5chan/src/lib/utils/post-utils.ts

export function hashStringToColor(str: string): string {
  if (!str) {
    return '';
  }

  let hash = 0;
  for (let i = 0; i < str.length; i++) {
    hash = str.charCodeAt(i) + ((hash << 5) - hash);
  }

  const r = (hash >> 24) & 0xff;
  const g = (hash >> 16) & 0xff;
  const b = (hash >> 8) & 0xff;

  return `rgb(${r}, ${g}, ${b})`;
}

export function getTextColorForBackground(rgb: string): string {
  const [r, g, b] = rgb.match(/\d+/g)?.map(Number) || [0, 0, 0];
  const brightness = r * 0.299 + g * 0.587 + b * 0.114;
  return brightness > 125 ? 'black' : 'white';
}

export const formatMarkdown = (content: string): string => {
  let md = content;
  if (md) {
    // Check if the content already contains valid Markdown patterns
    const alreadyFormattedPattern = /\n&nbsp;\n/;

    // help the user by formatting the content if it's not already formatted
    if (!alreadyFormattedPattern.test(md)) {
      // Replace single newline with "/n&nbsp;/n" if followed by a newline
      md = md.replace(/\n(?=\n)/g, '\n&nbsp;\n');
      // Replace single newline with double newline if between two characters
      md = md.replace(/\n(?=\S)/g, '\n\n');
    }
  }
  return md;
};

export function removeMarkdown(md: string): string {
  return md
    .replace(/\[([^\]]*?)\][\[\(].*?[\]\)]/g, '$1') // Remove links
    .replace(/[*_~`]/g, '') // Remove emphasis and code markers
    .replace(/^#+\s*(.+)$/gm, '$1') // Remove headers
    .replace(/^\s*[-*+]\s+/gm, '') // Remove list markers
    .replace(/^\s*>\s+/gm, '') // Remove blockquotes
    .replace(/^\s{1,2}\[(.*?)\]: (\S+)( ".*?")?\s*$/g, '') // Remove reference-style links
    .replace(/^(\n)?\s{0,}#{1,6}\s*( (.+))? +#+$|^(\n)?\s{0,}#{1,6}\s*( (.+))?$/gm, '$1$3$4$6') // Remove atx-style headers
    .replace(/([\*]+)(\S)(.*?\S)??\1/g, '$2$3') // Remove * emphasis
    .replace(/(^|\W)([_]+)(\S)(.*?\S)??\2($|\W)/g, '$1$3$4$5') // Remove _ emphasis
    .replace(/(`{3,})(.*?)\1/gm, '$2') // Remove code blocks
    .replace(/`(.+?)`/g, '$1') // Remove inline code
    .replace(/~(.*?)~/g, '$1') // Remove strike through
    .trim();
}