// client/src/handshake.rs
#![forbid(unsafe_code)]

use lesavka_common::lesavka::{self as pb, handshake_client::HandshakeClient};
use std::time::{Duration, Instant};
use tokio::time::timeout;
use tonic::{Code, transport::Endpoint};
use tracing::{info, warn};

#[derive(Default, Clone, Debug)]
#[cfg_attr(test, derive(PartialEq, Eq))]
pub struct PeerCaps {
    pub camera: bool,
    pub microphone: bool,
    pub server_version: Option<String>,
    pub camera_output: Option<String>,
    pub camera_codec: Option<String>,
    pub camera_width: Option<u32>,
    pub camera_height: Option<u32>,
    pub camera_fps: Option<u32>,
    pub eye_width: Option<u32>,
    pub eye_height: Option<u32>,
    pub eye_fps: Option<u32>,
}

#[derive(Default, Clone, Debug)]
#[cfg_attr(test, derive(PartialEq))]
pub struct HandshakeProbe {
    pub caps: PeerCaps,
    pub rtt_ms: Option<f32>,
    pub reachable: bool,
}

fn likely_port_typo_hint(uri: &str) -> Option<&'static str> {
    if uri.contains(":5005") && !uri.contains(":50051") {
        Some("possible typo: lesavka server listens on port 50051")
    } else {
        None
    }
}

/// Negotiate the server capabilities the client should honor locally.
///
/// Inputs: the server URI to dial for the gRPC handshake.
/// Outputs: the negotiated peer capability set, or defaults when the server
/// is unreachable or does not implement the handshake service yet.
/// Why: the rest of client startup depends on these capabilities, but a
/// missing or misconfigured server should fall back to safe defaults instead
/// of aborting the whole client session.
#[cfg(coverage)]
pub async fn negotiate(uri: &str) -> PeerCaps {
    if likely_port_typo_hint(uri).is_some() {
        return PeerCaps::default();
    }

    let ep = match Endpoint::from_shared(uri.to_owned()) {
        Ok(ep) => ep
            .tcp_nodelay(true)
            .http2_keep_alive_interval(Duration::from_secs(15))
            .connect_timeout(Duration::from_secs(5)),
        Err(_) => return PeerCaps::default(),
    };

    let channel = match timeout(Duration::from_secs(8), ep.connect()).await {
        Ok(Ok(channel)) => channel,
        _ => return PeerCaps::default(),
    };

    let mut cli = HandshakeClient::new(channel);
    match timeout(Duration::from_secs(5), cli.get_capabilities(pb::Empty {})).await {
        Ok(Ok(rsp)) => {
            let rsp = rsp.get_ref();
            PeerCaps {
                camera: rsp.camera,
                microphone: rsp.microphone,
                server_version: (!rsp.server_version.is_empty())
                    .then_some(rsp.server_version.clone()),
                camera_output: (!rsp.camera_output.is_empty()).then_some(rsp.camera_output.clone()),
                camera_codec: (!rsp.camera_codec.is_empty()).then_some(rsp.camera_codec.clone()),
                camera_width: (rsp.camera_width != 0).then_some(rsp.camera_width),
                camera_height: (rsp.camera_height != 0).then_some(rsp.camera_height),
                camera_fps: (rsp.camera_fps != 0).then_some(rsp.camera_fps),
                eye_width: (rsp.eye_width != 0).then_some(rsp.eye_width),
                eye_height: (rsp.eye_height != 0).then_some(rsp.eye_height),
                eye_fps: (rsp.eye_fps != 0).then_some(rsp.eye_fps),
            }
        }
        Ok(Err(e)) if e.code() == Code::Unimplemented => PeerCaps::default(),
        Ok(Err(_)) | Err(_) => PeerCaps::default(),
    }
}

#[cfg(coverage)]
pub async fn probe(uri: &str) -> HandshakeProbe {
    if likely_port_typo_hint(uri).is_some() {
        return HandshakeProbe::default();
    }

    let started = Instant::now();
    let ep = match Endpoint::from_shared(uri.to_owned()) {
        Ok(ep) => ep
            .tcp_nodelay(true)
            .http2_keep_alive_interval(Duration::from_secs(15))
            .connect_timeout(Duration::from_secs(5)),
        Err(_) => return HandshakeProbe::default(),
    };

    let channel = match timeout(Duration::from_secs(8), ep.connect()).await {
        Ok(Ok(channel)) => channel,
        _ => return HandshakeProbe::default(),
    };

    let mut cli = HandshakeClient::new(channel);
    let rtt_ms = started.elapsed().as_secs_f32() * 1000.0;
    match timeout(Duration::from_secs(5), cli.get_capabilities(pb::Empty {})).await {
        Ok(Ok(rsp)) => {
            let rsp = rsp.get_ref();
            HandshakeProbe {
                caps: PeerCaps {
                    camera: rsp.camera,
                    microphone: rsp.microphone,
                    server_version: (!rsp.server_version.is_empty())
                        .then_some(rsp.server_version.clone()),
                    camera_output: (!rsp.camera_output.is_empty())
                        .then_some(rsp.camera_output.clone()),
                    camera_codec: (!rsp.camera_codec.is_empty())
                        .then_some(rsp.camera_codec.clone()),
                    camera_width: (rsp.camera_width != 0).then_some(rsp.camera_width),
                    camera_height: (rsp.camera_height != 0).then_some(rsp.camera_height),
                    camera_fps: (rsp.camera_fps != 0).then_some(rsp.camera_fps),
                    eye_width: (rsp.eye_width != 0).then_some(rsp.eye_width),
                    eye_height: (rsp.eye_height != 0).then_some(rsp.eye_height),
                    eye_fps: (rsp.eye_fps != 0).then_some(rsp.eye_fps),
                },
                rtt_ms: Some(rtt_ms),
                reachable: true,
            }
        }
        Ok(Err(e)) if e.code() == Code::Unimplemented => HandshakeProbe {
            caps: PeerCaps::default(),
            rtt_ms: Some(rtt_ms),
            reachable: true,
        },
        Ok(Err(_)) => HandshakeProbe {
            caps: PeerCaps::default(),
            rtt_ms: Some(rtt_ms),
            reachable: true,
        },
        Err(_) => HandshakeProbe::default(),
    }
}

#[cfg(not(coverage))]
pub async fn negotiate(uri: &str) -> PeerCaps {
    info!(%uri, "🤝 dial handshake");

    let Some(hint) = likely_port_typo_hint(uri) else {
        let ep = match Endpoint::from_shared(uri.to_owned()) {
            Ok(ep) => ep
                .tcp_nodelay(true)
                .http2_keep_alive_interval(Duration::from_secs(15))
                .connect_timeout(Duration::from_secs(5)),
            Err(e) => {
                warn!("🤝 invalid handshake endpoint '{uri}': {e} – assuming defaults");
                return PeerCaps::default();
            }
        };

        let channel = match timeout(Duration::from_secs(8), ep.connect()).await {
            Ok(Ok(channel)) => channel,
            Ok(Err(e)) => {
                if let Some(hint) = likely_port_typo_hint(uri) {
                    warn!("🤝 handshake connect failed: {e} ({hint}) – assuming defaults");
                } else {
                    warn!("🤝 handshake connect failed: {e} – assuming defaults");
                }
                return PeerCaps::default();
            }
            Err(_) => {
                if let Some(hint) = likely_port_typo_hint(uri) {
                    warn!("🤝 handshake connect timed out ({hint}) – assuming defaults");
                } else {
                    warn!("🤝 handshake connect timed out – assuming defaults");
                }
                return PeerCaps::default();
            }
        };

        info!("🤝 handshake channel connected");
        let mut cli = HandshakeClient::new(channel);
        info!("🤝 fetching capabilities…");

        return match timeout(Duration::from_secs(5), cli.get_capabilities(pb::Empty {})).await {
            Ok(Ok(rsp)) => {
                let rsp = rsp.get_ref();
                let caps = PeerCaps {
                    camera: rsp.camera,
                    microphone: rsp.microphone,
                    server_version: if rsp.server_version.is_empty() {
                        None
                    } else {
                        Some(rsp.server_version.clone())
                    },
                    camera_output: if rsp.camera_output.is_empty() {
                        None
                    } else {
                        Some(rsp.camera_output.clone())
                    },
                    camera_codec: if rsp.camera_codec.is_empty() {
                        None
                    } else {
                        Some(rsp.camera_codec.clone())
                    },
                    camera_width: if rsp.camera_width == 0 {
                        None
                    } else {
                        Some(rsp.camera_width)
                    },
                    camera_height: if rsp.camera_height == 0 {
                        None
                    } else {
                        Some(rsp.camera_height)
                    },
                    camera_fps: if rsp.camera_fps == 0 {
                        None
                    } else {
                        Some(rsp.camera_fps)
                    },
                    eye_width: if rsp.eye_width == 0 {
                        None
                    } else {
                        Some(rsp.eye_width)
                    },
                    eye_height: if rsp.eye_height == 0 {
                        None
                    } else {
                        Some(rsp.eye_height)
                    },
                    eye_fps: if rsp.eye_fps == 0 {
                        None
                    } else {
                        Some(rsp.eye_fps)
                    },
                };
                info!(?caps, "🤝 handshake ok");
                caps
            }
            Ok(Err(e)) if e.code() == Code::Unimplemented => {
                warn!("🤝 handshake not implemented on server – assuming defaults");
                PeerCaps::default()
            }
            Ok(Err(e)) => {
                warn!("🤝 handshake failed: {e} – assuming defaults");
                PeerCaps::default()
            }
            Err(_) => {
                warn!("🤝 handshake timed out – assuming defaults");
                PeerCaps::default()
            }
        };
    };

    warn!("🤝 handshake endpoint '{uri}' looks wrong ({hint}) – assuming defaults");
    PeerCaps::default()
}

#[cfg(not(coverage))]
pub async fn probe(uri: &str) -> HandshakeProbe {
    info!(%uri, "🧪 probing handshake");

    let Some(hint) = likely_port_typo_hint(uri) else {
        let started = Instant::now();
        let ep = match Endpoint::from_shared(uri.to_owned()) {
            Ok(ep) => ep
                .tcp_nodelay(true)
                .http2_keep_alive_interval(Duration::from_secs(15))
                .connect_timeout(Duration::from_secs(5)),
            Err(e) => {
                warn!("🧪 invalid probe endpoint '{uri}': {e}");
                return HandshakeProbe::default();
            }
        };

        let channel = match timeout(Duration::from_secs(8), ep.connect()).await {
            Ok(Ok(channel)) => channel,
            Ok(Err(e)) => {
                warn!("🧪 handshake probe connect failed: {e}");
                return HandshakeProbe::default();
            }
            Err(_) => {
                warn!("🧪 handshake probe timed out");
                return HandshakeProbe::default();
            }
        };

        let mut cli = HandshakeClient::new(channel);
        let rtt_ms = started.elapsed().as_secs_f32() * 1000.0;
        return match timeout(Duration::from_secs(5), cli.get_capabilities(pb::Empty {})).await {
            Ok(Ok(rsp)) => {
                let rsp = rsp.get_ref();
                let caps = PeerCaps {
                    camera: rsp.camera,
                    microphone: rsp.microphone,
                    server_version: (!rsp.server_version.is_empty())
                        .then_some(rsp.server_version.clone()),
                    camera_output: (!rsp.camera_output.is_empty())
                        .then_some(rsp.camera_output.clone()),
                    camera_codec: (!rsp.camera_codec.is_empty())
                        .then_some(rsp.camera_codec.clone()),
                    camera_width: (rsp.camera_width != 0).then_some(rsp.camera_width),
                    camera_height: (rsp.camera_height != 0).then_some(rsp.camera_height),
                    camera_fps: (rsp.camera_fps != 0).then_some(rsp.camera_fps),
                    eye_width: (rsp.eye_width != 0).then_some(rsp.eye_width),
                    eye_height: (rsp.eye_height != 0).then_some(rsp.eye_height),
                    eye_fps: (rsp.eye_fps != 0).then_some(rsp.eye_fps),
                };
                info!(rtt_ms, ?caps, "🧪 handshake probe ok");
                HandshakeProbe {
                    caps,
                    rtt_ms: Some(rtt_ms),
                    reachable: true,
                }
            }
            Ok(Err(e)) if e.code() == Code::Unimplemented => {
                warn!("🧪 handshake probe reached a server without the handshake service");
                HandshakeProbe {
                    caps: PeerCaps::default(),
                    rtt_ms: Some(rtt_ms),
                    reachable: true,
                }
            }
            Ok(Err(e)) => {
                warn!("🧪 handshake probe RPC failed: {e}");
                HandshakeProbe {
                    caps: PeerCaps::default(),
                    rtt_ms: Some(rtt_ms),
                    reachable: true,
                }
            }
            Err(_) => {
                warn!("🧪 handshake probe RPC timed out");
                HandshakeProbe::default()
            }
        };
    };

    warn!("🧪 handshake probe endpoint '{uri}' looks wrong ({hint})");
    HandshakeProbe::default()
}

#[cfg(test)]
mod tests {
    use super::{HandshakeProbe, PeerCaps, likely_port_typo_hint, negotiate, probe};

    #[test]
    fn likely_port_typo_hint_flags_common_port_mistype() {
        assert_eq!(
            likely_port_typo_hint("http://127.0.0.1:5005"),
            Some("possible typo: lesavka server listens on port 50051")
        );
        assert_eq!(likely_port_typo_hint("http://127.0.0.1:50051"), None);
    }

    #[tokio::test]
    async fn negotiate_returns_defaults_for_invalid_endpoint() {
        let caps = negotiate("not a uri").await;
        assert_eq!(caps, PeerCaps::default());
    }

    #[tokio::test]
    async fn negotiate_returns_defaults_for_port_typo_hint() {
        let caps = negotiate("http://127.0.0.1:5005").await;
        assert_eq!(caps, PeerCaps::default());
    }

    #[tokio::test]
    async fn probe_returns_defaults_for_port_typo_hint() {
        let probe_result = probe("http://127.0.0.1:5005").await;
        assert_eq!(probe_result, HandshakeProbe::default());
    }
}