feat(nitro): support netlify zero-config deployments (#175)

src/presets/netlify.ts

@@ -1,11 +1,31 @@
+import { join } from 'upath'
+import { existsSync, readFile, writeFile } from 'fs-extra'
+import consola from 'consola'
 import { extendPreset } from '../utils'
-import { NitroPreset } from '../context'
+import { NitroContext, NitroPreset } from '../context'
 import { lambda } from './lambda'
 
 export const netlify: NitroPreset = extendPreset(lambda, {
   output: {
+    dir: '{{ _nuxt.rootDir }}/netlify/functions',
     publicDir: '{{ _nuxt.rootDir }}/dist'
   },
+  hooks: {
+    async 'nitro:compiled' (ctx: NitroContext) {
+      const redirectsPath = join(ctx._nuxt.rootDir, '_redirects')
+      let contents = '/* /.netlify/functions/server 200'
+      if (existsSync(redirectsPath)) {
+        const currentRedirects = await readFile(redirectsPath, 'utf-8')
+        if (currentRedirects.match(/^\/\* /m)) {
+          consola.info('Not adding Nitro fallback to `_redirects` (as an existing fallback was found).')
+          return
+        }
+        consola.info('Adding Nitro fallback to `_redirects` to handle all unmatched routes.')
+        contents = currentRedirects + '\n' + contents
+      }
+      await writeFile(redirectsPath, contents)
+    }
+  },
   ignore: [
     'netlify.toml',
     '_redirects'