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};

use tracing_subscriber::EnvFilter;
use tracing_subscriber::fmt;
use tracing_subscriber::prelude::*;

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,
        _ => default,
    }
}

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

fn init_tracing() -> Option<tracing_appender::non_blocking::WorkerGuard> {
    let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));

    let log_format = env_or("GITKS_LOG_FORMAT", "pretty");

    let fmt_layer = match log_format.as_str() {
        "json" => fmt::layer()
            .json()
            .with_target(true)
            .with_file(true)
            .with_line_number(true)
            .with_thread_ids(true)
            .with_span_events(fmt::format::FmtSpan::NEW | fmt::format::FmtSpan::CLOSE)
            .boxed(),
        _ => fmt::layer()
            .pretty()
            .with_target(true)
            .with_file(true)
            .with_line_number(true)
            .boxed(),
    };

    // Optional file output with rotation
    if let Ok(log_dir) = std::env::var("GITKS_LOG_DIR") {
            let rotation = match env_or("GITKS_LOG_ROTATION", "daily").as_str() {
                "hourly" => tracing_appender::rolling::Rotation::HOURLY,
                "never" => tracing_appender::rolling::Rotation::NEVER,
                _ => tracing_appender::rolling::Rotation::DAILY,
            };
            let retention = env_u64("GITKS_LOG_RETENTION", 7) as usize;

            let mut builder = tracing_appender::rolling::Builder::new()
                .rotation(rotation)
                .filename_prefix("gitks")
                .filename_suffix("log");

            if retention > 0 {
                builder = builder.max_log_files(retention);
            }

            let file_appender = builder.build(&log_dir).expect("failed to create log directory");
            let (non_blocking, guard) = tracing_appender::non_blocking(file_appender);

            let file_layer = fmt::layer()
                .json()
                .with_target(true)
                .with_file(true)
                .with_line_number(true)
                .with_writer(non_blocking)
                .with_filter(EnvFilter::new("info"))
                .boxed();

            tracing_subscriber::registry()
                .with(env_filter)
                .with(fmt_layer)
                .with(file_layer)
                .init();

            Some(guard)
        } else {
            tracing_subscriber::registry()
                .with(env_filter)
                .with(fmt_layer)
                .init();
            None
        }
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    dotenvy::dotenv().ok();
    let _log_guard = init_tracing();

    tracing::info!(
        version = env!("CARGO_PKG_VERSION"),
        log_format = %env_or("GITKS_LOG_FORMAT", "pretty"),
        "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!(
            max_age_secs = disk_cache_max_age,
            "disk cache enabled"
        );
        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);

    let pack_cache = if disk_cache_enabled {
        tracing::info!(
            pack_objects_cache = pack_cache_enabled,
            backpressure = pack_backpressure,
            "pack cache wrapper enabled"
        );
        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!(
            timeout_secs = hook_timeout,
            custom_hooks = allow_custom_hooks,
            "hooks enabled"
        );
        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!(
        interval_secs = health_check_interval,
        max_failures = max_health_failures,
        "health check configured"
    );

    let metrics_port = env_u64("GITKS_METRICS_PORT", 9100) as u16;
    let http_cancel = tokio_util::sync::CancellationToken::new();
    metrics::set_http_cancel_token(http_cancel.clone());
    let _metrics_handle = metrics::start_metrics_server(metrics_port);
    tracing::info!(port = metrics_port, "metrics server started");

    // Slow request threshold
    let slow_request_threshold = env_u64("GITKS_SLOW_REQUEST_THRESHOLD_MS", 5000);
    metrics::set_slow_request_threshold(slow_request_threshold);
    tracing::info!(
        threshold_ms = slow_request_threshold,
        "slow request detection configured"
    );

    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);

    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,
            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 raft_data_dir = repo_prefix.join(".gitks_raft");
    let (node_actor, node_handle) =
        init_actor_cluster(svc.clone(), storage_name.clone(), grpc_addr.clone(), raft_data_dir).await?;
    let svc = svc
        .with_actor(node_actor.clone())
        .with_grpc_addr(grpc_addr.clone());

    tracing::info!(
        addr = %addr,
        repo_prefix = %repo_prefix.display(),
        storage = %storage_name,
        advertise = %grpc_addr,
        "starting gitks gRPC server"
    );

    let _route_cache_cleanup = gitks::server::GitksService::start_route_cache_cleanup(svc.clone());

    serve(addr, svc).await?;

    // Gracefully shut down the HTTP metrics server
    http_cancel.cancel();

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

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