Cache QR invites from SOGS

sites/+components/qr_modals.php

@@ -1,56 +1,32 @@
 <?php
-	/*
-	 * @Deprecated
-	 */
 	function room_qr_code_cached($room_id) {
 		global $QR_CODES;
 		return "$QR_CODES/$room_id.png";
 	}
 
-	/*
-	 * Takes join URL and derives the invite.png path from it
+	/**
+	 * Derive URL of the invite code for a given room.
 	 */
-	function room_qr_code_native($join_url) {
-		// Ex.: https://open.getsession.org/session?public_key=[...]
-		// Goal: https://open.getsession.org/r/session/invite.png
-		// Note: No @legacy support (Ex.: https://reccacon.com/view/Ukraine/invite.png)
-		// TODO: How does this behave with unreliable connections to Chinese servers?
-		$exploded = explode("/", explode("?", $join_url)[0]); // everything before "?"
-		$png_url =
-			$exploded[0] . "//" .         // https://
-			$exploded[2] . "/r/" .        // open.getsession.org/r/
-			$exploded[3] . "/invite.png"; // session/invite.png
-
-//		fwrite(STDERR, "PNG URL: " . $png_url . PHP_EOL);
-		return $png_url;
+	function room_invite_png($room_id, $room) {
+		return $room->preview_link . "invite.png";
 	}
 
 	/*
-	 * @Deprecated
-	 * Use Google API to generate QR codes and encode them as base64
+	 * Fetch QR codes from SOGS server and encode them as base64
 	 */
-	function base64_qr_code($room_id, $join_url, $size = "512x512") {
-		// Could use http_build_query() instead, but I won't break what works.  
-		// https://developers.google.com/chart/infographics/docs/qr_codes
+	function base64_qr_code($room_id, $room, $size = "512x512") {
 		$png_cached = room_qr_code_cached($room_id);
-		if (file_exists($png_cached)) 
+		if (file_exists($png_cached)) {
 //			fwrite(STDERR, "QR code found for " . $room_id . PHP_EOL);
 			return base64_encode(file_get_contents($png_cached));
-//			fwrite(STDERR, "QR code NOT found for " . $room_id . PHP_EOL);
-		$data = urlencode($join_url);
-		$api_url =
-			"https://chart.googleapis.com/chart?cht=qr" .
-			"&chs=$size" .
-			"&chl=$data" .
-			"&chld=L|0"; 
-			// error correction level: L = 7%, M = 15%, Q = 25%, H = 30% 
-			// | margin in number of rows
-		$png = file_get_contents($api_url);
+		}
+//		fwrite(STDERR, "QR code NOT found for " . $room_id . PHP_EOL);
+		$png = file_get_contents(room_invite_png($room_id, $room));
 		file_put_contents($png_cached, $png);
 		return base64_encode($png);
 	}
-	
-	file_exists($QR_CODES) or mkdir($QR_CODES, 0700); // @Deprecated
+
+	file_exists($QR_CODES) or mkdir($QR_CODES, 0700);
 ?>
 
 <div id="modal-container">
@@ -61,20 +37,11 @@
 				&times;
 			</span>
 			<img
-				src="data:image/png;base64,<?=base64_qr_code($id, $room->join_link)?>"
-				alt="Community join link encoded as QR code"
-				class="qr-code"
-				loading="lazy"
-			>
-			<!--
-			<img
-				src="<?=room_qr_code_native($room->join_link)?>"
+				src="data:image/png;base64,<?=base64_qr_code($id, $room)?>"
 				alt="Community join link encoded as QR code"
 				class="qr-code"
 				loading="lazy"
-				referrerpolicy="no-referrer"
 			>
-			-->
 		</div>
 	</div>
 <?php endforeach; ?>