wip: basic hmr for dynamic routes

src/node/plugins/dynamicRoutesPlugin.ts

@@ -1,4 +1,4 @@
-import { loadConfigFromFile, type Plugin } from 'vite'
+import { loadConfigFromFile, type Plugin, type ViteDevServer } from 'vite'
 import fs from 'fs-extra'
 import c from 'picocolors'
 import path from 'path'
@@ -32,9 +32,67 @@ type ResolvedRouteConfig = UserRouteConfig & {
 }
 
 export const dynamicRoutesPlugin = async (
-  routes: string[]
+  initialRoutes: string[]
 ): Promise<Plugin> => {
+  let server: ViteDevServer
+  let [resolvedRoutes, routeFileToModulesMap] = await resolveRoutes(
+    initialRoutes
+  )
+
+  return {
+    name: 'vitepress:dynamic-routes',
+
+    configureServer(_server) {
+      server = _server
+    },
+
+    load(id) {
+      const matched = resolvedRoutes.find((r) => r.path === id)
+      if (matched) {
+        const { route, params, content } = matched
+        const routeFile = path.resolve(route)
+        routeFileToModulesMap[routeFile].push(id)
+
+        let baseContent = fs.readFileSync(routeFile, 'utf-8')
+
+        // inject raw content
+        // this is intended for integration with CMS
+        // we use a speical injection syntax so the content is rendered as
+        // static local content instead of included as runtime data.
+        if (content) {
+          baseContent = baseContent.replace(/<!--\s*@content\s*-->/, content)
+        }
+
+        // params are injected with special markers and extracted as part of
+        // __pageData in ../markdownTovue.ts
+        return `__VP_PARAMS_START${JSON.stringify(
+          params
+        )}__VP_PARAMS_END__${baseContent}`
+      }
+    },
+
+    async handleHotUpdate(ctx) {
+      const mods = routeFileToModulesMap[ctx.file]
+      if (mods) {
+        // path loader module updated, reset loaded routes
+        // TODO: make this more efficient by only reloading the invalidated route
+        // TODO: invlidate modules for paths that are no longer present
+        if (/\.paths\.[jt]s$/.test(ctx.file)) {
+          ;[resolvedRoutes, routeFileToModulesMap] = await resolveRoutes(
+            initialRoutes
+          )
+        }
+        for (const id of mods) {
+          ctx.modules.push(server.moduleGraph.getModuleById(id)!)
+        }
+      }
+    }
+  }
+}
+
+async function resolveRoutes(routes: string[]) {
   const pendingResolveRoutes: Promise<ResolvedRouteConfig[]>[] = []
+  const routeFileToModulesMap: Record<string, string[]> = {}
 
   for (const route of routes) {
     // locate corresponding route paths file
@@ -66,15 +124,20 @@ export const dynamicRoutesPlugin = async (
     }
 
     if (mod) {
+      // route md file and route paths loader file point to the same array
+      routeFileToModulesMap[mod.path] = routeFileToModulesMap[
+        path.resolve(route)
+      ] = []
+
       const resolveRoute = async (): Promise<ResolvedRouteConfig[]> => {
         const loader = mod.config.paths
         const paths = await (typeof loader === 'function' ? loader() : loader)
         return paths.map((userConfig) => {
           return {
-            route,
             path:
               '/' +
               route.replace(/\[(\w+)\]/g, (_, key) => userConfig.params[key]),
+            route,
             ...userConfig
           }
         })
@@ -83,28 +146,8 @@ export const dynamicRoutesPlugin = async (
     }
   }
 
-  const resolvedRoutes = (await Promise.all(pendingResolveRoutes)).flat()
-
-  return {
-    name: 'vitepress:dynamic-routes',
-    load(id) {
-      const matched = resolvedRoutes.find((r) => r.path === id)
-      if (matched) {
-        const { route, params, content } = matched
-        let baseContent = fs.readFileSync(route, 'utf-8')
-
-        // inject raw content at build time
-        if (content) {
-          baseContent = baseContent.replace(/<!--\s*@content\s*-->/, content)
-        }
-
-        // params are injected with special markers and extracted as part of
-        // __pageData in ../markdownTovue.ts
-        return `__VP_PARAMS_START${JSON.stringify(
-          params
-        )}__VP_PARAMS_END__${baseContent}`
-      }
-    }
-    // TODO HMR
-  }
+  return [
+    (await Promise.all(pendingResolveRoutes)).flat(),
+    routeFileToModulesMap
+  ] as const
 }