feat: prima versione del plugin, blocco e shortcode con iframe stampato lato server

assets/css/widget.css

@@ -0,0 +1,17 @@
+/* The widget is an iframe: it only needs to be as wide as its column and to
+   have no border of its own. Everything else lives inside the frame. */
+.pinfesta-embed {
+	display: block;
+	width: 100%;
+	border: 0;
+	overflow: hidden;
+}
+
+.pinfesta-empty {
+	margin: 0;
+	padding: 12px 14px;
+	border: 1px dashed currentColor;
+	border-radius: 8px;
+	font-size: 0.9em;
+	opacity: 0.75;
+}

assets/js/resize.js

@@ -0,0 +1,44 @@
+/**
+ * Keeps the widget as tall as its content.
+ *
+ * The framed page posts its height whenever it changes; we accept the message
+ * only when it comes from the Piazza in Festa origin and from a window that is
+ * one of our own iframes, then set the height. Nothing else leaves or enters
+ * the page.
+ */
+(function () {
+	'use strict';
+
+	var cfg = window.pinfestaCfg || {};
+	var origin = cfg.origin || '';
+
+	if (!origin) {
+		return;
+	}
+
+	window.addEventListener('message', function (event) {
+		if (event.origin !== origin) {
+			return;
+		}
+
+		var data = event.data;
+
+		if (!data || data.tipo !== 'piazzainfesta:altezza') {
+			return;
+		}
+
+		var altezza = parseInt(data.altezza, 10);
+
+		if (!altezza || altezza < 1) {
+			return;
+		}
+
+		var frames = document.querySelectorAll('iframe.pinfesta-embed');
+
+		for (var i = 0; i < frames.length; i++) {
+			if (frames[i].contentWindow === event.source) {
+				frames[i].style.height = altezza + 2 + 'px';
+			}
+		}
+	});
+})();