From 9fb9bed8062869cdc1419aac3297d6a649fa308a Mon Sep 17 00:00:00 2001
From: Sidharth Vinod <sidharthv96@gmail.com>
Date: Sun, 13 Aug 2023 18:51:02 +0530
Subject: [PATCH] chore: Add live-reload

---
 .esbuild/server.ts     | 89 ++++++++++++++++++++++++++++++++++--------
 demos/dev/example.html | 28 +++++++++++++
 package.json           |  3 +-
 pnpm-lock.yaml         |  3 ++
 4 files changed, 105 insertions(+), 18 deletions(-)

diff --git a/.esbuild/server.ts b/.esbuild/server.ts
index c93b4bbda..e25c0f714 100644
--- a/.esbuild/server.ts
+++ b/.esbuild/server.ts
@@ -1,29 +1,84 @@
 import express from 'express';
+import type { NextFunction, Request, Response } from 'express';
 import cors from 'cors';
 import { getBuildConfig } from './util.js';
 import { context } from 'esbuild';
+import chokidar from 'chokidar';
+
+const mermaidCtx = await context(
+  getBuildConfig({ minify: false, core: false, entryName: 'mermaid' })
+);
+const mermaidIIFECtx = await context(
+  getBuildConfig({ minify: false, core: false, entryName: 'mermaid', format: 'iife' })
+);
+const externalCtx = await context(
+  getBuildConfig({ minify: false, core: false, entryName: 'mermaid-example-diagram' })
+);
+const zenumlCtx = await context(
+  getBuildConfig({ minify: false, core: false, entryName: 'mermaid-zenuml' })
+);
+const contexts = [mermaidCtx, mermaidIIFECtx, externalCtx, zenumlCtx];
+
+const rebuildAll = async () => {
+  await Promise.all(contexts.map((ctx) => ctx.rebuild()));
+};
+
+let clients: { id: number; response: Response }[] = [];
+function eventsHandler(request: Request, response: Response, next: NextFunction) {
+  const headers = {
+    'Content-Type': 'text/event-stream',
+    Connection: 'keep-alive',
+    'Cache-Control': 'no-cache',
+  };
+  response.writeHead(200, headers);
+  const clientId = Date.now();
+  clients.push({
+    id: clientId,
+    response,
+  });
+  request.on('close', () => {
+    clients = clients.filter((client) => client.id !== clientId);
+  });
+}
+
+let timeoutId: NodeJS.Timeout | undefined = undefined;
+
+/**
+ * Debounce file change events to avoid rebuilding multiple times.
+ */
+function handleFileChange() {
+  if (timeoutId !== undefined) {
+    clearTimeout(timeoutId);
+  }
+  timeoutId = setTimeout(async () => {
+    await rebuildAll();
+    sendEventsToAll();
+    timeoutId = undefined;
+  }, 100);
+}
+
+function sendEventsToAll() {
+  clients.forEach(({ response }) => response.write(`data: ${Date.now()}\n\n`));
+}
 
 async function createServer() {
   const app = express();
-  const mermaidCtx = await context(
-    getBuildConfig({ minify: false, core: false, entryName: 'mermaid' })
-  );
-  const mermaidIIFECtx = await context(
-    getBuildConfig({ minify: false, core: false, entryName: 'mermaid', format: 'iife' })
-  );
-  const externalCtx = await context(
-    getBuildConfig({ minify: false, core: false, entryName: 'mermaid-example-diagram' })
-  );
-  const zenuml = await context(
-    getBuildConfig({ minify: false, core: false, entryName: 'mermaid-zenuml' })
-  );
-
-  mermaidCtx.watch();
-  mermaidIIFECtx.watch();
-  externalCtx.watch();
-  zenuml.watch();
+  chokidar
+    .watch('**/src/**/*.{js,ts,yaml,json}', {
+      ignoreInitial: true,
+      ignored: [/node_modules/, /dist/, /docs/, /coverage/],
+    })
+    .on('all', async (event, path) => {
+      // Ignore other events.
+      if (!['add', 'change'].includes(event)) {
+        return;
+      }
+      console.log(`${path} changed. Rebuilding...`);
+      handleFileChange();
+    });
 
   app.use(cors());
+  app.get('/events', eventsHandler);
   app.use(express.static('./packages/mermaid/dist'));
   app.use(express.static('./packages/mermaid-zenuml/dist'));
   app.use(express.static('./packages/mermaid-example-diagram/dist'));
diff --git a/demos/dev/example.html b/demos/dev/example.html
index 482343014..c13bd03ca 100644
--- a/demos/dev/example.html
+++ b/demos/dev/example.html
@@ -30,5 +30,33 @@ graph TB
       console.log(svg);
       el.innerHTML = svg;
     </script>
+
+    <script>
+      // Set to false to disable live reload
+      const liveReload = true;
+      // Connect to the server and reload the page if the server sends a reload message
+      const connectToEvents = () => {
+        const events = new EventSource('/events');
+        const loadTime = Date.now();
+        events.onmessage = (event) => {
+          const time = JSON.parse(event.data);
+          if (time && time > loadTime) {
+            location.reload();
+          }
+        };
+        events.onerror = (error) => {
+          console.error(error);
+          events.close();
+          // Try to reconnect after 1 second in case of errors
+          setTimeout(connectToEvents, 1000);
+        };
+        events.onopen = () => {
+          console.log('Connected to live reload server');
+        };
+      };
+      if (liveReload) {
+        connectToEvents();
+      }
+    </script>
   </body>
 </html>
diff --git a/package.json b/package.json
index bd45762f5..2e0391d5a 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,7 @@
     "git graph"
   ],
   "scripts": {
-    "build": "pnpm build:esbuild && pnpm build:types",
+    "build": "pnpm run -r clean && pnpm build:esbuild && pnpm build:types",
     "build:esbuild": "pnpm run -r clean && ts-node-esm --transpileOnly .esbuild/build.ts",
     "build:mermaid": "pnpm build:esbuild --mermaid",
     "build:viz": "pnpm build:esbuild --visualize",
@@ -82,6 +82,7 @@
     "@vitest/spy": "^0.33.0",
     "@vitest/ui": "^0.33.0",
     "ajv": "^8.12.0",
+    "chokidar": "^3.5.3",
     "concurrently": "^8.0.1",
     "cors": "^2.8.5",
     "cypress": "^12.10.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index e0f524dcd..d6e90660b 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -74,6 +74,9 @@ importers:
       ajv:
         specifier: ^8.12.0
         version: 8.12.0
+      chokidar:
+        specifier: ^3.5.3
+        version: 3.5.3
       concurrently:
         specifier: ^8.0.1
         version: 8.0.1