/**
 * Renders the sign-in page, which also requests password reset links.
 *
 * @module
 */

import { useState } from "react";
import { useNavigate } from "react-router";
import { t } from "@lingui/core/macro";
import { Trans } from "@lingui/react/macro";

import { API_URL } from "../config/api.ts";
import { deserializeAuthResponse } from "../utils/shared/deserialize.ts";
import type { AuthResponse, LoginUserRequest } from "../../shared/user.ts";
import type { Wire } from "../../shared/api.ts";
import { useAuth } from "../hooks/auth/useAuth.ts";
import { useDocumentTitle } from "../hooks/shared/useDocumentTitle.ts";
import { useHeightTransition } from "../hooks/shared/useHeightTransition.ts";
import { PageShell } from "../components/layout/PageShell.tsx";
import { expectOk } from "../utils/shared/api.ts";
import { FormError } from "../components/form/FormError.tsx";
import { FormProvider } from "react-hook-form";
import { SubmitButton } from "../components/form/SubmitButton.tsx";
import { TextField } from "../components/form/TextField.tsx";
import { useApiForm } from "../hooks/form/useApiForm.ts";

interface LoginValues {
  username: string;
  password: string;
}

interface ResetValues {
  email: string;
}

/**
 * Renders `/login`, for the signed out. A sign-in lands on `/`, and "Forgot
 * password?" unfolds the reset request form below.
 */
export function UserLogin(): React.JSX.Element {
  useDocumentTitle(t`Log in`);
  const navigate = useNavigate();
  const { login } = useAuth();
  const [showReset, setShowReset] = useState(false);
  const cardRef = useHeightTransition<HTMLDivElement>(showReset);

  const form = useApiForm<LoginValues>({
    defaultValues: { username: "", password: "" },
  });

  const onSubmit = form.submit(async ({ username, password }) => {
    const data = await expectOk<Wire<AuthResponse>>(
      await fetch(`${API_URL}/api/sessions`, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ username, password } satisfies LoginUserRequest),
      }),
    );
    login(deserializeAuthResponse(data));
    navigate("/");
  });

  return (
    <PageShell centered>
      <div className="auth-card" ref={cardRef}>
        <h1 className="auth-card-title">
          <Trans>Log in</Trans>
        </h1>

        <FormProvider {...form}>
          <form onSubmit={onSubmit} className="form">
            <FormError title={t`Login failed`} />
            <TextField<LoginValues>
              name="username"
              placeholder={t`Username`}
              autoFocus
              rules={{ required: true }}
            />
            <TextField<LoginValues>
              name="password"
              type="password"
              placeholder={t`Password`}
              rules={{ required: true }}
            />
            <SubmitButton pendingLabel={<Trans>Logging in…</Trans>}>
              <Trans>Log in</Trans>
            </SubmitButton>
          </form>
        </FormProvider>

        <p className="auth-card-footer">
          <button
            type="button"
            className="auth-link-btn"
            onClick={() => setShowReset((v) => !v)}
          >
            <Trans>Forgot password?</Trans>
          </button>
        </p>

        {showReset && <ResetRequestPanel />}

        <p className="auth-card-footer">
          <Trans>This is a mirage.</Trans>
        </p>
      </div>
    </PageShell>
  );
}

/**
 * Renders the form that asks the server to email a password reset link, which
 * leads to `/reset-password`.
 */
function ResetRequestPanel() {
  const [sent, setSent] = useState(false);
  const form = useApiForm<ResetValues>({ defaultValues: { email: "" } });

  const onSubmit = form.submit(async ({ email }) => {
    // The server answers 200 whether or not the address is known, so as not
    // to reveal which ones are. An error here means it failed.
    await expectOk(
      await fetch(`${API_URL}/api/password-resets`, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ email: email.trim() }),
      }),
    );
    setSent(true);
  });

  if (sent) {
    return (
      <div className="auth-reset-panel animate-in">
        <p className="auth-reset-sent">
          <Trans>
            If that address is registered you'll receive a reset link shortly.
          </Trans>
        </p>
      </div>
    );
  }

  return (
    <div className="auth-reset-panel animate-in">
      <FormProvider {...form}>
        <form onSubmit={onSubmit} className="form auth-reset-form">
          <FormError title={t`Request failed`} />
          <TextField<ResetValues>
            name="email"
            type="email"
            placeholder={t`Your email address`}
            autoFocus
            rules={{ required: true }}
          />
          <SubmitButton pendingLabel={<Trans>Sending…</Trans>}>
            <Trans>Send reset link</Trans>
          </SubmitButton>
        </form>
      </FormProvider>
    </div>
  );
}