use hyper::Method;

#[derive (Debug, PartialEq)]
pub enum Route <'a> {
	ClientAuditLog,
	ClientRelayIsUp,
	ClientServerGet {
		listen_code: &'a str,
		path: &'a str,
	},
	ClientServerList,
	ClientUnregisteredServers,
	Debug,
	DebugEndlessSink,
	DebugEndlessSource (Option <usize>),
	DebugGenKey,
	DebugMysteriousError,
	RegisterServer,
	Root,
	Scraper {
		rest: &'a str,
	},
	ServerHttpListen {
		listen_code: &'a str
	},
	ServerHttpResponse {
		request_code: &'a str,
	},
}

#[derive (Debug, PartialEq)]
pub enum Error {
	BadUriFormat,
	MethodNotAllowed,
	NotFound,
}

pub fn route_url <'a> (method: &Method, path: &'a str) -> Result <Route <'a>, Error> {
	if let Some (listen_code) = path.strip_prefix ("/7ZSFUKGV/http_listen/") {
		assert_method (method, Method::GET)?;
		
		Ok (Route::ServerHttpListen {
			listen_code
		})
	}
	else if let Some (request_code) = path.strip_prefix ("/7ZSFUKGV/http_response/") {
		assert_method (method, Method::POST)?;
		Ok (Route::ServerHttpResponse {
			request_code
		})
	}
	else if path == "/frontend/register" {
		assert_method (method, Method::POST)?;
		Ok (Route::RegisterServer)
	}
	else if let Some (rest) = path.strip_prefix ("/frontend/servers/") {
		// DRY T4H76LB3
		
		if rest.is_empty () {
			assert_method (method, Method::GET)?;
			Ok (Route::ClientServerList)
		}
		else if let Some (idx) = rest.find ('/') {
			let listen_code = &rest [0..idx];
			
			Ok (Route::ClientServerGet {
				listen_code, 
				path: &rest [idx..],
			})
		}
		else {
			assert_method (method, Method::GET)?;
			Err (Error::BadUriFormat)
		}
	}
	else if path == "/frontend/unregistered_servers" {
		assert_method (method, Method::GET)?;
		Ok (Route::ClientUnregisteredServers)
	}
	else if path == "/frontend/audit_log" {
		assert_method (method, Method::GET)?;
		Ok (Route::ClientAuditLog)
	}
	else if let Some (rest) = path.strip_prefix ("/frontend/debug/") {
		if rest.is_empty () {
			assert_method (method, Method::GET)?;
			Ok (Route::Debug)
		}
		else if rest == "endless_source" {
			assert_method (method, Method::GET)?;
			Ok (Route::DebugEndlessSource (None))
		}
		else if rest == "endless_source_throttled" {
			assert_method (method, Method::GET)?;
			Ok (Route::DebugEndlessSource (Some (1024 / 64)))
		}
		else if rest == "endless_sink" {
			assert_method (method, Method::POST)?;
			Ok (Route::DebugEndlessSink)
		}
		else if rest == "gen_key" {
			assert_method (method, Method::GET)?;
			Ok (Route::DebugGenKey)
		}
		else {
			Err (Error::NotFound)
		}
	}
	else if path == "/" {
		assert_method (method, Method::GET)?;
		Ok (Route::Root)
	}
	else if path == "/frontend/relay_up_check" {
		assert_method (method, Method::GET)?;
		Ok (Route::ClientRelayIsUp)
	}
	else if path == "/frontend/test_mysterious_error" {
		assert_method (method, Method::GET)?;
		Ok (Route::DebugMysteriousError)
	}
	else if let Some (rest) = path.strip_prefix ("/scraper/") {
		assert_method (method, Method::GET)?;
		Ok (Route::Scraper {
			rest
		})
	}
	else {
		tracing::error! ("URL routing failed for `{}`", path);
		Err (Error::NotFound)
	}
}

fn assert_method <M: PartialEq <Method>> (method: M, expected: Method) -> Result <(), Error>
{
	if method == expected {
		Ok (())
	}
	else {
		Err (Error::MethodNotAllowed)
	}
}

#[cfg (test)]
mod tests {
	use super::*;
	
	#[test]
	fn routing () {
		for (input, expected) in vec! [
			("/", Ok (Route::Root)),
		].into_iter () {
			let actual = route_url (&Method::GET, input);
			assert_eq! (actual, expected);
		}
		
		for (input, expected) in vec! [
			("/", Err (Error::MethodNotAllowed)),
		].into_iter () {
			let actual = route_url (&Method::POST, input);
			assert_eq! (actual, expected);
		}
	}
}