// Willkommens-Karte: gerendertes PNG (SVG → sharp). Aussehen kommt aus den
// Einstellungen (Config → Support → Willkommens-Karte), die Standardwerte sind
// der Marken-Look: Avatar mit Neon-Ring, großer Schriftzug, Member-Nummer.
import { readFileSync } from 'node:fs';
import sharp from 'sharp';
import { welcomeCard } from '../runtime-settings.js';

const W = 900;
const H = 300;
const MAX_IMAGE_BYTES = 8 * 1024 * 1024;

// Marke fürs Wasserzeichen: einmal beim Start lesen, nicht bei jedem Beitritt.
// Fehlt die Datei, bleibt die Karte einfach ohne — wie bei den anderen Bildern
// hier auch soll ein fehlendes Detail nicht die ganze Karte kosten.
// Erzeugt von docs/brand/build.py.
const MARK_URI = (() => {
    try {
        const pfad = new URL('./assets/mark-card.png', import.meta.url);
        return `data:image/png;base64,${readFileSync(pfad).toString('base64')}`;
    } catch {
        return '';
    }
})();

/** XML-Sonderzeichen im Usernamen entschärfen */
function esc(s) {
    return String(s).replaceAll('&', '&amp;').replaceAll('<', '&lt;').replaceAll('>', '&gt;')
        .replaceAll('"', '&quot;').replaceAll("'", '&apos;');
}

/**
 * Bild holen und als Data-URI einbetten. Gibt bei jedem Problem '' zurück —
 * die Karte wird dann ohne dieses Bild gerendert statt gar nicht.
 */
async function fetchDataUri(url, timeoutMs = 5000) {
    if (!/^https?:\/\//i.test(String(url ?? ''))) return '';
    try {
        const res = await fetch(url, { signal: AbortSignal.timeout(timeoutMs) });
        if (!res.ok) return '';
        const type = res.headers.get('content-type') ?? '';
        if (!type.startsWith('image/')) return '';
        const buf = Buffer.from(await res.arrayBuffer());
        if (buf.byteLength > MAX_IMAGE_BYTES) return '';
        return `data:${type.split(';')[0]};base64,${buf.toString('base64')}`;
    } catch {
        return '';
    }
}

/**
 * Karte rendern.
 * @param {{ username: string, avatarUrl?: string, memberNumber?: number }} member
 * @param {object} [override] — Aussehen für die Vorschau, sonst aus den Einstellungen
 * @returns {Promise<Buffer>} PNG-Buffer
 */
export async function buildWelcomeCard({ username, avatarUrl, memberNumber }, override) {
    const look = { ...welcomeCard(), ...(override ?? {}) };

    const [avatarData, bgData] = await Promise.all([
        fetchDataUri(avatarUrl),
        look.image ? fetchDataUri(look.image, 6000) : Promise.resolve(''),
    ]);

    const name = esc(username.length > 22 ? `${username.slice(0, 21)}…` : username);
    const number = Number(memberNumber) || 0;
    const sub = esc(String(look.sub).replaceAll('{count}', number || '?').slice(0, 40));
    const kicker = esc(look.kicker);
    // Über einem Hintergrundbild braucht der Text einen Schleier, sonst säuft er ab
    const veil = bgData
        ? `<rect width="${W}" height="${H}" fill="${look.background}" fill-opacity=".62"/>`
        : `<rect width="${W}" height="${H}" fill="url(#grid)"/>`;

    const svg = `<svg width="${W}" height="${H}" viewBox="0 0 ${W} ${H}" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
    <defs>
        <linearGradient id="line" x1="0" y1="0" x2="1" y2="0">
            <stop offset="0" stop-color="${look.accent}" stop-opacity="0"/>
            <stop offset=".3" stop-color="${look.accent}"/>
            <stop offset=".7" stop-color="${look.accent2}"/>
            <stop offset="1" stop-color="${look.accent2}" stop-opacity="0"/>
        </linearGradient>
        <linearGradient id="ring" x1="0" y1="0" x2="1" y2="1">
            <stop offset="0" stop-color="${look.accent}"/>
            <stop offset="1" stop-color="${look.accent2}"/>
        </linearGradient>
        <pattern id="grid" width="45" height="45" patternUnits="userSpaceOnUse">
            <path d="M 45 0 L 0 0 0 45" fill="none" stroke="${look.accent}" stroke-opacity=".06" stroke-width="1"/>
        </pattern>
        <clipPath id="avatar"><circle cx="150" cy="150" r="75"/></clipPath>
        <clipPath id="card"><rect width="${W}" height="${H}"/></clipPath>
    </defs>

    <rect width="${W}" height="${H}" fill="${look.background}"/>
    ${bgData
        ? `<image href="${bgData}" x="0" y="0" width="${W}" height="${H}" clip-path="url(#card)" preserveAspectRatio="xMidYMid slice"/>`
        : ''}
    ${veil}
    ${look.watermark && MARK_URI
        ? `<image href="${MARK_URI}" x="${W - 300}" y="5" width="290" height="290" opacity=".08"
        preserveAspectRatio="xMidYMid meet"/>`
        : ''}
    <rect x="0" y="0" width="${W}" height="3" fill="url(#line)"/>
    <rect x="0" y="${H - 3}" width="${W}" height="3" fill="url(#line)"/>

    <circle cx="150" cy="150" r="80" fill="none" stroke="url(#ring)" stroke-width="4"/>
    ${avatarData
        ? `<image href="${avatarData}" x="75" y="75" width="150" height="150" clip-path="url(#avatar)" preserveAspectRatio="xMidYMid slice"/>`
        : `<circle cx="150" cy="150" r="75" fill="#161616"/>
           <text x="150" y="172" text-anchor="middle" font-family="DejaVu Sans, sans-serif" font-size="64" fill="#8a8378">?</text>`}

    ${kicker
        ? `<text x="270" y="118" font-family="DejaVu Sans, sans-serif" font-weight="bold" font-size="26"
        letter-spacing="10" fill="#8a8378">${kicker}</text>`
        : ''}
    <text x="270" y="182" font-family="DejaVu Sans, sans-serif" font-weight="bold" font-size="52"
        fill="${look.text}">${name}</text>
    ${sub
        ? `<text x="270" y="228" font-family="DejaVu Sans, sans-serif" font-size="24"
        fill="${look.accent}">${sub}</text>`
        : ''}
</svg>`;

    return sharp(Buffer.from(svg)).png().toBuffer();
}