import matter from "gray-matter";
import { logger } from "../../utils/logger";
import type { ContentProcessorMiddleware, MiddlewareContext } from "./types";
/**
* Middleware to extract the title from Markdown content.
* Prioritizes YAML frontmatter 'title' field, falls back to first H1 heading.
*/
export class MarkdownMetadataExtractorMiddleware implements ContentProcessorMiddleware {
/**
* Processes the context to extract the title from Markdown.
* @param context The current processing context.
* @param next Function to call the next middleware.
*/
async process(context: MiddlewareContext, next: () => Promise<void>): Promise<void> {
try {
let title = "Untitled";
let frontmatterTitle: string | undefined;
// 1. Try to extract title from YAML frontmatter
try {
const file = matter(context.content);
if (file.data && file.data.title !== undefined && file.data.title !== null) {
// Convert to string to handle numeric titles (e.g. title: 2024)
frontmatterTitle = String(file.data.title).trim();
}
} catch (err) {
// Log warning but continue - don't crash the pipeline for bad frontmatter
logger.warn(
`Failed to parse markdown frontmatter: ${err instanceof Error ? err.message : String(err)}`,
);
}
if (frontmatterTitle && frontmatterTitle.length > 0) {
title = frontmatterTitle;
} else {
// 2. Fallback: Extract first H1 heading
const match = context.content.match(/^#\s+(.*)$/m);
if (match?.[1]) {
title = match[1].trim();
}
}
context.title = title;
} catch (error) {
context.errors.push(
new Error(
`Failed to extract metadata from Markdown: ${error instanceof Error ? error.message : String(error)}`,
),
);
}
await next();
}
}
