mergeContent method

String mergeContent(String local, String remote, { String? base, })

Merge two versions of a memory file.

Implementation

String mergeContent(String local, String remote, {String? base}) {
  final localSections = MemoryParser.parse(local);
  final remoteSections = MemoryParser.parse(remote);
  final baseSections = base != null
      ? MemoryParser.parse(base)
      : <MemorySection>[];

  final mergedSections = <MemorySection>[];
  final processedHeadings = <String>{};

  // Process local sections.
  for (final ls in localSections) {
    final rs = remoteSections
        .where((s) => s.heading == ls.heading)
        .firstOrNull;
    final bs = baseSections.where((s) => s.heading == ls.heading).firstOrNull;

    processedHeadings.add(ls.heading);

    if (rs == null) {
      // Only in local — keep if new (not in base) or if modified.
      if (bs == null || ls.content != bs.content) {
        mergedSections.add(ls);
      }
    } else if (ls.content == rs.content) {
      // Same in both — keep.
      mergedSections.add(ls);
    } else if (bs != null) {
      // Three-way merge.
      if (ls.content == bs.content) {
        // Only remote changed.
        mergedSections.add(
          MemorySection(
            heading: ls.heading,
            level: ls.level,
            content: rs.content,
          ),
        );
      } else if (rs.content == bs.content) {
        // Only local changed.
        mergedSections.add(ls);
      } else {
        // Both changed — concatenate with markers.
        mergedSections.add(
          MemorySection(
            heading: ls.heading,
            level: ls.level,
            content:
                '${ls.content}\n\n<!-- Remote changes -->\n${rs.content}',
          ),
        );
      }
    } else {
      // No base — concatenate.
      mergedSections.add(
        MemorySection(
          heading: ls.heading,
          level: ls.level,
          content: '${ls.content}\n\n${rs.content}',
        ),
      );
    }
  }

  // Add remote-only sections.
  for (final rs in remoteSections) {
    if (!processedHeadings.contains(rs.heading)) {
      mergedSections.add(rs);
    }
  }

  return MemoryParser.build(mergedSections);
}