import http, { IncomingMessage, ServerResponse } from "node:http";
import { URL } from "node:url";
import querystring from "node:querystring";

import Router from "./router";
import Tpl from "./template";

import { Request, Response, Middleware } from "./types";

export { Router, Tpl };

export default class Flummpress {
  private server?: http.Server;
  private errorHandler: Middleware;
  router: Router;
  tpl: Tpl;
  middleware: Middleware[];

  constructor() {
    this.router = new Router();
    this.tpl = new Tpl();
    this.middleware = [];
    this.errorHandler = async (req: Request, res: Response) => {
      res.writeHead(500).end("500 - Internal Server Error");
    };
  }

  /**
   * Adds middleware, routes, or template systems to the server.
   * @param {any} obj - An instance of Router, Tpl, or a middleware function.
   * @returns {this} - The current instance for chaining.
   */
  use(obj: Router | Tpl | Middleware): this {
    if(obj instanceof Router)
      this.router.use(obj);
    else if(obj instanceof Tpl)
      this.tpl = obj;
    else
      this.middleware.push(obj);
    return this;
  }

  setErrorHandler(handler: Middleware): this {
    this.errorHandler = handler;
    return this;
  }

  /**
   * Starts the HTTP server and begins listening for incoming requests.
   * @param {...any} args - Arguments passed to `http.Server.listen`.
   * @returns {this} - The current instance for chaining.
   */
  listen(...args: any[]): this {
    this.server = http
      .createServer(async (request: IncomingMessage, response: ServerResponse) => {
        const req = request as Request;
        const res = this.createResponse(response);
        const start = process.hrtime();

        try {
          this.parseRequest(req);

          for(const mw of this.middleware) {
            await mw(req, res, () => {});
          }

          const route = this.router.getRoute(req.parsedUrl.pathname, req.method!);

          if(route) {
            const [pathPattern, methods] = route;
            const method = req.method?.toLowerCase();
            const handler = methods[method!];
            const middleware = methods[`${method}mw`];

            for(const mw of middleware) {
              await mw(req, res, () => {});
            }

            if(handler) {
              req.params = req.parsedUrl.pathname.match(new RegExp(pathPattern))?.groups || {};
              req.post = await this.readBody(req);
              handler(req, res);
            }
            else {
              res.writeHead(405).end("405 - Method Not Allowed");
            }
          }
          else {
            res.writeHead(404).end("404 - Not Found");
          }
        }
        catch(err: any) {
          this.errorHandler(req, res, () => {});
        }

        console.log([
          `[${new Date().toISOString()}]`,
          `${(process.hrtime(start)[1] / 1e6).toFixed(2)}ms`,
          `${req.method} ${res.statusCode}`,
          req.parsedUrl.pathname,
        ].join(" | "));
      }).listen(...args);

    return this;
  }

  private parseRequest(req: Request): void {
    const url = new URL(req.url!.replace(/(?!^.)(\/+)?$/, ""), "http://localhost");
    req.parsedUrl = {
      pathname: url.pathname,
      split: url.pathname.split("/").slice(1),
      searchParams: url.searchParams,
      qs: Object.fromEntries(url.searchParams.entries()),
    };
    req.cookies = {};
    if(req.headers.cookie) {
      req.headers.cookie.split("; ").forEach(cookie => {
        const [key, value] = cookie.split("=");
        req.cookies[key] = decodeURIComponent(value);
      });
    }
  }

  /**
   * Reads and parses the body of an incoming HTTP request.
   * @param {IncomingMessage} req - The HTTP request object.
   * @returns {Promise<any>} - A promise that resolves to the parsed body data.
   */
  private async readBody(req: IncomingMessage): Promise<Record<string, string>> {
    return new Promise((resolve, reject) => {
      let body = "";

      req.on("data", (chunk) => {
        body += chunk;
      });

      req.on("end", () => {
        try {
          resolve(
            req.headers["content-type"] === "application/json"
              ? JSON.parse(body)
              : querystring.parse(body)
          );
        }
        catch(err: any) {
          reject(err);
        }
      });

      req.on("error", reject);
    });
  }

  private createResponse(response: ServerResponse): Response {
    const res = response as Response;

    res.reply = ({ code = 200, type = "text/html", body }) => {
      res.writeHead(code, { "Content-Type": `${type}; charset=utf-8` });
      res.end(body);
    };

    res.json = (body, code = 200) => {
      res.reply({ code, type: "application/json", body: JSON.stringify(body) });
    };

    res.html = (body, code = 200) => {
      res.reply({ code, type: "text/html", body });
    };

    res.redirect = (target, code = 302) => {
      res.writeHead(code, { Location: target });
      res.end();
    };

    return res;
  }
}