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

namespace yii\db\oci;

use yii\base\InvalidParamException;
use yii\db\Connection;
use yii\db\Exception;
use yii\db\Expression;

/**
 * QueryBuilder is the query builder for Oracle databases.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class QueryBuilder extends \yii\db\QueryBuilder
{
    /**
     * @var array mapping from abstract column types (keys) to physical column types (values).
     */
    public $typeMap = [
        Schema::TYPE_PK => 'NUMBER(10) NOT NULL PRIMARY KEY',
        Schema::TYPE_UPK => 'NUMBER(10) UNSIGNED NOT NULL PRIMARY KEY',
        Schema::TYPE_BIGPK => 'NUMBER(20) NOT NULL PRIMARY KEY',
        Schema::TYPE_UBIGPK => 'NUMBER(20) UNSIGNED NOT NULL PRIMARY KEY',
        Schema::TYPE_CHAR => 'CHAR(1)',
        Schema::TYPE_STRING => 'VARCHAR2(255)',
        Schema::TYPE_TEXT => 'CLOB',
        Schema::TYPE_SMALLINT => 'NUMBER(5)',
        Schema::TYPE_INTEGER => 'NUMBER(10)',
        Schema::TYPE_BIGINT => 'NUMBER(20)',
        Schema::TYPE_FLOAT => 'NUMBER',
        Schema::TYPE_DOUBLE => 'NUMBER',
        Schema::TYPE_DECIMAL => 'NUMBER',
        Schema::TYPE_DATETIME => 'TIMESTAMP',
        Schema::TYPE_TIMESTAMP => 'TIMESTAMP',
        Schema::TYPE_TIME => 'TIMESTAMP',
        Schema::TYPE_DATE => 'DATE',
        Schema::TYPE_BINARY => 'BLOB',
        Schema::TYPE_BOOLEAN => 'NUMBER(1)',
        Schema::TYPE_MONEY => 'NUMBER(19,4)',
    ];

    /**
     * @inheritdoc
     */
    protected $likeEscapeCharacter = '!';
    /**
     * `\` is initialized in [[buildLikeCondition()]] method since
     * we need to choose replacement value based on [[\yii\db\Schema::quoteValue()]].
     * @inheritdoc
     */
    protected $likeEscapingReplacements = [
        '%' => '!%',
        '_' => '!_',
        '!' => '!!',
    ];


    /**
     * @inheritdoc
     */
    public function buildOrderByAndLimit($sql, $orderBy, $limit, $offset)
    {
        $orderBy = $this->buildOrderBy($orderBy);
        if ($orderBy !== '') {
            $sql .= $this->separator . $orderBy;
        }

        $filters = [];
        if ($this->hasOffset($offset)) {
            $filters[] = 'rowNumId > ' . $offset;
        }
        if ($this->hasLimit($limit)) {
            $filters[] = 'rownum <= ' . $limit;
        }
        if (empty($filters)) {
            return $sql;
        }

        $filter = implode(' AND ', $filters);
        return <<<EOD
WITH USER_SQL AS ($sql),
    PAGINATION AS (SELECT USER_SQL.*, rownum as rowNumId FROM USER_SQL)
SELECT *
FROM PAGINATION
WHERE $filter
EOD;
    }

    /**
     * Builds a SQL statement for renaming a DB table.
     *
     * @param string $table the table to be renamed. The name will be properly quoted by the method.
     * @param string $newName the new table name. The name will be properly quoted by the method.
     * @return string the SQL statement for renaming a DB table.
     */
    public function renameTable($table, $newName)
    {
        return 'ALTER TABLE ' . $this->db->quoteTableName($table) . ' RENAME TO ' . $this->db->quoteTableName($newName);
    }

    /**
     * Builds a SQL statement for changing the definition of a column.
     *
     * @param string $table the table whose column is to be changed. The table name will be properly quoted by the method.
     * @param string $column the name of the column to be changed. The name will be properly quoted by the method.
     * @param string $type the new column type. The [[getColumnType]] method will be invoked to convert abstract column type (if any)
     * into the physical one. Anything that is not recognized as abstract type will be kept in the generated SQL.
     * For example, 'string' will be turned into 'varchar(255)', while 'string not null' will become 'varchar(255) not null'.
     * @return string the SQL statement for changing the definition of a column.
     */
    public function alterColumn($table, $column, $type)
    {
        $type = $this->getColumnType($type);

        return 'ALTER TABLE ' . $this->db->quoteTableName($table) . ' MODIFY ' . $this->db->quoteColumnName($column) . ' ' . $this->getColumnType($type);
    }

    /**
     * Builds a SQL statement for dropping an index.
     *
     * @param string $name the name of the index to be dropped. The name will be properly quoted by the method.
     * @param string $table the table whose index is to be dropped. The name will be properly quoted by the method.
     * @return string the SQL statement for dropping an index.
     */
    public function dropIndex($name, $table)
    {
        return 'DROP INDEX ' . $this->db->quoteTableName($name);
    }

    /**
     * @inheritdoc
     */
    public function resetSequence($table, $value = null)
    {
        $tableSchema = $this->db->getTableSchema($table);
        if ($tableSchema === null) {
            throw new InvalidParamException("Unknown table: $table");
        }
        if ($tableSchema->sequenceName === null) {
            return '';
        }

        if ($value !== null) {
            $value = (int) $value;
        } else {
            // use master connection to get the biggest PK value
            $value = $this->db->useMaster(function (Connection $db) use ($tableSchema) {
                return $db->createCommand("SELECT MAX(\"{$tableSchema->primaryKey}\") FROM \"{$tableSchema->name}\"")->queryScalar();
            }) + 1;
        }

        return "DROP SEQUENCE \"{$tableSchema->name}_SEQ\";"
            . "CREATE SEQUENCE \"{$tableSchema->name}_SEQ\" START WITH {$value} INCREMENT BY 1 NOMAXVALUE NOCACHE";
    }

    /**
     * @inheritdoc
     */
    public function addForeignKey($name, $table, $columns, $refTable, $refColumns, $delete = null, $update = null)
    {
        $sql = 'ALTER TABLE ' . $this->db->quoteTableName($table)
            . ' ADD CONSTRAINT ' . $this->db->quoteColumnName($name)
            . ' FOREIGN KEY (' . $this->buildColumns($columns) . ')'
            . ' REFERENCES ' . $this->db->quoteTableName($refTable)
            . ' (' . $this->buildColumns($refColumns) . ')';
        if ($delete !== null) {
            $sql .= ' ON DELETE ' . $delete;
        }
        if ($update !== null) {
            throw new Exception('Oracle does not support ON UPDATE clause.');
        }

        return $sql;
    }

    /**
     * @inheritdoc
     */
    public function insert($table, $columns, &$params)
    {
        $schema = $this->db->getSchema();
        if (($tableSchema = $schema->getTableSchema($table)) !== null) {
            $columnSchemas = $tableSchema->columns;
        } else {
            $columnSchemas = [];
        }
        $names = [];
        $placeholders = [];
        $values = ' DEFAULT VALUES';
        if ($columns instanceof \yii\db\Query) {
            list($names, $values, $params) = $this->prepareInsertSelectSubQuery($columns, $schema, $params);
        } else {
            foreach ($columns as $name => $value) {
                $names[] = $schema->quoteColumnName($name);
                if ($value instanceof Expression) {
                    $placeholders[] = $value->expression;
                    foreach ($value->params as $n => $v) {
                        $params[$n] = $v;
                    }
                } elseif ($value instanceof \yii\db\Query) {
                    list($sql, $params) = $this->build($value, $params);
                    $placeholders[] = "($sql)";
                } else {
                    $phName = self::PARAM_PREFIX . count($params);
                    $placeholders[] = $phName;
                    $params[$phName] = !is_array($value) && isset($columnSchemas[$name]) ? $columnSchemas[$name]->dbTypecast($value) : $value;
                }
            }
            if (empty($names) && $tableSchema !== null) {
                $columns = !empty($tableSchema->primaryKey) ? $tableSchema->primaryKey : [reset($tableSchema->columns)->name];
                foreach ($columns as $name) {
                    $names[] = $schema->quoteColumnName($name);
                    $placeholders[] = 'DEFAULT';
                }
            }
        }

        return 'INSERT INTO ' . $schema->quoteTableName($table)
            . (!empty($names) ? ' (' . implode(', ', $names) . ')' : '')
            . (!empty($placeholders) ? ' VALUES (' . implode(', ', $placeholders) . ')' : $values);
    }

    /**
     * Generates a batch INSERT SQL statement.
     * For example,
     *
     * ```php
     * $sql = $queryBuilder->batchInsert('user', ['name', 'age'], [
     *     ['Tom', 30],
     *     ['Jane', 20],
     *     ['Linda', 25],
     * ]);
     * ```
     *
     * Note that the values in each row must match the corresponding column names.
     *
     * @param string $table the table that new rows will be inserted into.
     * @param array $columns the column names
     * @param array $rows the rows to be batch inserted into the table
     * @return string the batch INSERT SQL statement
     */
    public function batchInsert($table, $columns, $rows)
    {
        if (empty($rows)) {
            return '';
        }

        $schema = $this->db->getSchema();
        if (($tableSchema = $schema->getTableSchema($table)) !== null) {
            $columnSchemas = $tableSchema->columns;
        } else {
            $columnSchemas = [];
        }

        $values = [];
        foreach ($rows as $row) {
            $vs = [];
            foreach ($row as $i => $value) {
                if (isset($columns[$i], $columnSchemas[$columns[$i]]) && !is_array($value)) {
                    $value = $columnSchemas[$columns[$i]]->dbTypecast($value);
                }
                if (is_string($value)) {
                    $value = $schema->quoteValue($value);
                } elseif ($value === false) {
                    $value = 0;
                } elseif ($value === null) {
                    $value = 'NULL';
                }
                $vs[] = $value;
            }
            $values[] = '(' . implode(', ', $vs) . ')';
        }
        if (empty($values)) {
            return '';
        }

        foreach ($columns as $i => $name) {
            $columns[$i] = $schema->quoteColumnName($name);
        }

        $tableAndColumns = ' INTO ' . $schema->quoteTableName($table)
        . ' (' . implode(', ', $columns) . ') VALUES ';

        return 'INSERT ALL ' . $tableAndColumns . implode($tableAndColumns, $values) . ' SELECT 1 FROM SYS.DUAL';
    }

    /**
     * @inheritdoc
     * @since 2.0.8
     */
    public function selectExists($rawSql)
    {
        return 'SELECT CASE WHEN EXISTS(' . $rawSql . ') THEN 1 ELSE 0 END FROM DUAL';
    }

    /**
     * @inheritdoc
     * @since 2.0.8
     */
    public function dropCommentFromColumn($table, $column)
    {
        return 'COMMENT ON COLUMN ' . $this->db->quoteTableName($table) . '.' . $this->db->quoteColumnName($column) . " IS ''";
    }

    /**
     * @inheritdoc
     * @since 2.0.8
     */
    public function dropCommentFromTable($table)
    {
        return 'COMMENT ON TABLE ' . $this->db->quoteTableName($table) . " IS ''";
    }

    /**
     * @inheritDoc
     */
    public function buildLikeCondition($operator, $operands, &$params)
    {
        if (!isset($this->likeEscapingReplacements['\\'])) {
            /*
             * Different pdo_oci8 versions may or may not implement PDO::quote(), so
             * yii\db\Schema::quoteValue() may or may not quote \.
             */
            $this->likeEscapingReplacements['\\'] = substr($this->db->quoteValue('\\'), 1, -1);
        }
        return parent::buildLikeCondition($operator, $operands, $params);
    }

    /**
     * @inheritdoc
     */
    public function buildInCondition($operator, $operands, &$params)
    {
        $splitCondition = $this->splitInCondition($operator, $operands, $params);
        if ($splitCondition !== null) {
            return $splitCondition;
        }

        return parent::buildInCondition($operator, $operands, $params);
    }

    /**
     * Oracle DBMS does not support more than 1000 parameters in `IN` condition.
     * This method splits long `IN` condition into series of smaller ones.
     *
     * @param string $operator
     * @param array $operands
     * @param array $params
     * @return null|string null when split is not required. Otherwise - built SQL condition.
     * @throws Exception
     * @since 2.0.12
     */
    protected function splitInCondition($operator, $operands, &$params)
    {
        if (!isset($operands[0], $operands[1])) {
            throw new Exception("Operator '$operator' requires two operands.");
        }

        list($column, $values) = $operands;

        if ($values instanceof \Traversable) {
            $values = iterator_to_array($values);
        }

        if (!is_array($values)) {
            return null;
        }

        $maxParameters = 1000;
        $count = count($values);
        if ($count <= $maxParameters) {
            return null;
        }

        $condition = [($operator === 'IN') ? 'OR' : 'AND'];
        for ($i = 0; $i < $count; $i += $maxParameters) {
            $condition[] = [$operator, $column, array_slice($values, $i, $maxParameters)];
        }

        return $this->buildCondition(['AND', $condition], $params);
    }

}