// ── Markdown rendering ──

import { esc } from './util.js';
import { state } from './state.js';

marked.use({ breaks: true, gfm: true, renderer: {
    link({ href, text }) {
        const isExternal = /^https?:\/\//.test(href);
        if (isExternal) return `<a href="${href}" target="_blank" rel="noopener">${text}</a>`;
        return `<a href="${href}">${text}</a>`;
    }
}});

const purifyConfig = {
    ALLOWED_TAGS: ['h1','h2','h3','h4','h5','h6','p','br','hr','ul','ol','li','a','strong','em','del','code','pre','blockquote','table','thead','tbody','tr','th','td','img','input','span','div','audio','source'],
    ALLOWED_ATTR: ['href','src','alt','width','height','type','checked','disabled','class','style','data-card-id','title','controls','preload','target','rel'],
    ALLOW_DATA_ATTR: true,
};

function normalizeListBlock(block) {
    const lines = String(block || '').replace(/\r\n?/g, '\n').split('\n');
    while (lines.length && !lines[0].trim()) lines.shift();
    while (lines.length && !lines[lines.length - 1].trim()) lines.pop();
    if (!lines.length) return '';

    const minIndent = lines
        .filter(l => l.trim())
        .map(l => (l.match(/^[ \t]*/) || [''])[0].replace(/\t/g, '    ').length)
        .reduce((min, n) => Math.min(min, n), Infinity);

    return lines
        .map(l => {
            const expanded = l.replace(/\t/g, '    ');
            if (!expanded.trim()) return '';
            return expanded.slice(Math.min(minIndent, expanded.length));
        })
        .join('\n');
}

export function renderMd(src) {
    let processed = String(src || '').replace(/\r\n?/g, '\n')
        // Gallery fenced block: ```gallery
        .replace(/```gallery\s*\n([\s\S]*?)(?:```|$)/g, (_, content) => {
            const imgs = [];
            const imgRe = /!\[([^\]]*)\]\(([^)]+)\)/g;
            let m;
            while ((m = imgRe.exec(content)) !== null) imgs.push({ alt: m[1], src: m[2].split(/\s/)[0] });
            if (!imgs.length) return '';
            return '<div class="md-gallery">' + imgs.map(i =>
                `<div class="md-gallery-item"><img src="${i.src}" alt="${esc(i.alt)}" loading="lazy"></div>`
            ).join('') + '</div>';
        })
        // Custom fenced list blocks: ```tree / ```bullets with or without closing ```
        .replace(/```(tree|bullets)\s*\n([\s\S]*?)(?:```|$)/g, (_, kind, content) => {
            const normalized = normalizeListBlock(content);
            return `\n<!-- list:${kind} -->\n${normalized}\n`;
        })
        // Help parser: ensure a list can start after text without requiring manual blank line
        .replace(/([^\n])\n(?=(?: {0,3}[-*+]\s| {0,3}\d+\.\s))/g, '$1\n\n')
        // Preserve extra blank lines as <br> spacers (3+ newlines = 1+ extra blank lines)
        .replace(/\n{3,}/g, m => '\n\n' + '<br>\n'.repeat(m.length - 2))
        // Ensure hr rules have one clean blank line before and after, keep extra <br> beyond that
        .replace(/<br>\n(---+|___+|\*\*\*+)\n/gm, '\n\n$1\n')
        .replace(/(---+|___+|\*\*\*+)\n<br>/gm, '$1\n\n');

    const linked = processed.replace(/\[\[([^\]]+)\]\]/g, (_, title) => {
        const card = state.cards.find(c => c.title.toLowerCase() === title.toLowerCase());
        if (card) return `<span class="card-link" data-card-id="${card.id}">${esc(title)}</span>`;
        return `<span class="card-link broken" title="card not found">${esc(title)}</span>`;
    });

    let html = marked.parse(linked);

    // Convert list hints before sanitize (DOMPurify strips comments)
    html = html.replace(/<!--\s*list:tree\s*-->\s*<ul>/g, '<ul class="tree-list">');
    html = html.replace(/<!--\s*list:bullets\s*-->\s*<ul>/g, '<ul class="bullet-list">');

    html = typeof DOMPurify !== 'undefined' ? DOMPurify.sanitize(html, purifyConfig) : html;
    return html;
}

export function addCodeCopyButtons(container) {
    if (!container) return;
    container.querySelectorAll('pre > code').forEach(code => {
        const pre = code.parentElement;
        if (pre.querySelector('.code-copy')) return;
        const btn = document.createElement('button');
        btn.className = 'code-copy';
        btn.type = 'button';
        btn.innerHTML = '<i class="ph ph-copy"></i>';
        btn.addEventListener('click', async () => {
            await navigator.clipboard.writeText(code.textContent);
            btn.classList.add('copied');
            btn.innerHTML = '<i class="ph ph-check"></i>';
            setTimeout(() => { btn.classList.remove('copied'); btn.innerHTML = '<i class="ph ph-copy"></i>'; }, 1500);
        });
        pre.appendChild(btn);
    });
}

export function stripMd(src) {
    return (src || '')
        .replace(/<img[^>]*>/gi, '')
        .replace(/<[^>]+>/g, '')
        .replace(/!\[[^\]]*\]\([^)]*\)/g, '')
        .replace(/\[\[([^\]]+)\]\]/g, '$1')
        .replace(/^#{1,6}\s+/gm, '')
        .replace(/(\*{1,3}|_{1,3}|~~)(.*?)\1/g, '$2')
        .replace(/\[([^\]]*)\]\([^)]*\)/g, '$1')
        .replace(/`{1,3}[^`]*`{1,3}/g, '')
        .replace(/^[-*>]\s+/gm, '')
        .replace(/^\d+\.\s+/gm, '')
        .replace(/\n{2,}/g, '\n')
        .trim();
}

export function getTodos(src) {
    const s = src || '';
    const total = (s.match(/- \[([ x])\]/g) || []).length;
    if (!total) return null;
    return { total, done: (s.match(/- \[x\]/g) || []).length };
}

export function firstImage(src) {
    const s = src || '';
    const md = s.match(/!\[[^\]]*\]\(([^)]+)\)/);
    if (md) return md[1];
    const html = s.match(/<img[^>]+src="([^"]+)"/i);
    return html ? html[1] : null;
}

export function leadingImage(src) {
    const s = (src || '').trimStart();
    if (!s) return null;
    const md = s.match(/^!\[[^\]]*\]\(([^)]+)\)/);
    if (md) return md[1].split(/\s+/)[0].replace(/^<(.+)>$/, '$1') || null;
    const html = s.match(/^<img[^>]+src=(['"])(.*?)\1/i);
    return html ? html[2] : null;
}