// Copyright 2023 Protocol Labs.
//
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//! Implementation of the [libp2p perf protocol](https://github.com/libp2p/specs/pull/478/).
//!
//! Do not use in untrusted environments.

#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]

use std::fmt::Display;

use instant::Duration;
use libp2p_swarm::StreamProtocol;

pub mod client;
mod protocol;
pub mod server;

pub const PROTOCOL_NAME: StreamProtocol = StreamProtocol::new("/perf/1.0.0");

/// Parameters for a single run, i.e. one stream, sending and receiving data.
///
/// Property names are from the perspective of the actor. E.g. `to_send` is the amount of data to
/// send, both as the client and the server.
#[derive(Debug, Clone, Copy)]
pub struct RunParams {
    pub to_send: usize,
    pub to_receive: usize,
}

/// Duration for a single run, i.e. one stream, sending and receiving data.
#[derive(Debug, Clone, Copy)]
pub struct RunDuration {
    pub upload: Duration,
    pub download: Duration,
}

pub struct Run {
    pub params: RunParams,
    pub duration: RunDuration,
}

impl Display for Run {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        const KILO: f64 = 1024.0;
        const MEGA: f64 = KILO * 1024.0;
        const GIGA: f64 = MEGA * 1024.0;

        fn format_bytes(bytes: usize) -> String {
            let bytes = bytes as f64;
            if bytes >= GIGA {
                format!("{:.2} GiB", bytes / GIGA)
            } else if bytes >= MEGA {
                format!("{:.2} MiB", bytes / MEGA)
            } else if bytes >= KILO {
                format!("{:.2} KiB", bytes / KILO)
            } else {
                format!("{} B", bytes)
            }
        }

        fn format_bandwidth(duration: Duration, bytes: usize) -> String {
            const KILO: f64 = 1024.0;
            const MEGA: f64 = KILO * 1024.0;
            const GIGA: f64 = MEGA * 1024.0;

            let bandwidth = (bytes as f64 * 8.0) / duration.as_secs_f64();

            if bandwidth >= GIGA {
                format!("{:.2} Gbit/s", bandwidth / GIGA)
            } else if bandwidth >= MEGA {
                format!("{:.2} Mbit/s", bandwidth / MEGA)
            } else if bandwidth >= KILO {
                format!("{:.2} Kbit/s", bandwidth / KILO)
            } else {
                format!("{:.2} bit/s", bandwidth)
            }
        }

        let Run {
            params: RunParams {
                to_send,
                to_receive,
            },
            duration: RunDuration { upload, download },
        } = self;

        write!(
            f,
            "uploaded {} in {:.4} s ({}), downloaded {} in {:.4} s ({})",
            format_bytes(*to_send),
            upload.as_secs_f64(),
            format_bandwidth(*upload, *to_send),
            format_bytes(*to_receive),
            download.as_secs_f64(),
            format_bandwidth(*download, *to_receive),
        )?;

        Ok(())
    }
}