use anyhow::{Context, Result, bail};
use std::fs;
use tracing::{info, instrument};

pub mod cli;
pub mod config;
pub mod downloader;

use cli::Args;
use config::Config;

/// The main application logic.
#[instrument(skip_all, fields(
    config_file = %args.input.display(),
    output_dir = %args.output.display()
))]
pub async fn run(args: Args) -> Result<()> {
    info!("Starting ruleset processor");

    // Load and parse the configuration file.
    let config = Config::load(&args.input)
        .with_context(|| format!("Failed to load config from {}", args.input.display()))?;

    // Ensure the output directory exists.
    fs::create_dir_all(&args.output).with_context(|| {
        format!(
            "Failed to create output directory '{}'",
            args.output.display()
        )
    })?;

    // Determine the set of files that should exist.
    let expected_files = config
        .get_expected_files(&args.output)
        .context("Failed to determine expected files from config")?;

    // Clean up any stale files.
    downloader::cleanup_stale_files(&args.output, &expected_files)?;

    // Proceed to download files defined in the config.
    let urls_to_download = config.extract_urls();
    if urls_to_download.is_empty() {
        info!("No rule sets with URLs found in config. Process complete.");
        return Ok(());
    }

    info!(
        count = urls_to_download.len(),
        "Found rule sets to download/update."
    );

    // Download all files concurrently.
    let download_report =
        downloader::download_all_rules(&urls_to_download, &args.output, args.concurrency).await?;

    info!(
        successful = download_report.successful,
        failed = download_report.failed,
        "Download process finished."
    );

    // If any downloads failed, abort with an error message.
    if download_report.failed > 0 {
        bail!(
            "Aborting due to {} download failures.",
            download_report.failed
        );
    }

    info!("Ruleset synchronization completed successfully.");
    Ok(())
}