docs-mcp-server

import crypto from "node:crypto"; import fs from "node:fs/promises"; import { ScraperError } from "../../utils/errors"; import { MimeTypeUtils } from "../../utils/mimeTypeUtils"; import { type ContentFetcher, type FetchOptions, FetchStatus, type RawContent, } from "./types"; /** * Fetches content from local file system. */ export class FileFetcher implements ContentFetcher { canFetch(source: string): boolean { return source.startsWith("file://"); } /** * Fetches the content of a file given a file:// URL, decoding percent-encoded paths as needed. * Uses enhanced MIME type detection for better source code file recognition. * Supports conditional fetching via ETag comparison for efficient refresh operations. */ async fetch(source: string, options?: FetchOptions): Promise<RawContent> { // Remove the file:// protocol prefix and handle both file:// and file:/// formats let filePath = source.replace(/^file:\/\/\/?/, ""); // Decode percent-encoded characters filePath = decodeURIComponent(filePath); // Ensure absolute path on Unix-like systems (if not already absolute) if (!filePath.startsWith("/") && process.platform !== "win32") { filePath = `/${filePath}`; } try { const stats = await fs.stat(filePath); // Generate current ETag from last modified time const currentEtag = crypto .createHash("md5") .update(stats.mtime.toISOString()) .digest("hex"); // Check if file has been modified (ETag comparison) if (options?.etag && options.etag === currentEtag) { // File hasn't changed - return NOT_MODIFIED status return { content: Buffer.from(""), mimeType: "text/plain", source, etag: currentEtag, lastModified: stats.mtime.toISOString(), status: FetchStatus.NOT_MODIFIED, }; } // File is new or has been modified - read the content const content = await fs.readFile(filePath); // Use enhanced MIME type detection that properly handles source code files const detectedMimeType = MimeTypeUtils.detectMimeTypeFromPath(filePath); const mimeType = detectedMimeType || "application/octet-stream"; return { content, mimeType, source, etag: currentEtag, lastModified: stats.mtime.toISOString(), status: FetchStatus.SUCCESS, // Don't assume charset for text files - let the pipeline detect it }; } catch (error: unknown) { // Check for file not found error if ((error as NodeJS.ErrnoException).code === "ENOENT") { return { content: Buffer.from(""), mimeType: "text/plain", source, status: FetchStatus.NOT_FOUND, }; } // For all other errors, throw a ScraperError throw new ScraperError( `Failed to read file ${filePath}: ${ (error as { message?: string }).message ?? "Unknown error" }`, false, error instanceof Error ? error : undefined, ); } } }