feat: support loading input from uri (#150)

initial support for loading input schemas from urls.

support for following relative links to other urls probably doesn't work
yet.

relates #43

Author: mnahkies

packages/openapi-code-generator/src/core/file-loader.ts

@@ -22,36 +22,48 @@ async function loadLocalFile(file: string): Promise<[string, any]> {
   file = path.resolve(file)
   const raw = fs.readFileSync(file, {encoding: "utf-8"})
 
-  let result: any | undefined
+  return [file, await parseFile(raw, file)]
+}
+
+async function loadRemoteFile(uri: string): Promise<[string, any]> {
+  const res = await fetch(uri)
+
+  if (!res.ok) {
+    throw new Error(`failed to fetch remote file '${uri}'`)
+  }
+
+  const raw = await res.text()
 
-  if (file.endsWith(".json")) {
+  return [uri, await parseFile(raw, uri)]
+}
+
+async function parseFile(raw: string, filepath: string): Promise<unknown> {
+  let result: unknown | undefined
+
+  // TODO: sniff format from raw text
+  if (filepath.endsWith(".json")) {
     try {
       result = JSON.parse(raw)
     } catch (err: any) {
       logger.error("error parsing json", err.stack)
-      throw new Error(`failed to parse json from file '${file}'`)
+      throw new Error(`failed to parse json from '${filepath}'`)
     }
   }
 
-  if (file.endsWith(".yaml") || file.endsWith(".yml")) {
+  if (filepath.endsWith(".yaml") || filepath.endsWith(".yml")) {
     try {
       result = yaml.load(raw)
     } catch (err: any) {
       logger.error("error parsing yaml", err.stack)
-      throw new Error(`failed to parse yaml from file '${file}'`)
+      throw new Error(`failed to parse yaml from '${filepath}'`)
     }
   }
 
   if (!result) {
-    throw new Error(`failed to load file '${file}'`)
+    throw new Error(`failed to parse '${filepath}'`)
   }
 
-  return [file, result]
-}
-
-async function loadRemoteFile(uri: string): Promise<[string, any]> {
-  // todo: https://github.com/mnahkies/openapi-code-generator/issues/43
-  throw new Error(`could not load ${uri} - not implemented,`)
+  return result
 }
 
 export function isRemote(location: string): boolean {

packages/openapi-code-generator/src/core/openapi-loader.ts

@@ -153,6 +153,7 @@ export class OpenapiLoader {
         throw new Error(`invalid $ref '${$ref}`)
       }
 
+      // TODO: support relative urls
       if (isRemote(file)) {
         return $ref
       }
@@ -192,7 +193,7 @@ export class OpenapiLoader {
     entryPoint: string,
     validator: OpenapiValidator,
   ): Promise<OpenapiLoader> {
-    entryPoint = path.resolve(entryPoint)
+    entryPoint = isRemote(entryPoint) ? entryPoint : path.resolve(entryPoint)
     const loader = new OpenapiLoader(entryPoint, validator)
 
     await loader.loadFile(entryPoint)