// ============================================================
// LoginModal — 登录 / 注册模态框
// 职责：在 LandingPage 上弹出的认证表单，复用现有 auth 系统
// ============================================================

import { useCallback, useEffect, useRef, useState } from "react";
import { useAuth } from "../../lib/auth";
import { useI18n } from "../../lib/i18n";

type AuthMode = "login" | "register";

interface LoginModalProps {
  initialMode?: AuthMode;
  onClose: () => void;
}

export function LoginModal({ initialMode = "login", onClose }: LoginModalProps) {
  const { login, register } = useAuth();
  const { t } = useI18n();
  const [mode, setMode] = useState<AuthMode>(initialMode);
  const [username, setUsername] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState("");
  const [isSubmitting, setIsSubmitting] = useState(false);
  const overlayRef = useRef<HTMLDivElement>(null);

  // 点击遮罩关闭
  const handleOverlayClick = useCallback(
    (e: React.MouseEvent) => {
      if (e.target === overlayRef.current) onClose();
    },
    [onClose]
  );

  // ESC 关闭
  useEffect(() => {
    const handler = (e: KeyboardEvent) => {
      if (e.key === "Escape") onClose();
    };
    window.addEventListener("keydown", handler);
    return () => window.removeEventListener("keydown", handler);
  }, [onClose]);

  // 阻止 body 滚动
  useEffect(() => {
    const prev = document.body.style.overflow;
    document.body.style.overflow = "hidden";
    return () => { document.body.style.overflow = prev; };
  }, []);

  const handleSubmit = useCallback(
    async (e: React.FormEvent) => {
      e.preventDefault();
      setError("");

      if (username.length < 3 || username.length > 64) {
        setError(t("auth.error.usernameLength"));
        return;
      }
      if (password.length < 8 || password.length > 72) {
        setError(t("auth.error.passwordLength"));
        return;
      }

      setIsSubmitting(true);
      const fn = mode === "login" ? login : register;
      const result = await fn(username, password);
      setIsSubmitting(false);

      if (result.error) {
        setError(result.error);
      }
      // 登录成功时 auth 状态更新，App 自动切到主界面，modal 自然消失
    },
    [username, password, mode, login, register, t]
  );

  const switchMode = useCallback(() => {
    setMode((m) => (m === "login" ? "register" : "login"));
    setError("");
  }, []);

  return (
    <div className="lp-modal-overlay" ref={overlayRef} onClick={handleOverlayClick}>
      <div className="lp-modal" role="dialog" aria-modal="true">
        <div className="lp-modal__inner">
          <button type="button" className="lp-modal__close" onClick={onClose} aria-label="Close">
            <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
              <line x1="18" y1="6" x2="6" y2="18" />
              <line x1="6" y1="6" x2="18" y2="18" />
            </svg>
          </button>

          <div className="lp-modal__header">
            <div className="lp-modal__logo">CamTalk</div>
            <div className="lp-modal__subtitle">{t("auth.subtitle")}</div>
          </div>

          <form onSubmit={handleSubmit}>
            <div className="lp-modal__tabs">
              <button
                type="button"
                className={`lp-modal__tab ${mode === "login" ? "lp-modal__tab--active" : ""}`}
                onClick={() => { setMode("login"); setError(""); }}
              >
                {t("auth.login")}
              </button>
              <button
                type="button"
                className={`lp-modal__tab ${mode === "register" ? "lp-modal__tab--active" : ""}`}
                onClick={() => { setMode("register"); setError(""); }}
              >
                {t("auth.register")}
              </button>
            </div>

            <label className="lp-modal__field">
              <span className="lp-modal__field-label">{t("auth.username")}</span>
              <input
                type="text"
                className="lp-modal__field-input"
                value={username}
                onChange={(e) => setUsername(e.target.value)}
                placeholder={t("auth.username.placeholder")}
                autoComplete="username"
                autoFocus
              />
            </label>

            <label className="lp-modal__field">
              <span className="lp-modal__field-label">{t("auth.password")}</span>
              <input
                type="password"
                className="lp-modal__field-input"
                value={password}
                onChange={(e) => setPassword(e.target.value)}
                placeholder={t("auth.password.placeholder")}
                autoComplete={mode === "login" ? "current-password" : "new-password"}
              />
            </label>

            {error && <div className="lp-modal__error">{error}</div>}

            <button type="submit" className="lp-modal__submit" disabled={isSubmitting}>
              {isSubmitting
                ? t("auth.submitting")
                : mode === "login"
                  ? t("auth.login")
                  : t("auth.register")}
            </button>
          </form>

          <div className="lp-modal__footer">
            {mode === "login" ? t("auth.noAccount") : t("auth.hasAccount")}
            <button type="button" className="lp-modal__link" onClick={switchMode}>
              {mode === "login" ? t("auth.register") : t("auth.login")}
            </button>
          </div>
        </div>
      </div>
    </div>
  );
}