import type { Facet } from './types';

export function escapeHtml(str: string): string {
  return str
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

export function renderFacets(text: string, facets?: Facet[]): string {
  if (!facets?.length) return escapeHtml(text);

  const encoder = new TextEncoder();
  const decoder = new TextDecoder();
  const bytes = encoder.encode(text);
  const sorted = [...facets].sort((a, b) => a.index.byteStart - b.index.byteStart);

  let result = '';
  let lastEnd = 0;

  for (const facet of sorted) {
    const { byteStart, byteEnd } = facet.index;
    result += escapeHtml(decoder.decode(bytes.slice(lastEnd, byteStart)));
    const facetText = escapeHtml(decoder.decode(bytes.slice(byteStart, byteEnd)));
    const feature = facet.features?.[0];

    if (feature?.$type === 'app.bsky.richtext.facet#link') {
      result += `<a href="${escapeHtml(feature.uri!)}" target="_blank" rel="noopener">${facetText}</a>`;
    } else if (feature?.$type === 'app.bsky.richtext.facet#mention') {
      result += `<a href="https://bsky.app/profile/${feature.did}" target="_blank" rel="noopener">${facetText}</a>`;
    } else if (feature?.$type === 'app.bsky.richtext.facet#tag') {
      result += `<a href="https://bsky.app/hashtag/${feature.tag}" target="_blank" rel="noopener">${facetText}</a>`;
    } else {
      result += facetText;
    }
    lastEnd = byteEnd;
  }

  result += escapeHtml(decoder.decode(bytes.slice(lastEnd)));
  return result;
}

export function timeAgo(dateStr: string): string {
  const now = Date.now();
  const then = new Date(dateStr).getTime();
  const diff = now - then;
  const mins = Math.floor(diff / 60000);
  const hours = Math.floor(diff / 3600000);
  const days = Math.floor(diff / 86400000);
  if (mins < 1) return 'just now';
  if (mins < 60) return `${mins}m`;
  if (hours < 24) return `${hours}h`;
  if (days < 7) return `${days}d`;
  return new Date(dateStr).toLocaleDateString('en-US', {
    month: 'short',
    day: 'numeric',
    ...(days > 365 ? { year: 'numeric' } : {}),
  });
}

export function formatDate(dateStr: string): string {
  return new Date(dateStr).toLocaleDateString('en-US', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
  });
}

export function formatDuration(seconds: number): string {
  const m = Math.floor(seconds / 60);
  const s = Math.floor(seconds % 60);
  return `${m}:${s.toString().padStart(2, '0')}`;
}

export function formatCount(n: number): string {
  if (n >= 1000000) return (n / 1000000).toFixed(1) + 'M';
  if (n >= 10000) return (n / 1000).toFixed(0) + 'K';
  if (n >= 1000) return (n / 1000).toFixed(1) + 'K';
  return String(n || 0);
}

export function slugify(str: string): string {
  return str
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-|-$/g, '');
}