use std::{collections::VecDeque, sync::Arc};
use tokio::sync::{broadcast, watch, RwLock};

use crate::atx::AtxController;
use crate::audio::AudioController;
use crate::auth::{SessionStore, UserStore};
use crate::config::ConfigStore;
use crate::events::{
    AtxDeviceInfo, AudioDeviceInfo, EventBus, HidDeviceInfo, MsdDeviceInfo, SystemEvent,
    TtydDeviceInfo, VideoDeviceInfo,
};
use crate::extensions::{ExtensionId, ExtensionManager};
use crate::hid::HidController;
use crate::msd::MsdController;
use crate::otg::OtgService;
use crate::rtsp::RtspService;
use crate::rustdesk::RustDeskService;
use crate::update::UpdateService;
use crate::video::VideoStreamManager;

/// Application-wide state shared across handlers
///
/// # Video Streaming
///
/// All video operations should go through `stream_manager`:
/// - `stream_manager.webrtc_streamer()` - WebRTC streaming (H264, extensible to VP8/VP9/H265)
/// - `stream_manager.mjpeg_handler()` - MJPEG stream handler
/// - `stream_manager.streamer()` - Low-level video capture
/// - `stream_manager.start()` / `stream_manager.stop()` - Stream control
/// - `stream_manager.stats()` - Stream statistics
/// - `stream_manager.list_devices()` - List video devices
pub struct AppState {
    /// Configuration store
    pub config: ConfigStore,
    /// Session store
    pub sessions: SessionStore,
    /// User store
    pub users: UserStore,
    /// OTG Service - centralized USB gadget lifecycle management
    /// This is the single owner of OtgGadgetManager, coordinating HID and MSD functions
    pub otg_service: Arc<OtgService>,
    /// Video stream manager (unified MJPEG/WebRTC management)
    /// This is the single entry point for all video operations.
    pub stream_manager: Arc<VideoStreamManager>,
    /// HID controller
    pub hid: Arc<HidController>,
    /// MSD controller (optional, may not be initialized)
    pub msd: Arc<RwLock<Option<MsdController>>>,
    /// ATX controller (optional, may not be initialized)
    pub atx: Arc<RwLock<Option<AtxController>>>,
    /// Audio controller
    pub audio: Arc<AudioController>,
    /// RustDesk remote access service (optional)
    pub rustdesk: Arc<RwLock<Option<Arc<RustDeskService>>>>,
    /// RTSP streaming service (optional)
    pub rtsp: Arc<RwLock<Option<Arc<RtspService>>>>,
    /// Extension manager (ttyd, gostc, easytier)
    pub extensions: Arc<ExtensionManager>,
    /// Event bus for real-time notifications
    pub events: Arc<EventBus>,
    /// Latest device info snapshot for WebSocket clients
    device_info_tx: watch::Sender<Option<SystemEvent>>,
    /// Online update service
    pub update: Arc<UpdateService>,
    /// Shutdown signal sender
    pub shutdown_tx: broadcast::Sender<()>,
    /// Recently revoked session IDs (for client kick detection)
    pub revoked_sessions: Arc<RwLock<VecDeque<String>>>,
    /// Data directory path
    data_dir: std::path::PathBuf,
}

impl AppState {
    /// Create new application state
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        config: ConfigStore,
        sessions: SessionStore,
        users: UserStore,
        otg_service: Arc<OtgService>,
        stream_manager: Arc<VideoStreamManager>,
        hid: Arc<HidController>,
        msd: Option<MsdController>,
        atx: Option<AtxController>,
        audio: Arc<AudioController>,
        rustdesk: Option<Arc<RustDeskService>>,
        rtsp: Option<Arc<RtspService>>,
        extensions: Arc<ExtensionManager>,
        events: Arc<EventBus>,
        update: Arc<UpdateService>,
        shutdown_tx: broadcast::Sender<()>,
        data_dir: std::path::PathBuf,
    ) -> Arc<Self> {
        let (device_info_tx, _device_info_rx) = watch::channel(None);

        Arc::new(Self {
            config,
            sessions,
            users,
            otg_service,
            stream_manager,
            hid,
            msd: Arc::new(RwLock::new(msd)),
            atx: Arc::new(RwLock::new(atx)),
            audio,
            rustdesk: Arc::new(RwLock::new(rustdesk)),
            rtsp: Arc::new(RwLock::new(rtsp)),
            extensions,
            events,
            device_info_tx,
            update,
            shutdown_tx,
            revoked_sessions: Arc::new(RwLock::new(VecDeque::new())),
            data_dir,
        })
    }

    /// Get data directory path
    pub fn data_dir(&self) -> &std::path::PathBuf {
        &self.data_dir
    }

    /// Subscribe to shutdown signal
    pub fn shutdown_signal(&self) -> broadcast::Receiver<()> {
        self.shutdown_tx.subscribe()
    }

    /// Subscribe to the latest device info snapshot.
    pub fn subscribe_device_info(&self) -> watch::Receiver<Option<SystemEvent>> {
        self.device_info_tx.subscribe()
    }

    /// Record revoked session IDs (bounded queue)
    pub async fn remember_revoked_sessions(&self, session_ids: Vec<String>) {
        if session_ids.is_empty() {
            return;
        }
        let mut guard = self.revoked_sessions.write().await;
        for id in session_ids {
            guard.push_back(id);
        }
        while guard.len() > 32 {
            guard.pop_front();
        }
    }

    /// Check if a session ID was revoked (kicked)
    pub async fn is_session_revoked(&self, session_id: &str) -> bool {
        let guard = self.revoked_sessions.read().await;
        guard.iter().any(|id| id == session_id)
    }

    /// Get complete device information for WebSocket clients
    ///
    /// This method collects the current state of all devices (video, HID, MSD, ATX, Audio)
    /// and returns a DeviceInfo event that can be sent to clients.
    /// Uses tokio::join! to collect all device info in parallel for better performance.
    pub async fn get_device_info(&self) -> SystemEvent {
        // Collect all device info in parallel
        let (video, hid, msd, atx, audio, ttyd) = tokio::join!(
            self.collect_video_info(),
            self.collect_hid_info(),
            self.collect_msd_info(),
            self.collect_atx_info(),
            self.collect_audio_info(),
            self.collect_ttyd_info(),
        );

        SystemEvent::DeviceInfo {
            video,
            hid,
            msd,
            atx,
            audio,
            ttyd,
        }
    }

    /// Publish DeviceInfo event to all connected WebSocket clients
    pub async fn publish_device_info(&self) {
        let device_info = self.get_device_info().await;
        let _ = self.device_info_tx.send(Some(device_info));
    }

    /// Collect video device information
    async fn collect_video_info(&self) -> VideoDeviceInfo {
        // Use stream_manager to get video info (includes stream_mode)
        self.stream_manager.get_video_info().await
    }

    /// Collect HID device information
    async fn collect_hid_info(&self) -> HidDeviceInfo {
        let state = self.hid.snapshot().await;

        HidDeviceInfo {
            available: state.available,
            backend: state.backend,
            initialized: state.initialized,
            online: state.online,
            supports_absolute_mouse: state.supports_absolute_mouse,
            keyboard_leds_enabled: state.keyboard_leds_enabled,
            led_state: state.led_state,
            device: state.device,
            error: state.error,
            error_code: state.error_code,
        }
    }

    /// Collect MSD device information (optional)
    async fn collect_msd_info(&self) -> Option<MsdDeviceInfo> {
        let msd_guard = self.msd.read().await;
        let msd = msd_guard.as_ref()?;

        let state = msd.state().await;
        let error = msd.monitor().error_message().await;
        Some(MsdDeviceInfo {
            available: state.available,
            mode: match state.mode {
                crate::msd::MsdMode::None => "none",
                crate::msd::MsdMode::Image => "image",
                crate::msd::MsdMode::Drive => "drive",
            }
            .to_string(),
            connected: state.connected,
            image_id: state.current_image.map(|img| img.id),
            error,
        })
    }

    /// Collect ATX device information (optional)
    async fn collect_atx_info(&self) -> Option<AtxDeviceInfo> {
        // Predefined backend strings to avoid repeated allocations
        const BACKEND_POWER_ONLY: &str = "power: configured, reset: none";
        const BACKEND_RESET_ONLY: &str = "power: none, reset: configured";
        const BACKEND_BOTH: &str = "power: configured, reset: configured";
        const BACKEND_NONE: &str = "none";

        let atx_guard = self.atx.read().await;
        let atx = atx_guard.as_ref()?;

        let state = atx.state().await;
        Some(AtxDeviceInfo {
            available: state.available,
            backend: match (state.power_configured, state.reset_configured) {
                (true, true) => BACKEND_BOTH,
                (true, false) => BACKEND_POWER_ONLY,
                (false, true) => BACKEND_RESET_ONLY,
                (false, false) => BACKEND_NONE,
            }
            .to_string(),
            initialized: state.power_configured || state.reset_configured,
            power_on: state.power_status == crate::atx::PowerStatus::On,
            error: None,
        })
    }

    /// Collect Audio device information (optional)
    async fn collect_audio_info(&self) -> Option<AudioDeviceInfo> {
        let status = self.audio.status().await;

        Some(AudioDeviceInfo {
            available: status.enabled,
            streaming: status.streaming,
            device: status.device,
            quality: status.quality.to_string(),
            error: status.error,
        })
    }

    /// Collect ttyd status information
    async fn collect_ttyd_info(&self) -> TtydDeviceInfo {
        let status = self.extensions.status(ExtensionId::Ttyd).await;

        TtydDeviceInfo {
            available: self.extensions.check_available(ExtensionId::Ttyd),
            running: status.is_running(),
        }
    }
}