import {useCallback, useEffect, useState} from 'react';
import {useTranslation} from 'react-i18next';
import {Loader2, Pencil, Send, Trash2} from 'lucide-react';
import {toast} from 'sonner';

import {Button} from '@/components/ui/button';
import {Card, CardContent, CardHeader, CardTitle} from '@/components/ui/card';
import {Input} from '@/components/ui/input';
import {Label} from '@/components/ui/label';
import {Textarea} from '@/components/ui/textarea';
import NewsEntry from '../components/NewsEntry.jsx';
import PageContainer from '../components/PageContainer.jsx';
import {MAX_NEWS_TEXT_LENGTH, MAX_NEWS_TITLE_LENGTH} from '../utils/limits.js';
import {createNews, deleteNews, fetchAdminNews, updateNews} from '../utils/news.js';

const emptyForm = () => ({titleEn: '', titleDe: '', textEn: '', textDe: ''});

/**
 * PLATFORM_ADMIN only: publish, preview, edit and delete the "What's new" entries. Auth checks the role.
 */
export default function AdminNewsPage() {
    const {t} = useTranslation();
    const [entries, setEntries] = useState([]);
    const [status, setStatus] = useState('loading');
    const [form, setForm] = useState(emptyForm);
    const [editing, setEditing] = useState(null);
    const [busy, setBusy] = useState(false);

    const load = useCallback(async () => {
        try {
            const response = await fetchAdminNews();
            if (response.status === 401) return;
            if (response.status === 403) {
                setStatus('forbidden');
                return;
            }
            if (!response.ok) {
                setStatus('error');
                return;
            }
            setEntries((await response.json()).results);
            setStatus('ready');
        } catch (err) {
            console.error('Admin news error:', err);
            setStatus('error');
        }
    }, []);

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

    const run = async (request, doneKey, onOk) => {
        setBusy(true);
        try {
            const response = await request();
            if (response.status === 401) return;
            if (response.ok) {
                toast.success(t(doneKey));
                onOk?.();
                await load();
            } else {
                toast.error(t('ADMIN_NEWS.ERROR'));
            }
        } catch (err) {
            console.error('Admin news action error:', err);
            toast.error(t('INFO.ERROR.NETWORK_FAILURE'));
        } finally {
            setBusy(false);
        }
    };

    const trimmed = () => ({
        titleEn: form.titleEn.trim(),
        titleDe: form.titleDe.trim(),
        textEn: form.textEn.trim(),
        textDe: form.textDe.trim(),
    });

    const reset = () => {
        setForm(emptyForm());
        setEditing(null);
    };

    const submit = (event) => {
        event.preventDefault();
        const news = trimmed();
        if (editing == null) run(() => createNews(news), 'ADMIN_NEWS.CREATED', reset);
        else run(() => updateNews(editing, news), 'ADMIN_NEWS.UPDATED', reset);
    };

    const edit = (entry) => {
        setEditing(entry.id);
        setForm({titleEn: entry.titleEn, titleDe: entry.titleDe ?? '', textEn: entry.textEn, textDe: entry.textDe ?? ''});
    };

    const remove = (entry) => {
        if (!window.confirm(t('ADMIN_NEWS.CONFIRM_DELETE'))) return;
        run(() => deleteNews(entry.id), 'ADMIN_NEWS.DELETED', () => editing === entry.id && reset());
    };

    const change = (field) => (event) => setForm({...form, [field]: event.target.value});

    if (status === 'forbidden') {
        return (
            <PageContainer className="px-4 py-6 md:px-8">
                <p className="text-sm text-muted-foreground">{t('ADMIN_NEWS.NO_ACCESS')}</p>
            </PageContainer>
        );
    }

    return (
        <PageContainer className="space-y-4 px-4 py-6 md:px-8">
            <Card>
                <CardHeader>
                    <CardTitle>{t(editing == null ? 'ADMIN_NEWS.NEW' : 'ADMIN_NEWS.EDIT')}</CardTitle>
                </CardHeader>
                <CardContent>
                    <form onSubmit={submit} className="space-y-4">
                        <div className="space-y-2">
                            <Label htmlFor="newsTitleEn">{t('ADMIN_NEWS.TITLE_EN')}</Label>
                            <Input id="newsTitleEn" required maxLength={MAX_NEWS_TITLE_LENGTH} value={form.titleEn} onChange={change('titleEn')}/>
                        </div>
                        <div className="space-y-2">
                            <Label htmlFor="newsTextEn">{t('ADMIN_NEWS.TEXT_EN')}</Label>
                            <Textarea id="newsTextEn" required maxLength={MAX_NEWS_TEXT_LENGTH} value={form.textEn} onChange={change('textEn')}/>
                        </div>
                        <div className="space-y-2">
                            <Label htmlFor="newsTitleDe">{t('ADMIN_NEWS.TITLE_DE')}</Label>
                            <Input id="newsTitleDe" maxLength={MAX_NEWS_TITLE_LENGTH} value={form.titleDe} onChange={change('titleDe')}/>
                        </div>
                        <div className="space-y-2">
                            <Label htmlFor="newsTextDe">{t('ADMIN_NEWS.TEXT_DE')}</Label>
                            <Textarea id="newsTextDe" maxLength={MAX_NEWS_TEXT_LENGTH} value={form.textDe} onChange={change('textDe')}/>
                            <p className="text-xs text-muted-foreground">{t('ADMIN_NEWS.TEXT_HELP')}</p>
                        </div>
                        {form.titleEn.trim() && form.textEn.trim() && (
                            <div className="space-y-2">
                                <p className="text-sm font-medium">{t('ADMIN_NEWS.PREVIEW')}</p>
                                <NewsEntry entry={{...trimmed(), publishedAt: new Date().toISOString()}}
                                           className="max-w-md rounded-lg border p-4"/>
                            </div>
                        )}
                        <div className="flex gap-2">
                            <Button type="submit" disabled={busy}>
                                {busy ? <Loader2 className="animate-spin"/> : <Send/>}
                                {t(editing == null ? 'ADMIN_NEWS.CREATE' : 'ADMIN_NEWS.SAVE')}
                            </Button>
                            {editing != null && (
                                <Button type="button" variant="outline" onClick={reset}>{t('ADMIN_NEWS.CANCEL')}</Button>
                            )}
                        </div>
                    </form>
                </CardContent>
            </Card>

            <Card>
                <CardHeader>
                    <CardTitle>{t('ADMIN_NEWS.LIST')}</CardTitle>
                </CardHeader>
                <CardContent>
                    {status === 'loading' && <Loader2 className="size-5 animate-spin text-muted-foreground"/>}
                    {status === 'error' && <p className="text-sm text-destructive">{t('ADMIN_NEWS.LOAD_ERROR')}</p>}
                    {status === 'ready' && entries.length === 0 && <p className="text-sm text-muted-foreground">{t('ADMIN_NEWS.EMPTY')}</p>}
                    {status === 'ready' && entries.length > 0 && (
                        <ul className="divide-y">
                            {entries.map((entry) => (
                                <li key={entry.id} className="flex flex-wrap items-start gap-3 py-3">
                                    <NewsEntry entry={entry} className="min-w-0 flex-1"/>
                                    <Button type="button" variant="outline" size="sm" disabled={busy} onClick={() => edit(entry)}>
                                        <Pencil/>{t('ADMIN_NEWS.EDIT_ACTION')}
                                    </Button>
                                    <Button type="button" variant="outline" size="sm" disabled={busy} onClick={() => remove(entry)}>
                                        <Trash2/>{t('ADMIN_NEWS.DELETE')}
                                    </Button>
                                </li>
                            ))}
                        </ul>
                    )}
                </CardContent>
            </Card>
        </PageContainer>
    );
}