//! Example demonstrating the atomicity limitations of the APT-DNF Bridge.
//!
//! This example shows how the APT-DNF Bridge provides transaction-like semantics
//! but does NOT provide true system-level atomicity.

use apt_dnf_bridge::{Package, Transaction};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    println!("APT-DNF Bridge - Atomicity Notes Example");
    println!("=====================================");

    // Create a transaction
    let mut tx = Transaction::new();
    
    // Add some operations
    let vim = Package::new("vim", "2:8.1.2269-1ubuntu5.14", "amd64");
    let nano = Package::new("nano", "2.9.3-2", "amd64");
    
    tx.add_install(vim).await?;
    tx.add_install(nano).await?;
    
    println!("Created transaction with {} operations", tx.len());
    
    // Resolve dependencies (this will validate the transaction)
    println!("Resolving dependencies...");
    tx.resolve().await?;
    println!("✓ Dependencies resolved successfully");
    
    // IMPORTANT: The commit() method does NOT provide true atomicity
    println!("\n⚠️  IMPORTANT ATOMICITY NOTES:");
    println!("   • This transaction provides transaction-like semantics");
    println!("   • It does NOT provide true system-level atomicity");
    println!("   • If the operation fails midway, the system could be left in a corrupted state");
    println!("   • For true atomicity, apt-ostree must handle this at a higher level");
    println!("   • This might involve operating on a temporary directory and performing an atomic pivot_root");
    
    println!("\nTransaction operations:");
    for (i, op) in tx.operations().iter().enumerate() {
        match op {
            apt_dnf_bridge::Operation::Install(pkg) => {
                println!("  {}: Install {}", i + 1, pkg.name);
            }
            apt_dnf_bridge::Operation::Remove(pkg) => {
                println!("  {}: Remove {}", i + 1, pkg.name);
            }
            apt_dnf_bridge::Operation::Upgrade(pkg) => {
                println!("  {}: Upgrade {}", i + 1, pkg.name);
            }
        }
    }
    
    println!("\nTo commit this transaction (commented out for safety):");
    println!("  tx.commit().await?;");
    
    println!("\nFor apt-ostree integration, consider:");
    println!("  1. Operating on a temporary directory");
    println!("  2. Performing all APT operations there");
    println!("  3. Using atomic pivot_root to switch to the new system state");
    println!("  4. Rolling back if any step fails");
    
    Ok(())
}