import { Client, SFTPWrapper, Stats } from 'ssh2';
import { WebSocket } from 'ws';
import { ClientState } from '../websocket'; // 导入统一的 ClientState

// 定义服务器状态的数据结构 (与前端 StatusMonitor.vue 匹配)
// Note: This interface seems out of place here, but keeping it for now as it was in the original file.
// Ideally, it should be in a shared types file.
interface ServerStatus {
    cpuPercent?: number;
    memPercent?: number;
    memUsed?: number; // MB
    memTotal?: number; // MB
    swapPercent?: number;
    swapUsed?: number; // MB
    swapTotal?: number; // MB
    diskPercent?: number;
    diskUsed?: number; // KB
    diskTotal?: number; // KB
    cpuModel?: string;
    netRxRate?: number; // Bytes per second
    netTxRate?: number; // Bytes per second
    netInterface?: string;
    osName?: string;
    loadAvg?: number[]; // 系统平均负载 [1min, 5min, 15min]
    timestamp: number; // 状态获取时间戳
}

// Interface for parsed network stats - Also seems out of place here.
interface NetworkStats {
    [interfaceName: string]: {
        rx_bytes: number;
        tx_bytes: number;
    }
}

// Note: These constants seem related to StatusMonitorService, not SftpService.
const DEFAULT_POLLING_INTERVAL = 1000;
const previousNetStats = new Map<string, { rx: number, tx: number, timestamp: number }>();

export class SftpService {
    private clientStates: Map<string, ClientState>; // 使用导入的 ClientState

    constructor(clientStates: Map<string, ClientState>) {
        this.clientStates = clientStates;
    }

    /**
     * 初始化 SFTP 会话
     * @param sessionId 会话 ID
     */
    async initializeSftpSession(sessionId: string): Promise<void> {
        const state = this.clientStates.get(sessionId);
        if (!state || !state.sshClient || state.sftp) {
            console.warn(`[SFTP] 无法为会话 ${sessionId} 初始化 SFTP：状态无效、SSH客户端不存在或 SFTP 已初始化。`);
            return;
        }
        if (!state.sshClient) {
             console.error(`[SFTP] 会话 ${sessionId} 的 SSH 客户端不存在，无法初始化 SFTP。`);
             return;
        }
        return new Promise((resolve, reject) => {
            state.sshClient.sftp((err, sftpInstance) => {
                if (err) {
                    console.error(`[SFTP] 为会话 ${sessionId} 初始化 SFTP 会话失败:`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp_error', payload: { connectionId: state.dbConnectionId, message: 'SFTP 初始化失败' } }));
                    reject(err);
                } else {
                    console.log(`[SFTP] 为会话 ${sessionId} 初始化 SFTP 会话成功。`);
                    state.sftp = sftpInstance;
                    state.ws.send(JSON.stringify({ type: 'sftp_ready', payload: { connectionId: state.dbConnectionId } }));
                    sftpInstance.on('end', () => {
                        console.log(`[SFTP] 会话 ${sessionId} 的 SFTP 会话已结束。`);
                        if (state) state.sftp = undefined;
                    });
                    sftpInstance.on('close', () => {
                        console.log(`[SFTP] 会话 ${sessionId} 的 SFTP 会话已关闭。`);
                         if (state) state.sftp = undefined;
                    });
                    sftpInstance.on('error', (sftpErr: Error) => {
                         console.error(`[SFTP] 会话 ${sessionId} 的 SFTP 会话出错:`, sftpErr);
                         if (state) state.sftp = undefined;
                         state?.ws.send(JSON.stringify({ type: 'sftp_error', payload: { connectionId: state.dbConnectionId, message: 'SFTP 会话错误' } }));
                    });
                    resolve();
                }
            });
        });
    }

    /**
     * 清理 SFTP 会话
     * @param sessionId 会话 ID
     */
    cleanupSftpSession(sessionId: string): void {
        const state = this.clientStates.get(sessionId);
        if (state?.sftp) {
            console.log(`[SFTP] 正在清理 ${sessionId} 的 SFTP 会话...`);
            state.sftp.end();
            state.sftp = undefined;
        }
    }

    // --- SFTP 操作方法 ---

    /** 读取目录内容 */
    async readdir(sessionId: string, path: string, requestId: string): Promise<void> {
        const state = this.clientStates.get(sessionId);
        if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 readdir (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:readdir:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId }));
             return;
        }
        console.debug(`[SFTP ${sessionId}] Received readdir request for ${path} (ID: ${requestId})`);
        try {
            state.sftp.readdir(path, (err, list) => {
                 if (err) {
                    console.error(`[SFTP ${sessionId}] readdir ${path} failed (ID: ${requestId}):`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp:readdir:error', path: path, payload: `读取目录失败: ${err.message}`, requestId: requestId }));
                 } else {
                    const files = list.map((item) => ({
                        filename: item.filename,
                        longname: item.longname,
                        attrs: {
                            size: item.attrs.size, uid: item.attrs.uid, gid: item.attrs.gid, mode: item.attrs.mode,
                            atime: item.attrs.atime * 1000, mtime: item.attrs.mtime * 1000,
                            isDirectory: item.attrs.isDirectory(), isFile: item.attrs.isFile(), isSymbolicLink: item.attrs.isSymbolicLink(),
                         }
                     }));
                    state.ws.send(JSON.stringify({ type: 'sftp:readdir:success', path: path, payload: files, requestId: requestId }));
                 }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] readdir ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:readdir:error', path: path, payload: `读取目录时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    /** 获取文件/目录状态信息 */
    async stat(sessionId: string, path: string, requestId: string): Promise<void> {
        const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 stat (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:stat:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId })); // Use specific error type
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received stat request for ${path} (ID: ${requestId})`);
        try {
            state.sftp.lstat(path, (err, stats: Stats) => {
                if (err) {
                    console.error(`[SFTP ${sessionId}] stat ${path} failed (ID: ${requestId}):`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp:stat:error', path: path, payload: `获取状态失败: ${err.message}`, requestId: requestId }));
                } else {
                     const fileStats = {
                         size: stats.size, uid: stats.uid, gid: stats.gid, mode: stats.mode,
                         atime: stats.atime * 1000, mtime: stats.mtime * 1000,
                         isDirectory: stats.isDirectory(), isFile: stats.isFile(), isSymbolicLink: stats.isSymbolicLink(),
                     };
                    // Send specific success type
                    state.ws.send(JSON.stringify({ type: 'sftp:stat:success', path: path, payload: fileStats, requestId: requestId }));
                }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] stat ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:stat:error', path: path, payload: `获取状态时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    /** 读取文件内容 */
    async readFile(sessionId: string, path: string, requestId: string): Promise<void> {
         const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 readFile (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:readfile:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId }));
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received readFile request for ${path} (ID: ${requestId})`);
        try {
            const readStream = state.sftp.createReadStream(path);
            let fileData = Buffer.alloc(0);
            let errorOccurred = false;

            readStream.on('data', (chunk: Buffer) => { fileData = Buffer.concat([fileData, chunk]); });
            readStream.on('error', (err: Error) => {
                if (errorOccurred) return; errorOccurred = true;
                console.error(`[SFTP ${sessionId}] readFile ${path} stream error (ID: ${requestId}):`, err);
                state.ws.send(JSON.stringify({ type: 'sftp:readfile:error', path: path, payload: `读取文件流错误: ${err.message}`, requestId: requestId }));
            });
            readStream.on('end', () => {
                if (!errorOccurred) {
                    console.log(`[SFTP ${sessionId}] readFile ${path} success, size: ${fileData.length} bytes (ID: ${requestId})`);
                    state.ws.send(JSON.stringify({ type: 'sftp:readfile:success', path: path, payload: { content: fileData.toString('base64'), encoding: 'base64' }, requestId: requestId }));
                }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] readFile ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:readfile:error', path: path, payload: `读取文件时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    /** 写入文件内容 */
    async writefile(sessionId: string, path: string, data: string, requestId: string): Promise<void> {
         const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 writefile (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:writefile:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId }));
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received writefile request for ${path} (ID: ${requestId})`);
        try {
            const buffer = Buffer.from(data, 'utf8');
            console.debug(`[SFTP ${sessionId}] Creating write stream for ${path} (ID: ${requestId})`);
            const writeStream = state.sftp.createWriteStream(path);
            let errorOccurred = false;

            writeStream.on('error', (err: Error) => {
                if (errorOccurred) return; // Prevent sending multiple errors
                errorOccurred = true;
                console.error(`[SFTP ${sessionId}] writefile ${path} stream error (ID: ${requestId}):`, err);
                state.ws.send(JSON.stringify({ type: 'sftp:writefile:error', path: path, payload: `写入文件流错误: ${err.message}`, requestId: requestId }));
            });

            // Listen for the 'close' event which indicates the stream has finished writing and the file descriptor is closed.
            writeStream.on('close', () => {
                if (!errorOccurred) {
                    console.log(`[SFTP ${sessionId}] writefile ${path} stream closed successfully (ID: ${requestId})`);
                    state.ws.send(JSON.stringify({ type: 'sftp:writefile:success', path: path, requestId: requestId }));
                }
            });

            console.debug(`[SFTP ${sessionId}] Writing ${buffer.length} bytes to ${path} (ID: ${requestId})`);
            writeStream.end(buffer); // Start writing and close the stream afterwards
            console.debug(`[SFTP ${sessionId}] writefile ${path} end() called (ID: ${requestId})`);

            // Success message is now sent in the 'close' event handler

        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] writefile ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:writefile:error', path: path, payload: `写入文件时发生意外错误: ${error.message}`, requestId: requestId }));
         }
    }

    /** 创建目录 */
    async mkdir(sessionId: string, path: string, requestId: string): Promise<void> {
         const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 mkdir (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:mkdir:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId })); // Use specific error type
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received mkdir request for ${path} (ID: ${requestId})`);
        try {
            state.sftp.mkdir(path, (err) => {
                if (err) {
                    console.error(`[SFTP ${sessionId}] mkdir ${path} failed (ID: ${requestId}):`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp:mkdir:error', path: path, payload: `创建目录失败: ${err.message}`, requestId: requestId }));
                } else {
                    console.log(`[SFTP ${sessionId}] mkdir ${path} success (ID: ${requestId})`);
                    state.ws.send(JSON.stringify({ type: 'sftp:mkdir:success', path: path, requestId: requestId })); // Send specific success type
                }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] mkdir ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:mkdir:error', path: path, payload: `创建目录时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    /** 删除空目录 */
     async rmdir(sessionId: string, path: string, requestId: string): Promise<void> {
         const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 rmdir (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:rmdir:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId })); // Use specific error type
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received rmdir request for ${path} (ID: ${requestId})`);
        try {
            state.sftp.rmdir(path, (err) => {
                if (err) {
                    console.error(`[SFTP ${sessionId}] rmdir ${path} failed (ID: ${requestId}):`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp:rmdir:error', path: path, payload: `删除目录失败: ${err.message}`, requestId: requestId }));
                } else {
                    console.log(`[SFTP ${sessionId}] rmdir ${path} success (ID: ${requestId})`);
                    state.ws.send(JSON.stringify({ type: 'sftp:rmdir:success', path: path, requestId: requestId })); // Send specific success type
                }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] rmdir ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:rmdir:error', path: path, payload: `删除目录时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    /** 删除文件 */
     async unlink(sessionId: string, path: string, requestId: string): Promise<void> {
         const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 unlink (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:unlink:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId })); // Use specific error type
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received unlink request for ${path} (ID: ${requestId})`);
        try {
            state.sftp.unlink(path, (err) => {
                if (err) {
                    console.error(`[SFTP ${sessionId}] unlink ${path} failed (ID: ${requestId}):`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp:unlink:error', path: path, payload: `删除文件失败: ${err.message}`, requestId: requestId }));
                } else {
                    console.log(`[SFTP ${sessionId}] unlink ${path} success (ID: ${requestId})`);
                    state.ws.send(JSON.stringify({ type: 'sftp:unlink:success', path: path, requestId: requestId })); // Send specific success type
                }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] unlink ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:unlink:error', path: path, payload: `删除文件时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    /** 重命名/移动文件或目录 */
     async rename(sessionId: string, oldPath: string, newPath: string, requestId: string): Promise<void> {
         const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 rename (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:rename:error', oldPath: oldPath, newPath: newPath, payload: 'SFTP 会话未就绪', requestId: requestId })); // Use specific error type
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received rename request ${oldPath} -> ${newPath} (ID: ${requestId})`);
        try {
            state.sftp.rename(oldPath, newPath, (err) => {
                if (err) {
                    console.error(`[SFTP ${sessionId}] rename ${oldPath} -> ${newPath} failed (ID: ${requestId}):`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp:rename:error', oldPath: oldPath, newPath: newPath, payload: `重命名/移动失败: ${err.message}`, requestId: requestId }));
                } else {
                    console.log(`[SFTP ${sessionId}] rename ${oldPath} -> ${newPath} success (ID: ${requestId})`);
                    state.ws.send(JSON.stringify({ type: 'sftp:rename:success', oldPath: oldPath, newPath: newPath, requestId: requestId })); // Send specific success type
                }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] rename ${oldPath} -> ${newPath} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:rename:error', oldPath: oldPath, newPath: newPath, payload: `重命名/移动时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    /** 修改文件/目录权限 */
     async chmod(sessionId: string, path: string, mode: number, requestId: string): Promise<void> {
         const state = this.clientStates.get(sessionId);
         if (!state || !state.sftp) {
             console.warn(`[SFTP] SFTP 未准备好，无法在 ${sessionId} 上执行 chmod (ID: ${requestId})`);
             state?.ws.send(JSON.stringify({ type: 'sftp:chmod:error', path: path, payload: 'SFTP 会话未就绪', requestId: requestId })); // Use specific error type
             return;
         }
        console.debug(`[SFTP ${sessionId}] Received chmod request for ${path} to ${mode.toString(8)} (ID: ${requestId})`);
        try {
            state.sftp.chmod(path, mode, (err) => {
                if (err) {
                    console.error(`[SFTP ${sessionId}] chmod ${path} to ${mode.toString(8)} failed (ID: ${requestId}):`, err);
                    state.ws.send(JSON.stringify({ type: 'sftp:chmod:error', path: path, payload: `修改权限失败: ${err.message}`, requestId: requestId }));
                } else {
                    console.log(`[SFTP ${sessionId}] chmod ${path} to ${mode.toString(8)} success (ID: ${requestId})`);
                    state.ws.send(JSON.stringify({ type: 'sftp:chmod:success', path: path, requestId: requestId })); // Send specific success type
                }
            });
        } catch (error: any) {
             console.error(`[SFTP ${sessionId}] chmod ${path} caught unexpected error (ID: ${requestId}):`, error);
             state.ws.send(JSON.stringify({ type: 'sftp:chmod:error', path: path, payload: `修改权限时发生意外错误: ${error.message}`, requestId: requestId }));
        }
    }

    // TODO: Implement file upload/download logic with progress reporting
    // async uploadFile(...)
    // async downloadFile(...)

}