/**
* Content splitter for atomic note system
*
* Splits large content into hub + children structure while preserving links.
*
* Phase 018: Uses title-style filenames (Obsidian-native)
* - Hub filename = sanitized title (e.g., "Green Peppers.md")
* - Child filename = sanitized section title (e.g., "Climate Requirements.md")
*/
import { join, basename } from 'path';
import type {
ContentAnalysis,
SectionInfo,
SplitResult,
SplitOptions,
HubContent,
ChildContent,
HubFrontmatter,
ChildFrontmatter,
LinkUpdate,
} from '../../types/atomic.js';
import { analyzeContent } from './analyzer.js';
import { shouldSplit } from './decision.js';
import { titleToFilename } from '../../utils/slugify.js';
import { stripWikiLinks } from '../../utils/markdown.js';
/**
* Split content based on the recommended strategy
*/
export function splitContent(
content: string,
options: SplitOptions
): SplitResult {
const decision = shouldSplit(content);
const analysis = analyzeContent(content);
// Choose the appropriate split function
switch (options.strategy ?? decision.suggestedStrategy) {
case 'by_sections':
return splitBySections(content, analysis, options);
case 'by_large_sections':
return splitByLargeSections(content, analysis, options);
case 'by_sub_concepts':
return splitBySubConcepts(content, analysis, options);
case 'hierarchical':
return splitHierarchical(content, analysis, options);
default:
return splitBySections(content, analysis, options);
}
}
/**
* Split content by H2 sections
* Phase 018: Uses title-style filenames for hub and children
*/
export function splitBySections(
content: string,
analysis: ContentAnalysis,
options: SplitOptions
): SplitResult {
const lines = stripFrontmatter(content).split('\n');
const { title, targetDir } = options;
// Clean the title for use in filenames
const cleanTitle = stripWikiLinks(title);
const hubFilename = titleToFilename(cleanTitle);
// Extract introduction (content before first H2)
const introLines: string[] = [];
for (let i = 0; i < lines.length; i++) {
const line = lines[i] ?? '';
if (line.startsWith('## ') && !line.startsWith('### ')) {
break;
}
// Skip the H1 title if present
if (!line.startsWith('# ') || i > 0) {
introLines.push(line);
}
}
// Build hub content
const hub = buildHubContent(
cleanTitle,
introLines.join('\n').trim(),
analysis.sections,
targetDir,
hubFilename,
options
);
// Build children from sections
const children: ChildContent[] = [];
const linksUpdated: LinkUpdate[] = [];
const hubPath = join(targetDir, hubFilename);
for (const section of analysis.sections) {
const sectionLines = lines.slice(section.startLine, section.endLine + 1);
const sectionContent = sectionLines.join('\n');
// Create child note with title-style filename
const cleanSectionTitle = stripWikiLinks(section.title);
const childFilename = titleToFilename(cleanSectionTitle);
const childPath = join(targetDir, childFilename);
const child = buildChildContent(
cleanSectionTitle,
sectionContent,
childPath,
hubPath,
cleanSectionTitle,
options
);
children.push(child);
// Track link updates
linksUpdated.push({
fromPath: hubPath,
originalTarget: cleanTitle,
newTarget: childPath,
});
}
// Update hub with children links
hub.content = updateHubWithChildren(hub.content, children);
return { hub, children, linksUpdated };
}
/**
* Split by extracting large sections only
* Phase 018: Uses title-style filenames for hub and children
*/
export function splitByLargeSections(
content: string,
analysis: ContentAnalysis,
options: SplitOptions
): SplitResult {
const lines = stripFrontmatter(content).split('\n');
const { title, targetDir } = options;
// Clean the title for use in filenames
const cleanTitle = stripWikiLinks(title);
const hubFilename = titleToFilename(cleanTitle);
// Find sections to extract (only large ones)
const largeSectionTitles = new Set(analysis.largeSections);
const sectionsToExtract = analysis.sections.filter((s) =>
largeSectionTitles.has(s.title)
);
const sectionsToKeep = analysis.sections.filter(
(s) => !largeSectionTitles.has(s.title)
);
// Build retained content
const retainedLines: string[] = [];
// Add intro (before first section)
const firstSectionStart = analysis.sections[0]?.startLine ?? lines.length;
for (let i = 0; i < firstSectionStart; i++) {
const line = lines[i] ?? '';
if (!line.startsWith('# ')) {
retainedLines.push(line);
}
}
// Add kept sections
for (const section of sectionsToKeep) {
const sectionLines = lines.slice(section.startLine, section.endLine + 1);
retainedLines.push('', ...sectionLines);
}
// Build hub
const hub = buildHubContent(
cleanTitle,
retainedLines.join('\n').trim(),
sectionsToExtract,
targetDir,
hubFilename,
options
);
// Build children from extracted sections
const children: ChildContent[] = [];
const linksUpdated: LinkUpdate[] = [];
const hubPath = join(targetDir, hubFilename);
for (const section of sectionsToExtract) {
const sectionLines = lines.slice(section.startLine, section.endLine + 1);
const sectionContent = sectionLines.join('\n');
// Create child note with title-style filename
const cleanSectionTitle = stripWikiLinks(section.title);
const childFilename = titleToFilename(cleanSectionTitle);
const childPath = join(targetDir, childFilename);
const child = buildChildContent(
cleanSectionTitle,
sectionContent,
childPath,
hubPath,
cleanSectionTitle,
options
);
children.push(child);
}
// Update hub with children links
hub.content = updateHubWithChildren(hub.content, children);
return { hub, children, linksUpdated };
}
/**
* Split by sub-concepts (H3+ headings)
* Phase 018: Uses title-style filenames for hub and children
*/
export function splitBySubConcepts(
content: string,
analysis: ContentAnalysis,
options: SplitOptions
): SplitResult {
const lines = stripFrontmatter(content).split('\n');
const { title, targetDir } = options;
// Clean the title for use in filenames
const cleanTitle = stripWikiLinks(title);
const hubFilename = titleToFilename(cleanTitle);
// Group sub-concepts by parent section
const groupedConcepts = new Map<string, typeof analysis.subConcepts>();
for (const subConcept of analysis.subConcepts) {
const parent = subConcept.parentSection ?? 'Overview';
const existing = groupedConcepts.get(parent) ?? [];
existing.push(subConcept);
groupedConcepts.set(parent, existing);
}
// Build hub with section summaries
const hubLines: string[] = [`# ${cleanTitle}`, ''];
// Add intro (before first section)
const firstSectionStart = analysis.sections[0]?.startLine ?? lines.length;
for (let i = 0; i < firstSectionStart; i++) {
const line = lines[i] ?? '';
if (!line.startsWith('# ')) {
hubLines.push(line);
}
}
const children: ChildContent[] = [];
const linksUpdated: LinkUpdate[] = [];
const hubPath = join(targetDir, hubFilename);
// Process each sub-concept
for (const subConcept of analysis.subConcepts) {
const subConceptLines = lines.slice(subConcept.startLine, subConcept.endLine + 1);
const subConceptContent = subConceptLines.join('\n');
// Create child note with title-style filename
const cleanSubConceptTitle = stripWikiLinks(subConcept.title);
const childFilename = titleToFilename(cleanSubConceptTitle);
const childPath = join(targetDir, childFilename);
// Promote heading to H2 for child note
const promotedContent = subConceptContent.replace(
/^#{3,6}\s+/,
'## '
);
const child = buildChildContent(
cleanSubConceptTitle,
promotedContent,
childPath,
hubPath,
cleanSubConceptTitle,
options
);
children.push(child);
}
const now = new Date().toISOString();
const hubFrontmatter: HubFrontmatter = {
type: `${options.originalFrontmatter?.type ?? 'research'}_hub`,
title: cleanTitle,
status: 'active',
children_count: children.length,
domain: options.domain,
created: (options.originalFrontmatter?.created as string) ?? now,
modified: now,
palace: {
version: 1,
...(options.layer ? { layer: options.layer } : {}),
},
};
const hub: HubContent = {
title: cleanTitle,
relativePath: join(targetDir, hubFilename),
content: hubLines.join('\n'),
frontmatter: hubFrontmatter,
};
// Update hub with children links
hub.content = updateHubWithChildren(hub.content, children);
return { hub, children, linksUpdated };
}
/**
* Create hierarchical structure with sub-hubs
*/
export function splitHierarchical(
content: string,
analysis: ContentAnalysis,
options: SplitOptions
): SplitResult {
// For now, delegate to section-based split
// In future, this could create nested hub structures
return splitBySections(content, analysis, options);
}
/**
* Build hub content structure
*/
function buildHubContent(
title: string,
introContent: string,
sections: SectionInfo[],
targetDir: string,
hubFilename: string,
options: SplitOptions
): HubContent {
const now = new Date().toISOString();
const frontmatter: HubFrontmatter = {
type: `${options.originalFrontmatter?.type ?? 'research'}_hub`,
title,
status: 'active',
children_count: sections.length,
domain: options.domain,
created: (options.originalFrontmatter?.created as string) ?? now,
modified: now,
palace: {
version: 1,
...(options.layer ? { layer: options.layer } : {}),
},
};
// Preserve additional original frontmatter
if (options.originalFrontmatter) {
const preserve = ['tags', 'aliases', 'source', 'confidence'];
for (const key of preserve) {
if (options.originalFrontmatter[key] !== undefined) {
frontmatter[key] = options.originalFrontmatter[key];
}
}
}
// Strip wiki-links from title to prevent heading corruption
const cleanTitle = stripWikiLinks(title);
const hubContent = `# ${cleanTitle}
${introContent}
## Knowledge Map
`;
return {
title: cleanTitle,
relativePath: join(targetDir, hubFilename),
content: hubContent,
frontmatter,
};
}
/**
* Build child content structure
* Phase 018: No parent field in frontmatter - use inline links instead (Zettelkasten style)
*/
function buildChildContent(
title: string,
sectionContent: string,
childPath: string,
hubPath: string,
fromSection: string,
options: SplitOptions
): ChildContent {
const now = new Date().toISOString();
// Strip wiki-links from title to prevent heading corruption
const cleanTitle = stripWikiLinks(title);
// Convert section heading to H1 and strip any wiki-links from it
let processedContent = sectionContent;
if (sectionContent.startsWith('## ')) {
const lines = sectionContent.split('\n');
// Replace ## with # and strip any wiki-links from the heading
const headingText = (lines[0] ?? '').replace(/^##\s+/, '');
lines[0] = `# ${stripWikiLinks(headingText)}`;
processedContent = lines.join('\n');
}
// Phase 018: No parent field - use inline links instead (Zettelkasten style)
const frontmatter: ChildFrontmatter = {
type: (options.originalFrontmatter?.type as string) ?? 'research',
title: cleanTitle,
status: 'active',
domain: options.domain,
created: (options.originalFrontmatter?.created as string) ?? now,
modified: now,
palace: {
version: 1,
...(options.layer ? { layer: options.layer } : {}),
},
};
return {
title: cleanTitle,
relativePath: childPath,
content: processedContent,
frontmatter,
fromSection,
};
}
/**
* Update hub content with links to children
* Phase 018: With title-style filenames, we can use title directly as link
*/
function updateHubWithChildren(
hubContent: string,
children: ChildContent[]
): string {
const childLinks = children.map((child) => {
// With title-style filenames, the filename (without .md) IS the title
// So [[Climate Requirements]] links to "Climate Requirements.md"
return `- [[${child.title}]]`;
});
return `${hubContent}
${childLinks.join('\n')}
## Related
`;
}
/**
* Strip frontmatter from content
*/
function stripFrontmatter(content: string): string {
const lines = content.split('\n');
if (lines[0] !== '---') {
return content;
}
let endIndex = -1;
for (let i = 1; i < lines.length; i++) {
if (lines[i] === '---') {
endIndex = i;
break;
}
}
if (endIndex === -1) {
return content;
}
return lines.slice(endIndex + 1).join('\n').trim();
}
/**
* Update wiki-links in content to point to new locations
*/
export function updateLinksInContent(
content: string,
linkUpdates: LinkUpdate[]
): string {
let updated = content;
for (const update of linkUpdates) {
// Update [[target]] and [[target|display]] formats
const escapedTarget = update.originalTarget.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
const linkRegex = new RegExp(
`\\[\\[${escapedTarget}(\\|[^\\]]+)?\\]\\]`,
'g'
);
updated = updated.replace(linkRegex, (match, display) => {
const newTarget = basename(update.newTarget, '.md');
return display ? `[[${newTarget}${display}]]` : `[[${newTarget}]]`;
});
}
return updated;
}
/**
* Check if splitting would result in valid atomic notes
*/
export function validateSplitResult(result: SplitResult, maxLines: number = 200): boolean {
// Check hub
const hubLines = result.hub.content.split('\n').length;
if (hubLines > 150) {
return false;
}
// Check children
for (const child of result.children) {
const childLines = child.content.split('\n').length;
if (childLines > maxLines) {
return false;
}
}
return true;
}
