File-based response support & static server

- Clean up UniversalPath implementation
    - Use Readable/Writable types correctly for stream methods
    - Add .list() methods for getting child files

- Make Response body specify explicit types and support
  writing Readable streams to the body

- Create a static file server that supports directory listing

src/http/HTTPError.ts

@@ -10,8 +10,9 @@ export class HTTPError extends ErrorWithContext {
     constructor(
         public readonly status: HTTPStatus = 500,
         public readonly message: string = '',
+        context?: {[key: string]: any},
     ) {
-        super('HTTP ERROR')
+        super('HTTP ERROR', context)
         this.message = message || HTTPMessage[status]
     }
 }

src/http/kernel/module/AbstractResolvedRouteHandlerHTTPModule.ts

@@ -4,6 +4,8 @@ import {Request} from '../../lifecycle/Request'
 import {plaintext} from '../../response/StringResponseFactory'
 import {ResponseFactory} from '../../response/ResponseFactory'
 import {json} from '../../response/JSONResponseFactory'
+import {UniversalPath} from '../../../util'
+import {file} from '../../response/FileResponseFactory'
 
 /**
  * Base class for HTTP kernel modules that apply some response from a route handler to the request.
@@ -22,6 +24,8 @@ export abstract class AbstractResolvedRouteHandlerHTTPModule extends HTTPKernelM
 
         if ( object instanceof ResponseFactory ) {
             await object.write(request)
+        } else if ( object instanceof UniversalPath ) {
+            await file(object).write(request)
         } else if ( typeof object !== 'undefined' ) {
             await json(object).write(request)
         } else {

src/http/lifecycle/Response.ts

@@ -2,6 +2,7 @@ import {Request} from './Request'
 import {ErrorWithContext, HTTPStatus, BehaviorSubject} from '../../util'
 import {ServerResponse} from 'http'
 import {HTTPCookieJar} from '../kernel/HTTPCookieJar'
+import {Readable} from 'stream'
 
 /**
  * Error thrown when the server tries to re-send headers after they have been sent once.
@@ -47,7 +48,7 @@ export class Response {
     private isBlockingWriteback = false
 
     /** The body contents that should be written to the response. */
-    public body = ''
+    public body: string | Buffer | Uint8Array | Readable = ''
 
     /**
      * Behavior subject fired right before the response content is written.
@@ -192,18 +193,29 @@ export class Response {
      * Write the headers and specified data to the client.
      * @param data
      */
-    public async write(data: unknown): Promise<void> {
+    public async write(data: string | Buffer | Uint8Array | Readable): Promise<void> {
         return new Promise<void>((res, rej) => {
             if ( !this.sentHeaders ) {
                 this.sendHeaders()
             }
-            this.serverResponse.write(data, error => {
-                if ( error ) {
-                    rej(error)
-                } else {
-                    res()
-                }
-            })
+
+            if ( data instanceof Readable ) {
+                data.pipe(this.serverResponse)
+                    .on('finish', () => {
+                        res()
+                    })
+                    .on('error', error => {
+                        rej(error)
+                    })
+            } else {
+                this.serverResponse.write(data, error => {
+                    if ( error ) {
+                        rej(error)
+                    } else {
+                        res()
+                    }
+                })
+            }
         })
     }
 
@@ -212,9 +224,14 @@ export class Response {
      */
     public async send(): Promise<void> {
         await this.sending$.next(this)
-        this.setHeader('Content-Length', String(this.body?.length ?? 0))
+
+        if ( !(this.body instanceof Readable) ) {
+            this.setHeader('Content-Length', String(this.body?.length ?? 0))
+        }
+
         await this.write(this.body ?? '')
         this.end()
+
         await this.sent$.next(this)
     }
 

src/http/response/FileResponseFactory.ts

@@ -0,0 +1,36 @@
+import {ResponseFactory} from './ResponseFactory'
+import {Request} from '../lifecycle/Request'
+import {ErrorWithContext, UniversalPath} from '../../util'
+
+/**
+ * Helper function that creates a FileResponseFactory for the given path.
+ * @param path
+ */
+export function file(path: UniversalPath): FileResponseFactory {
+    return new FileResponseFactory(path)
+}
+
+/**
+ * HTTP response factory that sends a file referenced by a given UniversalPath.
+ */
+export class FileResponseFactory extends ResponseFactory {
+    constructor(
+        /** The file to be sent. */
+        public readonly path: UniversalPath,
+    ) {
+        super()
+    }
+
+    public async write(request: Request): Promise<Request> {
+        if ( !(await this.path.isFile()) ) {
+            throw new ErrorWithContext(`Cannot write non-file resource as response: ${this.path}`, {
+                path: this.path,
+            })
+        }
+
+        request.response.setHeader('Content-Type', this.path.contentType || 'application/octet-stream')
+        request.response.setHeader('Content-Length', String(await this.path.sizeInBytes()))
+        request.response.body = await this.path.readStream()
+        return request
+    }
+}

src/http/servers/static.ts

@@ -0,0 +1,169 @@
+import {Request} from '../lifecycle/Request'
+import {ActivatedRoute} from '../routing/ActivatedRoute'
+import {Config} from '../../service/Config'
+import {Collection, HTTPStatus, UniversalPath, universalPath} from '../../util'
+import {Application} from '../../lifecycle/Application'
+import {HTTPError} from '../HTTPError'
+import {view, ViewResponseFactory} from '../response/ViewResponseFactory'
+import {redirect} from '../response/TemporaryRedirectResponseFactory'
+import {file} from '../response/FileResponseFactory'
+import {RouteHandler} from '../routing/Route'
+
+/**
+ * Defines the behavior of the static server.
+ */
+export interface StaticServerOptions {
+    /** If true, browsing to a directory route will show the directory listing page. */
+    directoryListing?: boolean
+
+    /** The path to the directory whose files should be served. */
+    basePath?: string | string[] | UniversalPath
+
+    /** If specified, only files with these extensions will be served. */
+    allowedExtensions?: string[]
+
+    /** If specified, files with these extensions will not be served. */
+    excludedExtensions?: string[]
+}
+
+/**
+ * HTTPError class thrown by the static server.
+ */
+export class StaticServerHTTPError extends HTTPError {
+
+}
+
+/**
+ * Build the response factory that shows the directory listing.
+ * @param dirname
+ * @param dirPath
+ */
+async function getDirectoryListingResponse(dirname: string, dirPath: UniversalPath): Promise<ViewResponseFactory> {
+    return view('@extollo:static:dirlist', {
+        dirname,
+        contents: (await (await dirPath.list())
+            .promiseMap(async path => {
+                const isDirectory = await path.isDirectory()
+                return {
+                    isDirectory,
+                    name: path.toBase,
+                    size: isDirectory ? '-' : await path.sizeForHumans(),
+                }
+            }))
+            .sortBy(row => {
+                return `${row.isDirectory ? 0 : 1}${row.name}`
+            })
+            .all(),
+    })
+}
+
+/**
+ * Returns true if the given file path has an extension that is allowed by
+ * the static server options.
+ * @param filePath
+ * @param options
+ */
+function isValidFileExtension(filePath: UniversalPath, options: StaticServerOptions): boolean {
+    return (
+        (
+            !options.allowedExtensions
+            || options.allowedExtensions.includes(filePath.ext)
+        )
+        && (
+            !options.excludedExtensions
+            || !options.excludedExtensions.includes(filePath.ext)
+        )
+    )
+}
+
+/**
+ * Resolve the configured base path into a universal path.
+ * Defaults to `{app path}/resources/static` if none provided.
+ * @param appPath
+ * @param basePath
+ */
+function getBasePath(appPath: UniversalPath, basePath?: string | string[] | UniversalPath): UniversalPath {
+    if ( basePath instanceof UniversalPath ) {
+        return basePath
+    }
+
+    if ( !basePath ) {
+        return appPath.concat('resources', 'static')
+    }
+
+    if ( Array.isArray(basePath) ) {
+        return appPath.concat(...basePath)
+    }
+
+    if ( basePath.startsWith('/') ) {
+        return universalPath(basePath)
+    }
+
+    return appPath.concat(basePath)
+}
+
+/**
+ * Get a route handler that serves a directory as static files.
+ * @param options
+ */
+export function staticServer(options: StaticServerOptions = {}): RouteHandler {
+    return async (request: Request) => {
+        const config = <Config> request.make(Config)
+        const route = <ActivatedRoute> request.make(ActivatedRoute)
+        const app = <Application> request.make(Application)
+
+        const staticConfig = config.get('server.builtIns.static', {})
+        const mergedOptions = {
+            ...staticConfig,
+            ...options,
+        }
+
+        // Resolve the path to the resource on the filesystem
+        const basePath = getBasePath(app.appPath(), mergedOptions.basePath)
+        const filePath = basePath.concat(...Collection.normalize<string>(route.params[0]))
+
+        // If the resolved path is outside of the base path, fail out
+        if ( !filePath.isChildOf(basePath) && !filePath.is(basePath) ) {
+            throw new StaticServerHTTPError(HTTPStatus.NOT_FOUND, 'File not found', {
+                basePath: basePath.toString(),
+                filePath: filePath.toString(),
+                route: route.path,
+                reason: 'Resolved file is not a child of the base path.',
+            })
+        }
+
+        // If the resolved file is an invalid file extension, fail out
+        if ( !isValidFileExtension(filePath, mergedOptions) ) {
+            throw new StaticServerHTTPError(HTTPStatus.NOT_FOUND, 'File not found', {
+                basePath: basePath.toString(),
+                filePath: filePath.toString(),
+                route: route.path,
+                allowedExtensions: mergedOptions.allowedExtensions,
+                excludedExtensions: mergedOptions.excludedExtensions,
+                reason: 'Resolved file is not an allowed extension type',
+            })
+        }
+
+        // If the resolved file does not exist on the filesystem, fail out
+        if ( !(await filePath.exists()) ) {
+            throw new StaticServerHTTPError(HTTPStatus.NOT_FOUND, `File not found: ${route.path}`, {
+                basePath: basePath.toString(),
+                filePath: filePath.toString(),
+                route: route.path,
+                reason: 'Resolved file does not exist on the filesystem',
+            })
+        }
+
+        // If the resolved path is a directory, send the directory listing response
+        if ( await filePath.isDirectory() ) {
+            if ( !route.path.endsWith('/') ) {
+                return redirect(`${route.path}/`)
+            }
+
+            return getDirectoryListingResponse(route.path, filePath)
+        }
+
+        // Otherwise, just send the file as the response body
+        return file(filePath)
+    }
+}