MarkdownParser.ts•5.96 kB
/**
* MarkdownParser - Parse markdown files for Writer's Aid
* Extracts frontmatter, headings, and content structure
*/
import { nanoid } from "nanoid";
import { createHash } from "crypto";
import type {
MarkdownFile,
MarkdownHeading,
Frontmatter,
} from "../markdown/types.js";
/**
* Result of parsing a markdown file
*/
export interface ParseResult {
file: MarkdownFile;
headings: MarkdownHeading[];
frontmatter: Frontmatter;
contentWithoutFrontmatter: string;
}
/**
* MarkdownParser class
*/
export class MarkdownParser {
/**
* Parse a markdown file
*/
parse(filePath: string, content: string): ParseResult {
const lines = content.split("\n");
// Extract frontmatter
const { frontmatter, contentStartLine } = this.extractFrontmatter(lines);
// Get content without frontmatter
const contentWithoutFrontmatter = lines.slice(contentStartLine).join("\n");
// Extract headings
const headings = this.extractHeadings(
lines,
contentStartLine,
filePath
);
// Calculate metadata
const contentHash = createHash("sha256")
.update(content)
.digest("hex");
const wordCount = this.countWords(contentWithoutFrontmatter);
const now = Date.now();
// Create file record
const file: MarkdownFile = {
id: nanoid(),
file_path: filePath,
title: frontmatter.title || this.extractTitleFromContent(headings),
content,
content_hash: contentHash,
word_count: wordCount,
created_at: now,
last_modified: now,
indexed_at: now,
};
return {
file,
headings,
frontmatter,
contentWithoutFrontmatter,
};
}
/**
* Extract YAML frontmatter from markdown
*/
private extractFrontmatter(
lines: string[]
): { frontmatter: Frontmatter; contentStartLine: number } {
const frontmatter: Frontmatter = {};
let contentStartLine = 0;
// Check for frontmatter (starts with ---)
if (lines[0]?.trim() === "---") {
let endLine = -1;
// Find closing ---
for (let i = 1; i < lines.length; i++) {
if (lines[i].trim() === "---") {
endLine = i;
break;
}
}
if (endLine > 0) {
// Parse YAML frontmatter
const yamlLines = lines.slice(1, endLine);
for (const line of yamlLines) {
const colonIndex = line.indexOf(":");
if (colonIndex > 0) {
const key = line.substring(0, colonIndex).trim();
let value: string | string[] | boolean = line
.substring(colonIndex + 1)
.trim();
// Handle arrays (e.g., tags: [foo, bar])
if (value.startsWith("[") && value.endsWith("]")) {
value = value
.slice(1, -1)
.split(",")
.map((v) => v.trim().replace(/^['"]|['"]$/g, ""));
}
// Handle booleans
else if (value === "true" || value === "false") {
value = value === "true";
}
// Remove quotes from strings
else if (
(value.startsWith('"') && value.endsWith('"')) ||
(value.startsWith("'") && value.endsWith("'"))
) {
value = value.slice(1, -1);
}
frontmatter[key] = value;
}
}
contentStartLine = endLine + 1;
}
}
return { frontmatter, contentStartLine };
}
/**
* Extract headings from markdown
*/
private extractHeadings(
lines: string[],
startLine: number,
fileId: string
): MarkdownHeading[] {
const headings: MarkdownHeading[] = [];
const headingStack: Array<{ level: number; id: string }> = [];
for (let i = startLine; i < lines.length; i++) {
const line = lines[i];
const headingMatch = line.match(/^(#{1,6})\s+(.+)$/);
if (headingMatch) {
const level = headingMatch[1].length;
const text = headingMatch[2].trim();
const slug = this.createSlug(text);
const id = nanoid();
// Find parent heading
let parentId: string | null = null;
// Pop stack until we find a heading with lower level
while (
headingStack.length > 0 &&
headingStack[headingStack.length - 1].level >= level
) {
headingStack.pop();
}
// Parent is the top of stack (if exists)
if (headingStack.length > 0) {
parentId = headingStack[headingStack.length - 1].id;
}
headings.push({
id,
file_id: fileId,
level,
text,
slug,
line_number: i + 1, // 1-indexed
parent_id: parentId,
});
// Push current heading onto stack
headingStack.push({ level, id });
}
}
return headings;
}
/**
* Create URL-friendly slug from heading text
*/
private createSlug(text: string): string {
return text
.toLowerCase()
.replace(/[^\w\s-]/g, "") // Remove special chars
.replace(/\s+/g, "-") // Replace spaces with hyphens
.replace(/-+/g, "-") // Replace multiple hyphens with single
.replace(/^-|-$/g, ""); // Remove leading/trailing hyphens
}
/**
* Extract title from first h1 heading
*/
private extractTitleFromContent(
headings: MarkdownHeading[]
): string | null {
const firstH1 = headings.find((h) => h.level === 1);
return firstH1?.text || null;
}
/**
* Count words in text
*/
private countWords(text: string): number {
// Remove code blocks
const withoutCodeBlocks = text.replace(/```[\s\S]*?```/g, "");
// Remove inline code
const withoutInlineCode = withoutCodeBlocks.replace(/`[^`]*`/g, "");
// Count words (split by whitespace)
const words = withoutInlineCode.trim().split(/\s+/);
return words[0] === "" ? 0 : words.length;
}
}