"use client";

import { useState, use } from "react";
import { useRouter } from "next/navigation";
import { PASSWORD_MIN_LENGTH, PASSWORD_POLICY_MESSAGE } from "@nexus/shared";
import { trpc } from "~/lib/trpc/client.js";

export default function AcceptInvitePage({ params }: { params: Promise<{ token: string }> }) {
  const { token } = use(params);
  const router = useRouter();

  const [password, setPassword] = useState("");
  const [confirm, setConfirm] = useState("");
  const [formError, setFormError] = useState<string | null>(null);
  const [done, setDone] = useState(false);

  const {
    data: invite,
    isLoading,
    error: inviteError,
  } = trpc.invite.getInvite.useQuery({ token }, { retry: false });

  const acceptMutation = trpc.invite.acceptInvite.useMutation({
    onSuccess: () => setDone(true),
    onError: (err) => setFormError(err.message),
  });

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    setFormError(null);
    if (password.length < PASSWORD_MIN_LENGTH) {
      setFormError(PASSWORD_POLICY_MESSAGE);
      return;
    }
    if (password !== confirm) {
      setFormError("Passwords do not match.");
      return;
    }
    await acceptMutation.mutateAsync({ token, password });
  }

  if (isLoading) {
    return (
      <div className="min-h-screen flex items-center justify-center bg-gray-50 dark:bg-gray-950">
        <p className="text-sm text-gray-500">Loading…</p>
      </div>
    );
  }

  if (inviteError || !invite) {
    return (
      <div className="min-h-screen flex items-center justify-center bg-gray-50 dark:bg-gray-950 p-4">
        <div className="w-full max-w-md rounded-2xl bg-white dark:bg-gray-900 shadow-lg p-8 text-center">
          <div className="text-4xl mb-4">🔗</div>
          <h1 className="text-lg font-semibold text-gray-900 dark:text-gray-100 mb-2">
            Invite link invalid or expired
          </h1>
          <p className="text-sm text-gray-500">
            {inviteError?.message ??
              "This invite link is no longer valid. Please request a new invitation from your administrator."}
          </p>
        </div>
      </div>
    );
  }

  if (done) {
    return (
      <div className="min-h-screen flex items-center justify-center bg-gray-50 dark:bg-gray-950 p-4">
        <div className="w-full max-w-md rounded-2xl bg-white dark:bg-gray-900 shadow-lg p-8 text-center">
          <div className="text-4xl mb-4">✅</div>
          <h1 className="text-lg font-semibold text-gray-900 dark:text-gray-100 mb-2">
            Account created
          </h1>
          <p className="text-sm text-gray-500 mb-6">Your account has been set up successfully.</p>
          <button
            type="button"
            onClick={() => router.push("/auth/signin")}
            className="rounded-lg bg-brand-600 px-5 py-2 text-sm font-semibold text-white hover:bg-brand-700 transition-colors"
          >
            Go to sign in
          </button>
        </div>
      </div>
    );
  }

  return (
    <div className="min-h-screen flex items-center justify-center bg-gray-50 dark:bg-gray-950 p-4">
      <div className="w-full max-w-md rounded-2xl bg-white dark:bg-gray-900 shadow-lg p-8">
        <div className="mb-6">
          <h1 className="text-xl font-bold text-gray-900 dark:text-gray-100">Accept invitation</h1>
          <p className="mt-1 text-sm text-gray-500">
            You have been invited as <strong>{invite.role}</strong> to Nexus. Set a password to
            activate your account (<span className="font-medium">{invite.email}</span>).
          </p>
        </div>

        <form onSubmit={handleSubmit} className="space-y-4">
          {formError && (
            <div className="rounded-lg bg-red-50 dark:bg-red-900/20 border border-red-200 dark:border-red-700 px-4 py-3 text-sm text-red-700 dark:text-red-400">
              {formError}
            </div>
          )}

          <div>
            <label className="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-1">
              Password
            </label>
            <input
              type="password"
              value={password}
              onChange={(e) => setPassword(e.target.value)}
              required
              minLength={PASSWORD_MIN_LENGTH}
              placeholder={`At least ${PASSWORD_MIN_LENGTH} characters`}
              className="w-full rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-gray-900 px-3 py-2 text-sm text-gray-900 dark:text-gray-100 focus:outline-none focus:ring-2 focus:ring-brand-400"
            />
          </div>

          <div>
            <label className="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-1">
              Confirm password
            </label>
            <input
              type="password"
              value={confirm}
              onChange={(e) => setConfirm(e.target.value)}
              required
              placeholder="Repeat your password"
              className="w-full rounded-lg border border-gray-300 dark:border-gray-600 bg-white dark:bg-gray-900 px-3 py-2 text-sm text-gray-900 dark:text-gray-100 focus:outline-none focus:ring-2 focus:ring-brand-400"
            />
          </div>

          <button
            type="submit"
            disabled={acceptMutation.isPending}
            className="w-full rounded-lg bg-brand-600 px-4 py-2 text-sm font-semibold text-white hover:bg-brand-700 transition-colors disabled:opacity-50"
          >
            {acceptMutation.isPending ? "Setting up account…" : "Create account"}
          </button>
        </form>
      </div>
    </div>
  );
}