// src/main.rs

use std::{process::exit, sync::Arc};

use axum::Router;
use dotenvy::dotenv;
use tokio::signal;
use tower_http::trace::TraceLayer;
use tracing::{error, info};
use tracing_subscriber::{EnvFilter, fmt, prelude::*};

mod config;
mod handlers;
mod mongo; // local module wrapping the Mongo client
mod routes;

use ::mongodb::Database; // external crate (absolute path avoids name clash)
use config::Config;
use mongo::MongoDb; // your wrapper

// Shared application state for online mode
pub struct AppState {
    pub db: Database,
    pub config: Config,
}

#[tokio::main]
async fn main() {
    // Load .env early
    dotenv().ok();

    // Tracing with a safe fallback if RUST_LOG is unset
    let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
    tracing_subscriber::registry()
        .with(fmt::layer())
        .with(env_filter)
        .init();

    // Load config
    let config = match Config::from_env() {
        Ok(c) => c,
        Err(e) => {
            error!("Failed to load config: {e}");
            exit(1);
        }
    };

    // Runtime OFFLINE switch: true if OFFLINE is 1/true/yes/on (case-insensitive)
    let offline = std::env::var("OFFLINE")
        .ok()
        .map(|v| matches!(v.to_ascii_lowercase().as_str(), "1" | "true" | "yes" | "on"))
        .unwrap_or(false);

    if offline {
        // Enforce loopback binding while offline
        if !config.bind_address.ip().is_loopback() {
            error!(
                "OFFLINE=true requires binding to a loopback address (e.g., 127.0.0.1:<port> or [::1]:<port>), got {}",
                config.bind_address
            );
            exit(1);
        }

        info!("OFFLINE mode enabled — not connecting to MongoDB");
        info!("Server starting on {}", config.bind_address);

        // Health-only, no state. Subrouter is typed to `()`.
        let app = Router::new()
            .nest("/health", routes::health::health::health_routes::<()>())
            .layer(TraceLayer::new_for_http());

        let listener = tokio::net::TcpListener::bind(config.bind_address)
            .await
            .unwrap();
        axum::serve(listener, app)
            .with_graceful_shutdown(shutdown_signal())
            .await
            .unwrap();
        return;
    }

    // --- Online (DB-enabled) path ---
    let mongo = match MongoDb::connect(&config).await {
        Ok(db) => db,
        Err(e) => {
            error!("Failed to connect to MongoDB: {e}");
            exit(1);
        }
    };

    let shared_state = Arc::new(AppState {
        db: mongo.database,
        config: config.clone(),
    });

    info!("Server starting on {}", config.bind_address);

    // Build subrouters typed with the same state as the root
    let health_router = routes::health::health::health_routes::<Arc<AppState>>();
    let user_router = routes::user::user::user_routes::<Arc<AppState>>();

    // Root router typed with state; set state once on the root
    let app = Router::<Arc<AppState>>::new()
        .nest("/health", health_router)
        .nest("/user", user_router)
        .with_state(shared_state)
        .layer(TraceLayer::new_for_http());

    let listener = tokio::net::TcpListener::bind(config.bind_address)
        .await
        .unwrap();
    axum::serve(listener, app)
        .with_graceful_shutdown(shutdown_signal())
        .await
        .unwrap();
}

async fn shutdown_signal() {
    let ctrl_c = async {
        signal::ctrl_c()
            .await
            .expect("Failed to install Ctrl+C handler");
    };

    #[cfg(unix)]
    let terminate = async {
        signal::unix::signal(signal::unix::SignalKind::terminate())
            .expect("Failed to install signal handler")
            .recv()
            .await;
    };

    #[cfg(not(unix))]
    let terminate = std::future::pending::<()>();

    tokio::select! {
        _ = ctrl_c => {},
        _ = terminate => {},
    }

    info!("Signal received, shutting down server gracefully");
}