"use client";

import { useEffect, useRef } from "react";
import { toast } from "sonner";

import {
  hasDeploymentChanged,
  normalizeDeploymentId,
} from "@/lib/deployment/version";
import {
  parseDeploymentStatusEvent,
  type DeploymentStatus,
} from "@/lib/deployment/status";

const UPDATE_TOAST_ID = "deployment-update";
const NOTICE_DURATION_MS = 10_000;

function noticeKey(deploymentId: string, status: DeploymentStatus): string {
  return `deployment-notice:${deploymentId}:${status}`;
}

function rememberNotice(seen: Set<string>, key: string): boolean {
  if (seen.has(key)) return false;
  try {
    if (sessionStorage.getItem(key)) return false;
    sessionStorage.setItem(key, "1");
  } catch {
    // In-memory deduplication still works when storage is unavailable.
  }
  seen.add(key);
  return true;
}

export function DeploymentUpdateNotifier({
  deploymentId,
}: {
  deploymentId: string;
}) {
  const currentDeployment = useRef(normalizeDeploymentId(deploymentId));
  const updateAvailable = useRef(false);
  const seenNotices = useRef(new Set<string>());

  useEffect(() => {
    const source = new EventSource("/api/active");
    const showReady = () => {
      if (updateAvailable.current) return;
      updateAvailable.current = true;
      toast("มีอัปเดตใหม่พร้อมใช้งาน", {
        id: UPDATE_TOAST_ID,
        description: "รีโหลดเพื่ออัปเดตเป็นเวอร์ชันล่าสุด",
        action: {
          label: "รีโหลด",
          onClick: () => window.location.reload(),
        },
        duration: Infinity,
      });
    };
    const receiveDeployment = (event: Event) => {
      if (!(event instanceof MessageEvent) || typeof event.data !== "string") {
        return;
      }
      const nextDeployment = normalizeDeploymentId(event.data);
      if (hasDeploymentChanged(currentDeployment.current, nextDeployment)) {
        showReady();
      }
    };
    const receiveStatus = (event: Event) => {
      if (!(event instanceof MessageEvent) || typeof event.data !== "string") {
        return;
      }
      const update = parseDeploymentStatusEvent(event.data);
      if (
        !update ||
        update.deploymentId === currentDeployment.current ||
        updateAvailable.current
      ) {
        return;
      }
      const key = noticeKey(update.deploymentId, update.status);
      if (!rememberNotice(seenNotices.current, key)) return;

      if (update.status === "ready") {
        showReady();
      } else if (update.status === "deploying") {
        toast("กำลังอัปเดตเว็บไซต์", {
          id: UPDATE_TOAST_ID,
          description: "เวอร์ชันใหม่จะพร้อมใช้งานในอีกไม่กี่นาที",
          duration: NOTICE_DURATION_MS,
        });
      } else {
        toast("การอัปเดตล่าช้า", {
          id: UPDATE_TOAST_ID,
          description: "เวอร์ชันปัจจุบันยังใช้งานได้ตามปกติ",
          duration: NOTICE_DURATION_MS,
        });
      }
    };

    source.addEventListener("deployment", receiveDeployment);
    source.addEventListener("deployment-status", receiveStatus);
    return () => {
      source.removeEventListener("deployment", receiveDeployment);
      source.removeEventListener("deployment-status", receiveStatus);
      source.close();
    };
  }, []);

  return null;
}