const fs = require('fs');
const path = require('path');

// A simple key regex to prevent path traversal
const validKeyRegex = /^[a-zA-Z0-9]+$/;

// handles saving and retrieving all documents
class FileDocumentStore {
    constructor(options) {
        this.basePath = options.path || './data';
        this.logger = options.logger;
        this.logger.info('Path to data: ' + this.basePath);
        // Create directory if it does not exist
        if (!fs.existsSync(this.basePath)) {
            fs.mkdirSync(this.basePath, { recursive: true, mode: '700' });
        }
    }

    // saves a new file to the filesystem
    set(key, data, callback) {
        if (!validKeyRegex.test(key)) {
            this.logger.warn(`Invalid key provided for set: ${key}`);
            return callback(false);
        }

        const resolvedBasePath = path.resolve(this.basePath);
        const filePath = path.resolve(resolvedBasePath, key);

        // Security check to ensure we are not writing outside of the data directory
        if (path.dirname(filePath) !== resolvedBasePath) {
            this.logger.error(`Path traversal attempt detected for key: ${key}`);
            return callback(false);
        }

        fs.writeFile(filePath, data, 'utf8', (err) => {
            if (err) {
                this.logger.error('Error writing file:', err);
                callback(false);
            } else {
                callback(true);
            }
        });
    }

    // gets an existing file from the filesystem
    get(key, callback) {
        if (!validKeyRegex.test(key)) {
            this.logger.warn(`Invalid key provided for get: ${key}`);
            return callback(false);
        }

        const resolvedBasePath = path.resolve(this.basePath);
        const filePath = path.resolve(resolvedBasePath, key);

        // Security check to ensure we are not reading outside of the data directory
        if (path.dirname(filePath) !== resolvedBasePath) {
            this.logger.error(`Path traversal attempt detected for key: ${key}`);
            return callback(false);
        }

        fs.readFile(filePath, 'utf8', (err, data) => {
            if (err) {
                // Don't log error if file just doesn't exist
                if (err.code !== 'ENOENT') {
                    this.logger.error('Error reading file:', err);
                }
                callback(false);
            } else {
                callback(data);
            }
        });
    }
}

module.exports = FileDocumentStore;