// Copyright 2024 RustFS Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#[allow(unsafe_code)]
mod generated;

use proto_gen::node_service::node_service_client::NodeServiceClient;
use rustfs_common::{
    GLOBAL_CONN_MAP, GLOBAL_MTLS_IDENTITY, GLOBAL_ROOT_CERT, evict_connection, internode_metrics::global_internode_metrics,
};
use std::{
    error::Error,
    time::{Duration, Instant},
};
use tonic::{
    Request, Status,
    service::interceptor::InterceptedService,
    transport::{Certificate, Channel, ClientTlsConfig, Endpoint},
};
use tracing::{debug, warn};

// Type alias for the complex client type
pub type NodeServiceClientType = NodeServiceClient<
    InterceptedService<Channel, Box<dyn Fn(Request<()>) -> Result<Request<()>, Status> + Send + Sync + 'static>>,
>;

pub use generated::*;

// Default 100 MB
pub const DEFAULT_GRPC_SERVER_MESSAGE_LEN: usize = 100 * 1024 * 1024;

/// Timeout for connection establishment - reduced for faster failure detection
const CONNECT_TIMEOUT_SECS: u64 = 3;

/// TCP keepalive interval - how often to probe the connection
const TCP_KEEPALIVE_SECS: u64 = 10;

/// HTTP/2 keepalive interval - application-layer heartbeat
const HTTP2_KEEPALIVE_INTERVAL_SECS: u64 = 5;

/// HTTP/2 keepalive timeout - how long to wait for PING ACK
const HTTP2_KEEPALIVE_TIMEOUT_SECS: u64 = 3;

/// Overall RPC timeout - maximum time for any single RPC operation
const RPC_TIMEOUT_SECS: u64 = 30;

/// Default HTTPS prefix for rustfs
/// This is the default HTTPS prefix for rustfs.
/// It is used to identify HTTPS URLs.
/// Default value: https://
const RUSTFS_HTTPS_PREFIX: &str = "https://";

/// Creates a new gRPC channel with optimized keepalive settings for cluster resilience.
///
/// This function is designed to detect dead peers quickly:
/// - Fast connection timeout (3s instead of default 30s+)
/// - Aggressive TCP keepalive (10s)
/// - HTTP/2 PING every 5s, timeout at 3s
/// - Overall RPC timeout of 30s (reduced from 60s)
pub async fn create_new_channel(addr: &str) -> Result<Channel, Box<dyn Error>> {
    debug!("Creating new gRPC channel to: {}", addr);
    let dial_started_at = Instant::now();

    let mut connector = Endpoint::from_shared(addr.to_string())?
        // Fast connection timeout for dead peer detection
        .connect_timeout(Duration::from_secs(CONNECT_TIMEOUT_SECS))
        // TCP-level keepalive - OS will probe connection
        .tcp_keepalive(Some(Duration::from_secs(TCP_KEEPALIVE_SECS)))
        // HTTP/2 PING frames for application-layer health check
        .http2_keep_alive_interval(Duration::from_secs(HTTP2_KEEPALIVE_INTERVAL_SECS))
        // How long to wait for PING ACK before considering connection dead
        .keep_alive_timeout(Duration::from_secs(HTTP2_KEEPALIVE_TIMEOUT_SECS))
        // Send PINGs even when no active streams (critical for idle connections)
        .keep_alive_while_idle(true)
        // Overall timeout for any RPC - fail fast on unresponsive peers
        .timeout(Duration::from_secs(RPC_TIMEOUT_SECS));

    let root_cert = GLOBAL_ROOT_CERT.read().await;
    if addr.starts_with(RUSTFS_HTTPS_PREFIX) {
        if root_cert.is_none() {
            debug!("No custom root certificate configured; using system roots for TLS: {}", addr);
            // If no custom root cert is configured, try to use system roots.
            connector = connector.tls_config(ClientTlsConfig::new())?;
        }
        if let Some(cert_pem) = root_cert.as_ref() {
            let ca = Certificate::from_pem(cert_pem);
            // Derive the hostname from the HTTPS URL for TLS hostname verification.
            let domain = addr
                .trim_start_matches(RUSTFS_HTTPS_PREFIX)
                .split('/')
                .next()
                .unwrap_or("")
                .split(':')
                .next()
                .unwrap_or("");
            let tls = if !domain.is_empty() {
                let mut cfg = ClientTlsConfig::new().ca_certificate(ca).domain_name(domain);
                let mtls_identity = GLOBAL_MTLS_IDENTITY.read().await;
                if let Some(id) = mtls_identity.as_ref() {
                    let identity = tonic::transport::Identity::from_pem(id.cert_pem.clone(), id.key_pem.clone());
                    cfg = cfg.identity(identity);
                }
                cfg
            } else {
                // Fallback: configure TLS without explicit domain if parsing fails.
                ClientTlsConfig::new().ca_certificate(ca)
            };
            connector = connector.tls_config(tls)?;
            debug!("Configured TLS with custom root certificate for: {}", addr);
        } else {
            return Err(std::io::Error::other(
                "HTTPS requested but no trusted roots are configured. Provide tls/ca.crt (or enable system roots via RUSTFS_TRUST_SYSTEM_CA=true)."
            ).into());
        }
    }

    let channel = match connector.connect().await {
        Ok(channel) => {
            global_internode_metrics().record_dial_result(dial_started_at.elapsed(), true);
            channel
        }
        Err(err) => {
            global_internode_metrics().record_dial_result(dial_started_at.elapsed(), false);
            return Err(err.into());
        }
    };

    // Cache the new connection
    {
        GLOBAL_CONN_MAP.write().await.insert(addr.to_string(), channel.clone());
    }

    debug!("Successfully created and cached gRPC channel to: {}", addr);
    Ok(channel)
}

/// Evict a connection from the cache after a failure.
/// This should be called when an RPC fails to ensure fresh connections are tried.
pub async fn evict_failed_connection(addr: &str) {
    warn!("Evicting failed gRPC connection: {}", addr);
    evict_connection(addr).await;
}