excel-parser-mcp/dist/detectors/file-detector.js

MCP server for parsing Excel documents and extracting test case data

import { fileTypeFromBuffer } from 'file-type';
import { SUPPORTED_FORMATS } from '../types/index.js';
export class FileTypeDetector {
    async detectExcelType(buffer) {
        try {
            // 方法1: 使用 file-type 库检测 MIME 类型
            const fileType = await fileTypeFromBuffer(buffer);
            if (fileType && SUPPORTED_FORMATS.includes(fileType.mime)) {
                return fileType.mime === 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' ? 'xlsx' : 'xls';
            }
            // 方法2: 检测魔术字节
            const magicType = this.detectByMagicBytes(buffer);
            if (magicType !== 'unknown') {
                return magicType;
            }
            return 'unknown';
        }
        catch (error) {
            console.warn('文件类型检测失败:', error);
            return 'unknown';
        }
    }
    detectByMagicBytes(buffer) {
        // Excel 2007+ (.xlsx) - 以 PK 开头的 ZIP 文件
        if (buffer.length >= 4 &&
            buffer[0] === 0x50 && buffer[1] === 0x4B &&
            (buffer[2] === 0x03 || buffer[2] === 0x05) &&
            (buffer[3] === 0x04 || buffer[3] === 0x06)) {
            // 进一步检查是否包含 Excel 特有的内容
            const content = buffer.toString('utf8');
            if (content.includes('xl/workbook.xml') ||
                content.includes('xl/worksheets/') ||
                content.includes('xl/sharedStrings.xml')) {
                return 'xlsx';
            }
        }
        // Excel 97-2003 (.xls) - Microsoft Office 文档格式
        if (buffer.length >= 8) {
            const signature = buffer.subarray(0, 8);
            const oleCfsSignature = Buffer.from([0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1]);
            if (signature.equals(oleCfsSignature)) {
                return 'xls';
            }
        }
        return 'unknown';
    }
    detectByFilename(filename) {
        const ext = filename.toLowerCase().split('.').pop();
        switch (ext) {
            case 'xlsx':
                return 'xlsx';
            case 'xls':
                return 'xls';
            default:
                return 'unknown';
        }
    }
    async isExcelFile(buffer, filename) {
        const detectedType = await this.detectExcelType(buffer);
        if (detectedType !== 'unknown') {
            return true;
        }
        // 如果魔术字节检测失败，尝试文件名检测
        if (filename) {
            const filenameType = this.detectByFilename(filename);
            return filenameType !== 'unknown';
        }
        return false;
    }
    validateFileSize(buffer, maxSize = 50 * 1024 * 1024) {
        return buffer.length <= maxSize;
    }
    validateFileIntegrity(buffer) {
        try {
            // 基本的文件完整性检查
            if (buffer.length < 512) {
                return false; // 文件过小，不可能是有效的 Excel 文件
            }
            // 检查是否有足够的数据进行解析
            return buffer.length > 0 && !this.isCorrupted(buffer);
        }
        catch {
            return false;
        }
    }
    isCorrupted(buffer) {
        // 简单的损坏检测
        // 检查文件是否全为零字节
        const isAllZeros = buffer.every(byte => byte === 0);
        if (isAllZeros)
            return true;
        // 检查文件是否全为相同字节
        const firstByte = buffer[0];
        const isAllSame = buffer.every(byte => byte === firstByte);
        if (isAllSame && buffer.length > 100)
            return true;
        return false;
    }
}
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