"use client";
/**
 * PwaInstallOverlay PWA 安装提示触发器
 *
 * 行为：
 *   - 调用方达到消息阈值后启用检查
 *   - 仅在浏览器可安装、尚未安装且未展示过时继续
 *   - 延迟 1.5 秒显示 PwaInstallDialog
 *   - 用户确认后调用浏览器安装提示
 */
import { useEffect } from "react";

import {
  canShowPwaInstallPromptOnce,
  recordPwaInstallPromptShown,
} from "@/lib/chat/pwa_install_prompt";
import { pwaUtil } from "@/utils/pwa";

import { PwaInstallDialog } from "./pwa-install-dialog";

const DIALOG_DELAY_MS = 1500;

export interface PwaInstallOverlayProps {
  enabled: boolean;
}

export function PwaInstallOverlay({ enabled }: PwaInstallOverlayProps) {
  useEffect(() => {
    if (!enabled) return;

    let mounted = true;
    let timer: number | undefined;
    let unsubscribe: (() => void) | undefined;

    const init = async () => {
      // 提前挂 beforeinstallprompt 监听，避免用户点 OK 时事件已在更早时机丢失。
      pwaUtil.prepareInstallPrompt();

      const tryScheduleDialog = async () => {
        const shouldShowDialog = await shouldShowPwaInstallDialog();
        if (!mounted || !shouldShowDialog || timer !== undefined) return;

        // 达到聊天数量阈值后稍作停顿，避免弹窗与消息刷新挤在同一瞬间。
        timer = window.setTimeout(() => {
          if (!mounted) return;
          showPwaDialog();
        }, DIALOG_DELAY_MS);
      };

      await tryScheduleDialog();
      unsubscribe = pwaUtil.subscribe(() => {
        void tryScheduleDialog();
      });
    };

    void init();
    return () => {
      mounted = false;
      unsubscribe?.();
      if (timer !== undefined) window.clearTimeout(timer);
    };
  }, [enabled]);

  return null;
}

async function shouldShowPwaInstallDialog() {
  if (!pwaUtil.canShowInstallEntry()) return false;
  return canShowPwaInstallPromptOnce();
}

function showPwaDialog() {
  if (typeof document === "undefined") return;
  // Persist before rendering so remounts cannot schedule a second dialog.
  void recordPwaInstallPromptShown();

  const root = document.createElement("div");
  document.body.appendChild(root);
  import("react-dom/client").then(({ createRoot }) => {
    const reactRoot = createRoot(root);
    reactRoot.render(<PwaInstallDialogMount rootEl={root} reactRoot={reactRoot} />);
  });
}

function PwaInstallDialogMount({
  rootEl,
  reactRoot,
}: {
  rootEl: HTMLElement;
  reactRoot: { unmount: () => void };
}) {
  return (
    <PwaInstallDialog
      onClose={() => {
        reactRoot.unmount();
        rootEl.remove();
      }}
      onInstall={async () => {
        // The utility owns deferred-prompt lookup and browser prompting.
        await pwaUtil.install();
      }}
    />
  );
}