import { createEffect, createMemo, createResource, createSignal, For, Show } from 'solid-js';
import { apiHost } from '../../consts';
import { download } from '../../helpers/download';
import { LoadingSpinner } from '../../components/spinner/LoadingSpinner';
import { drawWarningMap, type WeatherWarning, warningSeverity } from './warningDraw';
import { warningTemplates, type WarningOutput } from './warningTemplates';
import './warnings.css';

type WarningResponse = { source: string; fetchedAt: string; warnings: WeatherWarning[] };

const fetchWarnings = async (): Promise<WarningResponse> => {
    const response = await fetch(`${apiHost}/api/warnings`);
    if (!response.ok) throw new Error(`Warnings failed (${response.status})`);
    return response.json();
};

export function Warnings() {
    const [output, setOutput] = createSignal<WarningOutput>('3840x1440');
    const [title, setTitle] = createSignal('');
    const [selectedDate, setSelectedDate] = createSignal('all');
    const [phenomenon, setPhenomenon] = createSignal('all');
    const [artwork, setArtwork] = createSignal<{ background: HTMLImageElement; border: HTMLImageElement }>();
    const [data, { refetch }] = createResource(fetchWarnings);
    let canvas!: HTMLCanvasElement;

    const template = () => warningTemplates[output()];
    const loadedWarnings = () => data.error ? [] : data()?.warnings ?? [];
    const availableDates = createMemo(() => warningDates(loadedWarnings()));
    const phenomena = createMemo(() => [...new Set(loadedWarnings().map(item => item.phenomenon).filter(Boolean))].sort((a, b) => a.localeCompare(b, 'lv')));
    const filteredWarnings = createMemo(() => loadedWarnings().filter(warning => {
        const dateMatches = selectedDate() === 'all' || activeOnDate(warning, selectedDate());
        const phenomenonMatches = phenomenon() === 'all' || warning.phenomenon === phenomenon();
        return dateMatches && phenomenonMatches;
    }));
    const [selectedId, setSelectedId] = createSignal<string>();
    const selectedWarning = createMemo(() => filteredWarnings().find(item => item.id === selectedId()));

    const loadArtwork = () => {
        const current = template();
        setArtwork(undefined);
        const background = new Image();
        const border = new Image();
        let loaded = 0;
        const finish = () => {
            loaded += 1;
            if (loaded === 2 && template() === current) setArtwork({ background, border });
        };
        background.onload = finish;
        border.onload = finish;
        background.src = current.map;
        border.src = current.border;
    };

    createEffect(() => { output(); loadArtwork(); });
    createEffect(() => {
        const list = filteredWarnings();
        if (!list.some(item => item.id === selectedId())) setSelectedId(list[0]?.id);
    });
    createEffect(() => {
        const warning = selectedWarning();
        setTitle(warning ? defaultTitle(warning.phenomenon) : '');
    });
    createEffect(() => {
        const images = artwork();
        const current = template();
        const warning = selectedWarning();
        const currentTitle = title();
        if (!canvas || !images) return;
        if (canvas.width !== current.width) canvas.width = current.width;
        if (canvas.height !== current.height) canvas.height = current.height;
        void document.fonts.load(`700 ${current.title.fontSize}px Monda`).then(() =>
            drawWarningMap(canvas.getContext('2d')!, images.background, images.border, current, warning, currentTitle),
        );
    });

    const downloadPng = () => canvas.toBlob(blob => blob && download(blob, `bridinajumi-${output()}.png`), 'image/png');

    return <section class="pageWorkspace warningsPage">
        <div class="pageHeading warningsHeading">
            <div><span class="eyebrow">ĒTERA GRAFIKA</span><h1>Brīdinājumi</h1><p>Izvēlies vienu LVĢMC brīdinājumu, kas jārāda kartē; virsraksts aizpildās automātiski.</p></div>
            <span class="selectionCount">{filteredWarnings().length} {filteredWarnings().length === 1 ? 'brīdinājums' : 'brīdinājumi'}</span>
        </div>

        <section class="warningsSetup" aria-labelledby="warnings-settings">
            <div><h2 id="warnings-settings">1. Izvēlies izmēru</h2><div class="resolutionChoices">
                <button classList={{ active: output() === '1920x1080' }} onClick={() => setOutput('1920x1080')}>1920 × 1080</button>
                <button classList={{ active: output() === '3840x1440' }} onClick={() => setOutput('3840x1440')}>3840 × 1440</button>
            </div></div>
            <div class="warningFilters"><h2>2. Izvēlies brīdinājumu</h2><div class="warningFilterGrid">
                <label><span>Diena</span><select value={selectedDate()} onChange={event => setSelectedDate(event.currentTarget.value)}><option value="all">Viss periods</option><For each={availableDates()}>{date => <option value={date}>{formatDate(date)}</option>}</For></select></label>
                <label><span>Parādība</span><select value={phenomenon()} onChange={event => setPhenomenon(event.currentTarget.value)}><option value="all">Visas parādības</option><For each={phenomena()}>{item => <option value={item}>{item}</option>}</For></select></label>
                <label class="warningTitle"><span>Virsraksts</span><input type="text" value={title()} placeholder="Brīdinājums: vējš" onInput={event => setTitle(event.currentTarget.value)} /></label>
            </div></div>
        </section>

        <Show when={data.loading}><LoadingSpinner text="Ielādē LVĢMC brīdinājumus"/></Show>
        <Show when={data.error}><div class="inlineNotice error"><strong>Brīdinājumu datus neizdevās ielādēt.</strong><button class="secondary" onClick={() => refetch()}>Mēģināt vēlreiz</button></div></Show>
        <Show when={!data.loading && !data.error && filteredWarnings().length === 0}><div class="inlineNotice">Izvēlētajam periodam nav aktīvu brīdinājumu. Karti joprojām var priekšskatīt, bet tajā nebūs iekrāsotu teritoriju.</div></Show>

        <Show when={filteredWarnings().length > 0}><div class="warningSummary"><For each={filteredWarnings()}>{warning => {
            const active = () => warning.id === selectedId();
            return <button type="button" class={`warningCard ${warningSeverity(warning.intensity)}`} classList={{ active: active() }} aria-pressed={active()} onClick={() => setSelectedId(warning.id)}>
                <strong>{warning.phenomenon || 'Brīdinājums'}</strong>
                <Show when={active()}><div class="warningCardDetails">
                    <span>{warning.intensity} · {warning.regions}</span>
                    <small>{formatPeriod(warning.validFrom, warning.validUntil)}</small>
                    <Show when={warning.description}><p>{warning.description}</p></Show>
                    <Show when={warning.risks}><p class="warningRisks">{warning.risks}</p></Show>
                </div></Show>
            </button>;
        }}</For></div></Show>

        <section class="warningsPreview"><div class="mapToolbar"><div><strong>3. Kartes priekšskatījums</strong><span>{template().width} × {template().height} px eksports</span></div><button class="primary" disabled={data.loading || Boolean(data.error)} onClick={downloadPng}>Lejupielādēt PNG</button></div><div class="canvasFrame"><canvas ref={canvas} width={template().width} height={template().height}/></div></section>
    </section>;
}

function defaultTitle(phenomenon: string) {
    return phenomenon ? `Brīdinājums: ${phenomenon}` : '';
}

function datePart(value: string) {
    const match = value.trim().match(/^(\d{4}-\d{2}-\d{2})/);
    return match?.[1];
}

function warningDates(warnings: WeatherWarning[]) {
    const dates = new Set<string>();
    warnings.forEach(warning => {
        const from = datePart(warning.validFrom);
        const until = datePart(warning.validUntil);
        if (!from || !until) return;
        const cursor = new Date(`${from}T12:00:00Z`);
        const last = new Date(`${until}T12:00:00Z`);
        while (cursor.getTime() <= last.getTime()) {
            dates.add(cursor.toISOString().slice(0, 10));
            cursor.setUTCDate(cursor.getUTCDate() + 1);
        }
    });
    return [...dates].sort();
}

function activeOnDate(warning: WeatherWarning, date: string) {
    const from = datePart(warning.validFrom);
    const until = datePart(warning.validUntil);
    if (!from || !until) return false;
    return from <= date && until >= date;
}

function formatDate(value: string) {
    return new Intl.DateTimeFormat('lv-LV', { timeZone: 'Europe/Riga', weekday: 'short', day: '2-digit', month: '2-digit' }).format(new Date(`${value}T12:00:00Z`));
}

function formatPeriod(fromValue: string, untilValue: string) {
    const compact = (value: string) => value.trim().replace(/^(\d{4})-(\d{2})-(\d{2})[ T](\d{2}):(\d{2}).*$/, '$3.$2. $4:$5');
    return `${compact(fromValue)}–${compact(untilValue)}`;
}