadata for the named index.
     * @param string $name index name. The index name may contain schema name if any. Do not quote the index name.
     * @param boolean $refresh whether to reload the index schema even if it is found in the cache.
     * @return IndexSchema index metadata. Null if the named index does not exist.
     */
    public function getIndexSchema($name, $refresh = false)
    {
        if (isset($this->_indexes[$name]) && !$refresh) {
            return $this->_indexes[$name];
        }

        $db = $this->db;
        $realName = $this->getRawIndexName($name);

        if ($db->enableSchemaCache && !in_array($name, $db->schemaCacheExclude, true)) {
            /* @var $cache Cache */
            $cache = is_string($db->schemaCache) ? Yii::$app->get($db->schemaCache, false) : $db->schemaCache;
            if ($cache instanceof Cache) {
                $key = $this->getCacheKey($name);
                if ($refresh || ($index = $cache->get($key)) === false) {
                    $index = $this->loadIndexSchema($realName);
                    if ($index !== null) {
                        $cache->set($key, $index, $db->schemaCacheDuration, new TagDependency([
                            'tags' => $this->getCacheTag(),
                        ]));
                    }
                }

                return $this->_indexes[$name] = $index;
            }
        }

        return $this->_indexes[$name] = $this->loadIndexSchema($realName);
    }

    /**
     * Returns the cache key for the specified index name.
     * @param string $name the index name
     * @return mixed the cache key
     */
    protected function getCacheKey($name)
    {
        return [
            __CLASS__,
            $this->db->dsn,
            $this->db->username,
            $name,
        ];
    }

    /**
     * Returns the cache tag name.
     * This allows [[refresh()]] to invalidate all cached index schemas.
     * @return string the cache tag name
     */
    protected function getCacheTag()
    {
        return md5(serialize([
            __CLASS__,
            $this->db->dsn,
            $this->db->username,
        ]));
    }

    /**
     * Returns the metadata for all indexes in the database.
     * @param boolean $refresh whether to fetch the latest available index schemas. If this is false,
     * cached data may be returned if available.
     * @return IndexSchema[] the metadata for all indexes in the Sphinx.
     * Each array element is an instance of [[IndexSchema]] or its child class.
     */
    public function getIndexSchemas($refresh = false)
    {
        $indexes = [];
        foreach ($this->getIndexNames($refresh) as $name) {
            if (($index = $this->getIndexSchema($name, $refresh)) !== null) {
                $indexes[] = $index;
            }
        }

        return $indexes;
    }

    /**
     * Returns all index names in the Sphinx.
     * @param boolean $refresh whether to fetch the latest available index names. If this is false,
     * index names fetched previously (if available) will be returned.
     * @return string[] all index names in the Sphinx.
     */
    public function getIndexNames($refresh = false)
    {
        if (!isset($this->_indexNames) || $refresh) {
            $this->initIndexesInfo();
        }

        return $this->_indexNames;
    }

    /**
     * Returns all index types in the Sphinx.
     * @param boolean $refresh whether to fetch the latest available index types. If this is false,
     * index types fetched previously (if available) will be returned.
     * @return array all index types in the Sphinx in format: index name => index type.
     */
    public function getIndexTypes($refresh = false)
    {
        if (!isset($this->_indexTypes) || $refresh) {
            $this->initIndexesInfo();
        }

        return $this->_indexTypes;
    }

    /**
     * Initializes information about name and type of all index in the Sphinx.
     */
    protected function initIndexesInfo()
    {
        $this->_indexNames = [];
        $this->_indexTypes = [];
        $indexes = $this->findIndexes();
        foreach ($indexes as $index) {
            $indexName = $index['Index'];
            $this->_indexNames[] = $indexName;
            $this->_indexTypes[$indexName] = $index['Type'];
        }
    }

    /**
     * Returns all index names in the Sphinx.
     * @return array all index names in the Sphinx.
     */
    protected function findIndexes()
    {
        $sql = 'SHOW TABLES';

        return $this->db->createCommand($sql)->queryAll();
    }

    /**
     * @return QueryBuilder the query builder for this connection.
     */
    public function getQueryBuilder()
    {
        if ($this->_builder === null) {
            $this->_builder = $this->createQueryBuilder();
        }

        return $this->_builder;
    }

    /**
     * Determines the PDO type for the given PHP data value.
     * @param mixed $data the data whose PDO type is to be determined
     * @return integer the PDO type
     * @see http://www.php.net/manual/en/pdo.constants.php
     */
    public function getPdoType($data)
    {
        static $typeMap = [
            // php type => PDO type
            'boolean' => \PDO::PARAM_BOOL,
            'integer' => \PDO::PARAM_INT,
            'string' => \PDO::PARAM_STR,
            'resource' => \PDO::PARAM_LOB,
            'NULL' => \PDO::PARAM_NULL,
        ];
        $type = gettype($data);

        return isset($typeMap[$type]) ? $typeMap[$type] : \PDO::PARAM_STR;
    }

    /**
     * Refreshes the schema.
     * This method cleans up all cached index schemas so that they can be re-created later
     * to reflect the Sphinx schema change.
     */
    public function refresh()
    {
        /* @var $cache Cache */
        $cache = is_string($this->db->schemaCache) ? Yii::$app->get($this->db->schemaCache, false) : $this->db->schemaCache;
        if ($this->db->enableSchemaCache && $cache instanceof Cache) {
            TagDependency::invalidate($cache, $this->getCacheTag());
        }
        $this->_indexNames = [];
        $this->_indexes = [];
    }

    /**
     * Creates a query builder for the Sphinx.
     * @return QueryBuilder query builder instance
     */
    public function createQueryBuilder()
    {
        return new QueryBuilder($this->db);
    }

    /**
     * Quotes a string value for use in a query.
     * Note that if the parameter is not a string, it will be returned without change.
     * @param string $str string to be quoted
     * @return string the properly quoted string
     * @see http://www.php.net/manual/en/function.PDO-quote.php
     */
    public function quoteValue($str)
    {
        if (is_string($str)) {
            return $this->db->getSlavePdo()->quote($str);
        } else {
            return $str;
        }
    }

    /**
     * Quotes a index name for use in a query.
     * If the index name contains schema prefix, the prefix will also be properly quoted.
     * If the index name is already quoted or contains '(' or '{{',
     * then this method will do nothing.
     * @param string $name index name
     * @return string the properly quoted index name
     * @see quoteSimpleTableName
     */
    public function quoteIndexName($name)
    {
        if (strpos($name, '(') !== false || strpos($name, '{{') !== false) {
            return $name;
        }

        return $this->quoteSimpleIndexName($name);
    }

    /**
     * Quotes a column name for use in a query.
     * If the column name contains prefix, the prefix will also be properly quoted.
     * If the column name is already quoted or contains '(', '[[' or '{{',
     * then this method will do nothing.
     * @param string $name column name
     * @return string the properly quoted column name
     * @see quoteSimpleColumnName
     */
    public function quoteColumnName($name)
    {
        if (strpos($name, '(') !== false || strpos($name, '[[') !== false || strpos($name, '{{') !== false) {
            return $name;
        }
        if (($pos = strrpos($name, '.')) !== false) {
            $prefix = $this->quoteIndexName(substr($name, 0, $pos)) . '.';
            $name = substr($name, $pos + 1);
        } else {
            $prefix = '';
        }

        return $prefix . $this->quoteSimpleColumnName($name);
    }

    /**
     * Quotes a index name for use in a query.
     * A simple index name has no schema prefix.
     * @param string $name index name
     * @return string the properly quoted index name
     */
    public function quoteSimpleIndexName($name)
    {
        return strpos($name, "`") !== false ? $name : "`" . $name . "`";
    }

    /**
     * Quotes a column name for use in a query.
     * A simple column name has no prefix.
     * @param string $name column name
     * @return string the properly quoted column name
     */
    public function quoteSimpleColumnName($name)
    {
        return strpos($name, '`') !== false || $name === '*' ? $name : '`' . $name . '`';
    }

    /**
     * Returns the actual name of a given index name.
     * This method will strip off curly brackets from the given index name
     * and replace the percentage character '%' with [[Connection::indexPrefix]].
     * @param string $name the index name to be converted
     * @return string the real name of the given index name
     */
    public function getRawIndexName($name)
    {
        if (strpos($name, '{{') !== false) {
            $name = preg_replace('/\\{\\{(.*?)\\}\\}/', '\1', $name);

            return str_replace('%', $this->db->tablePrefix, $name);
        } else {
            return $name;
        }
    }

    /**
     * Extracts the PHP type from abstract DB type.
     * @param ColumnSchema $column the column schema information
     * @return string PHP type name
     */
    protected function getColumnPhpType($column)
    {
        static $typeMap = [ // abstract type => php type
            'smallint' => 'integer',
            'integer' => 'integer',
            'bigint' => 'integer',
            'boolean' => 'boolean',
            'float' => 'double',
        ];
        if (isset($typeMap[$column->type])) {
            if ($column->type === 'bigint') {
                return PHP_INT_SIZE == 8 ? 'integer' : 'string';
            } elseif ($column->type === 'integer') {
                return PHP_INT_SIZE == 4 ? 'string' : 'integer';
            } else {
                return $typeMap[$column->type];
            }
        } else {
            return 'string';
        }
    }

    /**
     * Collects the metadata of index columns.
     * @param IndexSchema $index the index metadata
     * @return boolean whether the index exists in the database
     * @throws \Exception if DB query fails
     */
    protected function findColumns($index)
    {
        $sql = 'DESCRIBE ' . $this->quoteSimpleIndexName($index->name);
        try {
            $columns = $this->db->createCommand($sql)->queryAll();
        } catch (\Exception $e) {
            $previous = $e->getPrevious();
            if ($previous instanceof \PDOException && strpos($previous->getMessage(), 'SQLSTATE[42S02') !== false) {
                // index does not exist
                // https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html#error_er_bad_table_error
                return false;
            }
            throw $e;
        }

        if (empty($columns[0]['Agent'])) {
            foreach ($columns as $info) {
                $column = $this->loadColumnSchema($info);
                $index->columns[$column->name] = $column;
                if ($column->isPrimaryKey) {
                    $index->primaryKey = $column->name;
                }
            }
        } else {
            // Distributed index :
            $agent = $this->getIndexSchema($columns[0]['Agent']);
            $index->columns = $agent->columns;
        }

        return true;
    }

    /**
     * Loads the column information into a [[ColumnSchema]] object.
     * @param array $info column information
     * @return ColumnSchema the column schema object
     */
    protected function loadColumnSchema($info)
    {
        $column = new ColumnSchema;

        $column->name = $info['Field'];
        $column->dbType = $info['Type'];

        $column->isPrimaryKey = ($column->name == 'id');

        $type = $info['Type'];
        if (isset($this->typeMap[$type])) {
            $column->type = $this->typeMap[$type];
        } else {
            $column->type = self::TYPE_STRING;
        }

        $column->isField = ($type == 'field');
        $column->isAttribute = !$column->isField;

        $column->isMva = ($type == 'mva');

        $column->phpType = $this->getColumnPhpType($column);

        return $column;
    }

    /**
     * Converts a DB exception to a more concrete one if possible.
     *
     * @param \Exception $e
     * @param string $rawSql SQL that produced exception
     * @return Exception
     */
    public function convertException(\Exception $e, $rawSql)
    {
        if ($e instanceof Exception) {
            return $e;
        } else {
            $message = $e->getMessage()  . "\nThe SQL being executed was: $rawSql";
            $errorInfo = $e instanceof \PDOException ? $e->errorInfo : null;
            return new Exception($message, $errorInfo, (int) $e->getCode(), $e);
        }
    }

    /**
     * Returns a value indicating whether a SQL statement is for read purpose.
     * @param string $sql the SQL statement
     * @return boolean whether a SQL statement is for read purpose.
     */
    public function isReadQuery($sql)
    {
        $pattern = '/^\s*(SELECT|SHOW|DESCRIBE)\b/i';
        return preg_match($pattern, $sql) > 0;
    }
}
