//! Background library sync task.
//! Fires 10 seconds after startup, then every N hours (read from app_settings).

use std::sync::Arc;
use std::time::Duration;

use domain::IProviderRegistry;

const STARTUP_DELAY_SECS: u64 = 10;
const DEFAULT_INTERVAL_HOURS: u64 = 6;

pub async fn run_library_sync(
    sync_adapter: Arc<dyn domain::LibrarySyncAdapter>,
    registry: Arc<tokio::sync::RwLock<Arc<infra::ProviderRegistry>>>,
    app_settings_repo: Arc<dyn domain::IAppSettingsRepository>,
) {
    tokio::time::sleep(Duration::from_secs(STARTUP_DELAY_SECS)).await;

    loop {
        tick(&sync_adapter, &registry).await;

        let interval_hours = load_interval_hours(&app_settings_repo).await;
        tokio::time::sleep(Duration::from_secs(interval_hours * 3600)).await;
    }
}

async fn load_interval_hours(repo: &Arc<dyn domain::IAppSettingsRepository>) -> u64 {
    repo.get("library_sync_interval_hours")
        .await
        .ok()
        .flatten()
        .and_then(|v| v.parse::<u64>().ok())
        .unwrap_or(DEFAULT_INTERVAL_HOURS)
}

async fn tick(
    sync_adapter: &Arc<dyn domain::LibrarySyncAdapter>,
    registry: &Arc<tokio::sync::RwLock<Arc<infra::ProviderRegistry>>>,
) {
    let reg = registry.read().await;
    let provider_ids: Vec<String> = reg.provider_ids();
    drop(reg);

    for provider_id in provider_ids {
        let reg = registry.read().await;
        let provider = match reg.get_provider(&provider_id) {
            Some(p) => p,
            None => continue,
        };
        drop(reg);

        tracing::info!("library-sync: syncing provider '{}'", provider_id);
        let result = sync_adapter.sync_provider(provider.as_ref(), &provider_id).await;

        if let Some(ref err) = result.error {
            tracing::warn!("library-sync: provider '{}' failed: {}", provider_id, err);
        } else {
            tracing::info!(
                "library-sync: provider '{}' done — {} items in {}ms",
                provider_id, result.items_found, result.duration_ms
            );
        }
    }
}