use std::path::Path;
use std::sync::Arc;

use desi_explorer_api::{config, routes, store};

use tracing_subscriber::EnvFilter;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    tracing_subscriber::fmt()
        .with_env_filter(
            EnvFilter::try_from_default_env()
                .unwrap_or_else(|_| EnvFilter::new("desi_explorer_api=info")),
        )
        .init();

    load_env_file()?;

    let config = config::Config::from_env()?;

    let catalog_store = match &config.desi_data {
        Some(path) => {
            tracing::info!(path = %path.display(), "loading DESI data");
            store::CatalogStore::load(Path::new(path))?
        }
        None => {
            tracing::warn!("API_DESI_DATA not set, serving placeholder catalogs");
            store::CatalogStore::placeholder()
        }
    };

    let app = routes::app_with_state(Arc::new(catalog_store));

    let listener = tokio::net::TcpListener::bind(&config.bind_addr).await?;
    tracing::info!("DESI Explorer API listening on {}", config.bind_addr);

    axum::serve(listener, app)
        .with_graceful_shutdown(shutdown_signal())
        .await?;

    Ok(())
}

/// Loads the env file named by `API_ENV_FILE` (if set) into the process
/// environment. Existing env vars are not overridden, so values passed
/// directly on the command line or by the Makefile take precedence.
fn load_env_file() -> anyhow::Result<()> {
    let path = std::env::var("API_ENV_FILE").unwrap_or_default();
    if path.is_empty() {
        return Ok(());
    }

    match dotenvy::from_path(&path) {
        Ok(_) => tracing::info!(%path, "loaded env file"),
        Err(err) => {
            return Err(anyhow::anyhow!(
                "failed to load API_ENV_FILE {path:?}: {err}"
            ))
        }
    }

    Ok(())
}

async fn shutdown_signal() {
    let _ = tokio::signal::ctrl_c().await;
    tracing::info!("shutting down");
}