From b47c9d75dfdff6580968ed1f28fd1d1607bf4777 Mon Sep 17 00:00:00 2001
From: Christian Georgi <christian.georgi@sap.com>
Date: Wed, 28 Oct 2020 10:55:35 +0100
Subject: [PATCH] Embed Swagger UI

---
 .gitignore            |  2 ++
 bookshop/package.json |  3 ++-
 bookshop/server.js    | 48 +++++++++++++++++++++++++++++++++++++++++++
 package.json          |  3 ++-
 4 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 bookshop/server.js

diff --git a/.gitignore b/.gitignore
index 1951715e..f3283db5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,5 @@ default-env.json
 packages/messageBox
 reviews/msg-box
 reviews/db/test.db
+
+*.openapi3.json
diff --git a/bookshop/package.json b/bookshop/package.json
index 6601ca5c..20294682 100644
--- a/bookshop/package.json
+++ b/bookshop/package.json
@@ -10,7 +10,8 @@
   "scripts": {
     "genres": "cds serve test/genres.cds",
     "start": "cds run",
-    "watch": "cds watch"
+    "watch": "cds watch",
+    "to-openapi": "cds compile srv --to openapi -s CatalogService -o srv"
   },
   "cds": {
     "requires": {
diff --git a/bookshop/server.js b/bookshop/server.js
new file mode 100644
index 00000000..819982b7
--- /dev/null
+++ b/bookshop/server.js
@@ -0,0 +1,48 @@
+const cds = require ('@sap/cds')
+const {resolve} = require ('path')
+const {promisify} = require('util')
+const readFile = promisify(require('fs').readFile)
+const swaggerUi = require ('swagger-ui-express')
+const DEBUG = cds.debug('openapi')
+
+let app, host, docCache={}
+
+cds
+  .on ('bootstrap', _app => { app = _app })
+  .on ('serving', service => {
+    const apiPath = '/api-docs'+service.path
+    console.log (`[Open API] - serving ${service.name} at ${apiPath}`)
+    app.use(apiPath, async (req, _, next) => {
+      req.swaggerDoc = await toOpenApiDoc(service, host, docCache)
+      next()
+    }, swaggerUi.serve, swaggerUi.setup())
+  })
+  .on ('listening', ({server})=> { host = 'localhost:'+server.address().port })
+
+async function toOpenApiDoc(service, host, cache) {
+  if (!cache[service.name]) {
+    const spec = await openApiFromFile(service)
+    if (spec) {
+      cache[service.name] = spec
+    }
+    else if (cds.compile.to.openapi) {  // on-the-fly exporter available?
+      DEBUG && DEBUG ('Compiling Open API spec for', service.name)
+      cache[service.name] = cds.compile.to.openapi (service.model, {
+        service: service.name,
+        scheme: 'http', host, basePath: service.path
+      })
+    }
+  }
+  return cache[service.name]
+}
+
+async function openApiFromFile(service) {
+  const fileName = resolve(`srv/${service.name}.openapi3.json`)
+  const file = await readFile(fileName).catch(()=>{/*no such file*/})
+  if (file) {
+    DEBUG && DEBUG ('Using Open API spec from file', fileName)
+    return JSON.parse(file)
+  }
+}
+
+module.exports = cds.server
diff --git a/package.json b/package.json
index f81fc148..7423acbb 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,8 @@
     "chai": "^4.2.0",
     "chai-as-promised": "^7.1.1",
     "chai-subset": "^1.6.0",
-    "sqlite3": "^5"
+    "sqlite3": "^5",
+    "swagger-ui-express": "^4.1.4"
   },
   "scripts": {
     "bookshop": "cds watch bookshop",