import { check, sleep } from "k6";
import http from "k6/http";
import exec from "k6/execution";
import { Counter } from "k6/metrics";
import { WebSocket } from "k6/websockets";

function required(name) {
  const value = __ENV[name];

  if (value === undefined || value === "") {
    throw new Error(`${name} is required`);
  }

  return value;
}

function nonNegativeInteger(name) {
  const value = Number(required(name));

  if (!Number.isInteger(value) || value < 0) {
    throw new Error(`${name} must be a non-negative integer`);
  }

  return value;
}

function positiveInteger(name) {
  const value = nonNegativeInteger(name);

  if (value === 0) {
    throw new Error(`${name} must be a positive integer`);
  }

  return value;
}

function nonNegativeNumber(name) {
  const value = Number(required(name));

  if (!Number.isFinite(value) || value < 0) {
    throw new Error(`${name} must be a non-negative number`);
  }

  return value;
}

const baseUrl = required("BASE_URL").replace(/\/+$/, "");

if (baseUrl !== "https://whoneedhelp.com") {
  throw new Error("The production read-only profile is pinned to https://whoneedhelp.com");
}

const httpVus = nonNegativeInteger("HTTP_VUS");
const websocketVus = nonNegativeInteger("WS_VUS");

if (httpVus + websocketVus === 0) {
  throw new Error("At least one HTTP or WebSocket VU is required");
}

const duration = required("DURATION");
const httpThinkSeconds = nonNegativeNumber("HTTP_THINK_SECONDS");
const websocketHoldMs = positiveInteger("WS_HOLD_MS");
const websocketConnectTimeoutMs = positiveInteger("WS_CONNECT_TIMEOUT_MS");
const websocketUrl =
  baseUrl.replace(/^http/, "ws") + "/live/websocket?vsn=2.0.0";

// This allowlist is intentionally compiled into the read-only profile. It
// contains GET-only public pages and the readiness endpoint. Authentication,
// registration, support submission, email delivery, and every mutating route
// are outside this file.
const publicRoutes = [
  { path: "/", endpoint: "home" },
  { path: "/safety", endpoint: "safety" },
  { path: "/privacy", endpoint: "privacy" },
  { path: "/terms", endpoint: "terms" },
  { path: "/users/log-in", endpoint: "login_page" },
  { path: "/users/register", endpoint: "registration_page" },
  { path: "/healthz/ready", endpoint: "readiness" },
];

const websocketOpened = new Counter("wnh_readonly_websocket_opened");
const websocketErrors = new Counter("wnh_readonly_websocket_errors");
const heartbeatReplies = new Counter("wnh_readonly_heartbeat_replies");

const scenarios = {};
const thresholds = {};

if (httpVus > 0) {
  scenarios.public_http = {
    executor: "constant-vus",
    exec: "publicHttp",
    vus: httpVus,
    duration,
  };
  thresholds.checks = [{ threshold: "rate==1", abortOnFail: true }];
  thresholds.http_req_failed = [{ threshold: "rate==0", abortOnFail: true }];
}

if (websocketVus > 0) {
  scenarios.phoenix_websocket = {
    executor: "constant-vus",
    exec: "phoenixWebsocket",
    vus: websocketVus,
    duration,
  };
  thresholds.wnh_readonly_websocket_errors = [
    { threshold: "count==0", abortOnFail: true },
  ];
}

export const options = {
  discardResponseBodies: true,
  scenarios,
  thresholds,
};

export function publicHttp() {
  const route = publicRoutes[exec.scenario.iterationInTest % publicRoutes.length];
  const response = http.get(`${baseUrl}${route.path}`, {
    redirects: 0,
    tags: { endpoint: route.endpoint, safety_scope: "production_readonly" },
    headers: { "User-Agent": "WhoNeedHelp-production-readonly-load/1" },
  });

  check(response, {
    [`GET ${route.path} returned 200`]: (candidate) => candidate.status === 200,
  });

  sleep(httpThinkSeconds);
}

export function phoenixWebsocket() {
  const socket = new WebSocket(websocketUrl, [], {
    tags: {
      endpoint: "phoenix_live_socket",
      safety_scope: "production_readonly",
    },
    headers: {
      Origin: baseUrl,
      "User-Agent": "WhoNeedHelp-production-readonly-load/1",
    },
  });
  const ref = `${__VU}-${__ITER}`;
  let opened = false;
  let closeTimer;
  const connectTimer = setTimeout(() => {
    if (!opened) {
      websocketErrors.add(1);
      socket.close();
    }
  }, websocketConnectTimeoutMs);

  socket.addEventListener("open", () => {
    opened = true;
    clearTimeout(connectTimer);
    websocketOpened.add(1);
    socket.send(JSON.stringify([null, ref, "phoenix", "heartbeat", {}]));
    closeTimer = setTimeout(() => socket.close(), websocketHoldMs);
  });

  socket.addEventListener("message", (event) => {
    let frame;

    try {
      frame = JSON.parse(event.data);
    } catch (_error) {
      return;
    }

    if (
      Array.isArray(frame) &&
      frame[1] === ref &&
      frame[2] === "phoenix" &&
      frame[3] === "phx_reply" &&
      frame[4]?.status === "ok"
    ) {
      heartbeatReplies.add(1);
    }
  });

  socket.addEventListener("error", () => {
    websocketErrors.add(1);
    clearTimeout(connectTimer);
    socket.close();
  });

  socket.addEventListener("close", () => {
    clearTimeout(connectTimer);

    if (closeTimer !== undefined) {
      clearTimeout(closeTimer);
    }
  });
}