import { useCallback, useEffect, useRef, useState } from "react";
import { useAccount, useConnect, useDisconnect, useSignMessage } from "wagmi";
import { bsc } from "wagmi/chains";
import { requestWalletNonce, verifyWalletSignature } from "./api";
import { hasWalletConnectProjectId } from "./RainbowWalletProvider";
import type { WalletKind } from "./injected";
import { useWallet } from "./WalletProvider";

export type WalletConnectLoginState = "idle" | "connecting" | "signing";

function isMobileDevice(): boolean {
  if (typeof navigator === "undefined") return false;
  return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini|Mobile/i.test(
    navigator.userAgent || "",
  );
}

/**
 * MetaMask / imToken QR fallback via RainbowKit + WalletConnect.
 *
 * Flow: open the RainbowKit connect modal (WalletConnect QR) -> once an account
 * is connected, request a nonce, sign it with `personal_sign` through wagmi,
 * verify against the backend and complete our own JWT login. The wagmi/WC
 * session is only needed for the signature, so we disconnect right after.
 *
 * Entirely gated behind a real `VITE_WALLETCONNECT_PROJECT_ID`: when it is
 * missing `available` is false and `start` is a no-op, so callers can hide or
 * disable the entry instead of triggering a connect with a fake project id.
 */
export function useWalletConnectLogin() {
  const available = hasWalletConnectProjectId();
  const { completeLogin } = useWallet();
  const { address, isConnected } = useAccount();
  const { signMessageAsync } = useSignMessage();
  const { connectAsync, connectors } = useConnect();
  const { disconnect } = useDisconnect();
  const [state, setState] = useState<WalletConnectLoginState>("idle");
  const [error, setError] = useState("");
  const [qrUri, setQrUri] = useState("");
  const pendingRef = useRef(false);
  const cleanupMessageRef = useRef<(() => void) | null>(null);

  const reset = useCallback(() => {
    pendingRef.current = false;
    cleanupMessageRef.current?.();
    cleanupMessageRef.current = null;
    setState("idle");
    setError("");
    setQrUri("");
  }, []);

  const start = useCallback(
    async (preferredWallet?: WalletKind) => {
      if (!available) return;
      setError("");
      setQrUri("");
      pendingRef.current = true;
      setState("connecting");

      const connector =
        connectors.find((item) => item.id === preferredWallet) ??
        connectors.find((item) => item.id === "walletConnect") ??
        connectors.find((item) => item.type === "walletConnect");

      if (!connector) {
        pendingRef.current = false;
        setQrUri("");
        setState("idle");
        setError("WalletConnect is not available");
        return;
      }

      console.info("[wallet-login] walletconnect connector", {
        preferredWallet,
        connectorId: connector.id,
        connectorName: connector.name,
        connectorType: connector.type,
      });

      const onMessage = (message: { type: string; data?: unknown }) => {
        if (
          message.type !== "display_uri" ||
          typeof message.data !== "string"
        ) {
          return;
        }
        console.info("[wallet-login] walletconnect display_uri", {
          preferredWallet,
          connectorId: connector.id,
        });
        setQrUri(message.data);
        if (preferredWallet === "tokenPocket" && isMobileDevice()) {
          window.location.href = `tpoutside://wc?uri=${encodeURIComponent(
            message.data,
          )}`;
        }
      };

      cleanupMessageRef.current?.();
      connector.emitter.on("message", onMessage);
      cleanupMessageRef.current = () =>
        connector.emitter.off("message", onMessage);

      try {
        await connector.disconnect().catch(() => undefined);
        await connectAsync({ chainId: bsc.id, connector });
      } catch (err) {
        pendingRef.current = false;
        setState("idle");
        setError(
          err instanceof Error ? err.message : "WalletConnect login failed",
        );
        cleanupMessageRef.current?.();
        cleanupMessageRef.current = null;
      }
    },
    [available, connectAsync, connectors],
  );

  useEffect(() => {
    if (!pendingRef.current || !isConnected || !address) return;
    pendingRef.current = false;
    setState("signing");
    let cancelled = false;
    void (async () => {
      try {
        const nonce = await requestWalletNonce(address);
        const signature = await signMessageAsync({ message: nonce.message });
        const verified = await verifyWalletSignature({
          address,
          message: nonce.message,
          signature,
        });
        if (cancelled) return;
        completeLogin(verified.token, verified.wallet);
        setState("idle");
      } catch (err) {
        if (!cancelled) {
          setError(
            err instanceof Error ? err.message : "WalletConnect login failed",
          );
          setQrUri("");
          setState("idle");
        }
      } finally {
        // We only needed a one-off signature, not a persistent wagmi session.
        disconnect();
      }
    })();
    return () => {
      cancelled = true;
    };
  }, [address, completeLogin, disconnect, isConnected, signMessageAsync]);

  return { available, state, error, qrUri, start, reset };
}