<?php
// File name:	xfileio.inc.php
// Description:	Extended PHP subroutine to read from/write to a file
// Date:	2002-04-16
// Author:	imacat <imacat@pristine.com.tw>
// Copyright:	Copyright (C) 2002-2009 Pristine Communications

// xfread: Read from file
//   Input: the file path $file
//   Output: the file content
function xfread($file)
{
    $size = filesize($file);
    // fread() does not allow reading of 0 bytes now
    if ($size == 0) {
        return "";
    }
    $fp = fopen($file, "r");
    flock($fp, LOCK_SH);
    $content = fread($fp, $size);
    flock($fp, LOCK_UN);
    fclose($fp);
    return $content;
}

// xfwrite: Write to a file
//   Input: the file path $file and the file content $content
//   Output: none
function xfwrite($file, $content)
{
    $fp = fopen($file, "w");
    flock($fp, LOCK_EX);
    fwrite($fp, $content);
    flock($fp, LOCK_UN);
    fclose($fp);
    return;
}

// xfappend: Append to a file
//   Input: the file path $file and the file content $content
//   Output: none
function xfappend($file, $content)
{
    // File not exists - create it with xfwrite()
    if (!file_exists($file)) {
        return xfwrite($file, $content);
    }
    $fp = fopen($file, "a");
    flock($fp, LOCK_EX);
    fwrite($fp, $content);
    flock($fp, LOCK_UN);
    fclose($fp);
    return;
}

// xfupdate: Update a file
//   Input: the file path $file and the file content $newcontent
//   Output: none
function xfupdate($file, $newcontent)
{
    // Write as a new file if the old file does not exist
    if (!file_exists($file) || filesize($file) != strlen($newcontent)) {
        xfwrite($file, $newcontent);
    
    // Old file exists -- compare the content and update only if necessary
    } else {
        $size = filesize($file);
        $fp = fopen($file, "r+");
        flock($fp, LOCK_EX);
        // fread() does not allow reading of 0 bytes now
        if ($size == 0) {
            $oldcontent = "";
        } else {
            $oldcontent = fread($fp, $size);
        }
        if ($oldcontent != $newcontent) {
            fseek($fp, 0, SEEK_SET);
            ftruncate($fp, 0);
            fwrite($fp, $newcontent);
        }
        flock($fp, LOCK_UN);
        fclose($fp);
    }
    
    // Clear the stat cache to avoid future mistakes like MIME types.
    clearstatcache();
    return;
}

// xfupdate_template: Update a file comparing with a template
//   Input: the file path $file, the new content template $tmpl
//          and its replacements $rep
//   Output: none
function xfupdate_template($file, $tmpl, $rep = null)
{
    // Obtain the replacements
    if (is_null($rep)) {
        $rep = function_exists("page_replacements")? page_replacements():
            array();
    }
    // Write as a new file if the old file does not exist
    if (!file_exists($file)) {
        $new = $tmpl;
        foreach (array_keys($rep) as $key) {
            $new = str_replace("<!--monica:$key-->", $rep[$key]["content"], $new);
        }
        xfwrite($file, $new);
    
    // Old file exists -- compare the content and update only if necessary
    } else {
        $size = filesize($file);
        $fp = fopen($file, "r+");
        flock($fp, LOCK_EX);
        if ($size == 0) {
            $old = "";
        } else {
            $old = fread($fp, filesize($file));
        }
        // Not matched
        if (_xfileio_template_updated($old, $tmpl, $rep)) {
            $new = $tmpl;
            foreach (array_keys($rep) as $key) {
                $new = str_replace("<!--monica:$key-->", $rep[$key]["content"], $new);
            }
            fseek($fp, 0, SEEK_SET);
            ftruncate($fp, 0);
            fwrite($fp, $new);
        }
        flock($fp, LOCK_UN);
        fclose($fp);
    }
    return;
}

// _xfileio_template_updated: If a page is updated comparing to the template
function _xfileio_template_updated($old, $tmpl, $rep)
{
    // Process piece by piece
    while (preg_match("/^(.*?)(<!--monica:(.+?)-->)(.*)$/s", $tmpl, $m)) {
        $plain = $m[1];
        $repsec = $m[2];
        $key = $m[3];
        $tmpl = $m[4];
        
        // Try to match the plain text part
        if (substr($old, 0, strlen($plain)) != $plain) {
            return true;
        }
        $old = substr($old, strlen($plain));
        
        // A valid replacement is found -- try to match the pattern
        if (array_key_exists($key, $rep)) {
            if (!preg_match("/^" . $rep[$key]["pattern"] . "(.*)$/s", $old, $m)) {
                return true;
            }
            $old = $m[1];
        
        // Not a valid replacement -- treat it as a plain text part
        } else {
            if (substr($old, 0, strlen($repsec)) != $repsec) {
                return true;
            }
            $old = substr($old, strlen($plain));
        }
    }
    // Check the remains as a plain text part
    if ($old != $tmpl) {
        return true;
    }
    return false;
}

?>