use eyre::{Context as EyreContext, Result};
use tonic::Code;
use tonic::transport::{Channel, Endpoint, Uri};
use tower::service_fn;

use hyper_util::rt::TokioIo;

#[cfg(unix)]
use tokio::net::UnixStream;

use crate::{
    aclient::{history::History, settings::Settings},
    api::{
        DAEMON_PROTOCOL_VERSION, DAEMON_VERSION,
        generated::{
            control::{
                StatusReply, StatusRequest, control_client::ControlClient as ControlServiceClient,
            },
            history::{
                EndHistoryReply, EndHistoryRequest, StartHistoryReply, StartHistoryRequest,
                TailHistoryReply, TailHistoryRequest,
                history_client::HistoryClient as HistoryServiceClient,
            },
        },
    },
};

fn daemon_matches_expected(version: &str, protocol: u32) -> bool {
    version == DAEMON_VERSION && protocol == DAEMON_PROTOCOL_VERSION
}

fn daemon_mismatch_message(version: &str, protocol: u32) -> String {
    if protocol == DAEMON_PROTOCOL_VERSION {
        format!("daemon is out of date: expected {DAEMON_VERSION}, got {version}")
    } else {
        format!("daemon protocol mismatch: expected {DAEMON_PROTOCOL_VERSION}, got {protocol}")
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum DaemonClientErrorKind {
    Connect,
    Unavailable,
    Unimplemented,
    Other,
}

#[must_use]
pub fn classify_error(error: &eyre::Report) -> DaemonClientErrorKind {
    for cause in error.chain() {
        if cause.downcast_ref::<tonic::transport::Error>().is_some() {
            return DaemonClientErrorKind::Connect;
        }

        if let Some(status) = cause.downcast_ref::<tonic::Status>() {
            return match status.code() {
                Code::Unavailable => DaemonClientErrorKind::Unavailable,
                Code::Unimplemented => DaemonClientErrorKind::Unimplemented,
                _ => DaemonClientErrorKind::Other,
            };
        }
    }

    DaemonClientErrorKind::Other
}

#[derive(Debug)]
pub enum Probe {
    Ready(ControlClient),
    NeedsRestart(String),
    Unreachable(eyre::Report),
}

/// Check if a client can reach the daemon.
pub async fn probe(path: String) -> Probe {
    let mut client = match ControlClient::new(path).await {
        Ok(client) => client,
        Err(err) => return Probe::Unreachable(err),
    };

    match client.status().await {
        Ok(status) => {
            if daemon_matches_expected(&status.version, status.protocol) {
                Probe::Ready(client)
            } else {
                Probe::NeedsRestart(daemon_mismatch_message(&status.version, status.protocol))
            }
        }
        Err(err) => Probe::Unreachable(err),
    }
}

// ============================================================================
// History Client
// ============================================================================

#[derive(Debug)]
pub struct HistoryClient {
    client: HistoryServiceClient<Channel>,
}

// Wrap the grpc client
impl HistoryClient {
    #[cfg(unix)]
    pub async fn new(path: String) -> Result<Self> {
        use eyre::Context;

        let log_path = path.clone();
        let channel = Endpoint::try_from("http://atuin_local_daemon:0")?
            .connect_with_connector(service_fn(move |_: Uri| {
                let path = path.clone();

                async move {
                    Ok::<_, std::io::Error>(TokioIo::new(UnixStream::connect(path.clone()).await?))
                }
            }))
            .await
            .wrap_err_with(|| {
                format!(
                    "failed to connect to local atuin daemon at {}. Is it running?",
                    &log_path
                )
            })?;

        let client = HistoryServiceClient::new(channel);

        Ok(Self { client })
    }

    pub async fn start_history(&mut self, h: History) -> Result<StartHistoryReply> {
        let req = StartHistoryRequest {
            command: h.command,
            cwd: h.cwd,
            hostname: h.hostname,
            session: h.session,
            timestamp: h.timestamp.unix_timestamp_nanos() as u64,
            author: h.author,
            intent: h.intent.unwrap_or_default(),
        };

        Ok(self.client.start_history(req).await?.into_inner())
    }

    pub async fn end_history(
        &mut self,
        id: String,
        duration: u64,
        exit: i64,
    ) -> Result<EndHistoryReply> {
        let req = EndHistoryRequest { id, exit, duration };

        Ok(self.client.end_history(req).await?.into_inner())
    }

    pub(crate) async fn tail_history(&mut self) -> Result<tonic::Streaming<TailHistoryReply>> {
        Ok(self
            .client
            .tail_history(TailHistoryRequest {})
            .await?
            .into_inner())
    }
}

// ============================================================================
// Control Client
// ============================================================================

/// Client for the Control gRPC service.
#[derive(Debug)]
pub struct ControlClient {
    client: ControlServiceClient<Channel>,
}

impl ControlClient {
    /// Connect to the daemon's control service.
    pub async fn new(path: String) -> Result<Self> {
        let log_path = path.clone();
        let channel = Endpoint::try_from("http://atuin_local_daemon:0")?
            .connect_with_connector(service_fn(move |_: Uri| {
                let path = path.clone();

                async move {
                    Ok::<_, std::io::Error>(TokioIo::new(UnixStream::connect(path.clone()).await?))
                }
            }))
            .await
            .wrap_err_with(|| {
                format!(
                    "failed to connect to local atuin daemon at {}. Is it running?",
                    &log_path
                )
            })?;

        let client = ControlServiceClient::new(channel);

        Ok(Self { client })
    }

    /// Connect using settings.
    #[cfg(unix)]
    pub async fn from_settings(settings: &Settings) -> Result<Self> {
        Self::new(settings.daemon.socket_path.clone()).await
    }

    pub async fn status(&mut self) -> Result<StatusReply> {
        Ok(self.client.status(StatusRequest {}).await?.into_inner())
    }
}