theseus/addon-build/docx-editor/patches.mjs

// Build-time patches applied to vendored mammoth.
//
// Why: mammoth's document model deliberately drops direct formatting that
// isn't semantic — run colour, paragraph line/space spacing — and flattens
// every numbering level to a bare isOrdered boolean. All three are v1 editor
// features (text colour, line spacing, numbered-list formats), so without
// these a document would visibly lose them on the first round-trip.
//
// Each patch asserts its anchor: if a mammoth upgrade moves the code, the
// build fails loudly instead of silently shipping an editor that eats
// formatting.
export const patches = [
  {
    file: "lib/docx/body-reader.js",
    find: `                highlight: readHighlightValue(element.firstOrEmpty("w:highlight").attributes["w:val"])`,
    replace: `                highlight: readHighlightValue(element.firstOrEmpty("w:highlight").attributes["w:val"]),
                color: readColorValue(element.firstOrEmpty("w:color").attributes["w:val"])`,
  },
  {
    file: "lib/docx/body-reader.js",
    find: `    function readUnderline(element) {`,
    replace: `    function readColorValue(value) {
        // w:color w:val is RRGGBB, or "auto" meaning "let the renderer pick".
        return /^[0-9a-fA-F]{6}$/.test(value || "") ? value.toUpperCase() : null;
    }

    function readParagraphSpacing(element) {
        var attrs = element.attributes;
        var line = attrs["w:line"];
        var num = function(v) { return /^-?[0-9]+$/.test(v || "") ? parseInt(v, 10) : null; };
        return {
            // w:line is 240ths of a line when w:lineRule is auto (the common
            // case); exact/atLeast are in twips and the reader leaves them be.
            line: num(line),
            lineRule: attrs["w:lineRule"] || null,
            before: num(attrs["w:before"]),
            after: num(attrs["w:after"])
        };
    }

    function readUnderline(element) {`,
  },
  {
    file: "lib/docx/body-reader.js",
    find: `                indent: readParagraphIndent(element.firstOrEmpty("w:ind"))`,
    replace: `                indent: readParagraphIndent(element.firstOrEmpty("w:ind")),
                spacing: readParagraphSpacing(element.firstOrEmpty("w:spacing")),
                // Word's horizontal rule is an empty paragraph with a bottom
                // border; without this the editor can't tell one from a
                // blank line, and can't write one back either.
                hasBottomBorder: readHasBottomBorder(element.firstOrEmpty("w:pBdr"))`,
  },
  {
    file: "lib/docx/body-reader.js",
    find: `    function readParagraphIndent(element) {`,
    replace: `    function readHasBottomBorder(element) {
        var bottom = element.firstOrEmpty("w:bottom").attributes["w:val"];
        return !!bottom && bottom !== "none" && bottom !== "nil";
    }

    function readParagraphIndent(element) {`,
  },
  // Images: mammoth hands back the file but not the size Word was drawing it
  // at (wp:extent, in EMU). Without it a picture the author scaled down to a
  // thumbnail would come back at full natural size on the next save.
  {
    file: "lib/docx/body-reader.js",
    find: `        return readImage(blipImageFile, altText).map(function(imageElement) {`,
    replace: `        var extentAttributes = element.firstOrEmpty("wp:extent").attributes;
        return readImage(blipImageFile, altText, extentAttributes).map(function(imageElement) {`,
  },
  {
    file: "lib/docx/body-reader.js",
    find: `    function readImage(imageFile, altText) {
        var contentType = contentTypes.findContentType(imageFile.path);

        var image = documents.Image({
            readImage: imageFile.read,
            altText: altText,
            contentType: contentType
        });`,
    replace: `    function readImage(imageFile, altText, extent) {
        var contentType = contentTypes.findContentType(imageFile.path);

        // 12700 EMU to the point.
        var emuToPt = function(v) {
            return /^[0-9]+$/.test(v || "") ? Math.round(parseInt(v, 10) / 12700 * 100) / 100 : null;
        };
        var image = documents.Image({
            readImage: imageFile.read,
            altText: altText,
            contentType: contentType,
            widthPt: emuToPt(extent && extent.cx),
            heightPt: emuToPt(extent && extent.cy)
        });`,
  },
  {
    file: "lib/documents.js",
    find: `        altText: options.altText,
        contentType: options.contentType`,
    replace: `        altText: options.altText,
        contentType: options.contentType,
        widthPt: options.widthPt == null ? null : options.widthPt,
        heightPt: options.heightPt == null ? null : options.heightPt`,
  },
  {
    file: "lib/documents.js",
    find: `        highlight: properties.highlight || null
    };
}`,
    replace: `        highlight: properties.highlight || null,
        color: properties.color || null
    };
}`,
  },
  {
    file: "lib/documents.js",
    find: `        indent: {
            start: indent.start || null,
            end: indent.end || null,
            firstLine: indent.firstLine || null,
            hanging: indent.hanging || null
        }
    };`,
    replace: `        indent: {
            start: indent.start || null,
            end: indent.end || null,
            firstLine: indent.firstLine || null,
            hanging: indent.hanging || null
        },
        spacing: properties.spacing || null,
        hasBottomBorder: !!properties.hasBottomBorder
    };`,
  },
  // Which numbering definition a list item belongs to. Word uses numId to
  // tell two adjacent lists apart — the point at which the numbering starts
  // again at 1 — and mammoth resolves it to a level and then forgets it,
  // which leaves the reader unable to see where one list ends and the next
  // begins.
  {
    file: "lib/docx/body-reader.js",
    find: `function readNumberingProperties(styleId, element, numbering) {
    var level = element.firstOrEmpty("w:ilvl").attributes["w:val"];
    var numId = element.firstOrEmpty("w:numId").attributes["w:val"];
    if (level !== undefined && numId !== undefined) {
        return numbering.findLevel(numId, level);
    }`,
    replace: `function readNumberingProperties(styleId, element, numbering) {
    var level = element.firstOrEmpty("w:ilvl").attributes["w:val"];
    var numId = element.firstOrEmpty("w:numId").attributes["w:val"];
    var withNumId = function(found, id) {
        return found == null ? found : Object.assign({}, found, {numId: id == null ? null : String(id)});
    };
    if (level !== undefined && numId !== undefined) {
        return withNumId(numbering.findLevel(numId, level), numId);
    }`,
  },
  {
    file: "lib/docx/body-reader.js",
    find: `    if (numId !== undefined) {
        return numbering.findLevel(numId, "0");
    }

    return null;
}`,
    replace: `    if (numId !== undefined) {
        return withNumId(numbering.findLevel(numId, "0"), numId);
    }

    return null;
}`,
  },
  {
    file: "lib/docx/numbering-xml.js",
    find: `            levelWithoutIndex = {
                isOrdered: isOrdered,`,
    replace: `            levelWithoutIndex = {
                numFmt: numFmt || null,
                isOrdered: isOrdered,`,
  },
  {
    file: "lib/docx/numbering-xml.js",
    find: `            levels[levelIndex] = {
                isOrdered: isOrdered,`,
    replace: `            levels[levelIndex] = {
                numFmt: numFmt || null,
                isOrdered: isOrdered,`,
  },
];

export function applyPatches(relPath, source) {
  let out = source;
  let hits = 0;
  for (const p of patches) {
    if (relPath !== "mammoth/" + p.file) continue;
    if (!out.includes(p.find)) {
      throw new Error(`mammoth patch anchor missing in ${p.file}:\n${p.find.slice(0, 90)}…\n` +
        `A mammoth upgrade probably moved it. Re-check the patch before shipping.`);
    }
    out = out.replace(p.find, p.replace);
    hits++;
  }
  return { code: out, hits };
}