import { FFmpeg } from "prism-media";
import type { Duplex, Readable } from "stream";

export interface FFmpegStreamOptions {
	fmt?: string;
	encoderArgs?: string[];
	seek?: number;
	skip?: boolean;
}

export function FFMPEG_ARGS_STRING(stream: string, fmt?: string) {
	// prettier-ignore
	return [
        "-reconnect", "1",
        "-reconnect_streamed", "1",
        "-reconnect_delay_max", "5",
        "-i", stream,
        "-analyzeduration", "0",
        "-loglevel", "0",
        "-f", `${typeof fmt === "string" ? fmt : "s16le"}`,
        "-ar", "48000",
        "-ac", "2"
    ];
}

export function FFMPEG_ARGS_PIPED(fmt?: string) {
	// prettier-ignore
	return [
        "-analyzeduration", "0",
        "-loglevel", "0",
        "-f", `${typeof fmt === "string" ? fmt : "s16le"}`,
        "-ar", "48000",
        "-ac", "2"
    ];
}

/**
 * Creates FFmpeg stream
 * @param stream The source stream
 * @param options FFmpeg stream options
 */
export function createFFmpegStream(stream: Readable | Duplex | string, options?: FFmpegStreamOptions) {
	if (options.skip && typeof stream !== "string") return stream;
	options ??= {};
	const args = typeof stream === "string" ? FFMPEG_ARGS_STRING(stream, options.fmt) : FFMPEG_ARGS_PIPED(options.fmt);

	if (!Number.isNaN(options.seek)) args.unshift("-ss", String(options.seek));
	if (Array.isArray(options.encoderArgs)) args.push(...options.encoderArgs);

	const transcoder = new FFmpeg({ shell: false, args });
	transcoder.on("close", () => transcoder.destroy());

	if (typeof stream !== "string") {
		stream.on("error", () => transcoder.destroy());
		stream.pipe(transcoder);
	}

	return transcoder;
}