source: trunk/lib/PageNumbers.inc.php

<?php
/**
 * The Strangecode Codebase - a general application development framework for PHP
 * For details visit the project site: <http://trac.strangecode.com/codebase/>
 * Copyright 2001-2012 Strangecode, LLC
 *
 * This file is part of The Strangecode Codebase.
 *
 * The Strangecode Codebase is free software: you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your option)
 * any later version.
 *
 * The Strangecode Codebase 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * The Strangecode Codebase. If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * PageNumbers.inc.php
 *
 * The PageNumbers class provides a common abstracted interface to the
 * multiple pages features. It sets the various numbers needed to display items
 * on a page, and includes functions for working with these numbers.
 * You must call set setTotalItems(), setPerPage() and setPageNumber() before calling calculate()
 * this the other various values will be set automatically. Then you can call printPerPageLinks,
 * printPageNumbers, etc, and use the various page object properties in your page templates.
 *
 * @author    Quinn Comendant <quinn@strangecode.com>
 * @version   1.61
 */

require_once dirname(__FILE__) . '/Prefs.inc.php';

class PageNumbers
{

    public $total_items;       // Total quantity of items.
    public $total_pages;       // The total number of pages.
    public $current_page = 1;  // Current page number.
    public $first_item;        // The counter for the first item on this page (zero index).
    public $last_item;         // The counter for the last item on this page (zero index).
    public $max_num_links = 5; // The max number of links to show on page (odd numbers look best).
    protected $_num_links;        // The number of links to show on page.
    protected $_per_page = 50;    // Items per page.

    // Flags to ensure all necessary values have been set before calling calculate().
    public $set_per_page_initialized = false;
    public $set_page_number_initialized = false;
    public $set_total_items_initialized = false;

    // These are initialized in the constructor.
    public $per_page_options;
    public $left_arrow;
    public $left_arrow_disabled;
    public $left_dbl_arrow;
    public $left_dbl_arrow_disabled;
    public $right_arrow;
    public $right_arrow_disabled;
    public $right_dbl_arrow;
    public $right_dbl_arrow_disabled;
    public $url_base;
    public $prefs;

    /**
     * PageNumbers constructor. All arguments are depreciated. Use set* functions instead.
     */
    public function __construct()
    {
        // Default options for the quantity per page links.
        $this->per_page_options = array(50, 100, 250, 1000);

        // Default options for the page number links.
        $this->left_arrow = _("back");
        $this->left_arrow_disabled = '<span style="color: #aaaaaa;">' . _("back") . '</span>';
        $this->left_dbl_arrow = '<strong>&laquo;</strong>';
        $this->left_dbl_arrow_disabled = '<span style="color: #aaaaaa;"><strong>&laquo;</strong></span>';
        $this->right_arrow = _("next");
        $this->right_arrow_disabled = '<span style="color: #aaaaaa;">' . _("next") . '</span>';
        $this->right_dbl_arrow = '<strong>&raquo;</strong>';
        $this->right_dbl_arrow_disabled = '<span style="color: #aaaaaa;"><strong>&raquo;</strong></span>';

        // Default url base. This will be set manually after instantiation
        // in special cases like using a /my/page/# scheme.
        $this->url_base = $_SERVER['PHP_SELF'] . '?page_number=';

        $this->prefs = new Prefs($_SERVER['PHP_SELF']);
        $this->prefs->setParam(array('persistent' => false));
    }

    private function _validNumber($num)
    {
        if (!isset($num) || '' == $num) {
            return false;
        }
        return preg_match('/^\d+$/', $num);
    }

    /**
     * Set the number of items per page.
     */
    public function setPerPage($per_page, $default=25, $save_value=true)
    {
        // (1) By provided argument, if valid.
        // (2) By saved preference, if available.
        // (3) Set to default value if provided and valid.
        // (4) Keep as Class default of 25.
        if ($this->_validNumber($per_page) && $per_page > 0) {
            $this->_per_page = $per_page;
            if ($save_value) {
                $this->prefs->set('items_per_page', $this->_per_page);
            }
        } else if ($save_value && $this->prefs->exists('items_per_page')) {
            $this->_per_page = (int)$this->prefs->get('items_per_page');
        } else if ($this->_validNumber($default) && $default > 0) {
            $this->_per_page = $default;
        }
        $this->set_per_page_initialized = true;
    }

    /**
     * Set the current page number.
     */
    public function setPageNumber($page_number, $save_value=true)
    {
        // (1) By provided argument, if valid.
        // (2) By saved preference, if available.
        // (3) Don't change from what was provided at class instantiation.
        if ($this->_validNumber($page_number)) {
            if ($page_number < 1) {
                // FIXME: How to go back around to the last page? Hmmm. Set to 1 for now.
                $this->current_page = 1;
            } else {
                $this->current_page = $page_number;
            }
            if ($save_value) {
                $this->prefs->set('page_number', $this->current_page);
            }
        } else if ($save_value && $this->prefs->exists('page_number')) {
            $this->current_page = (int)$this->prefs->get('page_number');
        }
        $this->set_page_number_initialized = true;
    }

    /**
     * Set the total number of items.
     */
    public function setTotalItems($total_items)
    {
        if ($this->_validNumber($total_items) && $total_items > 0) {
            $this->total_items = $total_items;
        } else {
            $this->total_items = 0;
        }
        $this->set_total_items_initialized = true;
    }

    /**
     * After $total_items or other options are set, this function calculates
     * all the other numbers needed. If you set any variables manually,
     * for example if $page_number comes from
     * some place other than the GET or POST array, you should call this
     * function manually, otherwise it happens at object instantiation.
     *
     * @access public
     */
    public function calculate()
    {
        $app =& App::getInstance();

        if (!$this->set_per_page_initialized) {
            $app->logMsg(sprintf('set_per_page not initialized'), LOG_ERR, __FILE__, __LINE__);
        }
        if (!$this->set_page_number_initialized) {
            $app->logMsg(sprintf('set_page_number not initialized'), LOG_ERR, __FILE__, __LINE__);
        }
        if (!$this->set_total_items_initialized) {
            $app->logMsg(sprintf('set_total_items not initialized'), LOG_ERR, __FILE__, __LINE__);
        }

        // If the specified page exceeds total pages or is less than 1, set the page to 1.
        if ($this->_per_page * $this->current_page >= $this->total_items + $this->_per_page || $this->_per_page * $this->current_page < 1) {
            $this->current_page = 1;
        }

        // The first item to be shown on this page.
        $this->first_item = ($this->current_page - 1) * $this->_per_page;

        // The last item to be shown on this page.
        if ($this->total_items < $this->current_page * $this->_per_page) {
            $this->last_item = $this->total_items - 1;
        } else {
            $this->last_item = $this->current_page * $this->_per_page - 1;
        }

        // Zeroing. Just in case. Paranoia. Yeah, negative numbers perturb me.
        if ($this->first_item < 1) {
            $this->first_item = 0;
        }
        if ($this->last_item < 1) {
            $this->last_item = 0;
        }
        if ($this->total_items < 1) {
            $this->total_items = 0;
        }

        // The total number of pages.
        $this->total_pages = ceil($this->total_items / $this->_per_page);

        // Figure out how many page number links to print.
        if ($this->total_pages >= $this->max_num_links) {
            $this->_num_links = $this->max_num_links;
        } else {
            $this->_num_links = $this->total_pages;
        }
    }

    /**
     * Returns the SQL code to limit query to items that are on current page.
     */
    public function getLimitSQL()
    {
        $app =& App::getInstance();
        $db =& DB::getInstance();

        if ($this->_validNumber($this->first_item) && $this->_validNumber($this->_per_page)) {
            return ' LIMIT ' . $db->escapeString($this->first_item) . ', ' . $db->escapeString($this->_per_page) . ' ';
        } else {
            $app->logMsg(sprintf('Could not find SQL to LIMIT by %s %s.', $this->first_item, $this->_per_page), LOG_WARNING, __FILE__, __LINE__);
            return '';
        }
    }

    /**
     * Prints links to change the number of items shown per page.
     *
     * @access public
     */
    public function printPerPageLinks($query_key='per_page')
    {
        $app =& App::getInstance();

        $sp = '';
        for ($i=0; $i<sizeof($this->per_page_options); $i++) {
            if ($this->_per_page != $this->per_page_options[$i]) {
                printf('%s<a href="%s">%s</a>',
                    $sp,
                    $app->oHREF($_SERVER['PHP_SELF'] . '?' . $query_key . '=' . $this->per_page_options[$i]),
                    $this->per_page_options[$i]
                );
            } else {
                echo $sp . '<strong>' . $this->per_page_options[$i] . '</strong>';
            }
            $sp = '&nbsp;';
        }
    }

    /**
     * Outputs an $app->oHREF compatible url that goes to the page $page_number.
     * Depends on $this->base_url to build the url onto. This is used in the
     * page_number.ihtml template.
     *
     * @param  int   $page_number    The page number this page will go to.
     *
     * @return string                The URL.
     *
     * @access public
     */
    public function getPageNumURL($page_number, $carry_args=null)
    {
        $app =& App::getInstance();

        return $app->oHREF($this->url_base . $page_number, $carry_args);
    }
    public function printPageNumURL($page_number, $carry_args=null)
    {
        echo $this->getPageNumURL($page_number, $carry_args);
    }

    /**
     * Returns an array of page number links.
     *
     * @access public
     */
    public function getPageNumbersArray($carry_args=null)
    {
        $page_numbers = array();

        for ($i = 1; $i <= $this->total_pages; $i++) {
            $page_numbers[] = array(
                'number' => $i,
                'url' => $this->getPageNumURL($i, $carry_args),
                'current' => ($this->current_page == $i)
            );
        }

        return $page_numbers;
    }

    /**
     * Returns a string containing the page number links.
     *
     * @access public
     */
    public function getPageNumbers($carry_args=null)
    {
        $page_numbers_string = '';

        if ($this->current_page > $this->total_pages - floor($this->_num_links / 2)) {
            $high_num = $this->total_pages;
            $low_num = $high_num - $this->_num_links + 1;
        } else {
            $low_num = $this->current_page - floor($this->_num_links / 2);
            if ($low_num < 1) {
                $low_num = 1;
            }
            $high_num = $low_num + $this->_num_links - 1;
        }

        if ($this->current_page != 1) {
            // Print "first" and "previous" page links.
            if ($this->left_dbl_arrow) {
                $page_numbers_string .= sprintf('<a href="%s" title="%s">%s</a>&nbsp;', $this->getPageNumURL(1, $carry_args), _("Go to the first page"), $this->left_dbl_arrow);
            }
            if ($this->left_arrow) {
                $page_numbers_string .= sprintf('<a href="%s" title="%s">%s</a>&nbsp;&nbsp;', $this->getPageNumURL($this->current_page - 1, $carry_args), _("Go back one page"), $this->left_arrow);
            }
            // Print links to specific page numbers before the current page.
            for ($i = $low_num; $i < $this->current_page; $i++) {
                $page_numbers_string .= sprintf('<a href="%s">%s</a>&nbsp;', $this->getPageNumURL($i, $carry_args), $i);
            }
        } else {
            if ($this->left_dbl_arrow) {
                $page_numbers_string .= $this->left_dbl_arrow_disabled . '&nbsp;';
            }
            if ($this->left_arrow) {
                $page_numbers_string .= $this->left_arrow_disabled . '&nbsp;';
            }
        }

        if ($this->_num_links > 0) {
            // Print the current page number.
            $page_numbers_string .= sprintf('<strong>%s</strong>&nbsp;', $this->current_page);
        }

        if ($this->current_page < $this->total_pages) {
            // Print links to specific page numbers after the current page.
            for ($i = $this->current_page + 1; $i <= $high_num; $i++) {
                $page_numbers_string .= sprintf('<a href="%s">%s</a>&nbsp;', $this->getPageNumURL($i, $carry_args), $i);
            }
            // Print "last" and "next" page links.
            if ($this->right_arrow) {
                $page_numbers_string .= sprintf('<a href="%s" title="%s">%s</a>&nbsp;&nbsp;', $this->getPageNumURL($this->current_page + 1, $carry_args), _("Go forward one page"), $this->right_arrow);
            }
            if ($this->right_dbl_arrow) {
                $page_numbers_string .= sprintf('<a href="%s" title="%s">%s</a>&nbsp;&nbsp;', $this->getPageNumURL($this->total_pages, $carry_args), _("Go to the last page"), $this->right_dbl_arrow);
            }
        } else {
            if ($this->right_arrow_disabled) {
                $page_numbers_string .= $this->right_arrow_disabled . '&nbsp;';
            }
            if ($this->right_dbl_arrow_disabled) {
                $page_numbers_string .= $this->right_dbl_arrow_disabled;
            }
        }

        return $page_numbers_string;
    }

    public function printPageNumbers($carry_args=null)
    {
        echo $this->getPageNumbers($carry_args);
    }

}