<?php

class thumb {
  protected string $imagedir;
  protected string $thumbdir;
  protected string $thumburl;

  protected int $w = 200;
  protected int $h = 200;

  const IMAGE_HANDLERS = [
    IMAGETYPE_JPEG => [
        'load' => 'imagecreatefromjpeg',
        'save' => 'imagejpeg',
        'quality' => 100
    ],
    IMAGETYPE_PNG => [
        'load' => 'imagecreatefrompng',
        'save' => 'imagepng',
        'quality' => 0
    ],
    IMAGETYPE_GIF => [
        'load' => 'imagecreatefromgif',
        'save' => 'imagegif',
    ],
    IMAGETYPE_WEBP => [
        'load'    => 'imagecreatefromwebp',
        'save'    => 'imagecreatewebp',
        'quality' => 90
    ]
  ];

  public function __construct($idir, $tdir, $turl, $width, $heigth) {
    $this->imagedir = $idir;
    $this->thumbdir = $tdir;
    $this->thumburl = $turl;
    $this->w        = $width;
    $this->h        = $heigth;
  }

  public function get_thumb($iname) {
    $src     = $this->imagedir.$iname;
    $ext     = pathinfo($iname, PATHINFO_EXTENSION);
    $dstname = hash('sha256', $src);
    $dstpath = $this->thumbdir.$dstname.'.'.$ext;


    if (!file_exists($dstpath)) {
      $type  = exif_imagetype($src);
      if ($type == 0) {
        error_log("$src: Unknown Image Type");
        return "img/error.png";
      }

      $image = call_user_func(self::IMAGE_HANDLERS[$type]['load'], $src);

      if ($image == false) {
        error_log("$src: Image Loading Failed");
        return "img/error.png";
      }

      $srcwidth  = imagesx($image);
      $srcheight = imagesy($image);


      $ratio  = min($this->w / $srcwidth, $this->h / $srcheight);
      $width  = round($srcwidth*$ratio);
      $height = round($srcheight*$ratio);

      $thumbnail = imagecreatetruecolor($width, $height);

      if ($type == IMAGETYPE_GIF || $type == IMAGETYPE_PNG) {
        imagecolortransparent($thumbnail, imagecolorallocate($thumbnail, 0, 0, 0));
        if ($type == IMAGETYPE_PNG) {
            imagealphablending($thumbnail, false);
            imagesavealpha($thumbnail, true);
        }
      }

      imagecopyresampled($thumbnail, $image, 0, 0, 0, 0, $width, $height, $srcwidth, $srcheight);
      if ($type != IMAGETYPE_GIF) {
        call_user_func(self::IMAGE_HANDLERS[$type]['save'],$thumbnail,$dstpath,self::IMAGE_HANDLERS[$type]['quality']);
      } else {
        call_user_func(self::IMAGE_HANDLERS[$type]['save'],$thumbnail,$dstpath);
      }
      imagedestroy($image);
      imagedestroy($thumbnail);
    }
    return $this->thumburl.$dstname.'.'.$ext;
  }
}

?>