import { useEffect, useRef, useState } from 'react';

import { requestVerificationCode } from '@/lib/api/auth';
import { ImApiError } from '@/lib/api/client';

const PHONE_RE = /^\d{11}$/;

interface VerificationCodeButtonProps {
  phone: string;
  scene: 'reset_password';
  onChallenge: (challengeId: string) => void;
  onError: (message: string) => void;
}

/** "获取验证码" button with resend countdown. Ported from the old app's VerificationButton. */
export function VerificationCodeButton({ phone, scene, onChallenge, onError }: VerificationCodeButtonProps) {
  const [seconds, setSeconds] = useState(0);
  const [busy, setBusy] = useState(false);
  const timerRef = useRef<number | undefined>(undefined);

  // Without this, navigating away mid-countdown (e.g. switching from register back to login)
  // leaves the interval running against an unmounted component indefinitely until it naturally
  // reaches 0 -- a real resource leak, not just a React warning, since nothing else ever clears it.
  useEffect(() => () => window.clearInterval(timerRef.current), []);

  // A countdown started for one phone number must not block sending a code to a DIFFERENT one --
  // otherwise correcting a mistyped number mid-cooldown leaves the button stuck disabled (still
  // counting down for the old number) until the old timer happens to run out on its own.
  useEffect(() => {
    window.clearInterval(timerRef.current);
    setSeconds(0);
  }, [phone]);

  const tick = (initial: number) => {
    window.clearInterval(timerRef.current);
    setSeconds(initial);
    timerRef.current = window.setInterval(() => {
      setSeconds((s) => {
        if (s <= 1) {
          window.clearInterval(timerRef.current);
          return 0;
        }
        return s - 1;
      });
    }, 1000);
  };

  const click = async () => {
    if (busy || seconds > 0 || !PHONE_RE.test(phone)) return;
    // The phone number this request is actually FOR -- captured now, not read again after the
    // `await`. Without this, editing the phone field (e.g. fixing a typo) while the request is in
    // flight lets a stale response apply a challenge_id/countdown for the OLD number to whatever
    // number is now showing, with nothing on screen indicating the mismatch -- the eventual
    // verification would silently operate on an account the user never intended.
    const requestedPhone = phone;
    setBusy(true);
    try {
      const data = await requestVerificationCode(scene, requestedPhone);
      if (requestedPhone !== phone) return;
      onChallenge(data.challenge_id);
      tick(data.resend_after_seconds || 60);
    } catch (err) {
      if (requestedPhone !== phone) return;
      onError(err instanceof ImApiError ? err.message : '获取验证码失败');
      // Rate-limited but a still-valid challenge already exists for this phone/scene -- reuse it.
      const details = err instanceof ImApiError ? (err.details as Record<string, unknown> | undefined) : undefined;
      if (typeof details?.retry_after_seconds === 'number') tick(details.retry_after_seconds);
      if (typeof details?.challenge_id === 'string') onChallenge(details.challenge_id);
    } finally {
      setBusy(false);
    }
  };

  return (
    <button
      type="button"
      onClick={click}
      disabled={busy || seconds > 0 || !PHONE_RE.test(phone)}
      className="h-9 w-32 flex-none rounded-lg bg-accent-soft-bg text-sm text-accent disabled:bg-[#e6e9ee] disabled:text-text-tertiary-3"
    >
      {seconds > 0 ? `重新获取 (${seconds}s)` : busy ? '发送中…' : '获取验证码'}
    </button>
  );
}