From b6311d242f6775c973bd005e33f4cbb99653bd54 Mon Sep 17 00:00:00 2001
From: Hayleigh Thompson <me@hayleigh.dev>
Date: Thu, 20 Jul 2023 21:56:25 +0100
Subject: :sparkles: Add proper svg support.

---
 src/lustre/html.gleam    |   6 ++-
 src/runtime.ffi.mjs      |  19 +++++++--
 test/examples/index.html |   6 +++
 test/examples/svg.gleam  | 109 +++++++++++++++++++++++++++++++++++++++++++++++
 test/examples/svg.html   |  17 ++++++++
 5 files changed, 152 insertions(+), 5 deletions(-)
 create mode 100644 test/examples/svg.gleam
 create mode 100644 test/examples/svg.html

diff --git a/src/lustre/html.gleam b/src/lustre/html.gleam
index f925d95..4c7cf8c 100644
--- a/src/lustre/html.gleam
+++ b/src/lustre/html.gleam
@@ -847,7 +847,11 @@ pub fn svg(
   attrs: List(Attribute(msg)),
   children: List(Element(msg)),
 ) -> Element(msg) {
-  element("svg", attrs, children)
+  element(
+    "svg",
+    [attribute.attribute("xmlns", "http://www.w3.org/2000/svg"), ..attrs],
+    children,
+  )
 }
 
 /// The top-level element in MathML. Every valid MathML instance must be wrapped
diff --git a/src/runtime.ffi.mjs b/src/runtime.ffi.mjs
index b76a29f..babd0b8 100644
--- a/src/runtime.ffi.mjs
+++ b/src/runtime.ffi.mjs
@@ -1,9 +1,9 @@
-import { h, t } from "./lustre/element.mjs";
+import { element, text } from "./lustre/element.mjs";
 import { List } from "./gleam.mjs";
 import { Some, None } from "../gleam_stdlib/gleam/option.mjs";
 
-const Element = h("").constructor;
-const Text = t("").constructor;
+const Element = element("").constructor;
+const Text = text("").constructor;
 
 export function morph(prev, curr) {
   if (curr instanceof Element) {
@@ -31,7 +31,10 @@ export function morph(prev, curr) {
 // ELEMENTS --------------------------------------------------------------------
 
 function createElement(prev, curr) {
-  const el = document.createElement(curr[0]);
+  const el =
+    curr[0] === "svg"
+      ? document.createElementNS("http://www.w3.org/2000/svg", "svg")
+      : document.createElement(curr[0]);
 
   let attr = curr[1];
   while (attr.head) {
@@ -39,6 +42,10 @@ function createElement(prev, curr) {
     attr = attr.tail;
   }
 
+  if (curr[0] === "svg" && !el.getAttribute("xmlns")) {
+    el.setAttribute("xmlns", "http://www.w3.org/2000/svg");
+  }
+
   let child = curr[2];
   while (child.head) {
     el.appendChild(morph(null, child.head));
@@ -59,6 +66,10 @@ function morphElement(prev, curr) {
     currAttr = currAttr.tail;
   }
 
+  if (curr[0] === "svg" && !currAttrs.has("xmlns")) {
+    currAttrs.set("xmlns", "http://www.w3.org/2000/svg");
+  }
+
   for (const { name, value: prevValue } of prevAttrs) {
     if (!currAttrs.has(name)) prev.removeAttribute(name);
     const value = currAttrs.get(name);
diff --git a/test/examples/index.html b/test/examples/index.html
index 1dda01b..70d4196 100644
--- a/test/examples/index.html
+++ b/test/examples/index.html
@@ -16,6 +16,12 @@
       <li>
         <a href="nested.html">nested</a>
       </li>
+      <li>
+        <a href="svg.html">svg</a>
+      </li>
+      <li>
+        <a href="components.html">components</a>
+      </li>
     </menu>
   </body>
 </html>
diff --git a/test/examples/svg.gleam b/test/examples/svg.gleam
new file mode 100644
index 0000000..f1859d4
--- /dev/null
+++ b/test/examples/svg.gleam
@@ -0,0 +1,109 @@
+// IMPORTS ---------------------------------------------------------------------
+
+import gleam/int
+import lustre
+import lustre/attribute.{attribute}
+import lustre/element.{Element, element, text}
+import lustre/html.{button, div, p, svg}
+import lustre/event
+
+// MAIN ------------------------------------------------------------------------
+
+pub fn main() {
+  // A `simple` lustre application doesn't produce `Effect`s. These are best to 
+  // start with if you're just getting started with lustre or you know you don't
+  // need the runtime to manage any side effects.
+  let app = lustre.simple(init, update, render)
+  let assert Ok(_) = lustre.start(app, "[data-lustre-app]")
+}
+
+// MODEL -----------------------------------------------------------------------
+
+pub type Model =
+  Int
+
+pub fn init() -> Model {
+  0
+}
+
+// UPDATE ----------------------------------------------------------------------
+
+pub opaque type Msg {
+  Incr
+  Decr
+  Reset
+}
+
+pub fn update(model: Model, msg: Msg) -> Model {
+  case msg {
+    Incr -> model + 1
+    Decr -> model - 1
+    Reset -> 0
+  }
+}
+
+// VIEW ------------------------------------------------------------------------
+
+pub fn render(model: Model) -> Element(Msg) {
+  div(
+    [],
+    [
+      button([event.on_click(Incr)], [plus()]),
+      button([event.on_click(Decr)], [minus()]),
+      button([event.on_click(Reset)], [text("Reset")]),
+      p([], [text(int.to_string(model))]),
+    ],
+  )
+}
+
+fn plus() {
+  svg(
+    [
+      attribute("width", "15"),
+      attribute("height", "15"),
+      attribute("viewBox", "0 0 15 15"),
+      attribute("fill", "none"),
+    ],
+    [
+      element(
+        "path",
+        [
+          attribute(
+            "d",
+            "M8 2.75C8 2.47386 7.77614 2.25 7.5 2.25C7.22386 2.25 7 2.47386 7 2.75V7H2.75C2.47386 7 2.25 7.22386 2.25 7.5C2.25 7.77614 2.47386 8 2.75 8H7V12.25C7 12.5261 7.22386 12.75 7.5 12.75C7.77614 12.75 8 12.5261 8 12.25V8H12.25C12.5261 8 12.75 7.77614 12.75 7.5C12.75 7.22386 12.5261 7 12.25 7H8V2.75Z",
+          ),
+          attribute("fill", "currentColor"),
+          attribute("fill-rule", "evenodd"),
+          attribute("clip-rule", "evenodd"),
+        ],
+        [],
+      ),
+    ],
+  )
+}
+
+fn minus() {
+  svg(
+    [
+      attribute("width", "15"),
+      attribute("height", "15"),
+      attribute("viewBox", "0 0 15 15"),
+      attribute("fill", "none"),
+    ],
+    [
+      element(
+        "path",
+        [
+          attribute(
+            "d",
+            "M2.25 7.5C2.25 7.22386 2.47386 7 2.75 7H12.25C12.5261 7 12.75 7.22386 12.75 7.5C12.75 7.77614 12.5261 8 12.25 8H2.75C2.47386 8 2.25 7.77614 2.25 7.5Z",
+          ),
+          attribute("fill", "currentColor"),
+          attribute("fill-rule", "evenodd"),
+          attribute("clip-rule", "evenodd"),
+        ],
+        [],
+      ),
+    ],
+  )
+}
diff --git a/test/examples/svg.html b/test/examples/svg.html
new file mode 100644
index 0000000..10daddd
--- /dev/null
+++ b/test/examples/svg.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>lustre | svg</title>
+
+    <script type="module">
+      import { main } from "../../build/dev/javascript/lustre/examples/counter.mjs";
+
+      document.addEventListener("DOMContentLoaded", main);
+    </script>
+  </head>
+  <body>
+    <div data-lustre-app></div>
+  </body>
+</html>
-- 
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