add AssetMiddleware for react-router routing priority

Config/droplet.json

@@ -38,6 +38,7 @@
         "xfp-middleware",
         "error",
         "date",
+        "asset-middleware",
         "file"
     ],
 

Sources/App/Middleware/AssetMidleware.swift

@@ -0,0 +1,38 @@
+import Foundation
+import HTTP
+import libc
+
+/// Servers files from the supplied public directory
+/// on not found errors.
+public final class AssetMiddleware: Middleware {
+
+    private var assetDirs: [String]
+    private var publicDir: String
+
+    private let loader = DataFile()
+    private let chunkSize: Int
+
+    public init(assetDirs: [String], publicDir: String, chunkSize: Int? = nil) {
+        // Remove last "/" from the publicDir if present, so we can directly append uri path from the request.
+        self.assetDirs = assetDirs
+        self.publicDir = publicDir.finished(with: "/")
+        self.chunkSize = chunkSize ?? 32_768 // 2^15
+    }
+
+    public func respond(to request: Request, chainingTo next: Responder) throws -> Response {
+        var path = request.uri.path
+        guard !path.contains("../") else {
+            throw HTTP.Status.forbidden
+        }
+        if path.hasPrefix("/") {
+            path = String(path.dropFirst())
+        }
+        if assetDirs.index(where: { path.starts(with: $0) }) != nil {
+            let filePath = publicDir + path
+            let ifNoneMatch = request.headers["If-None-Match"]
+            return try Response(filePath: filePath, ifNoneMatch: ifNoneMatch, chunkSize: chunkSize)
+        }
+        return try next.respond(to: request)
+    }
+}
+

Sources/Run/main.swift

@@ -19,9 +19,18 @@ import XFPMiddleware
 /// if no command is given, it will default to "serve"
 let config = try Config()
 try config.setup()
+
 let xfpMiddleware = XFPMiddleware()
 config.addConfigurable(middleware: xfpMiddleware, name: "xfp-middleware")
 
+let assetDirs = [
+    "js/",
+    "images/",
+]
+
+let assetMiddleware = AssetMiddleware(assetDirs: assetDirs, publicDir: config.publicDir)
+config.addConfigurable(middleware: assetMiddleware, name: "asset-middleware")
+
 let drop = try Droplet(config)
 try drop.setup()