json-mcp-filter/build/strategies/LocalFileStrategy.js

MCP server providing JSON schema generation and filtering tools using quicktype

import { promises as fs } from 'fs';
import { resolve } from 'path';
import { JsonIngestionStrategy } from './JsonIngestionStrategy.js';
/**
 * Strategy for ingesting JSON from local file system files
 */
export class LocalFileStrategy extends JsonIngestionStrategy {
    maxFileSize = 50 * 1024 * 1024; // 50MB limit
    canHandle(source) {
        // Handle local file paths - not URLs
        // Covers: ./file.json, /abs/path/file.json, C:\Windows\file.json, file.json
        return !source.startsWith('http://') && !source.startsWith('https://');
    }
    async ingest(source) {
        try {
            // Resolve and validate file path - keeping existing logic
            const resolvedPath = resolve(source);
            // Check file size before reading
            let fileStats;
            try {
                fileStats = await fs.stat(resolvedPath);
            }
            catch (error) {
                return {
                    success: false,
                    error: {
                        type: 'file_not_found',
                        message: `File not found: ${resolvedPath}`,
                        details: error
                    }
                };
            }
            // Check if file size exceeds limit
            if (fileStats.size > this.maxFileSize) {
                return {
                    success: false,
                    error: {
                        type: 'content_too_large',
                        message: `File too large (${Math.round(fileStats.size / 1024 / 1024)}MB). This tool is optimized for JSON files under ${Math.round(this.maxFileSize / 1024 / 1024)}MB.`,
                        details: {
                            fileSize: fileStats.size,
                            maxSize: this.maxFileSize,
                            filePath: resolvedPath
                        }
                    }
                };
            }
            // Read file content - keeping existing error handling
            let jsonContent;
            try {
                jsonContent = await fs.readFile(resolvedPath, 'utf-8');
            }
            catch (error) {
                return {
                    success: false,
                    error: {
                        type: 'file_not_found',
                        message: `Failed to read file: ${resolvedPath}`,
                        details: error
                    }
                };
            }
            // Validate JSON content
            return this.validateJsonContent(jsonContent);
        }
        catch (error) {
            return {
                success: false,
                error: {
                    type: 'validation_error',
                    message: 'Unexpected error during file processing',
                    details: error
                }
            };
        }
    }
    getMetadata() {
        return {
            name: 'LocalFileStrategy',
            description: 'Reads JSON data from local file system with 50MB size limit',
            supportedSources: ['Local file paths (relative and absolute)', 'JSON files under 50MB']
        };
    }
}