use std::{
	convert::Infallible,
	error::Error,
	io::SeekFrom,
	path::PathBuf,
	sync::Arc,
	time::Duration,
};

use hyper::{
	StatusCode,
	Uri,
};
use lazy_static::*;
use regex::Regex;
use reqwest::{
	Body,
	Client,
};
use tokio::{
	fs::File,
	io::AsyncReadExt,
	sync::mpsc::{
		channel,
	},
	time::delay_for,
};

use ptth::http_serde::*;

fn parse_range_header (range_str: &str) -> (Option <u64>, Option <u64>) {
	lazy_static! {
		static ref RE: Regex = Regex::new (r"^(\d+)-(\d+)$").expect ("Couldn't compile regex for Range header");
	}
	
	let caps = match RE.captures (range_str) {
		Some (x) => x,
		_ => return (None, None),
	};
	let start = caps.get (1).map (|x| x.as_str ());
	let end = caps.get (2).map (|x| x.as_str ());
	
	let start = start.map (|x| u64::from_str_radix (x, 10).ok ()).flatten ();
	let end = end.map (|x| u64::from_str_radix (x, 10).ok ()).flatten ();
	
	(start, end)
}

#[tokio::main]
async fn main () -> Result <(), Box <dyn Error>> {
	let client = Arc::new (Client::new ());
	
	let mut backoff_delay = 0;
	
	loop {
		if backoff_delay > 0 {
			delay_for (Duration::from_millis (backoff_delay)).await;
		}
		
		let _uri = Uri::builder ()
			.scheme ("http")
			.authority ("127.0.0.1:4000")
			.path_and_query ("/http_listen/alien_wildlands")
		.build ().unwrap ();
		
		let req_req = client.get ("http://127.0.0.1:4000/http_listen/alien_wildlands");
		
		//println! ("Step 1");
		let req_resp = match req_req.send ().await {
			Err (e) => {
				println! ("Err: {:?}", e);
				backoff_delay = backoff_delay * 2 + 500;
				continue;
			},
			Ok (r) => {
				backoff_delay = 0;
				r
			},
		};
		
		if req_resp.status () != StatusCode::OK {
			continue;
		}
		
		println! ("Step 3");
		
		let body = req_resp.bytes ().await?;
		let parts: RequestParts = match rmp_serde::from_read_ref (&body)
		{
			Ok (x) => x,
			_ => continue,
		};
		
		let (req_id, uri) = (parts.id, parts.uri);
		
		println! ("Client requested {}", uri);
		let mut range_start = None;
		let mut range_end = None;
		
		for (k, v) in parts.headers.iter () {
			let v = std::str::from_utf8 (v).unwrap ();
			println! ("{}: {}", k, v);
			
			if k == "range" {
				let (start, end) = parse_range_header (v);
				range_start = start;
				range_end = end;
			}
		}
		
		println! ("Step 4/5");
		
		println! ("Step 6");
		let client = client.clone ();
		tokio::spawn (async move {
			let (tx, rx) = channel (2);
			
			let mut path = PathBuf::from ("/home/user");
				path.push (&uri [1..]);
			let mut f = File::open (path).await.unwrap ();
			
			if let Some (start) = range_start {
				f.seek (SeekFrom::Start (start)).await.unwrap ();
			}
			
			tokio::spawn (async move {
				//println! ("Opening file {:?}", path);
				
				let mut tx = tx;
				//let mut bytes_sent = 0;
				
				loop {
					let mut buffer = vec! [0u8; 65_536];
					let bytes_read = f.read (&mut buffer).await.unwrap ();
					
					buffer.truncate (bytes_read);
					
					if bytes_read == 0 {
						break;
					}
					
					if tx.send (Ok::<_, Infallible> (buffer)).await.is_err () {
						break;
					}
					
					//bytes_sent += bytes_read;
					//println! ("Sent {} bytes", bytes_sent);
					
					delay_for (Duration::from_millis (50)).await;
				}
			});
			
			let resp_req = client.post (&format! ("http://127.0.0.1:4000/http_response/{}", req_id)).body (Body::wrap_stream (rx));
			
			println! ("Step 6");
			if let Err (e) = resp_req.send ().await {
				println! ("Err: {:?}", e);
			}
		});
	}
}