class InsertQuery

class InsertQuery extends Query {
    
    /**
     * The table on which to insert.
     *
     * @var string
     */
    protected $table;
    
    /**
     * An array of fields on which to insert.
     *
     * @var array
     */
    protected $insertFields = array();
    
    /**
     * An array of fields that should be set to their database-defined defaults.
     *
     * @var array
     */
    protected $defaultFields = array();
    
    /**
     * A nested array of values to insert.
     *
     * $insertValues is an array of arrays. Each sub-array is either an
     * associative array whose keys are field names and whose values are field
     * values to insert, or a non-associative array of values in the same order
     * as $insertFields.
     *
     * Whether multiple insert sets will be run in a single query or multiple
     * queries is left to individual drivers to implement in whatever manner is
     * most appropriate. The order of values in each sub-array must match the
     * order of fields in $insertFields.
     *
     * @var array
     */
    protected $insertValues = array();
    
    /**
     * A SelectQuery object to fetch the rows that should be inserted.
     *
     * @var SelectQueryInterface
     */
    protected $fromQuery;
    
    /**
     * Constructs an InsertQuery object.
     *
     * @param DatabaseConnection $connection
     *   A DatabaseConnection object.
     * @param string $table
     *   Name of the table to associate with this query.
     * @param array $options
     *   Array of database options.
     */
    public function __construct($connection, $table, array $options = array()) {
        if (!isset($options['return'])) {
            $options['return'] = Database::RETURN_INSERT_ID;
        }
        parent::__construct($connection, $options);
        $this->table = $table;
    }
    
    /**
     * Adds a set of field->value pairs to be inserted.
     *
     * This method may only be called once. Calling it a second time will be
     * ignored. To queue up multiple sets of values to be inserted at once,
     * use the values() method.
     *
     * @param $fields
     *   An array of fields on which to insert. This array may be indexed or
     *   associative. If indexed, the array is taken to be the list of fields.
     *   If associative, the keys of the array are taken to be the fields and
     *   the values are taken to be corresponding values to insert. If a
     *   $values argument is provided, $fields must be indexed.
     * @param $values
     *   An array of fields to insert into the database. The values must be
     *   specified in the same order as the $fields array.
     *
     * @return InsertQuery
     *   The called object.
     */
    public function fields(array $fields, array $values = array()) {
        if (empty($this->insertFields)) {
            if (empty($values)) {
                if (!is_numeric(key($fields))) {
                    $values = array_values($fields);
                    $fields = array_keys($fields);
                }
            }
            $this->insertFields = $fields;
            if (!empty($values)) {
                $this->insertValues[] = $values;
            }
        }
        return $this;
    }
    
    /**
     * Adds another set of values to the query to be inserted.
     *
     * If $values is a numeric-keyed array, it will be assumed to be in the same
     * order as the original fields() call. If it is associative, it may be
     * in any order as long as the keys of the array match the names of the
     * fields.
     *
     * @param $values
     *   An array of values to add to the query.
     *
     * @return InsertQuery
     *   The called object.
     */
    public function values(array $values) {
        if (is_numeric(key($values))) {
            $this->insertValues[] = $values;
        }
        else {
            // Reorder the submitted values to match the fields array.
            foreach ($this->insertFields as $key) {
                $insert_values[$key] = $values[$key];
            }
            // For consistency, the values array is always numerically indexed.
            $this->insertValues[] = array_values($insert_values);
        }
        return $this;
    }
    
    /**
     * Specifies fields for which the database defaults should be used.
     *
     * If you want to force a given field to use the database-defined default,
     * not NULL or undefined, use this method to instruct the database to use
     * default values explicitly. In most cases this will not be necessary
     * unless you are inserting a row that is all default values, as you cannot
     * specify no values in an INSERT query.
     *
     * Specifying a field both in fields() and in useDefaults() is an error
     * and will not execute.
     *
     * @param $fields
     *   An array of values for which to use the default values
     *   specified in the table definition.
     *
     * @return InsertQuery
     *   The called object.
     */
    public function useDefaults(array $fields) {
        $this->defaultFields = $fields;
        return $this;
    }
    
    /**
     * Sets the fromQuery on this InsertQuery object.
     *
     * @param SelectQueryInterface $query
     *   The query to fetch the rows that should be inserted.
     *
     * @return InsertQuery
     *   The called object.
     */
    public function from(SelectQueryInterface $query) {
        $this->fromQuery = $query;
        return $this;
    }
    
    /**
     * Executes the insert query.
     *
     * @return
     *   The last insert ID of the query, if one exists. If the query
     *   was given multiple sets of values to insert, the return value is
     *   undefined. If no fields are specified, this method will do nothing and
     *   return NULL. That makes it safe to use in multi-insert loops.
     */
    public function execute() {
        // If validation fails, simply return NULL. Note that validation routines
        // in preExecute() may throw exceptions instead.
        if (!$this->preExecute()) {
            return NULL;
        }
        // If we're selecting from a SelectQuery, finish building the query and
        // pass it back, as any remaining options are irrelevant.
        if (!empty($this->fromQuery)) {
            $sql = (string) $this;
            // The SelectQuery may contain arguments, load and pass them through.
            return $this->connection
                ->query($sql, $this->fromQuery
                ->getArguments(), $this->queryOptions);
        }
        $last_insert_id = 0;
        // Each insert happens in its own query in the degenerate case. However,
        // we wrap it in a transaction so that it is atomic where possible. On many
        // databases, such as SQLite, this is also a notable performance boost.
        $transaction = $this->connection
            ->startTransaction();
        try {
            $sql = (string) $this;
            foreach ($this->insertValues as $insert_values) {
                $last_insert_id = $this->connection
                    ->query($sql, $insert_values, $this->queryOptions);
            }
        } catch (Exception $e) {
            // One of the INSERTs failed, rollback the whole batch.
            $transaction->rollback();
            // Rethrow the exception for the calling code.
            throw $e;
        }
        // Re-initialize the values array so that we can re-use this query.
        $this->insertValues = array();
        // Transaction commits here where $transaction looses scope.
        return $last_insert_id;
    }
    
    /**
     * Implements PHP magic __toString method to convert the query to a string.
     *
     * @return string
     *   The prepared statement.
     */
    public function __toString() {
        // Create a sanitized comment string to prepend to the query.
        $comments = $this->connection
            ->makeComment($this->comments);
        // Default fields are always placed first for consistency.
        $insert_fields = array_merge($this->defaultFields, $this->insertFields);
        if (!empty($this->fromQuery)) {
            return $comments . 'INSERT INTO {' . $this->table . '} (' . implode(', ', $insert_fields) . ') ' . $this->fromQuery;
        }
        // For simplicity, we will use the $placeholders array to inject
        // default keywords even though they are not, strictly speaking,
        // placeholders for prepared statements.
        $placeholders = array();
        $placeholders = array_pad($placeholders, count($this->defaultFields), 'default');
        $placeholders = array_pad($placeholders, count($this->insertFields), '?');
        return $comments . 'INSERT INTO {' . $this->table . '} (' . implode(', ', $insert_fields) . ') VALUES (' . implode(', ', $placeholders) . ')';
    }
    
    /**
     * Preprocesses and validates the query.
     *
     * @return
     *   TRUE if the validation was successful, FALSE if not.
     *
     * @throws FieldsOverlapException
     * @throws NoFieldsException
     */
    public function preExecute() {
        // Confirm that the user did not try to specify an identical
        // field and default field.
        if (array_intersect($this->insertFields, $this->defaultFields)) {
            throw new FieldsOverlapException('You may not specify the same field to have a value and a schema-default value.');
        }
        if (!empty($this->fromQuery)) {
            // We have to assume that the used aliases match the insert fields.
            // Regular fields are added to the query before expressions, maintain the
            // same order for the insert fields.
            // This behavior can be overridden by calling fields() manually as only the
            // first call to fields() does have an effect.
            $this->fields(array_merge(array_keys($this->fromQuery
                ->getFields()), array_keys($this->fromQuery
                ->getExpressions())));
        }
        else {
            // Don't execute query without fields.
            if (count($this->insertFields) + count($this->defaultFields) == 0) {
                throw new NoFieldsException('There are no fields available to insert with.');
            }
        }
        // If no values have been added, silently ignore this query. This can happen
        // if values are added conditionally, so we don't want to throw an
        // exception.
        if (!isset($this->insertValues[0]) && count($this->insertFields) > 0 && empty($this->fromQuery)) {
            return FALSE;
        }
        return TRUE;
    }

}