use std::path::PathBuf;
use std::time::Duration;

use gitks::actor::init_actor_cluster;
use gitks::cluster::{ClusterConfig, ClusterManager};
use gitks::disk_cache::DiskCache;
use gitks::hooks::HookManager;
use gitks::metrics;
use gitks::server::{GitksService, serve};

const DEFAULT_HOST: &str = "0.0.0.0";
const DEFAULT_PORT: &str = "50051";
const DEFAULT_STORAGE_NAME: &str = "default";

fn env_or(key: &str, default: &str) -> String {
    std::env::var(key).unwrap_or_else(|_| default.into())
}

fn env_bool(key: &str, default: bool) -> bool {
    match std::env::var(key).as_deref() {
        Ok("true" | "1" | "yes") => true,
        Ok("false" | "0" | "no") => false,
        Ok(_) => default,
        Err(_) => default,
    }
}

fn env_u64(key: &str, default: u64) -> u64 {
    std::env::var(key)
        .ok()
        .and_then(|v| v.parse().ok())
        .unwrap_or(default)
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    dotenvy::dotenv().ok();
    tracing_subscriber::fmt().init();

    tracing::info!(version = env!("CARGO_PKG_VERSION"), "gitks starting up");

    let host = env_or("GITKS_HOST", DEFAULT_HOST);
    let port = env_or("GITKS_PORT", DEFAULT_PORT);
    let storage_name = env_or("STORAGE_NAME", DEFAULT_STORAGE_NAME);
    let grpc_addr =
        std::env::var("GITKS_ADVERTISE_ADDR").unwrap_or_else(|_| format!("http://{host}:{port}"));

    let repo_prefix = std::env::var("REPO_PREFIX_PATH")
        .map_err(|_| "REPO_PREFIX_PATH environment variable is required (e.g. /data/repos)")?;
    let repo_prefix = PathBuf::from(&repo_prefix);
    if !repo_prefix.is_absolute() {
        return Err("REPO_PREFIX_PATH must be an absolute path".into());
    }
    if !repo_prefix.exists() {
        tracing::info!(path = %repo_prefix.display(), "creating repo prefix directory");
        std::fs::create_dir_all(&repo_prefix)?;
    }

    // Disk cache configuration
    let disk_cache_enabled = env_bool("GITKS_DISK_CACHE_ENABLED", false);
    let disk_cache_max_age = env_u64("GITKS_DISK_CACHE_MAX_AGE", 300);

    let disk_cache = DiskCache::new(
        repo_prefix.clone(),
        env!("CARGO_PKG_VERSION").to_string(),
        disk_cache_max_age,
        disk_cache_enabled,
    );

    if disk_cache_enabled {
        tracing::info!("disk cache enabled, max_age={disk_cache_max_age}s");
        disk_cache.cleanup_on_startup()?;
        gitks::disk_cache::start_cache_cleanup_task(disk_cache.clone(), Duration::from_secs(300));
    } else {
        tracing::info!("disk cache disabled");
    }

    // Pack cache configuration
    let pack_cache_enabled = env_bool("GITKS_PACK_CACHE_ENABLED", false);
    let pack_backpressure = env_bool("GITKS_PACK_CACHE_BACKPRESSURE", true);

    // Pack cache: needs disk_cache. If disk_cache is enabled, info/refs cache
    // is always available via PackCache wrapper. pack-objects caching is
    // additionally controlled by GITKS_PACK_CACHE_ENABLED.
    let pack_cache = if disk_cache_enabled {
        tracing::info!(
            "pack cache wrapper enabled, pack-objects cache={pack_cache_enabled}, backpressure={pack_backpressure}"
        );
        Some(gitks::pack_cache::PackCache::new(
            disk_cache.clone(),
            pack_backpressure,
        ))
    } else {
        None
    };

    // Hook manager configuration
    let hooks_enabled = env_bool("GITKS_HOOKS_ENABLED", true);
    let server_hooks_dir = std::env::var("GITKS_SERVER_HOOKS_DIR")
        .ok()
        .map(PathBuf::from);
    let hook_callback_addr = std::env::var("GITKS_HOOK_CALLBACK_ADDR").ok();
    let hook_timeout = env_u64("GITKS_HOOK_TIMEOUT", 30);
    let allow_custom_hooks = env_bool("GITKS_ALLOW_CUSTOM_HOOKS", true);

    let hook_manager = if hooks_enabled {
        tracing::info!("hooks enabled, timeout={hook_timeout}s, custom_hooks={allow_custom_hooks}");
        Some(HookManager::new(
            repo_prefix.clone(),
            server_hooks_dir,
            hook_callback_addr,
            Duration::from_secs(hook_timeout),
            allow_custom_hooks,
        ))
    } else {
        tracing::info!("hooks disabled");
        None
    };

    // Health check / election configuration
    let health_check_interval = env_u64("GITKS_HEALTH_CHECK_INTERVAL", 1);
    let max_health_failures = env_u64("GITKS_MAX_HEALTH_FAILURES", 10);

    tracing::info!(
        "health check: interval={health_check_interval}s, max_failures={max_health_failures}"
    );

    let metrics_port = env_u64("GITKS_METRICS_PORT", 9100) as u16;
    let _metrics_handle = metrics::start_metrics_server(metrics_port);
    tracing::info!("metrics server on port {metrics_port}");

    //
    // When GITKS_ETCD_ENDPOINTS is set, the node:
    //   1. Starts a ractor_cluster NodeServer (TCP listener)
    //   2. Connects to etcd and registers itself
    //   3. Discovers existing peers → establishes ractor_cluster TCP connections
    //   4. Watches etcd for future peer join/leave events
    //
    // Once ractor_cluster connections are up, pg::get_members() automatically
    // returns remote actors — no changes needed in actor/handler.rs.
    //
    // When GITKS_ETCD_ENDPOINTS is unset or etcd is unreachable, the node
    // falls back to standalone mode (existing local-only behavior).
    let etcd_endpoints = std::env::var("GITKS_ETCD_ENDPOINTS")
        .ok()
        .filter(|s| !s.is_empty())
        .map(|s| {
            s.split(',')
                .map(str::trim)
                .map(String::from)
                .collect::<Vec<_>>()
        });

    let cluster_port = env_or("GITKS_CLUSTER_PORT", "4697")
        .parse::<u16>()
        .unwrap_or(4697);
    let cluster_cookie = env_or("GITKS_CLUSTER_COOKIE", "gitks-default-cookie");
    let lease_ttl = env_u64("GITKS_LEASE_TTL", 15) as i64;
    let connect_timeout_ms = env_u64("GITKS_ETCD_CONNECT_TIMEOUT", 5000);

    // Resolve the hostname/address other nodes use to reach our NodeServer.
    // Priority: GITKS_CLUSTER_HOSTNAME > POD_IP (K8s) > HOSTNAME env > "localhost"
    let cluster_hostname = std::env::var("GITKS_CLUSTER_HOSTNAME")
        .or_else(|_| std::env::var("POD_IP"))
        .or_else(|_| std::env::var("HOSTNAME"))
        .unwrap_or_else(|_| "localhost".to_string());

    let _cluster: Option<ClusterManager> = if let Some(endpoints) = etcd_endpoints {
        tracing::info!(
            endpoints = ?endpoints,
            cluster_port = cluster_port,
            cluster_hostname = %cluster_hostname,
            "starting cluster discovery via etcd"
        );
        let config = ClusterConfig {
            etcd_endpoints: endpoints,
            storage_name: storage_name.clone(),
            grpc_addr: grpc_addr.clone(),
            cluster_port,
            cookie: cluster_cookie,
            lease_ttl_secs: lease_ttl,
            connect_timeout_ms,
            cluster_hostname,
        };
        match ClusterManager::start(config).await {
            Ok(cm) => {
                tracing::info!("cluster discovery active");
                Some(cm)
            }
            Err(e) => {
                tracing::warn!(error = %e, "etcd unavailable, running in standalone mode");
                None
            }
        }
    } else {
        tracing::info!("GITKS_ETCD_ENDPOINTS not set, running in standalone mode");
        None
    };

    let addr: std::net::SocketAddr = format!("{host}:{port}").parse()?;
    let mut svc = GitksService::new(repo_prefix.clone());

    if disk_cache_enabled {
        svc = svc.with_disk_cache(disk_cache);
    }
    if let Some(pc) = pack_cache {
        svc = svc.with_pack_cache(pc);
    }
    if let Some(hm) = hook_manager {
        svc = svc.with_hook_manager(hm);
    }

    let (node_actor, node_handle) =
        init_actor_cluster(svc.clone(), storage_name.clone(), grpc_addr.clone()).await?;
    let svc = svc
        .with_actor(node_actor.clone())
        .with_grpc_addr(grpc_addr.clone());

    tracing::info!(
        "starting gitks gRPC server on {addr}, repo prefix: {}, storage: {storage_name}, advertise: {grpc_addr}",
        repo_prefix.display()
    );

    serve(addr, svc).await?;

    node_actor.stop(None);
    node_handle.await?;

    tracing::info!("gitks shut down");
    Ok(())
}