import { JsonManager } from './json_manager';
import { TcpCommunicator } from "./tcp_communicator";
import { operationCodes } from '../network/operation_codes';
import path from 'path';
import fs from 'fs';
import crypto from 'crypto';
import { ParsedMessage } from "../network/message_handler";

export class BackupRetrievalWorker {
    private userConfig: JsonManager;
    private applicationInfo: JsonManager;
    private readonly clientPort: number;
    private readonly destinationPath: string;
    private encryptionKey: Buffer | null = null;
    private iv: Buffer | null = null;
    private tcpCommunicator: TcpCommunicator | null = null;
    private stopRequested: boolean = false;
    private isBusy: boolean = false;

    constructor(userConfigPath: string, applicationInfoPath: string, clientPort: number, destinationPath: string) {
        this.userConfig = new JsonManager(userConfigPath);
        this.applicationInfo = new JsonManager(applicationInfoPath);
        this.clientPort = clientPort;
        this.destinationPath = destinationPath;
    }

    // Logging helper function
    private log(message: string, level: 'log' | 'error' = 'log'): void {
        const prefix = '[BackupRetrievalWorker]';
        if (level === 'error') {
            console.error(`${prefix} ${message}`);
        } else {
            console.log(`${prefix} ${message}`);
        }
    }

    async start(): Promise<void> {
        if(!this.stopRequested) return;
        this.isBusy = true;
        try {
            const userInfo = await this.userConfig.readValue('user_info');
            if (!userInfo || !userInfo.name) {
                throw new Error('User information or name is missing.');
            }
            const userName = userInfo.name;

            const encryptionData = await this.userConfig.readValue('encryption_key');
            if (!encryptionData || !encryptionData.key || !encryptionData.iv) {
                throw new Error('Encryption key or IV is missing.');
            }

            this.encryptionKey = Buffer.from(encryptionData.key, 'base64');
            this.iv = Buffer.from(encryptionData.iv, 'base64');

            const activeUsersIp = await this.applicationInfo.readValue('users_ip');
            if (!activeUsersIp || !activeUsersIp.length) {
                throw new Error('No active users found.');
            }

            for (const ip of activeUsersIp) {
                const success = await this.processBackupForIp(ip, userName);
                if (!success) {
                    throw new Error(`Failed to retrieve backup from ${ip}`);
                }
                this.log(`Backup retrieved successfully from ${ip}`);
            }

            process.send?.({ type: 'showAlert', message: 'Backup retrieval completed successfully.' });
            process.send?.({ type: 'changeContent', page: 'main_menu' });
        } catch (error: any) {
            this.log(`Error in BackupRetrievalWorker: ${error.message}`, 'error');
            process.send?.({ type: 'showAlert', message: `A problem occurred: ${error.message}` });
            process.send?.({ type: 'changeContent', page: 'main_menu' });
        }
        finally {
            this.isBusy = false;
        }

        if (global.gc) {
            global.gc();
        }
    }

    private async processBackupForIp(ip: string, userName: string): Promise<boolean> {
        this.tcpCommunicator = new TcpCommunicator(ip, this.clientPort);
        if (!await this.tcpCommunicator.connect()) {
            this.log(`Failed to connect to ${ip}`, 'error');
            return true;
        }

        const backupExists = await this.checkIfBackupExists(userName);
        if (!backupExists) {
            this.log(`No backup found for user ${userName} on IP ${ip}`);
            await this.tcpCommunicator.disconnect();
            return true;
        }

        const backupStructure = await this.requestBackupStructure(userName);
        if (!backupStructure || Object.keys(backupStructure).length === 0) {
            this.log(`No files found in backup structure for user ${userName} on IP ${ip}`);
            await this.tcpCommunicator.disconnect();
            return true;
        }

        for (const relativeFilePath of Object.keys(backupStructure)) {
            const fileRequestSuccess = await this.requestBackupFile(userName, relativeFilePath);
            if (!fileRequestSuccess) {
                await this.tcpCommunicator.disconnect();
                throw new Error(`Failed to retrieve file ${relativeFilePath} from backup for user ${userName} on IP ${ip}`);
            }
        }

        await this.tcpCommunicator.disconnect();
        return true;
    }

    private async checkIfBackupExists(userName: string): Promise<boolean> {
        if (!this.tcpCommunicator) return false;

        const metaInfo = { name: userName };
        if (!await this.tcpCommunicator.sendMessage(operationCodes.IS_BACKUP_CREATED, metaInfo)) return false;

        const response = await this.waitForResponse();
        return response?.metaInfo?.backupExists === true;
    }

    private async requestBackupStructure(userName: string): Promise<any> {
        if (!this.tcpCommunicator) return false;

        const metaInfo = { name: userName };
        if (!await this.tcpCommunicator.sendMessage(operationCodes.GET_BACKUP_STRUCTURE, metaInfo)) return null;

        const response = await this.waitForResponse();
        return response?.metaInfo?.structure || null;
    }

    private async requestBackupFile(userName: string, relativeFilePath: string): Promise<boolean> {
        if (!this.tcpCommunicator) return false;

        const metaInfo = { name: userName, relativeFilePath };
        if (!await this.tcpCommunicator.sendMessage(operationCodes.REQ_FILE_FROM_BACKUP, metaInfo)) return false;

        const response = await this.waitForResponse();
        if (response?.operationCode === operationCodes.OK && response.metaInfo && response.fileContent) {
            return this.saveFile(response.metaInfo.relativeFilePath, response.fileContent.toString('base64'));
        }
        return false;
    }

    private saveFile(relativeFilePath: string, fileContent: string): boolean {
        if (!this.encryptionKey || !this.iv) {
            throw new Error('Encryption key or IV is not set.');
        }

        let encryptedBuffer: Buffer;
        try {
            encryptedBuffer = Buffer.from(fileContent, 'base64');
        } catch (error: any) {
            throw new Error(`Error decoding base64 file content: ${error.message}`);
        }

        let decryptedContent: Buffer;
        try {
            const decipher = crypto.createDecipheriv('aes-256-cbc', this.encryptionKey, this.iv);
            decryptedContent = Buffer.concat([decipher.update(encryptedBuffer), decipher.final()]);
        } catch (error: any) {
            throw new Error(`Error decrypting file: ${error.message}`);
        }

        const fullFilePath = path.join(this.destinationPath, relativeFilePath);
        try {
            const dirPath = path.dirname(fullFilePath);
            if (!fs.existsSync(dirPath)) {
                fs.mkdirSync(dirPath, { recursive: true });
            }
            fs.writeFileSync(fullFilePath, decryptedContent);
            this.log(`File saved successfully: ${fullFilePath}`);
            return true;
        } catch (error: any) {
            throw new Error(`Error saving file ${relativeFilePath}: ${error.message}`);
        }
    }

    async stop(): Promise<void> {
        this.stopRequested = true; // Signal that stop is requested

        // Wait for any ongoing process to complete if busy
        while (this.isBusy) {
            await new Promise((resolve) => setTimeout(resolve, 100));
        }

        console.log("[BackupManager] Stopped successfully.");
    }

    private async waitForResponse(): Promise<ParsedMessage | null> {
        return new Promise((resolve) => {
            const idResponseCheck = setInterval(async () => {
                if (!this.tcpCommunicator) return null;
                if (this.tcpCommunicator.hasResponseArrived()) {
                    clearInterval(idResponseCheck);
                    resolve(this.tcpCommunicator.getLastResult());
                }
            }, 100);
        });
    }
}