<?php

class CoverController {

	static function get_cover($_request, $id, $filename, $size = false) {

		$rev = new Revision($id);
		if ($rev === false) return "";

		$path = $rev->path();

		$pdf = new PDF($path . "/doc.pdf");
		if (!$pdf->exists()) {
			return [404, "Not Found"];
		}

		if (!$size) {
			$imgpath = sprintf("%s/cover.jpg", $path);
		} else {
			$imgpath = sprintf("%s/cover-%d.jpg", $path, $size);
		}

		$file = new File($imgpath);

		if ($file->exists()) {
			$h = $file->hash();
			$h = "\"$h\"";
			if ($h == $_request->header("If-None-Match")) {
				return [304, "Not Modified", [
					"ETag" => $h,
					"Cache-Control" => "public, max-age=86400, must-revalidate",
				]];
			}
			return new Image($file);
		}

		$cover = new Image($path . "/cover.jpg");
		if (!$cover->exists()) {
			$pdf->extract_page(0, $cover->path());
			$cover = new Image($path . "/cover.jpg");
		}

		if (!$cover->exists()) {
			return [404, "Not Found"];
		}

		if ($size === false) $size = $cover->width();

		if ($size >= $cover->width()) {
			$h = $cover->hash();
			$h = "\"$h\"";
			if ($h == $_request->header("If-None-Match")) {
				return [304, "Not Modified", [
					"ETag" => $h,
					"Cache-Control" => "public, max-age=86400, must-revalidate",
				]];
			}
			return $cover;
		}

		$cover->scale($size);
		$img = $cover->save($imgpath, "image/jpeg");
		return $img;
	}
	
}