import React, { useCallback, useEffect, useState } from 'react';
import { Link, useLocation, useSearchParams } from 'react-router-dom';
import { LogOut, Settings } from 'lucide-react';
import { Button } from '@/components/ui/button';
import { cn } from '@/lib/utils';
import { apiFetch } from '@/lib/api';

/**
 * Sign-in (Google). Workspace details and switching context live in Settings / session. OAuth callback sets session.
 */
export default function GoogleAuthBar() {
    const location = useLocation();
    const [searchParams, setSearchParams] = useSearchParams();
    const [phase, setPhase] = useState('loading');
    const [googleOn, setGoogleOn] = useState(false);
    const [user, setUser] = useState(null);
    const refresh = useCallback(async () => {
        try {
            const [st, me] = await Promise.all([
                apiFetch('/api/auth/status').then((r) => r.json()),
                apiFetch('/api/auth/me').then((r) => (r.ok ? r.json() : null)),
            ]);
            setGoogleOn(!!st.googleConfigured);
            setUser(me);
            setPhase('ready');
            if (typeof window !== 'undefined') {
                window.dispatchEvent(new CustomEvent('emailout-auth-changed'));
            }
        } catch {
            setPhase('error');
        }
    }, []);

    useEffect(() => {
        refresh();
    }, [refresh]);

    useEffect(() => {
        const err = searchParams.get('auth_error');
        if (!err) return;
        if (err === 'access_denied') {
            console.info('Google sign-in was cancelled.');
        } else if (err === 'invite_email_mismatch') {
            console.warn(
                'Invitation email does not match your Google account. Sign in with the invited address.'
            );
        } else {
            console.warn('Google sign-in error:', err);
        }
        const next = new URLSearchParams(searchParams);
        next.delete('auth_error');
        setSearchParams(next, { replace: true });
    }, [searchParams, setSearchParams]);

    const logout = async () => {
        try {
            await apiFetch('/api/auth/logout', { method: 'POST' });
            setUser(null);
            if (typeof window !== 'undefined') {
                window.dispatchEvent(new CustomEvent('emailout-auth-changed'));
            }
        } catch (e) {
            console.error(e);
        }
    };

    const inviteParam = searchParams.get('invite');
    const googleHref = inviteParam
        ? `/api/auth/google?invite=${encodeURIComponent(inviteParam)}`
        : '/api/auth/google';

    if (phase === 'loading' || (phase === 'ready' && !googleOn)) {
        if (phase === 'loading') {
            return (
                <div
                    className="h-9 w-24 shrink-0 rounded-md bg-slate-100/80 animate-pulse"
                    aria-hidden
                />
            );
        }
        return null;
    }

    if (phase === 'error') {
        return null;
    }

    if (user) {
        const settingsActive =
            location.pathname === '/settings' || location.pathname.startsWith('/settings/');
        return (
            <div className="flex max-w-[min(100vw-6rem,28rem)] flex-wrap items-center justify-end gap-2">
                <Button
                    asChild
                    variant="ghost"
                    size="icon"
                    className={cn(
                        'h-9 w-9 shrink-0 text-slate-600 hover:text-violet-700 hover:bg-violet-50',
                        settingsActive && 'text-violet-700 bg-violet-50'
                    )}
                    title="Settings"
                    aria-current={settingsActive ? 'page' : undefined}
                >
                    <Link to="/settings">
                        <Settings className="h-5 w-5" aria-hidden />
                        <span className="sr-only">Settings</span>
                    </Link>
                </Button>
                {user.picture ? (
                    <img
                        src={user.picture}
                        alt=""
                        className="h-8 w-8 shrink-0 rounded-full border border-slate-200 object-cover"
                        referrerPolicy="no-referrer"
                    />
                ) : null}
                <span className="hidden min-w-0 truncate text-sm text-slate-600 lg:inline">
                    {user.name || user.email || 'Signed in'}
                </span>
                <Button
                    type="button"
                    variant="outline"
                    size="sm"
                    className="shrink-0 gap-1"
                    onClick={logout}
                    title="Sign out"
                >
                    <LogOut className="h-3.5 w-3.5" />
                    <span className="hidden sm:inline">Sign out</span>
                </Button>
            </div>
        );
    }

    return (
        <Button
            asChild
            variant="outline"
            size="sm"
            className={cn(
                'shrink-0 gap-2 border-slate-200 bg-white text-slate-800 shadow-sm',
                'hover:bg-slate-50'
            )}
        >
            <a href={googleHref} className="inline-flex items-center gap-2">
                <GoogleMark className="h-4 w-4 shrink-0" />
                <span className="whitespace-nowrap">Sign in with Google</span>
            </a>
        </Button>
    );
}

function GoogleMark({ className }) {
    return (
        <svg className={className} viewBox="0 0 24 24" aria-hidden>
            <path
                fill="#4285F4"
                d="M22.56 12.25c0-.78-.07-1.53-.2-2.25H12v4.26h5.92c-.26 1.37-1.04 2.53-2.21 3.31v2.77h3.57c2.08-1.92 3.28-4.74 3.28-8.09z"
            />
            <path
                fill="#34A853"
                d="M12 23c2.97 0 5.46-.98 7.28-2.66l-3.57-2.77c-.98.66-2.23 1.06-3.71 1.06-2.86 0-5.29-1.93-6.16-4.53H2.18v2.84C3.99 20.53 7.7 23 12 23z"
            />
            <path
                fill="#FBBC05"
                d="M5.84 14.09c-.22-.66-.35-1.36-.35-2.09s.13-1.43.35-2.09V7.07H2.18C1.43 8.55 1 10.22 1 12s.43 3.45 1.18 4.93l2.85-2.22.81-.62z"
            />
            <path
                fill="#EA4335"
                d="M12 5.38c1.62 0 3.06.56 4.21 1.64l3.15-3.15C17.45 2.09 14.97 1 12 1 7.7 1 3.99 3.47 2.18 7.07l3.66 2.84c.87-2.6 3.3-4.53 6.16-4.53z"
            />
        </svg>
    );
}
