// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
// Structured similarly to Go's cookie.go
// https://github.com/golang/go/blob/master/src/net/http/cookie.go
import { ServerRequest, Response } from "./server.ts";
import { assert } from "../testing/asserts.ts";
import { toIMF } from "../datetime/mod.ts";

export interface Cookies {
  [key: string]: string;
}

export interface Cookie {
  name: string;
  value: string;
  expires?: Date;
  maxAge?: number;
  domain?: string;
  path?: string;
  secure?: boolean;
  httpOnly?: boolean;
  sameSite?: SameSite;
  unparsed?: string[];
}

export type SameSite = "Strict" | "Lax";

function toString(cookie: Cookie): string {
  const out: string[] = [];
  out.push(`${cookie.name}=${cookie.value}`);

  // Fallback for invalid Set-Cookie
  // ref: https://tools.ietf.org/html/draft-ietf-httpbis-cookie-prefixes-00#section-3.1
  if (cookie.name.startsWith("__Secure")) {
    cookie.secure = true;
  }
  if (cookie.name.startsWith("__Host")) {
    cookie.path = "/";
    cookie.secure = true;
    delete cookie.domain;
  }

  if (cookie.secure) {
    out.push("Secure");
  }
  if (cookie.httpOnly) {
    out.push("HttpOnly");
  }
  if (Number.isInteger(cookie.maxAge!)) {
    assert(cookie.maxAge! > 0, "Max-Age must be an integer superior to 0");
    out.push(`Max-Age=${cookie.maxAge}`);
  }
  if (cookie.domain) {
    out.push(`Domain=${cookie.domain}`);
  }
  if (cookie.sameSite) {
    out.push(`SameSite=${cookie.sameSite}`);
  }
  if (cookie.path) {
    out.push(`Path=${cookie.path}`);
  }
  if (cookie.expires) {
    let dateString = toIMF(cookie.expires);
    out.push(`Expires=${dateString}`);
  }
  if (cookie.unparsed) {
    out.push(cookie.unparsed.join("; "));
  }
  return out.join("; ");
}

/**
 * Parse the cookies of the Server Request
 * @param req Server Request
 */
export function getCookies(req: ServerRequest): Cookies {
  if (req.headers.has("Cookie")) {
    const out: Cookies = {};
    const c = req.headers.get("Cookie")!.split(";");
    for (const kv of c) {
      const cookieVal = kv.split("=");
      const key = cookieVal.shift()!.trim();
      out[key] = cookieVal.join("=");
    }
    return out;
  }
  return {};
}

/**
 * Set the cookie header properly in the Response
 * @param res Server Response
 * @param cookie Cookie to set
 * @param [cookie.name] Name of the cookie
 * @param [cookie.value] Value of the cookie
 * @param [cookie.expires] Expiration Date of the cookie
 * @param [cookie.maxAge] Max-Age of the Cookie. Must be integer superior to 0
 * @param [cookie.domain] Specifies those hosts to which the cookie will be sent
 * @param [cookie.path] Indicates a URL path that must exist in the request.
 * @param [cookie.secure] Indicates if the cookie is made using SSL & HTTPS.
 * @param [cookie.httpOnly] Indicates that cookie is not accessible via
 *                          Javascript
 * @param [cookie.sameSite] Allows servers to assert that a cookie ought not to
 *                          be sent along with cross-site requests
 * Example:
 *
 *     setCookie(response, { name: 'deno', value: 'runtime',
 *        httpOnly: true, secure: true, maxAge: 2, domain: "deno.land" });
 */
export function setCookie(res: Response, cookie: Cookie): void {
  if (!res.headers) {
    res.headers = new Headers();
  }
  // TODO (zekth) : Add proper parsing of Set-Cookie headers
  // Parsing cookie headers to make consistent set-cookie header
  // ref: https://tools.ietf.org/html/rfc6265#section-4.1.1
  res.headers.set("Set-Cookie", toString(cookie));
}

/**
 *  Set the cookie header properly in the Response to delete it
 * @param res Server Response
 * @param name Name of the cookie to Delete
 * Example:
 *
 *     delCookie(res,'foo');
 */
export function delCookie(res: Response, name: string): void {
  setCookie(res, {
    name: name,
    value: "",
    expires: new Date(0)
  });
}