<?php
error_reporting(~E_ALL);
//$start = microtime_float();

function microtime_float() {
  list($usec,$sec) = explode(' ', microtime());
  return((float)$usec + (float)$sec);
}

/* Trouve le fichier avec le timestamp le plus recent
 * et supprime les caches obsoletes
 *
 */
function cache_find( $path, &$pic_file ) {
  $pic_file = '';
  $file = '';
  $timestamp = 0;
  $cachedir = opendir($path);
  $next_file = readdir($cachedir);
  while( $next_file !== FALSE )  {
    if( $next_file!='.' && $next_file!='..' ) {
      $next_timestamp = filemtime($path.$next_file);
      if( $next_timestamp < $timestamp ) {
        unlink( $path.$next_file );
      } else {
        if( $timestamp > 0 ) {
          unlink( $path.$file );
        }
        $file = $next_file;
        $timestamp = $next_timestamp;
      } 
    }
    $next_file = readdir($cachedir);
  }
  closedir( $cachedir );
  if( $file!='' ) {
    $pic_file = file_get_contents( $path.$file );
  }
  return( $pic_file != '' );
}

/* Trouve l'image la plus recente dans un repertoire
 * "%s%02d%02d.jpg"
 */
function brute_image_find( $path, $format, &$file ) {
  $h = 0;
  $m = 0;
  $timestamp = 0;

  for( $i = 0;  $i < 60;  $i++ ) {
    $this_file = sprintf($format,$m);
    $this_time = filemtime($path.$this_file);
    if( $this_time > $timestamp ) {
      $timestamp = $this_time;
      $file = $this_file;
    }
    $m = $m + 1;
    if( $m > 59 ) {
      $m = 0;
      $h = $h +1;
      if( $h > 23 ) {
        $h = 0;
      }
    }
  }
}

function find( $path, $format, $tolerance, &$file ) {
  $now = time();
  $timestamp = filemtime($path.$file);
  if( $now - $timestamp > $tolerance ) {
/*    $this_file = sprintf($format, strftime("%M",$now));
    $this_time = filemtime($path.$this_file);
    echo $this_file." ".$file." ".($now - $this_time)." )))";
    if( ($now - $this_time) <= $tolerance ) {
      $file = $this_file;
    }
*/
    return( FALSE );
  }
  return( TRUE );
}

function cache_write( $path, $string ) {
  $tempfile = tempnam($path,"pnc");
  $file = fopen($tempfile,"w");
  fwrite($file,$string);
  fclose($file);
}

$tolerance = 60; /* En seconde */
$cache_file = '';
$cache_path = './cache/';

$pic_file = '';
$pic_path = './';
$pic_format1 = 'webcam_thumb-%02d.jpg';
$pic_format2 = 'webcam_thumb-%s.jpg';

if( cache_find( $cache_path, $pic_file )===FALSE ) {
  brute_image_find( $pic_path, $pic_format1, $pic_file );
  cache_write( $cache_path, $pic_file );
} else {
  if( !find( $pic_path, $pic_format2, $tolerance, $pic_file ) ) {;
    brute_image_find( $pic_path, $pic_format1, $pic_file );
    cache_write( $cache_path, $pic_file );
  }
}

//$end = microtime_float();
//echo "$pic_file :".(($end - $start)*1000)."ms";

/*header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

header('Content-Length: '.filesize($pic_file));
header('Content-type: image/jpeg');
readfile($pic_file);*/
//echo $pic_file;

header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

header('Content-Length: '.filesize($pic_file));
header('Content-type: image/jpeg');
readfile($pic_file);
?>