import { readFile, unlink, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { BadRequestException, Injectable, Logger } from "@nestjs/common";
import ffmpeg from "fluent-ffmpeg";
import { v4 as uuidv4 } from "uuid";
import type { MediaProcessingResult } from "../../common/interfaces/media.interface";
import type { IMediaProcessorStrategy } from "./media-processor.strategy";

@Injectable()
export class VideoProcessorStrategy implements IMediaProcessorStrategy {
	private readonly logger = new Logger(VideoProcessorStrategy.name);

	canHandle(mimeType: string): boolean {
		return mimeType.startsWith("video/") || mimeType === "image/gif";
	}

	async process(
		buffer: Buffer,
		options: { format: "webm" | "av1" } = { format: "webm" },
	): Promise<MediaProcessingResult> {
		const { format } = options;
		const tempInput = join(tmpdir(), `${uuidv4()}.tmp`);
		const tempOutput = join(
			tmpdir(),
			`${uuidv4()}.${format === "av1" ? "mp4" : "webm"}`,
		);

		try {
			await writeFile(tempInput, buffer);

			await new Promise<void>((resolve, reject) => {
				let command = ffmpeg(tempInput);

				if (format === "webm") {
					command = command
						.toFormat("webm")
						.videoCodec("libvpx-vp9")
						.audioCodec("libopus")
						.addOutputOptions("-crf", "30", "-b:v", "0");
				} else {
					command = command
						.toFormat("mp4")
						.videoCodec("libaom-av1")
						.audioCodec("libopus")
						.addOutputOptions("-crf", "34", "-b:v", "0", "-strict", "experimental");
				}

				command
					.on("end", () => resolve())
					.on("error", (err) => reject(err))
					.save(tempOutput);
			});

			const processedBuffer = await readFile(tempOutput);

			return {
				buffer: processedBuffer,
				mimeType: format === "av1" ? "video/mp4" : "video/webm",
				extension: format === "av1" ? "mp4" : "webm",
				size: processedBuffer.length,
			};
		} catch (error) {
			this.logger.error(`Error processing video: ${error.message}`);
			throw new BadRequestException("Failed to process video");
		} finally {
			await unlink(tempInput).catch(() => {});
			await unlink(tempOutput).catch(() => {});
		}
	}
}