//! GuruRMM Agent - Cross-platform Remote Monitoring and Management Agent
//!
//! This agent connects to the GuruRMM server, reports system metrics,
//! monitors services (watchdog), and executes remote commands.

mod claude;
mod config;
mod device_id;
mod metrics;
mod service;
mod transport;
mod updater;

use anyhow::{Context, Result};
use clap::{Parser, Subcommand};
use std::path::PathBuf;
use std::sync::Arc;
use tokio::sync::RwLock;
use tracing::{error, info, warn};

use crate::config::AgentConfig;
use crate::metrics::MetricsCollector;
use crate::transport::WebSocketClient;

/// GuruRMM Agent - Remote Monitoring and Management
#[derive(Parser)]
#[command(name = "gururmm-agent")]
#[command(author, version, about, long_about = None)]
struct Cli {
    /// Path to configuration file
    #[arg(short, long, default_value = "agent.toml")]
    config: PathBuf,

    /// Subcommand to run
    #[command(subcommand)]
    command: Option<Commands>,
}

#[derive(Subcommand)]
enum Commands {
    /// Run the agent (default)
    Run,

    /// Install as a system service
    Install {
        /// Server WebSocket URL (e.g., wss://rmm-api.example.com/ws)
        #[arg(long)]
        server_url: Option<String>,

        /// API key for authentication
        #[arg(long)]
        api_key: Option<String>,

        /// Skip legacy service detection and cleanup
        #[arg(long, default_value = "false")]
        skip_legacy_check: bool,
    },

    /// Uninstall the system service
    Uninstall,

    /// Start the installed service
    Start,

    /// Stop the installed service
    Stop,

    /// Show agent status
    Status,

    /// Generate a sample configuration file
    GenerateConfig {
        /// Output path for config file
        #[arg(short, long, default_value = "agent.toml")]
        output: PathBuf,
    },

    /// Run as Windows service (called by SCM, not for manual use)
    #[command(hide = true)]
    Service,
}

/// Shared application state
pub struct AppState {
    pub config: AgentConfig,
    pub metrics_collector: MetricsCollector,
    pub connected: RwLock<bool>,
}

#[tokio::main]
async fn main() -> Result<()> {
    // Initialize logging
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::from_default_env()
                .add_directive("gururmm_agent=info".parse()?)
                .add_directive("info".parse()?),
        )
        .init();

    let cli = Cli::parse();

    match cli.command.unwrap_or(Commands::Run) {
        Commands::Run => run_agent(cli.config).await,
        Commands::Install { server_url, api_key, skip_legacy_check } => {
            install_service(server_url, api_key, skip_legacy_check).await
        }
        Commands::Uninstall => uninstall_service().await,
        Commands::Start => start_service().await,
        Commands::Stop => stop_service().await,
        Commands::Status => show_status(cli.config).await,
        Commands::GenerateConfig { output } => generate_config(output).await,
        Commands::Service => run_as_windows_service(),
    }
}

/// Run as a Windows service (called by SCM)
fn run_as_windows_service() -> Result<()> {
    #[cfg(windows)]
    {
        service::windows::run_as_service()
    }

    #[cfg(not(windows))]
    {
        anyhow::bail!("Windows service mode is only available on Windows");
    }
}

/// Main agent runtime loop
async fn run_agent(config_path: PathBuf) -> Result<()> {
    info!("GuruRMM Agent starting...");

    // Load configuration
    let config = AgentConfig::load(&config_path)?;
    info!("Loaded configuration from {:?}", config_path);
    info!("Server URL: {}", config.server.url);

    // Initialize metrics collector
    let metrics_collector = MetricsCollector::new();
    info!("Metrics collector initialized");

    // Create shared state
    let state = Arc::new(AppState {
        config: config.clone(),
        metrics_collector,
        connected: RwLock::new(false),
    });

    // Start the WebSocket client with auto-reconnect
    let ws_state = Arc::clone(&state);
    let ws_handle = tokio::spawn(async move {
        loop {
            info!("Connecting to server...");
            match WebSocketClient::connect_and_run(Arc::clone(&ws_state)).await {
                Ok(_) => {
                    warn!("WebSocket connection closed normally, reconnecting...");
                }
                Err(e) => {
                    error!("WebSocket error: {}, reconnecting in 10 seconds...", e);
                }
            }

            // Mark as disconnected
            *ws_state.connected.write().await = false;

            // Wait before reconnecting
            tokio::time::sleep(tokio::time::Duration::from_secs(10)).await;
        }
    });

    // Start metrics collection loop
    let metrics_state = Arc::clone(&state);
    let metrics_handle = tokio::spawn(async move {
        let interval = metrics_state.config.metrics.interval_seconds;
        let mut interval_timer = tokio::time::interval(tokio::time::Duration::from_secs(interval));

        loop {
            interval_timer.tick().await;

            // Collect metrics (they'll be sent via WebSocket if connected)
            let metrics = metrics_state.metrics_collector.collect().await;
            if *metrics_state.connected.read().await {
                info!(
                    "Metrics: CPU={:.1}%, Mem={:.1}%, Disk={:.1}%",
                    metrics.cpu_percent, metrics.memory_percent, metrics.disk_percent
                );
            }
        }
    });

    // Wait for shutdown signal
    tokio::select! {
        _ = tokio::signal::ctrl_c() => {
            info!("Received shutdown signal");
        }
        _ = ws_handle => {
            error!("WebSocket task ended unexpectedly");
        }
        _ = metrics_handle => {
            error!("Metrics task ended unexpectedly");
        }
    }

    info!("GuruRMM Agent shutting down");
    Ok(())
}

/// Install the agent as a system service
async fn install_service(
    server_url: Option<String>,
    api_key: Option<String>,
    skip_legacy_check: bool,
) -> Result<()> {
    #[cfg(windows)]
    {
        service::windows::install(server_url, api_key, skip_legacy_check)
    }

    #[cfg(target_os = "linux")]
    {
        install_systemd_service(server_url, api_key, skip_legacy_check).await
    }

    #[cfg(target_os = "macos")]
    {
        let _ = (server_url, api_key, skip_legacy_check); // Suppress unused warnings
        return Err(anyhow::anyhow!(
            "macOS launchd service installation is not yet implemented.\n\
             For now, you can run the agent manually or create a launchd plist.\n\
             See: https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingLaunchdJobs.html"
        ));
    }
}

/// Legacy service names to check for and clean up (Linux)
#[cfg(target_os = "linux")]
const LINUX_LEGACY_SERVICE_NAMES: &[&str] = &[
    "gururmm",           // Old name without -agent suffix
    "guru-rmm-agent",    // Alternative naming
    "GuruRMM-Agent",     // Case variant
];

/// Clean up legacy Linux service installations
#[cfg(target_os = "linux")]
fn cleanup_legacy_linux_services() -> Result<()> {
    use std::process::Command;

    info!("Checking for legacy service installations...");

    for legacy_name in LINUX_LEGACY_SERVICE_NAMES {
        // Check if service exists
        let status = Command::new("systemctl")
            .args(["status", legacy_name])
            .output();

        if let Ok(output) = status {
            if output.status.success() || String::from_utf8_lossy(&output.stderr).contains("Loaded:") {
                info!("Found legacy service '{}', removing...", legacy_name);

                // Stop the service
                let _ = Command::new("systemctl")
                    .args(["stop", legacy_name])
                    .status();

                // Disable the service
                let _ = Command::new("systemctl")
                    .args(["disable", legacy_name])
                    .status();

                // Remove unit file
                let unit_file = format!("/etc/systemd/system/{}.service", legacy_name);
                if std::path::Path::new(&unit_file).exists() {
                    info!("Removing legacy unit file: {}", unit_file);
                    let _ = std::fs::remove_file(&unit_file);
                }
            }
        }
    }

    // Check for legacy binaries in common locations
    let legacy_binary_locations = [
        "/usr/local/bin/gururmm",
        "/usr/bin/gururmm",
        "/opt/gururmm/gururmm",
        "/opt/gururmm/agent",
    ];

    for legacy_path in legacy_binary_locations {
        if std::path::Path::new(legacy_path).exists() {
            info!("Found legacy binary at '{}', removing...", legacy_path);
            let _ = std::fs::remove_file(legacy_path);
        }
    }

    // Reload systemd to pick up removed unit files
    let _ = Command::new("systemctl")
        .args(["daemon-reload"])
        .status();

    Ok(())
}

/// Install as a systemd service (Linux)
#[cfg(target_os = "linux")]
async fn install_systemd_service(
    server_url: Option<String>,
    api_key: Option<String>,
    skip_legacy_check: bool,
) -> Result<()> {
    use std::process::Command;

    const SERVICE_NAME: &str = "gururmm-agent";
    const INSTALL_DIR: &str = "/usr/local/bin";
    const CONFIG_DIR: &str = "/etc/gururmm";
    const SYSTEMD_DIR: &str = "/etc/systemd/system";

    info!("Installing GuruRMM Agent as systemd service...");

    // Check if running as root
    if !nix::unistd::geteuid().is_root() {
        anyhow::bail!("Installation requires root privileges. Please run with sudo.");
    }

    // Clean up legacy installations unless skipped
    if !skip_legacy_check {
        if let Err(e) = cleanup_legacy_linux_services() {
            warn!("Legacy cleanup warning: {}", e);
        }
    }

    // Get the current executable path
    let current_exe = std::env::current_exe()
        .context("Failed to get current executable path")?;

    let binary_dest = format!("{}/{}", INSTALL_DIR, SERVICE_NAME);
    let config_dest = format!("{}/agent.toml", CONFIG_DIR);
    let unit_file = format!("{}/{}.service", SYSTEMD_DIR, SERVICE_NAME);

    // Create config directory
    info!("Creating config directory: {}", CONFIG_DIR);
    std::fs::create_dir_all(CONFIG_DIR)
        .context("Failed to create config directory")?;

    // Copy binary
    info!("Copying binary to: {}", binary_dest);
    std::fs::copy(&current_exe, &binary_dest)
        .context("Failed to copy binary")?;

    // Make binary executable
    Command::new("chmod")
        .args(["+x", &binary_dest])
        .status()
        .context("Failed to set binary permissions")?;

    // Handle configuration
    let config_needs_manual_edit;
    if !std::path::Path::new(&config_dest).exists() {
        info!("Creating config: {}", config_dest);

        // Start with sample config
        let mut config = crate::config::AgentConfig::sample();

        // Apply provided values
        if let Some(url) = &server_url {
            config.server.url = url.clone();
        }
        if let Some(key) = &api_key {
            config.server.api_key = key.clone();
        }

        let toml_str = toml::to_string_pretty(&config)?;
        std::fs::write(&config_dest, toml_str)
            .context("Failed to write config file")?;

        // Set restrictive permissions on config (contains API key)
        Command::new("chmod")
            .args(["600", &config_dest])
            .status()
            .context("Failed to set config permissions")?;

        config_needs_manual_edit = server_url.is_none() || api_key.is_none();
    } else {
        info!("Config already exists: {}", config_dest);
        config_needs_manual_edit = false;

        // If server_url or api_key provided, update existing config
        if server_url.is_some() || api_key.is_some() {
            info!("Updating existing configuration...");
            let config_content = std::fs::read_to_string(&config_dest)?;
            let mut config: crate::config::AgentConfig = toml::from_str(&config_content)
                .context("Failed to parse existing config")?;

            if let Some(url) = &server_url {
                config.server.url = url.clone();
            }
            if let Some(key) = &api_key {
                config.server.api_key = key.clone();
            }

            let toml_str = toml::to_string_pretty(&config)?;
            std::fs::write(&config_dest, toml_str)
                .context("Failed to update config file")?;
        }
    }

    // Create systemd unit file
    let unit_content = format!(r#"[Unit]
Description=GuruRMM Agent - Remote Monitoring and Management
Documentation=https://github.com/azcomputerguru/gururmm
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
ExecStart={binary} --config {config} run
Restart=always
RestartSec=10
StandardOutput=journal
StandardError=journal
SyslogIdentifier={service}

# Security hardening
NoNewPrivileges=true
ProtectSystem=strict
ProtectHome=read-only
PrivateTmp=true
ReadWritePaths=/var/log

[Install]
WantedBy=multi-user.target
"#,
        binary = binary_dest,
        config = config_dest,
        service = SERVICE_NAME
    );

    info!("Creating systemd unit file: {}", unit_file);
    std::fs::write(&unit_file, unit_content)
        .context("Failed to write systemd unit file")?;

    // Reload systemd daemon
    info!("Reloading systemd daemon...");
    let status = Command::new("systemctl")
        .args(["daemon-reload"])
        .status()
        .context("Failed to reload systemd")?;

    if !status.success() {
        anyhow::bail!("systemctl daemon-reload failed");
    }

    // Enable the service
    info!("Enabling service...");
    let status = Command::new("systemctl")
        .args(["enable", SERVICE_NAME])
        .status()
        .context("Failed to enable service")?;

    if !status.success() {
        anyhow::bail!("systemctl enable failed");
    }

    println!("\n[OK] GuruRMM Agent installed successfully!");
    println!("\nInstalled files:");
    println!("  Binary: {}", binary_dest);
    println!("  Config: {}", config_dest);
    println!("  Service: {}", unit_file);

    if config_needs_manual_edit {
        println!("\n[WARNING] IMPORTANT: Edit {} with your server URL and API key!", config_dest);
        println!("\nNext steps:");
        println!("  1. Edit {} with your server URL and API key", config_dest);
        println!("  2. Start the service: sudo systemctl start {}", SERVICE_NAME);
    } else {
        println!("\nStarting service...");
        let status = Command::new("systemctl")
            .args(["start", SERVICE_NAME])
            .status();

        if status.is_ok() && status.unwrap().success() {
            println!("[OK] Service started successfully!");
        } else {
            println!("[WARNING] Failed to start service. Check logs: sudo journalctl -u {} -f", SERVICE_NAME);
        }
    }

    println!("\nUseful commands:");
    println!("  Status: sudo systemctl status {}", SERVICE_NAME);
    println!("  Logs:   sudo journalctl -u {} -f", SERVICE_NAME);
    println!("  Stop:   sudo systemctl stop {}", SERVICE_NAME);
    println!("  Start:  sudo systemctl start {}", SERVICE_NAME);

    Ok(())
}

/// Uninstall the system service
async fn uninstall_service() -> Result<()> {
    #[cfg(windows)]
    {
        service::windows::uninstall()
    }

    #[cfg(target_os = "linux")]
    {
        uninstall_systemd_service().await
    }

    #[cfg(target_os = "macos")]
    {
        return Err(anyhow::anyhow!(
            "macOS launchd service uninstallation is not yet implemented.\n\
             If you created a launchd plist manually, remove it from ~/Library/LaunchAgents/ or /Library/LaunchDaemons/"
        ));
    }
}

/// Uninstall systemd service (Linux)
#[cfg(target_os = "linux")]
async fn uninstall_systemd_service() -> Result<()> {
    use std::process::Command;

    const SERVICE_NAME: &str = "gururmm-agent";
    const INSTALL_DIR: &str = "/usr/local/bin";
    const CONFIG_DIR: &str = "/etc/gururmm";
    const SYSTEMD_DIR: &str = "/etc/systemd/system";

    info!("Uninstalling GuruRMM Agent...");

    if !nix::unistd::geteuid().is_root() {
        anyhow::bail!("Uninstallation requires root privileges. Please run with sudo.");
    }

    let binary_path = format!("{}/{}", INSTALL_DIR, SERVICE_NAME);
    let unit_file = format!("{}/{}.service", SYSTEMD_DIR, SERVICE_NAME);

    // Stop the service if running
    info!("Stopping service...");
    let _ = Command::new("systemctl")
        .args(["stop", SERVICE_NAME])
        .status();

    // Disable the service
    info!("Disabling service...");
    let _ = Command::new("systemctl")
        .args(["disable", SERVICE_NAME])
        .status();

    // Remove unit file
    if std::path::Path::new(&unit_file).exists() {
        info!("Removing unit file: {}", unit_file);
        std::fs::remove_file(&unit_file)?;
    }

    // Remove binary
    if std::path::Path::new(&binary_path).exists() {
        info!("Removing binary: {}", binary_path);
        std::fs::remove_file(&binary_path)?;
    }

    // Reload systemd
    let _ = Command::new("systemctl")
        .args(["daemon-reload"])
        .status();

    println!("\n[OK] GuruRMM Agent uninstalled successfully!");
    println!("\nNote: Config directory {} was preserved.", CONFIG_DIR);
    println!("Remove it manually if no longer needed: sudo rm -rf {}", CONFIG_DIR);

    Ok(())
}

/// Start the installed service
async fn start_service() -> Result<()> {
    #[cfg(windows)]
    {
        service::windows::start()
    }

    #[cfg(target_os = "linux")]
    {
        use std::process::Command;

        info!("Starting GuruRMM Agent service...");

        let status = Command::new("systemctl")
            .args(["start", "gururmm-agent"])
            .status()
            .context("Failed to start service")?;

        if status.success() {
            println!("[OK] Service started successfully");
            println!("Check status: sudo systemctl status gururmm-agent");
        } else {
            anyhow::bail!("Failed to start service. Check: sudo journalctl -u gururmm-agent -n 50");
        }

        Ok(())
    }

    #[cfg(target_os = "macos")]
    {
        return Err(anyhow::anyhow!(
            "macOS launchd service start is not yet implemented.\n\
             If you created a launchd plist manually, use: launchctl load <plist-path>"
        ));
    }
}

/// Stop the installed service
async fn stop_service() -> Result<()> {
    #[cfg(windows)]
    {
        service::windows::stop()
    }

    #[cfg(target_os = "linux")]
    {
        use std::process::Command;

        info!("Stopping GuruRMM Agent service...");

        let status = Command::new("systemctl")
            .args(["stop", "gururmm-agent"])
            .status()
            .context("Failed to stop service")?;

        if status.success() {
            println!("[OK] Service stopped successfully");
        } else {
            anyhow::bail!("Failed to stop service");
        }

        Ok(())
    }

    #[cfg(target_os = "macos")]
    {
        return Err(anyhow::anyhow!(
            "macOS launchd service stop is not yet implemented.\n\
             If you created a launchd plist manually, use: launchctl unload <plist-path>"
        ));
    }
}

/// Show agent status
async fn show_status(config_path: PathBuf) -> Result<()> {
    // On Windows, show service status
    #[cfg(windows)]
    {
        service::windows::status()?;
        println!();
    }

    // Try to load config for additional info
    match AgentConfig::load(&config_path) {
        Ok(config) => {
            println!("Configuration");
            println!("=============");
            println!("Config file: {:?}", config_path);
            println!("Server URL: {}", config.server.url);
            println!("Metrics interval: {} seconds", config.metrics.interval_seconds);
            println!("Watchdog enabled: {}", config.watchdog.enabled);

            // Collect current metrics
            let collector = MetricsCollector::new();
            let metrics = collector.collect().await;

            println!("\nCurrent System Metrics:");
            println!("  CPU Usage: {:.1}%", metrics.cpu_percent);
            println!("  Memory Usage: {:.1}%", metrics.memory_percent);
            println!(
                "  Memory Used: {:.2} GB",
                metrics.memory_used_bytes as f64 / 1_073_741_824.0
            );
            println!("  Disk Usage: {:.1}%", metrics.disk_percent);
            println!(
                "  Disk Used: {:.2} GB",
                metrics.disk_used_bytes as f64 / 1_073_741_824.0
            );
        }
        Err(_) => {
            println!("\nConfig file {:?} not found or invalid.", config_path);
            #[cfg(windows)]
            println!("Service config location: {}\\agent.toml", service::windows::CONFIG_DIR);
        }
    }

    Ok(())
}

/// Generate a sample configuration file
async fn generate_config(output: PathBuf) -> Result<()> {
    let sample_config = AgentConfig::sample();
    let toml_str = toml::to_string_pretty(&sample_config)?;

    std::fs::write(&output, toml_str)?;
    println!("Sample configuration written to {:?}", output);
    println!("\nEdit this file with your server URL and API key, then run:");
    println!("  gururmm-agent --config {:?} run", output);

    Ok(())
}