rustpad/static/js/image-alias.js

/*
 * Copyright (C) 2026 Mateusz Gruszczyński @linuxiarz.pl
 * Source-Available Code / Dual-Licensed.
 *
 * Free for non-commercial and evaluation use under terms of BSL/GPLv3.
 * Commercial or production use requires a valid paid license.
 * See LICENSE file in repository root for details.
 */

const IMAGE_ALIAS_SOURCE = String.raw`\[(image|img)=([^,\]\s]+)(?:,([^\]]*))?\]`;
const ALIGNMENTS = new Set(["left", "center", "right"]);
const MAX_IMAGE_DIMENSION = 10000;

function cleanText(value, fallback = "") {
  return String(value ?? fallback)
    .replace(/\]/g, ")")
    .replace(/[\r\n]+/g, " ")
    .trim();
}

function validDimension(value) {
  const number = Math.round(Number(value));
  return Number.isFinite(number) && number >= 1 && number <= MAX_IMAGE_DIMENSION ? number : null;
}

function inlineCodeRanges(value) {
  const ranges = [];
  const pattern = /`[^`]+`/g;
  for (const match of String(value || "").matchAll(pattern)) {
    ranges.push([match.index, match.index + match[0].length]);
  }
  return ranges;
}

function isInsideRange(index, ranges) {
  return ranges.some(([start, end]) => index >= start && index < end);
}

export function imageAliasPattern(flags = "gi") {
  return new RegExp(IMAGE_ALIAS_SOURCE, flags);
}

export function parseImageAlias(value) {
  const match = String(value || "").match(new RegExp(`^${IMAGE_ALIAS_SOURCE}$`, "i"));
  if (!match) return null;

  const [, kind, filename, tail = ""] = match;
  const parts = tail.split(",");
  let align = null;
  let width = null;
  let height = null;

  while (parts.length) {
    const part = parts.at(-1).trim();
    const alignment = part.match(/^a=(left|center|right)$/i);
    if (alignment) {
      align = alignment[1].toLowerCase();
      parts.pop();
      continue;
    }

    const size = part.match(/^size=(\d{1,5})x(\d{1,5})$/i);
    if (size) {
      const nextWidth = validDimension(size[1]);
      const nextHeight = validDimension(size[2]);
      if (nextWidth && nextHeight) {
        width = nextWidth;
        height = nextHeight;
      }
      parts.pop();
      continue;
    }
    break;
  }

  return {
    kind: kind.toLowerCase(),
    filename,
    label: cleanText(parts.join(","), filename) || filename,
    align,
    width,
    height,
    raw: match[0],
  };
}

export function buildImageAlias(options = {}) {
  const filename = cleanText(options.filename, "image").replace(/[,\s]/g, "_") || "image";
  const label = cleanText(options.label, filename) || filename;
  const kind = String(options.kind || "image").toLowerCase() === "img" ? "img" : "image";
  const align = ALIGNMENTS.has(String(options.align || "").toLowerCase())
    ? String(options.align).toLowerCase()
    : null;
  const width = validDimension(options.width);
  const height = validDimension(options.height);
  const parts = [label];
  if (align) parts.push(`a=${align}`);
  if (width && height) parts.push(`size=${width}x${height}`);

  return `[${kind}=${filename},${parts.join(",")}]`;
}

export function updateImageAliasInLine(line, aliasIndex, patch = {}) {
  const source = String(line || "");
  const targetIndex = Number(aliasIndex);
  if (!Number.isInteger(targetIndex) || targetIndex < 0) return null;

  const codeRanges = inlineCodeRanges(source);
  let index = 0;
  let changed = false;
  const value = source.replace(imageAliasPattern(), (match, ...args) => {
    const offset = args.at(-2);
    if (isInsideRange(offset, codeRanges) || index++ !== targetIndex) return match;
    const parsed = parseImageAlias(match);
    if (!parsed) return match;
    changed = true;
    return buildImageAlias({ ...parsed, ...patch });
  });

  return changed ? value : null;
}

export function updateImageAliasInLineBySource(line, aliasSource, occurrence = 0, patch = {}) {
  const source = String(line || "");
  const target = String(aliasSource || "");
  const targetOccurrence = Number(occurrence);
  if (!target || !Number.isInteger(targetOccurrence) || targetOccurrence < 0) return null;

  const codeRanges = inlineCodeRanges(source);
  let matchedOccurrence = 0;
  let changed = false;
  const value = source.replace(imageAliasPattern(), (match, ...args) => {
    const offset = args.at(-2);
    if (isInsideRange(offset, codeRanges) || match !== target || matchedOccurrence++ !== targetOccurrence) return match;
    const parsed = parseImageAlias(match);
    if (!parsed) return match;
    changed = true;
    return buildImageAlias({ ...parsed, ...patch });
  });

  return changed ? value : null;
}