use std::{
	convert::TryFrom,
	io::{
		self,
		Write,
	},
	time::Duration,
};

use reqwest::{
	Client,
	StatusCode,
};
use tokio::{
	stream::StreamExt,
	time::interval,
};
use tracing::{
	debug, warn
};
use tracing_subscriber::{
	EnvFilter,
	fmt,
	fmt::format::FmtSpan,
};

#[tokio::main]
async fn main () -> Result <(), anyhow::Error> {
	fmt ()
		.with_env_filter (EnvFilter::from_default_env ())
		.with_span_events (FmtSpan::CLOSE)
		.init ()
	;
	
	let client = Client::default ();
	
	let server = "http://127.0.0.1:4000/files/log.txt";
	
	let mut total_bytes_received = 0_u64;
	let mut timer = interval (Duration::from_secs (2));
	
	loop {
		timer.tick ().await;
		
		let resp = match client
		.get (server)
		.header ("range", format! ("bytes={}-", total_bytes_received))
		.send ().await {
			Err (e) => {
				warn! ("Reqwest send error: {:?}", e);
				continue;
			}
			Ok (x) => x,
		};
		
		let status = resp.status ();
		
		match status {
			StatusCode::RANGE_NOT_SATISFIABLE => continue,
			StatusCode::PARTIAL_CONTENT => (),
			sc => {
				debug! ("status code: {}", sc);
				continue;
			},
		}
		
		let mut stream = resp.bytes_stream ();
		
		while let Some (chunk) = stream.next ().await {
			let chunk = match chunk {
				Ok (x) => x,
				Err (_) => break,
			};
			io::stdout ().write_all (&chunk)?;
			total_bytes_received += u64::try_from (chunk.len ())?;
		}
	}
	
	Ok (())
}