import assertUnreachable from '../../lang/assertUnreachable';
import type express from 'express';

export type HttpRoute = string;
export type RoutePath = string;
export type RouteHandler = (request: express.Request, response: express.Response) => void | Promise<void>;

export class HttpRouteManager {
  private readonly _staticGETRoutes: Record<HttpRoute, RoutePath>;
  private readonly _getRoutes: Record<HttpRoute, RouteHandler>;
  private readonly _postRoutes: Record<HttpRoute, RouteHandler>;
  private readonly _putRoutes: Record<HttpRoute, RouteHandler>;
  private readonly _deleteRoutes: Record<HttpRoute, RouteHandler>;

  constructor() {
    this._staticGETRoutes = {};
    this._getRoutes = {};
    this._postRoutes = {};
    this._putRoutes = {};
    this._deleteRoutes = {};
  }

  public registerStaticRoute(routePath: RoutePath, destination: string) {
    if (this._staticGETRoutes[routePath]) {
      throw new Error(`Error: Static route [${routePath}] is already defined`);
    }

    this._staticGETRoutes[routePath] = destination;
  }

  public register(verb: 'GET' | 'POST' | 'PUT' | 'DELETE', route: string, handler: RouteHandler) {
    const isRouteDefined = (routes: Record<HttpRoute, RouteHandler>, routePath: string) => !!routes[routePath];

    switch (verb) {
      case 'GET':
        if (isRouteDefined(this._getRoutes, route)) {
          throw new Error(`Error: Route [${route}] is already defined`);
        }

        this._getRoutes[route] = handler;

        break;

      case 'POST':
        if (isRouteDefined(this._postRoutes, route)) {
          throw new Error(`Error: Route [${route}] is already defined`);
        }

        this._postRoutes[route] = handler;

        break;

      case 'PUT':
        if (isRouteDefined(this._putRoutes, route)) {
          throw new Error(`Error: Route [${route}] is already defined`);
        }

        this._putRoutes[route] = handler;

        break;

      case 'DELETE':
        if (isRouteDefined(this._deleteRoutes, route)) {
          throw new Error(`Error: Route [${route}] is already defined`);
        }

        this._deleteRoutes[route] = handler;

        break;

      default:
        assertUnreachable(verb);
    }
  }

  public getStaticGETRoutes(): Record<HttpRoute, RoutePath> {
    return this._staticGETRoutes;
  }

  public getGETRoutes(): Record<HttpRoute, RouteHandler> {
    return this._getRoutes;
  }

  public getPOSTRoutes(): Record<HttpRoute, RouteHandler> {
    return this._postRoutes;
  }

  public getPUTRoutes(): Record<HttpRoute, RouteHandler> {
    return this._putRoutes;
  }

  public getDELETERoutes(): Record<HttpRoute, RouteHandler> {
    return this._deleteRoutes;
  }
}