Initial implementation

Author: snapshotpl

command-bus.ts

@@ -0,0 +1,85 @@
+interface Command {
+
+}
+
+
+interface CommandHandler {
+  handle(commmand: Command): any;
+}
+
+
+interface NextMiddleware {
+  executeNext(command: Command): any;
+}
+
+
+interface Middleware {
+  execute(command: Command, next: NextMiddleware): any;
+}
+
+
+interface CommandNameExtractor {
+  extract(command: Command): string;
+}
+
+
+interface HandlerLocator {
+  getHandlerForCommand(commandName: string): CommandHandler;
+}
+
+
+interface CommandBus {
+  handle(comand: Command): void;
+}
+
+
+class CommandHandlerMiddleware implements Middleware
+{
+  constructor(readonly handlerLocator: HandlerLocator, readonly commandNameExtractor: CommandNameExtractor) {
+  }
+
+  execute(command: Command, next: NextMiddleware): any
+  {
+    let className: string = this.commandNameExtractor.extract(command);
+
+    return this.handlerLocator.getHandlerForCommand(className).handle(command);
+  }
+}
+
+
+class InMemoryCommandBus implements CommandBus {
+  readonly commands: Command[];
+
+  handle(command: Command): void {
+    this.commands.push(command);
+  }
+}
+
+
+class Commander implements CommandBus {
+  private middlewareChain;
+
+  constructor(readonly middlewares: Middleware[]) {
+    this.middlewareChain = this.createExcecutionChain(middlewares);
+  }
+
+  handle(command: Command): void {
+    this.middlewareChain.executeNext(command);
+  }
+
+  private createExcecutionChain(middlewares: Middleware[]): NextMiddleware {
+    let lastCallable: NextMiddleware = (new class implements NextMiddleware {
+      executeNext(command: Command): any {
+      }
+    });
+
+    for(let i: number = middlewares.length; i >= 0; i--) {
+      lastCallable = (new class implements NextMiddleware {
+        executeNext(command: Command): any {
+          return middlewares[i].execute(command, lastCallable);
+        }
+      });
+    }
+    return lastCallable;
+  }
+}