feat: Initial clean release of CHM

packages/lib/services/conflict/autoMergeNote.ts

@@ -0,0 +1,57 @@
+import { autoMerge, MergedSection } from './diffNotes';
+
+export interface NoteVersion {
+	title: string;
+	body: string;
+}
+
+// A title is a conflict only when the both sides changed it differently
+export const mergeTitle = (base: string, local: string, remote: string) => {
+	if (local === remote) return { merged: local, conflict: false };
+	if (base === local) return { merged: remote, conflict: false };
+	if (base === remote) return { merged: local, conflict: false };
+	return { merged: '', conflict: true };
+};
+
+// Only conflict sections differ between the two sides; everything else is shared between them
+const buildBody = (sections: MergedSection[], conflictSide: 'localText' | 'remoteText'): string => {
+	const lineCount = conflictSide === 'localText' ? 'localLineCount' : 'remoteLineCount';
+	return sections
+		.filter(section => section.type !== 'conflict' || section[lineCount] !== 0)
+		.map(section => section.type === 'conflict' ? (section[conflictSide] ?? '') : section.text)
+		.join('\n');
+};
+
+export interface PartialMergeResult {
+	fullyMerged: boolean;
+	// Non-conflicting changes are merged, and any remaining conflicts keep the user's version
+	resolvedLocal: NoteVersion;
+	// Same, but remaining conflicts kept as the incoming side
+	resolvedCurrent: NoteVersion;
+}
+
+export default (base: NoteVersion, local: NoteVersion, remote: NoteVersion): PartialMergeResult => {
+	const title = mergeTitle(base.title ?? '', local.title ?? '', remote.title ?? '');
+
+	const localBody = local.body ?? '';
+	const remoteBody = remote.body ?? '';
+
+	if (localBody === remoteBody && !title.conflict) {
+		return { fullyMerged: true, resolvedLocal: { title: title.merged, body: localBody }, resolvedCurrent: { title: title.merged, body: localBody } };
+	}
+
+	const merged = autoMerge(base.body ?? '', localBody, remoteBody);
+	const bodyFullyMerged = !merged.sections.some(s => s.type === 'conflict');
+
+	return {
+		fullyMerged: bodyFullyMerged && !title.conflict,
+		resolvedLocal: {
+			title: title.conflict ? (local.title ?? '') : title.merged,
+			body: bodyFullyMerged ? merged.mergedText : buildBody(merged.sections, 'localText'),
+		},
+		resolvedCurrent: {
+			title: title.conflict ? (remote.title ?? '') : title.merged,
+			body: bodyFullyMerged ? merged.mergedText : buildBody(merged.sections, 'remoteText'),
+		},
+	};
+};