cm-dashboard/dashboard/src/ui/mod.rs

use anyhow::Result;
use crossterm::event::{Event, KeyCode};
use ratatui::{
    layout::{Constraint, Direction, Layout, Rect},
    style::Style,
    widgets::{Block, Paragraph},
    Frame,
};
use std::collections::HashMap;
use std::time::Instant;
use tracing::info;
use wake_on_lan::MagicPacket;

pub mod theme;
pub mod widgets;

use crate::config::DashboardConfig;
use crate::metrics::MetricStore;
use cm_dashboard_shared::Status;
use theme::{Components, Layout as ThemeLayout, Theme, Typography};
use widgets::{BackupWidget, ServicesWidget, SystemWidget, Widget};




/// Panel types for focus management

/// Widget states for a specific host
#[derive(Clone)]
pub struct HostWidgets {
    /// System widget state (includes CPU, Memory, NixOS info, Storage)
    pub system_widget: SystemWidget,
    /// Services widget state
    pub services_widget: ServicesWidget,
    /// Backup widget state
    pub backup_widget: BackupWidget,
    /// Last update time for this host
    pub last_update: Option<Instant>,
}

impl HostWidgets {
    pub fn new() -> Self {
        Self {
            system_widget: SystemWidget::new(),
            services_widget: ServicesWidget::new(),
            backup_widget: BackupWidget::new(),
            last_update: None,
        }
    }
}


/// Main TUI application
pub struct TuiApp {
    /// Widget states per host (hostname -> HostWidgets)
    host_widgets: HashMap<String, HostWidgets>,
    /// Current active host
    current_host: Option<String>,
    /// Available hosts
    available_hosts: Vec<String>,
    /// Host index for navigation
    host_index: usize,
    /// Should quit application
    should_quit: bool,
    /// Track if user manually navigated away from localhost
    user_navigated_away: bool,
    /// Dashboard configuration
    config: DashboardConfig,
    /// Cached localhost hostname to avoid repeated system calls
    localhost: String,
}

impl TuiApp {
    pub fn new(config: DashboardConfig) -> Self {
        let localhost = gethostname::gethostname().to_string_lossy().to_string();
        let mut app = Self {
            host_widgets: HashMap::new(),
            current_host: None,
            available_hosts: config.hosts.keys().cloned().collect(),
            host_index: 0,
            should_quit: false,
            user_navigated_away: false,
            config,
            localhost,
        };
        
        // Sort predefined hosts
        app.available_hosts.sort();
        
        // Initialize with first host if available
        if !app.available_hosts.is_empty() {
            app.current_host = Some(app.available_hosts[0].clone());
        }
        
        app
    }

    /// Get or create host widgets for the given hostname
    fn get_or_create_host_widgets(&mut self, hostname: &str) -> &mut HostWidgets {
        self.host_widgets
            .entry(hostname.to_string())
            .or_insert_with(HostWidgets::new)
    }

    /// Update widgets with structured data from store (only for current host)
    pub fn update_metrics(&mut self, metric_store: &MetricStore) {
        if let Some(hostname) = self.current_host.clone() {
            // Get structured data for this host
            if let Some(agent_data) = metric_store.get_agent_data(&hostname) {
                let host_widgets = self.get_or_create_host_widgets(&hostname);

                // Update all widgets with structured data directly
                host_widgets.system_widget.update_from_agent_data(agent_data);
                host_widgets.services_widget.update_from_agent_data(agent_data);
                host_widgets.backup_widget.update_from_agent_data(agent_data);

                host_widgets.last_update = Some(Instant::now());
            }
        }
    }

    /// Update available hosts with localhost prioritization
    pub fn update_hosts(&mut self, discovered_hosts: Vec<String>) {
        // Start with configured hosts (always visible)
        let mut all_hosts: Vec<String> = self.config.hosts.keys().cloned().collect();
        
        // Add any discovered hosts that aren't already configured
        for host in discovered_hosts {
            if !all_hosts.contains(&host) {
                all_hosts.push(host);
            }
        }
        
        
        all_hosts.sort();
        self.available_hosts = all_hosts;
        
        // Get the current hostname (localhost) for auto-selection
        if !self.available_hosts.is_empty() {
            if self.available_hosts.contains(&self.localhost) && !self.user_navigated_away {
                // Localhost is available and user hasn't navigated away - switch to it
                self.current_host = Some(self.localhost.clone());
                // Find the actual index of localhost in the sorted list
                self.host_index = self.available_hosts.iter().position(|h| h == &self.localhost).unwrap_or(0);
            } else if self.current_host.is_none() {
                // No current host - select first available (which is localhost if available)
                self.current_host = Some(self.available_hosts[0].clone());
                self.host_index = 0;
            } else if let Some(ref current) = self.current_host {
                if !self.available_hosts.contains(current) {
                    // Current host disconnected - select first available and reset navigation flag
                    self.current_host = Some(self.available_hosts[0].clone());
                    self.host_index = 0;
                    self.user_navigated_away = false; // Reset since we're forced to switch
                } else if let Some(index) = self.available_hosts.iter().position(|h| h == current) {
                    // Update index for current host
                    self.host_index = index;
                }
            }
        }
    }

    /// Handle keyboard input
    pub fn handle_input(&mut self, event: Event) -> Result<()> {
        if let Event::Key(key) = event {
            match key.code {
                KeyCode::Char('q') => {
                    self.should_quit = true;
                }
                KeyCode::Left => {
                    self.navigate_host(-1);
                }
                KeyCode::Right => {
                    self.navigate_host(1);
                }
                KeyCode::Char('r') => {
                    // System rebuild command - works on any panel for current host
                    if let Some(hostname) = self.current_host.clone() {
                        let connection_ip = self.get_connection_ip(&hostname);
                        // Create command that shows logo, rebuilds, and waits for user input
                        let logo_and_rebuild = format!(
                            "echo 'Rebuilding system: {} ({})' && ssh -tt {}@{} \"bash -ic '{}'\"",
                            hostname,
                            connection_ip,
                            self.config.ssh.rebuild_user,
                            connection_ip,
                            self.config.ssh.rebuild_cmd
                        );
                        
                        std::process::Command::new("tmux")
                            .arg("split-window")
                            .arg("-v")
                            .arg("-p")
                            .arg("30")
                            .arg(&logo_and_rebuild)
                            .spawn()
                            .ok(); // Ignore errors, tmux will handle them
                    }
                }
                KeyCode::Char('B') => {
                    // Backup command - works on any panel for current host
                    if let Some(hostname) = self.current_host.clone() {
                        let connection_ip = self.get_connection_ip(&hostname);
                        // Create command that shows logo, runs backup, and waits for user input
                        let logo_and_backup = format!(
                            "echo 'Running backup: {} ({})' && ssh -tt {}@{} \"bash -ic '{}'\"",
                            hostname,
                            connection_ip,
                            self.config.ssh.rebuild_user,
                            connection_ip,
                            format!("{} start borgbackup", self.config.ssh.service_manage_cmd)
                        );
                        
                        std::process::Command::new("tmux")
                            .arg("split-window")
                            .arg("-v")
                            .arg("-p")
                            .arg("30")
                            .arg(&logo_and_backup)
                            .spawn()
                            .ok(); // Ignore errors, tmux will handle them
                    }
                }
                KeyCode::Char('s') => {
                    // Service start command via SSH with progress display
                    if let (Some(service_name), Some(hostname)) = (self.get_selected_service(), self.current_host.clone()) {
                        let connection_ip = self.get_connection_ip(&hostname);
                        let service_start_command = format!(
                            "echo 'Starting service: {} on {}' && ssh -tt {}@{} \"bash -ic '{} start {}'\"",
                            service_name,
                            hostname,
                            self.config.ssh.rebuild_user,
                            connection_ip,
                            self.config.ssh.service_manage_cmd,
                            service_name
                        );
                        
                        std::process::Command::new("tmux")
                            .arg("split-window")
                            .arg("-v")
                            .arg("-p")
                            .arg("30")
                            .arg(&service_start_command)
                            .spawn()
                            .ok(); // Ignore errors, tmux will handle them
                    }
                }
                KeyCode::Char('S') => {
                    // Service stop command via SSH with progress display
                    if let (Some(service_name), Some(hostname)) = (self.get_selected_service(), self.current_host.clone()) {
                        let connection_ip = self.get_connection_ip(&hostname);
                        let service_stop_command = format!(
                            "echo 'Stopping service: {} on {}' && ssh -tt {}@{} \"bash -ic '{} stop {}'\"",
                            service_name,
                            hostname,
                            self.config.ssh.rebuild_user,
                            connection_ip,
                            self.config.ssh.service_manage_cmd,
                            service_name
                        );
                        
                        std::process::Command::new("tmux")
                            .arg("split-window")
                            .arg("-v")
                            .arg("-p")
                            .arg("30")
                            .arg(&service_stop_command)
                            .spawn()
                            .ok(); // Ignore errors, tmux will handle them
                    }
                }
                KeyCode::Char('L') => {
                    // Show service logs via service-manage script in tmux split window
                    if let (Some(service_name), Some(hostname)) = (self.get_selected_service(), self.current_host.clone()) {
                        let connection_ip = self.get_connection_ip(&hostname);
                        let logs_command = format!(
                            "ssh -tt {}@{} '{} logs {}'",
                            self.config.ssh.rebuild_user,
                            connection_ip,
                            self.config.ssh.service_manage_cmd,
                            service_name
                        );
                        
                        std::process::Command::new("tmux")
                            .arg("split-window")
                            .arg("-v")
                            .arg("-p")
                            .arg("30")
                            .arg(&logs_command)
                            .spawn()
                            .ok(); // Ignore errors, tmux will handle them
                    }
                }
                KeyCode::Char('w') => {
                    // Wake on LAN for offline hosts
                    if let Some(hostname) = self.current_host.clone() {
                        // Check if host has MAC address configured
                        if let Some(host_details) = self.config.hosts.get(&hostname) {
                            if let Some(mac_address) = &host_details.mac_address {
                                // Parse MAC address and send WoL packet
                                let mac_bytes = Self::parse_mac_address(mac_address);
                                match mac_bytes {
                                    Ok(mac) => {
                                        match MagicPacket::new(&mac).send() {
                                            Ok(_) => {
                                                info!("WakeOnLAN packet sent successfully to {} ({})", hostname, mac_address);
                                            }
                                            Err(e) => {
                                                tracing::error!("Failed to send WakeOnLAN packet to {}: {}", hostname, e);
                                            }
                                        }
                                    }
                                    Err(_) => {
                                        tracing::error!("Invalid MAC address format for {}: {}", hostname, mac_address);
                                    }
                                }
                            }
                        }
                    }
                }
                KeyCode::Char('t') => {
                    // Open SSH terminal session in tmux window
                    if let Some(hostname) = self.current_host.clone() {
                        let connection_ip = self.get_connection_ip(&hostname);
                        let ssh_command = format!(
                            "echo 'Opening SSH terminal to: {}' && ssh -tt {}@{}",
                            hostname,
                            self.config.ssh.rebuild_user,
                            connection_ip
                        );
                        
                        std::process::Command::new("tmux")
                            .arg("split-window")
                            .arg("-v")
                            .arg("-p")
                            .arg("30") // Use 30% like other commands
                            .arg(&ssh_command)
                            .spawn()
                            .ok(); // Ignore errors, tmux will handle them
                    }
                }
                KeyCode::Tab => {
                    // Tab cycles to next host
                    self.navigate_host(1);
                }
                KeyCode::Up | KeyCode::Char('k') => {
                    // Move service selection up
                    if let Some(hostname) = self.current_host.clone() {
                        let host_widgets = self.get_or_create_host_widgets(&hostname);
                        host_widgets.services_widget.select_previous();
                    }
                }
                KeyCode::Down | KeyCode::Char('j') => {
                    // Move service selection down
                    if let Some(hostname) = self.current_host.clone() {
                        let total_services = {
                            let host_widgets = self.get_or_create_host_widgets(&hostname);
                            host_widgets.services_widget.get_total_services_count()
                        };
                        let host_widgets = self.get_or_create_host_widgets(&hostname);
                        host_widgets.services_widget.select_next(total_services);
                    }
                }
                _ => {}
            }
        }
        Ok(())
    }

    /// Navigate between hosts
    fn navigate_host(&mut self, direction: i32) {
        if self.available_hosts.is_empty() {
            return;
        }

        let len = self.available_hosts.len();
        if direction > 0 {
            self.host_index = (self.host_index + 1) % len;
        } else {
            self.host_index = if self.host_index == 0 {
                len - 1
            } else {
                self.host_index - 1
            };
        }

        self.current_host = Some(self.available_hosts[self.host_index].clone());
        
        // Check if user navigated away from localhost
        if let Some(ref current) = self.current_host {
            if current != &self.localhost {
                self.user_navigated_away = true;
            } else {
                self.user_navigated_away = false; // User navigated back to localhost
            }
        }
        
        info!("Switched to host: {}", self.current_host.as_ref().unwrap());
    }





    /// Get the currently selected service name from the services widget
    fn get_selected_service(&self) -> Option<String> {
        if let Some(hostname) = &self.current_host {
            if let Some(host_widgets) = self.host_widgets.get(hostname) {
                return host_widgets.services_widget.get_selected_service();
            }
        }
        None
    }


    /// Should quit application
    pub fn should_quit(&self) -> bool {
        self.should_quit
    }







    /// Render the dashboard (real btop-style multi-panel layout)
    pub fn render(&mut self, frame: &mut Frame, metric_store: &MetricStore) {
        let size = frame.size();

        // Clear background to true black like btop
        frame.render_widget(
            Block::default().style(Style::default().bg(Theme::background())),
            size,
        );

        // Create real btop-style layout: multi-panel with borders
        // Three-section layout: title bar, main content, statusbar
        let main_chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Length(1), // Title bar
                Constraint::Min(0),    // Main content area
                Constraint::Length(1), // Statusbar
            ])
            .split(size);

        // New layout: left panels | right services (100% height)
        let content_chunks = ratatui::layout::Layout::default()
            .direction(Direction::Horizontal)
            .constraints([
                Constraint::Percentage(ThemeLayout::LEFT_PANEL_WIDTH), // Left side: system, backup
                Constraint::Percentage(ThemeLayout::RIGHT_PANEL_WIDTH), // Right side: services (100% height)
            ])
            .split(main_chunks[1]); // main_chunks[1] is now the content area (between title and statusbar)

        // Check if current host is offline
        let current_host_offline = if let Some(hostname) = self.current_host.clone() {
            self.calculate_host_status(&hostname, metric_store) == Status::Offline
        } else {
            true // No host selected is considered offline
        };

        // If host is offline, render wake-up message instead of panels
        if current_host_offline {
            self.render_offline_host_message(frame, main_chunks[1]);
            self.render_btop_title(frame, main_chunks[0], metric_store);
            self.render_statusbar(frame, main_chunks[2]);
            return;
        }

        // Check if backup panel should be shown
        let show_backup = if let Some(hostname) = self.current_host.clone() {
            let host_widgets = self.get_or_create_host_widgets(&hostname);
            host_widgets.backup_widget.has_data()
        } else {
            false
        };

        // Left side: dynamic layout based on backup data availability
        let left_chunks = if show_backup {
            // Show both system and backup panels
            ratatui::layout::Layout::default()
                .direction(Direction::Vertical)
                .constraints([
                    Constraint::Percentage(ThemeLayout::SYSTEM_PANEL_HEIGHT), // System section
                    Constraint::Percentage(ThemeLayout::BACKUP_PANEL_HEIGHT), // Backup section
                ])
                .split(content_chunks[0])
        } else {
            // Show only system panel (full height)
            ratatui::layout::Layout::default()
                .direction(Direction::Vertical)
                .constraints([Constraint::Percentage(100)]) // System section takes full height
                .split(content_chunks[0])
        };

        // Render title bar
        self.render_btop_title(frame, main_chunks[0], metric_store);

        // Render new panel layout
        self.render_system_panel(frame, left_chunks[0], metric_store);
        if show_backup && left_chunks.len() > 1 {
            self.render_backup_panel(frame, left_chunks[1]);
        }

        // Render services widget for current host
        if let Some(hostname) = self.current_host.clone() {
            let is_focused = true; // Always show service selection
            let host_widgets = self.get_or_create_host_widgets(&hostname);
            host_widgets
                .services_widget
                .render(frame, content_chunks[1], is_focused); // Services takes full right side
        }

        // Render statusbar at the bottom
        self.render_statusbar(frame, main_chunks[2]); // main_chunks[2] is the statusbar area

    }

    /// Render btop-style minimal title with host status colors
    fn render_btop_title(&self, frame: &mut Frame, area: Rect, metric_store: &MetricStore) {
        use ratatui::style::Modifier;
        use ratatui::text::{Line, Span};
        use theme::StatusIcons;

        if self.available_hosts.is_empty() {
            let title_text = "cm-dashboard • no hosts discovered";
            let title = Paragraph::new(title_text)
                .style(Style::default().fg(Theme::background()).bg(Theme::status_color(Status::Unknown)));
            frame.render_widget(title, area);
            return;
        }

        // Calculate worst-case status across all hosts (excluding offline)
        let mut worst_status = Status::Ok;
        for host in &self.available_hosts {
            let host_status = self.calculate_host_status(host, metric_store);
            // Don't include offline hosts in status aggregation
            if host_status != Status::Offline {
                worst_status = Status::aggregate(&[worst_status, host_status]);
            }
        }

        // Use the worst status color as background
        let background_color = Theme::status_color(worst_status);

        // Split the title bar into left and right sections
        let chunks = Layout::default()
            .direction(Direction::Horizontal)
            .constraints([Constraint::Length(22), Constraint::Min(0)])
            .split(area);

        // Left side: "cm-dashboard" text with version
        let title_text = format!(" cm-dashboard v{}", env!("CARGO_PKG_VERSION"));
        let left_span = Span::styled(
            &title_text, 
            Style::default().fg(Theme::background()).bg(background_color).add_modifier(Modifier::BOLD)
        );
        let left_title = Paragraph::new(Line::from(vec![left_span]))
            .style(Style::default().bg(background_color));
        frame.render_widget(left_title, chunks[0]);

        // Right side: hosts with status indicators
        let mut host_spans = Vec::new();
        
        for (i, host) in self.available_hosts.iter().enumerate() {
            if i > 0 {
                host_spans.push(Span::styled(
                    " ", 
                    Style::default().fg(Theme::background()).bg(background_color)
                ));
            }

            // Always show normal status icon based on metrics (no command status at host level)
            let host_status = self.calculate_host_status(host, metric_store);
            let status_icon = StatusIcons::get_icon(host_status);

            // Add status icon with background color as foreground against status background
            host_spans.push(Span::styled(
                format!("{} ", status_icon),
                Style::default().fg(Theme::background()).bg(background_color),
            ));

            if Some(host) == self.current_host.as_ref() {
                // Selected host in bold background color against status background
                host_spans.push(Span::styled(
                    host.clone(),
                    Style::default()
                        .fg(Theme::background())
                        .bg(background_color)
                        .add_modifier(Modifier::BOLD),
                ));
            } else {
                // Other hosts in normal background color against status background
                host_spans.push(Span::styled(
                    host.clone(),
                    Style::default().fg(Theme::background()).bg(background_color),
                ));
            }
        }

        // Add right padding
        host_spans.push(Span::styled(
            " ", 
            Style::default().fg(Theme::background()).bg(background_color)
        ));

        let host_line = Line::from(host_spans);
        let host_title = Paragraph::new(vec![host_line])
            .style(Style::default().bg(background_color))
            .alignment(ratatui::layout::Alignment::Right);
        frame.render_widget(host_title, chunks[1]);
    }

    /// Calculate overall status for a host based on its structured data
    fn calculate_host_status(&self, hostname: &str, metric_store: &MetricStore) -> Status {
        // Check if we have structured data for this host
        if let Some(_agent_data) = metric_store.get_agent_data(hostname) {
            // Return OK since we have data
            Status::Ok
        } else {
            Status::Offline
        }
    }

    /// Render dynamic statusbar with context-aware shortcuts
    fn render_statusbar(&self, frame: &mut Frame, area: Rect) {
        let shortcuts = self.get_context_shortcuts();
        let statusbar_text = shortcuts.join(" • ");
        
        let statusbar = Paragraph::new(statusbar_text)
            .style(Typography::secondary())
            .alignment(ratatui::layout::Alignment::Center);
            
        frame.render_widget(statusbar, area);
    }

    /// Get context-aware shortcuts based on focused panel
    fn get_context_shortcuts(&self) -> Vec<String> {
        let mut shortcuts = Vec::new();
        
        // Global shortcuts
        shortcuts.push("Tab: Host".to_string());
        shortcuts.push("↑↓/jk: Select".to_string());
        shortcuts.push("r: Rebuild".to_string());
        shortcuts.push("B: Backup".to_string());
        shortcuts.push("s/S: Start/Stop".to_string());
        shortcuts.push("L: Logs".to_string());
        shortcuts.push("t: Terminal".to_string());
        shortcuts.push("w: Wake".to_string());
        
        // Always show quit
        shortcuts.push("q: Quit".to_string());
        
        shortcuts
    }

    fn render_system_panel(&mut self, frame: &mut Frame, area: Rect, _metric_store: &MetricStore) {
        let system_block = Components::widget_block("system");
        let inner_area = system_block.inner(area);
        frame.render_widget(system_block, area);
        // Get current host widgets, create if none exist
        if let Some(hostname) = self.current_host.clone() {
            // Clone the config to avoid borrowing issues
            let config = self.config.clone();
            let host_widgets = self.get_or_create_host_widgets(&hostname);
            host_widgets.system_widget.render(frame, inner_area, &hostname, Some(&config));
        }
    }

    fn render_backup_panel(&mut self, frame: &mut Frame, area: Rect) {
        let backup_block = Components::widget_block("backup");
        let inner_area = backup_block.inner(area);
        frame.render_widget(backup_block, area);

        // Get current host widgets for backup widget
        if let Some(hostname) = self.current_host.clone() {
            let host_widgets = self.get_or_create_host_widgets(&hostname);
            host_widgets.backup_widget.render(frame, inner_area);
        }
    }

    /// Render offline host message with wake-up option
    fn render_offline_host_message(&self, frame: &mut Frame, area: Rect) {
        use ratatui::layout::Alignment;
        use ratatui::style::Modifier;
        use ratatui::text::{Line, Span};
        use ratatui::widgets::{Block, Borders, Paragraph};

        // Get hostname for message
        let hostname = self.current_host.as_ref()
            .map(|h| h.as_str())
            .unwrap_or("Unknown");

        // Check if host has MAC address for wake-on-LAN
        let has_mac = self.current_host.as_ref()
            .and_then(|hostname| self.config.hosts.get(hostname))
            .and_then(|details| details.mac_address.as_ref())
            .is_some();

        // Create message content
        let mut lines = vec![
            Line::from(Span::styled(
                format!("Host '{}' is offline", hostname),
                Style::default().fg(Theme::muted_text()).add_modifier(Modifier::BOLD),
            )),
            Line::from(""),
        ];

        if has_mac {
            lines.push(Line::from(Span::styled(
                "Press 'w' to wake up host",
                Style::default().fg(Theme::primary_text()).add_modifier(Modifier::BOLD),
            )));
        } else {
            lines.push(Line::from(Span::styled(
                "No MAC address configured - cannot wake up",
                Style::default().fg(Theme::muted_text()),
            )));
        }

        // Create centered message
        let message = Paragraph::new(lines)
            .block(Block::default()
                .borders(Borders::ALL)
                .border_style(Style::default().fg(Theme::muted_text()))
                .title(" Offline Host ")
                .title_style(Style::default().fg(Theme::muted_text()).add_modifier(Modifier::BOLD)))
            .style(Style::default().bg(Theme::background()).fg(Theme::primary_text()))
            .alignment(Alignment::Center);

        // Center the message in the available area
        let popup_area = ratatui::layout::Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Percentage(40),
                Constraint::Length(6),
                Constraint::Percentage(40),
            ])
            .split(area)[1];

        let popup_area = ratatui::layout::Layout::default()
            .direction(Direction::Horizontal)
            .constraints([
                Constraint::Percentage(25),
                Constraint::Percentage(50),
                Constraint::Percentage(25),
            ])
            .split(popup_area)[1];

        frame.render_widget(message, popup_area);
    }

    /// Parse MAC address string (e.g., "AA:BB:CC:DD:EE:FF") to [u8; 6]
    /// Get the connection IP for a hostname based on host configuration
    fn get_connection_ip(&self, hostname: &str) -> String {
        if let Some(host_details) = self.config.hosts.get(hostname) {
            host_details.get_connection_ip(hostname)
        } else {
            hostname.to_string()
        }
    }

    fn parse_mac_address(mac_str: &str) -> Result<[u8; 6], &'static str> {
        let parts: Vec<&str> = mac_str.split(':').collect();
        if parts.len() != 6 {
            return Err("MAC address must have 6 parts separated by colons");
        }

        let mut mac = [0u8; 6];
        for (i, part) in parts.iter().enumerate() {
            match u8::from_str_radix(part, 16) {
                Ok(byte) => mac[i] = byte,
                Err(_) => return Err("Invalid hexadecimal byte in MAC address"),
            }
        }
        Ok(mac)
    }
}