HTML5 Routing Compatibility Middleware for Vapor 2

Config+Setup.swift

extension Config {
    public func setup() throws {
        // ...
        addConfigurable(middleware: Html5RoutingMiddleware.init, name: "html5")
    }
    
    // ...
}

droplet.json

{
    // ...
    "middleware": [
        "error",
        "html5", // <-- make sure this is before "file"
        "date",
        "file"
    ],
    
    // ...
}

Html5RoutingMiddleware.swift

import Vapor
import HTTP
import Foundation

public final class Html5RoutingMiddleware: Middleware {
    private let loader = DataFile()
    public let defaultPath: String
    
    public init(defaultPath: String) {
        self.defaultPath = defaultPath
    }

    public func respond(to request: Request, chainingTo next: Responder) throws -> Response {
        do {
            return try next.respond(to: request)
        }
        catch let error as AbortError where error.status == .notFound {
            guard request.headers["X-Requested-With"] != "XMLHttpRequest" else {
                throw error
            }
            
            guard
                let attributes = try? Foundation.FileManager.default.attributesOfItem(atPath: defaultPath),
                let modifiedAt = attributes[.modificationDate] as? Date,
                let fileSize = attributes[.size] as? NSNumber
                else {
                    throw Abort.notFound
            }
            
            var headers: [HeaderKey: String] = [:]
            
            // Generate ETag value, "HEX value of last modified date" + "-" + "file size"
            let fileETag = "\(modifiedAt.timeIntervalSince1970)-\(fileSize.intValue)"
            headers["ETag"] = fileETag
            
            // Check if file has been cached already and return NotModified response if the etags match
            if fileETag == request.headers["If-None-Match"] {
                return Response(status: .notModified, headers: headers, body: .data([]))
            }
            
            // Set Content-Type header based on the media type
            // Only set Content-Type if file not modified and returned above.
            if
                let fileExtension = defaultPath.components(separatedBy: ".").last,
                let type = Request.mediaTypes[fileExtension]
            {
                headers["Content-Type"] = type
            }
            
            // File exists and was not cached, returning content of file.
            if let fileBody = try? loader.read(at: defaultPath) {
                return Response(status: .ok, headers: headers, body: .data(fileBody))
            } else {
                print("unable to load path")
                throw Abort.notFound
            }
        }
    }
}

extension Html5RoutingMiddleware: ConfigInitializable {
    public convenience init(config: Config) throws {
        let path = config.publicDir + (config["html5", "index"]?.string ?? "index.html")
        self.init(defaultPath: path)
    }
}

Routes.swift

final class Routes: RouteCollection {
    func build(_ builder: RouteBuilder) throws {
        // ...
        
        // Make sure to remove any "*" and "/" route handlers!
        // E.g. the api-template has a "*" route that prints the request details. Kill it.

        // ...
    }
}