apt-dnf-bridge-workspace/examples/backend_selection.rs

//! Example demonstrating backend selection and switching.

use apt_dnf_bridge::{
    BackendConfig, Package, TransactionV2, PackageDatabaseV2,
};

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

    // 1. Auto-detect the best available backend
    println!("1. Auto-detecting best backend...");
    let tx = TransactionV2::new().await?;
    let (backend_name, backend_version) = tx.backend_info();
    println!("   Selected backend: {} v{}", backend_name, backend_version);

    // 2. Create a transaction with shell backend explicitly
    println!("\n2. Creating transaction with shell backend...");
    let config = BackendConfig {
        enable_logging: true,
        use_cache: true,
        max_cache_size: 1000,
        command_timeout: Some(300),
    };
    let shell_tx = TransactionV2::with_shell_backend(config).await?;
    let (shell_name, shell_version) = shell_tx.backend_info();
    println!("   Shell backend: {} v{}", shell_name, shell_version);

    // 3. Create a package database with mock backend for testing
    println!("\n3. Creating package database with mock backend...");
    let mock_config = BackendConfig {
        enable_logging: true,
        use_cache: true,
        max_cache_size: 100,
        command_timeout: Some(30),
    };
    let mut mock_db = PackageDatabaseV2::with_mock_backend(mock_config).await?;
    let (_mock_name, mock_version) = mock_db.backend_info();
    println!("   Mock backend: v{}", mock_version);

    // 4. Demonstrate backend capabilities
    println!("\n4. Testing backend capabilities...");
    
    // Test mock backend
    println!("   Testing mock backend:");
    let packages = mock_db.find_packages("vim").await?;
    println!("     Found {} packages matching 'vim'", packages.len());
    
    if let Some(pkg_info) = mock_db.get_package_info("vim").await? {
        println!("     Package info: {} {}", pkg_info.name, pkg_info.version);
    }

    // Test shell backend (if available)
    println!("   Testing shell backend:");
    let mut shell_db = PackageDatabaseV2::with_shell_backend(BackendConfig::default()).await?;
    let shell_packages = shell_db.find_packages("vim").await?;
    println!("     Found {} packages matching 'vim'", shell_packages.len());

    // 5. Demonstrate transaction with different backends
    println!("\n5. Testing transactions with different backends...");
    
    let vim = Package::new("vim", "2:8.1.2269-1ubuntu5.14", "amd64");
    
    // Mock transaction
    let mut mock_tx = TransactionV2::with_mock_backend(BackendConfig::default()).await?;
    mock_tx.add_install(vim.clone()).await?;
    println!("   Mock transaction: {} operations", mock_tx.len());
    
    let resolution = mock_tx.resolve().await?;
    println!("   Mock resolution: resolvable={}, summary='{}'", 
             resolution.resolvable, resolution.summary);

    // Shell transaction (if available)
    let mut shell_tx = TransactionV2::with_shell_backend(BackendConfig::default()).await?;
    shell_tx.add_install(vim).await?;
    println!("   Shell transaction: {} operations", shell_tx.len());
    
    let shell_resolution = shell_tx.resolve().await?;
    println!("   Shell resolution: resolvable={}, summary='{}'", 
             shell_resolution.resolvable, shell_resolution.summary);

    // 6. Show backend statistics
    println!("\n6. Backend statistics:");
    let mock_stats = mock_db.get_backend_stats().await?;
    println!("   Mock backend stats:");
    println!("     Commands executed: {}", mock_stats.commands_executed);
    println!("     Packages queried: {}", mock_stats.packages_queried);
    println!("     Cache hit rate: {:.2}%", mock_stats.cache_hit_rate * 100.0);

    let shell_stats = shell_db.get_backend_stats().await?;
    println!("   Shell backend stats:");
    println!("     Commands executed: {}", shell_stats.commands_executed);
    println!("     Packages queried: {}", shell_stats.packages_queried);
    println!("     Cache hit rate: {:.2}%", shell_stats.cache_hit_rate * 100.0);

    println!("\n✅ Backend selection example completed successfully!");
    println!("\n💡 Key benefits of pluggable backends:");
    println!("   • Start with simple shell backend (reliable)");
    println!("   • Switch to libapt backend when available (more powerful)");
    println!("   • Use mock backend for testing (fast, predictable)");
    println!("   • Same API works with all backends");

    Ok(())
}