import { Readable } from "node:stream";
import {
	Injectable,
	InternalServerErrorException,
	Logger,
} from "@nestjs/common";
import { ConfigService } from "@nestjs/config";
import * as NodeClam from "clamscan";
import type {
	IMediaService,
	MediaProcessingResult,
	ScanResult,
} from "../common/interfaces/media.interface";
import { ImageProcessorStrategy } from "./strategies/image-processor.strategy";
import { VideoProcessorStrategy } from "./strategies/video-processor.strategy";

interface ClamScanner {
	scanStream(
		stream: Readable,
	): Promise<{ isInfected: boolean; viruses: string[] }>;
}

@Injectable()
export class MediaService implements IMediaService {
	private readonly logger = new Logger(MediaService.name);
	private clamscan: ClamScanner | null = null;
	private isClamAvInitialized = false;

	constructor(
		private readonly configService: ConfigService,
		private readonly imageProcessor: ImageProcessorStrategy,
		private readonly videoProcessor: VideoProcessorStrategy,
	) {
		this.initClamScan();
	}

	private async initClamScan() {
		try {
			const scanner = await new NodeClam().init({
				clamdscan: {
					host: this.configService.get<string>("CLAMAV_HOST", "localhost"),
					port: this.configService.get<number>("CLAMAV_PORT", 3310),
					timeout: 60000,
				},
				preference: "clamdscan",
			});
			this.clamscan = scanner;
			this.isClamAvInitialized = true;
			this.logger.log("ClamAV scanner initialized successfully");
		} catch (error) {
			this.logger.warn(
				`ClamAV scanner could not be initialized: ${error.message}. Antivirus scanning will be skipped.`,
			);
		}
	}

	async scanFile(buffer: Buffer, filename: string): Promise<ScanResult> {
		if (!this.isClamAvInitialized || !this.clamscan) {
			this.logger.warn("ClamAV not initialized, skipping scan");
			return { isInfected: false };
		}

		try {
			const stream = Readable.from(buffer);
			const { isInfected, viruses } = await this.clamscan.scanStream(stream);

			if (isInfected) {
				this.logger.error(
					`Virus detected in file ${filename}: ${viruses.join(", ")}`,
				);
			}

			return {
				isInfected,
				virusName: isInfected ? viruses[0] : undefined,
			};
		} catch (error) {
			this.logger.error(`Error scanning file ${filename}: ${error.message}`);
			throw new InternalServerErrorException("Error during virus scan");
		}
	}

	async processImage(
		buffer: Buffer,
		format: "webp" | "avif" = "webp",
	): Promise<MediaProcessingResult> {
		return this.imageProcessor.process(buffer, { format });
	}

	async processVideo(
		buffer: Buffer,
		format: "webm" | "av1" = "webm",
	): Promise<MediaProcessingResult> {
		return this.videoProcessor.process(buffer, { format });
	}
}