<?php

/**
 * Part of the Joomla Framework Database Package
 *
 * @copyright  Copyright (C) 2005 - 2021 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\Database;

/**
 * Joomla Framework Database Driver Class
 *
 * @since  1.0
 */
class DatabaseIterator implements \Countable, \Iterator
{
    /**
     * The class of object to create.
     *
     * @var    string
     * @since  1.0
     */
    protected $class;

    /**
     * The name of the column to use for the key of the database record.
     *
     * @var    mixed
     * @since  1.0
     */
    private $column;

    /**
     * The current database record.
     *
     * @var    mixed
     * @since  1.0
     */
    private $current;

    /**
     * A numeric or string key for the current database record.
     *
     * @var    scalar
     * @since  1.0
     */
    private $key;

    /**
     * The number of fetched records.
     *
     * @var    integer
     * @since  1.0
     */
    private $fetched = 0;

    /**
     * The statement holding the result set to iterate.
     *
     * @var    StatementInterface
     * @since  1.0
     */
    protected $statement;

    /**
     * Database iterator constructor.
     *
     * @param   StatementInterface  $statement  The statement holding the result set to iterate.
     * @param   string              $column     An option column to use as the iterator key.
     * @param   string              $class      The class of object that is returned.
     *
     * @since   1.0
     * @throws  \InvalidArgumentException
     */
    public function __construct(StatementInterface $statement, $column = null, $class = \stdClass::class)
    {
        if (!class_exists($class)) {
            throw new \InvalidArgumentException(sprintf('new %s(*%s*, cursor)', \get_class($this), \gettype($class)));
        }

        if ($statement) {
            $fetchMode = $class === \stdClass::class ? FetchMode::STANDARD_OBJECT : FetchMode::CUSTOM_OBJECT;

            // PDO doesn't allow extra arguments for \PDO::FETCH_CLASS, so only forward the class for the custom object mode
            if ($fetchMode === FetchMode::STANDARD_OBJECT) {
                $statement->setFetchMode($fetchMode);
            } else {
                $statement->setFetchMode($fetchMode, $class);
            }
        }

        $this->statement = $statement;
        $this->class     = $class;
        $this->column    = $column;
        $this->fetched   = 0;
        $this->next();
    }

    /**
     * Database iterator destructor.
     *
     * @since   1.0
     */
    public function __destruct()
    {
        if ($this->statement) {
            $this->freeResult();
        }
    }

    /**
     * Get the number of rows in the result set for the executed SQL given by the cursor.
     *
     * @return  integer  The number of rows in the result set.
     *
     * @see     Countable::count()
     * @since   1.0
     */
    #[\ReturnTypeWillChange]
    public function count()
    {
        if ($this->statement) {
            return $this->statement->rowCount();
        }

        return 0;
    }

    /**
     * The current element in the iterator.
     *
     * @return  object
     *
     * @see     Iterator::current()
     * @since   1.0
     */
    #[\ReturnTypeWillChange]
    public function current()
    {
        return $this->current;
    }

    /**
     * The key of the current element in the iterator.
     *
     * @return  scalar
     *
     * @see     Iterator::key()
     * @since   1.0
     */
    #[\ReturnTypeWillChange]
    public function key()
    {
        return $this->key;
    }

    /**
     * Moves forward to the next result from the SQL query.
     *
     * @return  void
     *
     * @see     Iterator::next()
     * @since   1.0
     */
    #[\ReturnTypeWillChange]
    public function next()
    {
        // Set the default key as being the number of fetched object
        $this->key = $this->fetched;

        // Try to get an object
        $this->current = $this->fetchObject();

        // If an object has been found
        if ($this->current) {
            // Set the key as being the indexed column (if it exists)
            if ($this->column && isset($this->current->{$this->column})) {
                $this->key = $this->current->{$this->column};
            }

            // Update the number of fetched object
            $this->fetched++;
        }
    }

    /**
     * Rewinds the iterator.
     *
     * This iterator cannot be rewound.
     *
     * @return  void
     *
     * @see     Iterator::rewind()
     * @since   1.0
     */
    #[\ReturnTypeWillChange]
    public function rewind()
    {
    }

    /**
     * Checks if the current position of the iterator is valid.
     *
     * @return  boolean
     *
     * @see     Iterator::valid()
     * @since   1.0
     */
    #[\ReturnTypeWillChange]
    public function valid()
    {
        return (bool) $this->current;
    }

    /**
     * Method to fetch a row from the result set cursor as an object.
     *
     * @return  mixed  Either the next row from the result set or false if there are no more rows.
     *
     * @since   1.0
     */
    protected function fetchObject()
    {
        if ($this->statement) {
            return $this->statement->fetch();
        }

        return false;
    }

    /**
     * Method to free up the memory used for the result set.
     *
     * @return  void
     *
     * @since   1.0
     */
    protected function freeResult()
    {
        if ($this->statement) {
            $this->statement->closeCursor();
        }
    }
}