pub mod api;
pub mod cache;
pub mod config;
pub mod error;
pub mod etcd;
pub mod grpc;
pub mod models;
pub mod pb;
pub mod queue;
pub mod service;
pub mod session;
pub mod storage;

use std::net::SocketAddr;
use std::sync::Arc;

use actix_web::cookie::Key;
use actix_web::{App, HttpResponse, HttpServer, web};
use sqlx::Executor;

use crate::cache::AppCache;
use crate::cache::redis::AppRedis;
use crate::config::AppConfig;
use crate::error::{AppError, AppResult};
use crate::etcd::EtcdRegistry;
use crate::models::db::AppDatabase;
use crate::queue::NatsQueue;
use crate::service::AppService;
use crate::session::RedisSessionStore;
use crate::storage::s3::AppS3Storage;
use utoipa::OpenApi;

/// A ready-to-run appks HTTP + gRPC server.
///
/// Use [`AppksServerBuilder`] to construct an instance from configuration.
pub struct AppksServer {
    service: AppService,
    db: AppDatabase,
    config: AppConfig,
    redis: AppRedis,
    rpc_addr: SocketAddr,
    rpc_listener: tokio::net::TcpListener,
}

/// Builder for [`AppksServer`].
///
/// # Examples
///
/// ```no_run
/// use appks::{AppksServer, config::AppConfig};
///
/// # async fn example() -> Result<(), Box<dyn std::error::Error>> {
/// let config = AppConfig::load();
/// let server = AppksServer::builder()
///     .config(config)
///     .build()
///     .await?;
/// server.serve().await?;
/// # Ok(())
/// # }
/// ```
pub struct AppksServerBuilder {
    config: Option<AppConfig>,
}

impl AppksServer {
    /// Create a new builder.
    pub fn builder() -> AppksServerBuilder {
        AppksServerBuilder::default()
    }

    /// Returns a reference to the inner [`AppService`].
    ///
    /// Useful when embedding appks in another application without running
    /// the built-in HTTP/gRPC servers — you can wire routes manually.
    pub fn service(&self) -> &AppService {
        &self.service
    }

    /// Start the HTTP and gRPC servers and block until shutdown.
    pub async fn serve(self) -> AppResult<()> {
        // Spawn gRPC server
        {
            let grpc_service = self.service.clone();
            let rpc_addr = self.rpc_addr;
            let rpc_listener = self.rpc_listener;
            tokio::spawn(async move {
                if let Err(e) =
                    crate::grpc::start_grpc_server(rpc_addr, rpc_listener, grpc_service).await
                {
                    tracing::error!(error = %e, "gRPC server failed");
                }
            });
        }

        // Background JWT key rotation
        {
            let token_service = self.service.internal_auth.clone();
            tokio::spawn(async move {
                let mut interval = tokio::time::interval(std::time::Duration::from_secs(600));
                interval.tick().await; // skip first immediate tick
                loop {
                    interval.tick().await;
                    match token_service.rotate_if_needed().await {
                        Ok(true) => tracing::info!("signing key rotated"),
                        Ok(false) => tracing::debug!("signing key rotation not needed"),
                        Err(e) => tracing::error!(error = %e, "signing key rotation failed"),
                    }
                }
            });
        }

        // HTTP server
        let host = self
            .config
            .get_env_or::<String>("APP_HTTP_HOST", "0.0.0.0".to_string())?;
        let port = self
            .config
            .get_env_or::<u16>("APP_HTTP_PORT", 8000)?;
        let workers = self.config.get_env_or::<usize>(
            "APP_HTTP_WORKERS",
            std::thread::available_parallelism()
                .map(|n| n.get())
                .unwrap_or(1),
        )?;
        let bind_addr = format!("{host}:{port}");
        let session_key = build_session_key(&self.config)?;
        let session_cfg = self.config.session_config()?;
        let redis = self.redis.clone();
        let service = self.service.clone();

        tracing::info!(addr = %bind_addr, workers, "http server listening");

        HttpServer::new(move || {
            let session_store = RedisSessionStore::new(redis.clone());
            let session_middleware =
                session_cfg.build_middleware(session_store, session_key.clone());

            App::new()
                .wrap(actix_web::middleware::Logger::default())
                .app_data(web::Data::new(service.clone()))
                .wrap(session_middleware)
                .route("/healthz", web::get().to(healthz))
                .route("/readyz", web::get().to(readyz))
                .route("/openapi.json", web::get().to(openapi_json))
                .configure(crate::api::routes::init_routes)
        })
        .workers(workers)
        .bind(bind_addr)?
        .run()
        .await?;

        self.db.close().await;
        Ok(())
    }
}

impl AppksServerBuilder {
    /// Set the server configuration.
    pub fn config(mut self, config: AppConfig) -> Self {
        self.config = Some(config);
        self
    }

    /// Build the server, connecting to all infrastructure (DB, Redis, S3, etcd, NATS)
    /// and creating the service layer.
    pub async fn build(self) -> AppResult<AppksServer> {
        let config = self.config.unwrap_or_else(AppConfig::load);
        validate_session_secret(&config)?;

        tracing::info!("starting AppKS");

        let db = AppDatabase::from_config(&config).await?;
        db.writer().execute("SELECT 1").await?;
        sqlx::migrate!("./migrate")
            .run(db.writer())
            .await
            .map_err(|e| AppError::Config(format!("database migration failed: {e}")))?;

        let redis = AppRedis::from_config(&config).await?;
        let cache = Arc::new(AppCache::from_config(&config).await?);
        let storage = AppS3Storage::from_config(&config).await?;

        let rpc_host = config.get_env_or::<String>("APP_RPC_SELF_HOST", "0.0.0.0".to_string())?;
        let rpc_port = config.get_env_or::<u16>("APP_RPC_SELF_PORT", 50050)?;
        let rpc_addr: SocketAddr = format!("{rpc_host}:{rpc_port}")
            .parse()
            .map_err(|e| AppError::Config(format!("invalid gRPC address: {e}")))?;

        let rpc_listener = tokio::net::TcpListener::bind(rpc_addr).await.map_err(|e| {
            AppError::Config(format!("gRPC bind failed on {rpc_addr}: {e}"))
        })?;

        let registry = Arc::new(EtcdRegistry::connect(&config).await?);
        registry.start_discovery().await?;
        registry
            .register_self(&config.rpc_self_service_name()?)
            .await?;

        let nats = Arc::new(NatsQueue::connect(&config).await?);

        let service = AppService::new(
            env!("CARGO_PKG_VERSION").to_string(),
            db.clone(),
            redis.clone(),
            cache,
            config.clone(),
            storage,
            registry,
            nats,
        )
        .await;

        Ok(AppksServer {
            service,
            db,
            config,
            redis,
            rpc_addr,
            rpc_listener,
        })
    }
}

impl Default for AppksServerBuilder {
    fn default() -> Self {
        Self { config: None }
    }
}

async fn healthz() -> HttpResponse {
    HttpResponse::Ok().json(serde_json::json!({ "status": "ok" }))
}

async fn readyz(service: web::Data<AppService>) -> Result<HttpResponse, AppError> {
    service.ctx.db.writer().execute("SELECT 1").await?;
    Ok(HttpResponse::Ok().json(serde_json::json!({ "status": "ready" })))
}

async fn openapi_json() -> HttpResponse {
    HttpResponse::Ok().json(crate::api::openapi::OpenApiDoc::openapi())
}

fn build_session_key(config: &AppConfig) -> AppResult<Key> {
    let secret = session_secret(config)?;
    Ok(Key::derive_from(secret.as_bytes()))
}

fn validate_session_secret(config: &AppConfig) -> AppResult<()> {
    session_secret(config).map(|_| ())
}

fn session_secret(config: &AppConfig) -> AppResult<String> {
    let secret = config
        .env
        .get("APP_SESSION_SECRET")
        .map(|s| s.trim())
        .filter(|s| s.len() >= 32)
        .ok_or_else(|| AppError::Config("APP_SESSION_SECRET must be at least 32 bytes".into()))?;
    Ok(secret.to_string())
}