// ============================================================
// AuthPage — 登录 / 注册页面
// 职责：用户认证表单，支持登录和注册模式切换
// ============================================================

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

type AuthMode = "login" | "register";

export function AuthPage() {
  const { login, register } = useAuth();
  const { t } = useI18n();
  const [mode, setMode] = useState<AuthMode>("login");
  const [username, setUsername] = useState("");
  const [password, setPassword] = useState("");
  const [error, setError] = useState("");
  const [isSubmitting, setIsSubmitting] = useState(false);

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

      // 前端校验
      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);
      }
    },
    [username, password, mode, login, register, t]
  );

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

  return (
    <div className="auth-page">
      <div className="auth-card">
        <div className="auth-card__header">
          <h1 className="auth-card__logo">CamTalk</h1>
          <p className="auth-card__subtitle">{t("auth.subtitle")}</p>
        </div>

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

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

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

          {error && <div className="auth-form__error">{error}</div>}

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

        <p className="auth-card__footer">
          {mode === "login" ? t("auth.noAccount") : t("auth.hasAccount")}
          <button className="auth-card__link" onClick={toggleMode}>
            {mode === "login" ? t("auth.register") : t("auth.login")}
          </button>
        </p>
      </div>
    </div>
  );
}