<?php
/********************************************************************************
Bob's Graphic Novel Viewer Script
Version 1.2, 2004-02, James Paige

Copyright (c) 2004 James Paige

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
********************************************************************************/

/*-----------------------------------------------------*/
/* Configuration Constants                             */

define("PAGE_TITLE","Bob the Hamster - Graphic Novel");
define("COPYRIGHT_TEXT",'All artwork &copy;2002-2004 James Paige');
define("PAGE_FILE_TYPE",'png');
define("THUMB_FILE_TYPE",'png');

/*-----------------------------------------------------*/
/* General purpose functions */

/* This function accepts a path and an optional regular
   expression, and returns an array of all filenames in
   that path that match the regex (or all files if no)
   regex is specified */

function list_files($path,$regex=''){
  $result=array();
  /* make sure the specified path is really a directory */
  if(is_dir($path)) {
    /* open the path and return a directory handle */
    if($dh=opendir($path)){
      /* for each file returned by the directory handle... */
      while(($file = readdir($dh)) !== false){
        if($file[0]=='.'){
          /* ignore hidden files and the special dirs */
        }else{
          if($regex){
            /* if a regex was specified, match against it */
            if(preg_match($regex,$file)){
              /* a match was found, append it to the
                 result array */
              $result[]=$file;
            }
          }else{
            /* if no wildcard is specified, unconditionally
               append the filename to the result array */
            $result[]=$file;
          }
        }
      }
      /* leaving the directory handle open would be
         harmless yet impolite :) */
      closedir($dh);
    }
  }
  /* and return the array of filenames */
  return($result);
}

/*-----------------------------------------------------*/
/* Application-specific functions                      */

/* This function generates a global list of available
   chapters. Since this list is used in many different
   places it is best to generate it once globally */
function build_chapter_list(){
  global $chapter_list;
  /* list all files with names that are prefixed with
     three digits and a dash */
  $chapters=list_files('./','/...-.*/');
  /* the list comes in in inode order, which is more or
     less random. We must alphabetize it */
  sort($chapters);
  /* now we iterate through the list of chapters to build
     a list of chapter information objects */
  foreach($chapters as $key=>$chapter){
    /* first store the chapter's full folder name */
    $chapter_list[$key]['folder']=$chapter;
    /* then parse the chapter name and number */
    parse_chapter_info($chapter,$chapter_list[$key]['name'],$chapter_list[$key]['number']);
  }
}

/* This function builds a list of the pages
   in the currently selected chapter. It is global
   just like the chapter list. */
function get_page_list($chapter){
  global $chapter_list,$page_list;
  /* all pages are files with the prefix "page-"
     followed by alphabetically correct numbers that
     ensure the pages will be sorted into the correct
     order. */
  $page_list=list_files($chapter_list[$chapter]['folder'],'/page-.*\.'.PAGE_FILE_TYPE.'/');
  sort($page_list);
}

/* This function examines a chapter folder name and
   extracts the chapter number and the chapter title */
function parse_chapter_info($file,&$name,&$number){
  /* strip the prefix and substitute spaces for
     underscores to generate the chapter name */
  $name=str_replace('_',' ',substr($file,4));
  /* convert the prefix into an integer to
     generate the chapter number */
  $number=(int)substr($file,0,3);
}

/* This function returns a string with the URL for
   a specified page and chapter */
function page_link($chapter,$page=0){
  return(sprintf('%s?chapter=%s&page=%s',$_SERVER['SCRIPT_NAME'],urlencode($chapter),urlencode($page)));
}

/* This function imports the chapter variable and
   ensures that it has a legal numeric value */
function sanity_check_chapter(&$chapter){
  if(isset($_REQUEST['chapter'])) $chapter=(int)$_REQUEST['chapter'];
  if(!is_numeric($chapter)) unset($chapter);
}

/* This function imports the page number variable
   and ensures that it has a legal numeric value */
function sanity_check_page(&$page){
  if(isset($_REQUEST['page'])) $page=(int)$_REQUEST['page'];
  if(!is_numeric($page)) $page=0;
}

/* This function returns a link to the next page, or an empty string if this is the last page */
function next_page_url($page, $chapter){
  global $chapter_list,$page_list;

  /* pre-calculate the last page and chapter */
  $last_chapter=sizeof($chapter_list)-1;
  $last_page=sizeof($page_list)-1;

  if($page<$last_page){
    /* when looking at any page except the last
       page, the link points to $page+1 */
    return page_link($chapter,$page+1);
  }else{
    /* when looking at the last page... */
    if($chapter<$last_chapter){
      /* when looking at the last page of any
         chapter except the last one, the link
         points to the first page of the next
         chapter */
      return page_link($chapter+1,0);
    }else{
      /* when looking at the last page of the last
         chapter, the link is not a link at all */
      return '';
    }
  }
}

/*-----------------------------------------------------*/
/* Output Functions                                    */

/* This function outputs a list of thumbnail images
   that link to the first page of each chapter */
function list_thumbnails(){
  global $chapter_list;
  foreach($chapter_list as $chapter_ID=>$chapter){
    printf('<a href="%s"><img src="%s/thumbnail.%s" alt="[%s:%s]" title="Chapter %s - %s"></a> '."\n"
           ,page_link($chapter_ID)
           ,$chapter['folder']
           ,THUMB_FILE_TYPE
           ,$chapter['number']
           ,$chapter['name']
           ,$chapter['number']
           ,$chapter['name'])
           ;
  }
}

/* this function outputs the index navigation */
function output_index_navigation(){
?>

<p>
<a href="/">Hamster Republic</a> -&gt;
<big><b>Bob's Graphic Novel</b></big>
</p>

<hr>

<?php
}

/* This function outputs the navigation links;
   index, back and next */
function output_page_navigation($chapter,$page){
  global $chapter_list,$page_list;

  /* pre-calculate the last page and chapter */
  $last_chapter=sizeof($chapter_list)-1;
  $last_page=sizeof($page_list)-1;

  $link_index='<img src="support_images/chapter-index.png" alt="[chapter index]" border="0">';
  $link_prev='<img src="support_images/previous.png" alt="[previous]" border="0">';
  $link_prev_disabled='<img src="support_images/previous-grey.png" alt="" border="0">';
  $link_next='<img src="support_images/next.png" alt="[next]" border="0">';
  $link_next_disabled='<img src="support_images/next-grey.png" alt="" border="0">';

  /* now the previous-page link */
  if($page>0){
    /* when looking at any page but the first,
       the link points to $page-1 */
    printf('<a href="%s">%s</a>'."\n",page_link($chapter,$page-1),$link_prev);
  }else{
    /* when looking at the first page... */
    if($chapter>0){
      /* when looking at the first page of any
         chapter other than the first one, the
         link points to the last page of the
         previous chapter */
      printf('<a href="%s">%s</a>'."\n",page_link($chapter-1,-1),$link_prev);
    }else{
      /* when looking at the first page of the
         first chapter, the link is not a link
         at all */
      printf('%s'."\n",$link_prev_disabled);
    }
  }

  /* The index link is easy. It never changes. */
  printf('<a href="%s">%s</a>'."\n",$_SERVER['SCRIPT_NAME'],$link_index);

  /* output the next-page link */
  if($page<$last_page){
    /* when looking at any page except the last
       page, the link points to $page+1 */
    printf('<a href="%s">%s</a>'."\n",page_link($chapter,$page+1),$link_next);
  }else{
    /* when looking at the last page... */
    if($chapter<$last_chapter){
      /* when looking at the last page of any
         chapter except the last one, the link
         points to the first page of the next
         chapter */
      printf('<a href="%s">%s</a>'."\n",page_link($chapter+1,0),$link_next);
    }else{
      /* when looking at the last page of the last
         chapter, the link is not a link at all */
      printf('%s'."\n",$link_next_disabled);
    }
  }
  printf('<br>'."\n");
  printf('<hr>'."\n");
}

/* This function outputs the body of the page */
function show_page($chapter,$page){
  global $chapter_list,$page_list;

  /* pre-calculate the last page */
  $last=sizeof($page_list)-1;

  /* if $page is -1 then select the
     last page in the chapter. (this
     is used by the "previous" page
     navigation link) */
  if($page==-1) $page=$last;

  /* read the alt text */
  $alt_file_name=sprintf('./%s/alt.txt',$chapter_list[$chapter]['folder']);
  if(is_readable($alt_file_name)){
    $alt_file_data=file($alt_file_name);
    $alt=htmlentities(trim(str_replace("\n",'',strip_tags($alt_file_data[1+$page]))),ENT_QUOTES);
  }else{
    $alt=sprintf('Page %s',$page);
  }

  /* I think this looks better centered. */
  printf('<center>'."\n");

  /* output the navigation links */
  output_page_navigation($chapter,$page);

  /* output a link to the next page enclosing the current page */
  $next_url = next_page_url($page, $chapter);
  if($next_url) printf('<a href="%s">', $next_url);
 

  /* output the <img> tag that contains the
     actual comic image */
  printf('<img src="%s/%s" alt="[%s]" border="0">'
         ,$chapter_list[$chapter]['folder']
         ,$page_list[$page]
         ,$alt
        );

  /* end the big next-page link */
  if($next_url) printf('</a>');

  printf('</center>'."\n");
}

/* This function outputs a simplified header for
   the index page */
function show_index_header(){
  printf('<html><head>'."\n");

  /* output the title */
  printf("<title>%s</title>\n",PAGE_TITLE);
  printf('<link rel="icon" href="favicon.ico" type="image/x-icon" />'."\n");
  printf('<link rel="stylesheet" href="style.css" type="text/css" />'."\n");

  printf('</head><body>'."\n");
}

/* This function outputs the html headers and the
   title, and opens the html body tag */
function show_page_header($chapter,$page){
  global $chapter_list;
  printf('<html><head>'."\n");

  /* output the title including chapter name and page number */
  printf("<title>%s - %s - Page %s</title>\n",PAGE_TITLE,$chapter_list[$chapter]['name'],$page);

  /* output the favorites icon */
  printf('<link rel="icon" href="favicon.ico" type="image/x-icon" />'."\n");

  /* generate the prefetch headers for the next page */
  generate_prefetch_link($chapter,$page);

  printf('</head><body>'."\n");
}

function generate_prefetch_link($chapter,$page){
  global $chapter_list,$page_list;
  $last=sizeof($page_list)-1;
  $last_chapter=sizeof($chapter_list)-1;
  if($page<$last){
    /* if we are looking at anything other than the
       last page, we output a <link> header that
       instructs browsers to prefetch the next page */
    printf('<link rel="prefetch" href="%s/%s">'."\n",$chapter_list[$chapter]['folder'],$page_list[$page+1]);
  }else{
    /* if we are looking at the last page of a series */
    if($chapter<$last_chapter){
      /* if we are on the last page of any chapter
         other than the last one, we output a <link>
         header instructing the browser to prefetch
         the first page of the next chapter. */
      /* it is neccisary to list the pages of the next
         chapter because we only already have the pages
         of the current chapter in memory */
      $next_chapter_page_list=list_files($chapter_list[$chapter+1]['folder'],'/page-.*\.'.PAGE_FILE_TYPE.'/');
      sort($next_chapter_page_list);
      /* and here we output the link it would not
         really be an unreasonable assumption to
         assume that every chapter will have at least
         one page, but I hate making assuptions, even
         reasonable ones :) */
      if(sizeof($next_chapter_page_list)){
        printf('<link rel="prefetch" href="%s/%s">'."\n",$chapter_list[$chapter+1]['folder'],$next_chapter_page_list[0]);
      }
      /* and then we discard the list of the next
         chapter's pages from memory, as we will not
         need it any further */
      unset($next_chapter_page_list);
    }
  }
}

/* This function outputs the html footers and
   the copyright information */
function show_page_footer(){
  printf('<center><p>%s</p></center>'."\n",COPYRIGHT_TEXT);
  printf('<p style="float:right;font-size:small;"><a href="sourcecode.txt">source code</a></p>');
  printf('</body></html>'."\n");
}

function output_info(){
  printf("<hr>\n");

  $greeter='';
  $greeters=list_files('./greeter/','/.*\.png/');
  if(count($greeters)) $greeter=$greeters[array_rand($greeters,1)];

  if($greeter) printf('<img src="greeter/%s" alt="" style="float:left;">'."\n",$greeter);
?>

<p>
Once upon a time, there was a Hamster named Bob. He was the eldest of 144 siblings, all of whom were also named Bob (yes, even his sisters). He grew up a happy hamster child, starred in a few <a href="/dl/">obscure computer games</a>, started a revolution and founded <a href="/">his own country</a>, saved the world from unspeakable evil once or twice, and finally decided to settle down and get a <i>real</i> job. Sound mundane? Well, nothing stays simple long in Bob's life.
</p>

<p>
New chapters are uploaded on a strict schedule of whenever-I-feel-like-it.
</p>

<?php
}

/*-----------------------------------------------------*/
/* Execution starts here                               */

build_chapter_list();
sanity_check_chapter($chapter);
sanity_check_page($page);

if(isset($chapter)){
  /* if a chapter is selected... */
  get_page_list($chapter);
  show_page_header($chapter,$page);
  show_page($chapter,$page);
}else{
  /* if no chapter is set, list the thumbnails */
  show_index_header();
  output_index_navigation();
  list_thumbnails();
  output_info();
}

show_page_footer();

/*-----------------------------------------------------*/

?>