From 4331545853618ec7a58eb5d1a9e4030423349cf6 Mon Sep 17 00:00:00 2001
From: Caleb Williams <caleb.d.williams@gmail.com>
Date: Wed, 24 Jul 2019 11:55:47 -0500
Subject: [PATCH] feat(proxy): Add proxy support

---
 README.md    |   7 ++++
 src/index.js | 103 +++++++++++++++++++++++++++++++++++++--------------
 2 files changed, 82 insertions(+), 28 deletions(-)

diff --git a/README.md b/README.md
index c1a8e19..54674aa 100644
--- a/README.md
+++ b/README.md
@@ -88,6 +88,13 @@ serve({
   headers: {
     'Access-Control-Allow-Origin': '*',
     foo: 'bar'
+  },
+
+  // Set up simple proxy
+  // this will route all traffic starting with
+  // `/api` to http://localhost:8181/api
+  proxy: {
+    api: 'http://localhost:8181'
   }
 })
 ```
diff --git a/src/index.js b/src/index.js
index ec9ee3c..8fae80d 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,6 +1,6 @@
 import { readFile } from 'fs'
-import { createServer as createHttpsServer } from 'https'
-import { createServer } from 'http'
+import https, { createServer as createHttpsServer } from 'https'
+import http, { createServer } from 'http'
 import { resolve } from 'path'
 
 import mime from 'mime'
@@ -22,9 +22,20 @@ function serve (options = { contentBase: '' }) {
   options.headers = options.headers || {}
   options.https = options.https || false
   options.openPage = options.openPage || ''
+  options.proxy = options.proxy || {}
   mime.default_type = 'text/plain'
 
-  const requestListener = (request, response) => {
+  // Use http or https as needed
+  const http_s = options.https ? https : http
+
+  const proxies = Object.keys(options.proxy).map(proxy => ({
+    proxy,
+    destination: options.proxy[proxy],
+    test: new RegExp(`\/${proxy}`)
+  }))
+
+
+  const requestListener = (request, response) => {    
     // Remove querystring
     const urlPath = decodeURI(request.url.split('?')[0])
 
@@ -32,31 +43,62 @@ function serve (options = { contentBase: '' }) {
       response.setHeader(key, options.headers[key])
     })
 
-    readFileFromContentBase(options.contentBase, urlPath, function (error, content, filePath) {
-      if (!error) {
-        return found(response, filePath, content)
-      }
-      if (error.code !== 'ENOENT') {
-        response.writeHead(500)
-        response.end('500 Internal Server Error' +
-          '\n\n' + filePath +
-          '\n\n' + Object.values(error).join('\n') +
-          '\n\n(rollup-plugin-serve)', 'utf-8')
-        return
-      }
-      if (options.historyApiFallback) {
-        var fallbackPath = typeof options.historyApiFallback === 'string' ? options.historyApiFallback : '/index.html'
-        readFileFromContentBase(options.contentBase, fallbackPath, function (error, content, filePath) {
-          if (error) {
-            notFound(response, filePath)
-          } else {
-            found(response, filePath, content)
-          }
-        })
-      } else {
-        notFound(response, filePath)
-      }
-    })
+    // Find the appropriate proxy for the request if one exists
+    const proxy = proxies.find(({ test }) => request.url.match(test))
+
+    // If a proxy exists, forward the request to the appropriate server
+    if (proxy && proxy.destination) {
+      const { destination } = proxy
+      const newDestination = `${destination}${request.url}`
+      const { headers, method, statusCode } = request
+
+      // Get the request contents
+      let body = '';
+      request.on('data', chunk => body += chunk)
+
+      // Forward the request
+      request.on('end', () => {
+        const proxyRequest = http_s
+          .request(newDestination, { headers, method }, (proxyResponse) => {
+            let data = ''
+            proxyResponse.on('data', chunk => data += chunk)
+            proxyResponse.on('end', () => {
+              Object.keys(proxyResponse.headers).forEach(key => response.setHeader(key, proxyResponse.headers[key]))
+              foundProxy(response, proxyResponse.statusCode, data)
+            })
+          })
+          .end(body, 'utf-8')
+          
+        proxyRequest.on('error', err => console.error(`There was a problem with the request for ${request.url}: ${err}`))
+        proxyRequest.end()
+      })
+    } else {
+      readFileFromContentBase(options.contentBase, urlPath, function (error, content, filePath) {
+        if (!error) {
+          return found(response, filePath, content)
+        }
+        if (error.code !== 'ENOENT') {
+          response.writeHead(500)
+          response.end('500 Internal Server Error' +
+            '\n\n' + filePath +
+            '\n\n' + Object.values(error).join('\n') +
+            '\n\n(rollup-plugin-serve)', 'utf-8')
+          return
+        }
+        if (options.historyApiFallback) {
+          var fallbackPath = typeof options.historyApiFallback === 'string' ? options.historyApiFallback : '/index.html'
+          readFileFromContentBase(options.contentBase, fallbackPath, function (error, content, filePath) {
+            if (error) {
+              notFound(response, filePath)
+            } else {
+              found(response, filePath, content)
+            }
+          })
+        } else {
+          notFound(response, filePath)
+        }
+      })
+    }
   }
 
   // release previous server instance if rollup is reloading configuration in watch mode
@@ -127,6 +169,11 @@ function found (response, filePath, content) {
   response.end(content, 'utf-8')
 }
 
+function foundProxy (response, status, content) {
+  response.writeHead(status)
+  response.end(content, 'utf-8')
+}
+
 function green (text) {
   return '\u001b[1m\u001b[32m' + text + '\u001b[39m\u001b[22m'
 }