class InternetSpeedChecker {
	private downloadSpeed: number | null = 0;
	private uploadSpeed: number | null = 0;
	private unit: string = "bps"; // Initial unit is bps

	private convertSpeed(speed: number | null): { value: number; unit: string } {
		if (speed === null || speed === 0) {
			return { value: 0, unit: "bps" };
		}

		if (speed > 1e9) {
			return { value: speed / 1e9, unit: "Gbps" };
		} else if (speed > 1e6) {
			return { value: speed / 1e6, unit: "Mbps" };
		} else if (speed > 1e3) {
			return { value: speed / 1e3, unit: "Kbps" };
		} else {
			return { value: speed, unit: "bps" };
		}
	}

	private async measureDownloadSpeed(): Promise<void> {
		const url = "https://www.cloudflare.com/cdn-cgi/trace";

		const startTime = new Date().getTime();

		try {
			const response = await fetch(url);
			if (!response.ok) {
				throw new Error(`HTTP error! Status: ${response.status}`);
			}

			const reader = response.body?.getReader();
			if (!reader) {
				throw new Error("ReadableStream not supported.");
			}

			let totalBytes = 0;

			while (true) {
				const { done, value } = await reader.read();

				if (done) {
					break;
				}

				totalBytes += value?.length || 0;
			}

			const endTime = new Date().getTime();
			const durationInSeconds = (endTime - startTime) / 1000;
			const speedBytesPerSecond = totalBytes / durationInSeconds;

			this.downloadSpeed = speedBytesPerSecond;
		} catch (error) {
			this.downloadSpeed = 0; // Set to 0 if there's an error (no connection)
			if (error instanceof Error) {
				console.error("Error measuring download speed:", error.message);
			} else {
				console.error("Unknown error type:", error);
			}
		}
	}

	private async measureUploadSpeed(): Promise<void> {
		const uploadData = new Array(1024 * 1024).fill("a").join("");
		const url = "https://httpbin.org/post";

		const startTime = new Date().getTime();

		try {
			const response = await fetch(url, {
				method: "POST",
				body: uploadData,
			});

			if (!response.ok) {
				throw new Error(`HTTP error! Status: ${response.status}`);
			}

			const endTime = new Date().getTime();
			const durationInSeconds = (endTime - startTime) / 1000;

			const speedBytesPerSecond = uploadData.length / durationInSeconds;

			this.uploadSpeed = speedBytesPerSecond;
		} catch (error) {
			this.uploadSpeed = 0; // Set to 0 if there's an error (no connection)
			if (error instanceof Error) {
				console.error("Error measuring upload speed:", error.message);
			} else {
				console.error("Unknown error type:", error);
			}
		}
	}

	public getFormattedDownloadSpeed(): string {
		return `${this.convertSpeed(this.downloadSpeed).value.toFixed(2)} ${this.convertSpeed(this.downloadSpeed).unit}`;
	}

	public getFormattedUploadSpeed(): string {
		return `${this.convertSpeed(this.uploadSpeed).value.toFixed(2)} ${this.convertSpeed(this.uploadSpeed).unit}`;
	}

	public startSpeedCheck(): void {
		setInterval(() => {
			this.measureDownloadSpeed();
			this.measureUploadSpeed();
			this.getFormattedDownloadSpeed();
			this.getFormattedUploadSpeed();
		}, 1000);
	}
}

const speedChecker = new InternetSpeedChecker();
speedChecker.startSpeedCheck();

export default speedChecker;