use std::sync::Arc;

use anyhow::Result;
use tokio::sync::{Notify, RwLock, Semaphore};

use tracing::{error, warn};
use zbus::{Connection, connection, interface};

// Object paths
pub const ROOT_OBJECT_PATH: &str = "/org/craftknight/camper_widget";
pub const BATTERY_OBJECT_PATH: &str = "/org/craftknight/camper_widget/Battery";
pub const SOLAR_OBJECT_PATH: &str = "/org/craftknight/camper_widget/Solar";
pub const AC_INPUT_OBJECT_PATH: &str = "/org/craftknight/camper_widget/AcInput";
pub const AC_LOAD_OBJECT_PATH: &str = "/org/craftknight/camper_widget/AcLoad";

#[derive(Clone)]
pub struct SharedState {
    // Status interface data
    pub connected: Arc<RwLock<bool>>,

    // Battery interface data
    pub battery_soc: Arc<RwLock<f64>>,
    pub battery_power: Arc<RwLock<f64>>,
    pub battery_state: Arc<RwLock<String>>,

    // Solar interface data
    pub solar_power: Arc<RwLock<f64>>,

    // AC input interface data
    pub ac_input_power: Arc<RwLock<f64>>,

    // AC load interface data
    pub ac_load_power: Arc<RwLock<f64>>,

    // Config reload notification
    pub config_reload_notify: Arc<Notify>,

    // Backpressure for D-Bus signal emission
    pub signal_semaphore: Arc<Semaphore>,
}

impl Default for SharedState {
    fn default() -> Self {
        Self {
            connected: Arc::new(RwLock::new(false)),
            battery_soc: Arc::new(RwLock::new(0.0)),
            battery_power: Arc::new(RwLock::new(0.0)),
            battery_state: Arc::new(RwLock::new("idle".to_string())),
            solar_power: Arc::new(RwLock::new(0.0)),
            ac_input_power: Arc::new(RwLock::new(0.0)),
            ac_load_power: Arc::new(RwLock::new(0.0)),
            config_reload_notify: Arc::new(Notify::new()),
            signal_semaphore: Arc::new(Semaphore::new(10)),
        }
    }
}

#[derive(Clone)]
pub struct StatusInterface {
    state: SharedState,
}

impl StatusInterface {
    fn new(state: SharedState) -> Self {
        Self { state }
    }
}

#[derive(Clone)]
pub struct BatteryInterface {
    state: SharedState,
}

impl BatteryInterface {
    fn new(state: SharedState) -> Self {
        Self { state }
    }
}

#[derive(Clone)]
pub struct SolarInterface {
    state: SharedState,
}

impl SolarInterface {
    fn new(state: SharedState) -> Self {
        Self { state }
    }
}

#[derive(Clone)]
pub struct AcInputInterface {
    state: SharedState,
}

impl AcInputInterface {
    fn new(state: SharedState) -> Self {
        Self { state }
    }
}

#[derive(Clone)]
pub struct AcLoadInterface {
    state: SharedState,
}

impl AcLoadInterface {
    fn new(state: SharedState) -> Self {
        Self { state }
    }
}

#[derive(Clone)]
pub struct ConfigInterface {
    #[allow(dead_code)]
    state: SharedState,
}

impl ConfigInterface {
    fn new(state: SharedState) -> Self {
        Self { state }
    }
}

// Status interface - Connected property
#[interface(name = "org.craftknight.CamperWidget.Status")]
impl StatusInterface {
    #[zbus(property(emits_changed_signal = "true"))]
    async fn connected(&self) -> bool {
        *self.state.connected.read().await
    }
}

// Battery interface - SoC, Power, State properties
#[interface(name = "org.craftknight.CamperWidget.Battery")]
impl BatteryInterface {
    #[zbus(property(emits_changed_signal = "true"))]
    async fn soc(&self) -> f64 {
        *self.state.battery_soc.read().await
    }

    #[zbus(property(emits_changed_signal = "true"))]
    async fn power(&self) -> f64 {
        *self.state.battery_power.read().await
    }

    #[zbus(property(emits_changed_signal = "true"))]
    async fn state(&self) -> String {
        self.state.battery_state.read().await.clone()
    }
}

// Solar interface - Power property
#[interface(name = "org.craftknight.CamperWidget.Solar")]
impl SolarInterface {
    #[zbus(property(emits_changed_signal = "true"))]
    async fn power(&self) -> f64 {
        *self.state.solar_power.read().await
    }
}

// AC input interface - Power property
#[interface(name = "org.craftknight.CamperWidget.AcInput")]
impl AcInputInterface {
    #[zbus(property(emits_changed_signal = "true"))]
    async fn power(&self) -> f64 {
        *self.state.ac_input_power.read().await
    }
}

// AC load interface - Power property
#[interface(name = "org.craftknight.CamperWidget.AcLoad")]
impl AcLoadInterface {
    #[zbus(property(emits_changed_signal = "true"))]
    async fn power(&self) -> f64 {
        *self.state.ac_load_power.read().await
    }
}

// Config interface for handling configuration reloads
#[interface(name = "org.craftknight.CamperWidget.Config")]
impl ConfigInterface {
    /// Reload configuration method
    async fn reload(&self) -> zbus::fdo::Result<()> {
        self.state.config_reload_notify.notify_one();
        Ok(())
    }
}

// Start a session bus service and return the connection; keep it alive in main
pub async fn start_service() -> Result<(Connection, SharedState)> {
    let shared = SharedState::default();

    let status_server = StatusInterface::new(shared.clone());
    let battery_server = BatteryInterface::new(shared.clone());
    let solar_server = SolarInterface::new(shared.clone());
    let ac_input_server = AcInputInterface::new(shared.clone());
    let ac_load_server = AcLoadInterface::new(shared.clone());
    let config_server = ConfigInterface::new(shared.clone());

    let conn = connection::Builder::session()?
        .name("org.craftknight.CamperWidget")?
        .serve_at(ROOT_OBJECT_PATH, status_server)?
        .serve_at(ROOT_OBJECT_PATH, config_server)?
        .serve_at(BATTERY_OBJECT_PATH, battery_server)?
        .serve_at(SOLAR_OBJECT_PATH, solar_server)?
        .serve_at(AC_INPUT_OBJECT_PATH, ac_input_server)?
        .serve_at(AC_LOAD_OBJECT_PATH, ac_load_server)?
        .build()
        .await?;

    Ok((conn, shared))
}

/// Start a D-Bus service at a custom address (for integration testing).
pub async fn start_service_at(address: &str) -> Result<(Connection, SharedState)> {
    let shared = SharedState::default();

    let status_server = StatusInterface::new(shared.clone());
    let battery_server = BatteryInterface::new(shared.clone());
    let solar_server = SolarInterface::new(shared.clone());
    let ac_input_server = AcInputInterface::new(shared.clone());
    let ac_load_server = AcLoadInterface::new(shared.clone());
    let config_server = ConfigInterface::new(shared.clone());

    let conn = connection::Builder::address(address)?
        .name("org.craftknight.CamperWidget")?
        .serve_at(ROOT_OBJECT_PATH, status_server)?
        .serve_at(ROOT_OBJECT_PATH, config_server)?
        .serve_at(BATTERY_OBJECT_PATH, battery_server)?
        .serve_at(SOLAR_OBJECT_PATH, solar_server)?
        .serve_at(AC_INPUT_OBJECT_PATH, ac_input_server)?
        .serve_at(AC_LOAD_OBJECT_PATH, ac_load_server)?
        .build()
        .await?;

    Ok((conn, shared))
}

// Property types for individual updates
#[derive(Debug, Clone, PartialEq)]
pub enum PropertyType {
    BatterySoc,
    BatteryPower,
    BatteryState,
    SolarPower,
    AcInputPower,
    AcLoadPower,
}

// Update connected status and emit signal
pub async fn update_connected_status(
    conn: &Connection,
    state: &SharedState,
    connected: bool,
) -> Result<()> {
    let object_server = conn.object_server();

    let mut guard = state.connected.write().await;
    if *guard != connected {
        *guard = connected;
        // Emit signal for connected status asynchronously
        let object_server_clone = object_server.clone();
        match state.signal_semaphore.clone().try_acquire_owned() {
            Ok(permit) => {
                tokio::spawn(async move {
                    let _permit = permit;
                    if let Ok(iface_ref) = object_server_clone
                        .interface::<_, StatusInterface>(ROOT_OBJECT_PATH)
                        .await
                    {
                        let iface = iface_ref.get_mut().await;
                        if let Err(e) = iface.connected_changed(iface_ref.signal_emitter()).await {
                            error!("Connected: Failed to emit signal: {}", e);
                        }
                    } else {
                        error!("Connected: Failed to get interface at {}", ROOT_OBJECT_PATH);
                    }
                });
            }
            Err(_) => {
                warn!("Signal emission backpressure: dropping signal for Connected");
            }
        }
    }

    Ok(())
}

// Update battery state from a string directly (used by Batteries topic)
pub async fn update_battery_state_str(
    conn: &Connection,
    state: &SharedState,
    state_str: &str,
) -> Result<()> {
    let object_server = conn.object_server();
    let mut guard = state.battery_state.write().await;
    if *guard != state_str {
        *guard = state_str.to_string();
        let object_server_clone = object_server.clone();
        match state.signal_semaphore.clone().try_acquire_owned() {
            Ok(permit) => {
                tokio::spawn(async move {
                    let _permit = permit;
                    if let Ok(iface_ref) = object_server_clone
                        .interface::<_, BatteryInterface>(BATTERY_OBJECT_PATH)
                        .await
                    {
                        let iface = iface_ref.get_mut().await;
                        if let Err(e) = iface.state_changed(iface_ref.signal_emitter()).await {
                            error!("BatteryState: Failed to emit signal: {}", e);
                        }
                    }
                });
            }
            Err(_) => {
                warn!("Signal emission backpressure: dropping signal for BatteryState");
            }
        }
    }
    Ok(())
}

// Update a single DBus property immediately
pub async fn update_single_property(
    conn: &Connection,
    state: &SharedState,
    property_type: &PropertyType,
    value: f64,
) -> Result<()> {
    let object_server = conn.object_server();

    match property_type {
        PropertyType::BatterySoc => {
            let mut guard = state.battery_soc.write().await;
            if (*guard - value).abs() > f64::EPSILON {
                *guard = value;
                // Emit signal for battery SoC asynchronously
                let object_server_clone = object_server.clone();
                match state.signal_semaphore.clone().try_acquire_owned() {
                    Ok(permit) => {
                        tokio::spawn(async move {
                            let _permit = permit;
                            if let Ok(iface_ref) = object_server_clone
                                .interface::<_, BatteryInterface>(BATTERY_OBJECT_PATH)
                                .await
                            {
                                let iface = iface_ref.get_mut().await;
                                if let Err(e) = iface.soc_changed(iface_ref.signal_emitter()).await
                                {
                                    error!("BatterySoc: Failed to emit signal: {}", e);
                                }
                            } else {
                                error!(
                                    "BatterySoc: Failed to get interface at {}",
                                    BATTERY_OBJECT_PATH
                                );
                            }
                        });
                    }
                    Err(_) => {
                        warn!("Signal emission backpressure: dropping signal for BatterySoc");
                    }
                }
            }
        }
        PropertyType::BatteryPower => {
            let mut guard = state.battery_power.write().await;
            if (*guard - value).abs() > f64::EPSILON {
                *guard = value;
                // Emit signal for battery power asynchronously
                let object_server_clone = object_server.clone();
                match state.signal_semaphore.clone().try_acquire_owned() {
                    Ok(permit) => {
                        tokio::spawn(async move {
                            let _permit = permit;
                            if let Ok(iface_ref) = object_server_clone
                                .interface::<_, BatteryInterface>(BATTERY_OBJECT_PATH)
                                .await
                            {
                                let iface = iface_ref.get_mut().await;
                                if let Err(e) =
                                    iface.power_changed(iface_ref.signal_emitter()).await
                                {
                                    error!("BatteryPower: Failed to emit signal: {}", e);
                                }
                            } else {
                                error!(
                                    "BatteryPower: Failed to get interface at {}",
                                    BATTERY_OBJECT_PATH
                                );
                            }
                        });
                    }
                    Err(_) => {
                        warn!("Signal emission backpressure: dropping signal for BatteryPower");
                    }
                }
            }
        }
        PropertyType::BatteryState => {
            let state_str = if value > 5.0 {
                "charging".to_string()
            } else if value < -5.0 {
                "discharging".to_string()
            } else {
                "idle".to_string()
            };

            let mut guard = state.battery_state.write().await;
            if *guard != state_str {
                *guard = state_str.clone();
                // Emit signal for battery state asynchronously
                let object_server_clone = object_server.clone();
                match state.signal_semaphore.clone().try_acquire_owned() {
                    Ok(permit) => {
                        tokio::spawn(async move {
                            let _permit = permit;
                            if let Ok(iface_ref) = object_server_clone
                                .interface::<_, BatteryInterface>(BATTERY_OBJECT_PATH)
                                .await
                            {
                                let iface = iface_ref.get_mut().await;
                                if let Err(e) =
                                    iface.state_changed(iface_ref.signal_emitter()).await
                                {
                                    error!("BatteryState: Failed to emit signal: {}", e);
                                }
                            } else {
                                error!(
                                    "BatteryState: Failed to get interface at {}",
                                    BATTERY_OBJECT_PATH
                                );
                            }
                        });
                    }
                    Err(_) => {
                        warn!("Signal emission backpressure: dropping signal for BatteryState");
                    }
                }
            }
        }
        PropertyType::SolarPower => {
            let mut guard = state.solar_power.write().await;
            if (*guard - value).abs() > f64::EPSILON {
                *guard = value;
                // Emit signal for solar power asynchronously
                let object_server_clone = object_server.clone();
                match state.signal_semaphore.clone().try_acquire_owned() {
                    Ok(permit) => {
                        tokio::spawn(async move {
                            let _permit = permit;
                            if let Ok(iface_ref) = object_server_clone
                                .interface::<_, SolarInterface>(SOLAR_OBJECT_PATH)
                                .await
                            {
                                let iface = iface_ref.get_mut().await;
                                if let Err(e) =
                                    iface.power_changed(iface_ref.signal_emitter()).await
                                {
                                    error!("SolarPower: Failed to emit signal: {}", e);
                                }
                            } else {
                                error!(
                                    "SolarPower: Failed to get interface at {}",
                                    SOLAR_OBJECT_PATH
                                );
                            }
                        });
                    }
                    Err(_) => {
                        warn!("Signal emission backpressure: dropping signal for SolarPower");
                    }
                }
            }
        }
        PropertyType::AcInputPower => {
            let mut guard = state.ac_input_power.write().await;
            if (*guard - value).abs() > f64::EPSILON {
                *guard = value;
                let object_server_clone = object_server.clone();
                match state.signal_semaphore.clone().try_acquire_owned() {
                    Ok(permit) => {
                        tokio::spawn(async move {
                            let _permit = permit;
                            if let Ok(iface_ref) = object_server_clone
                                .interface::<_, AcInputInterface>(AC_INPUT_OBJECT_PATH)
                                .await
                            {
                                let iface = iface_ref.get_mut().await;
                                if let Err(e) =
                                    iface.power_changed(iface_ref.signal_emitter()).await
                                {
                                    error!("AcInputPower: Failed to emit signal: {}", e);
                                }
                            } else {
                                error!(
                                    "AcInputPower: Failed to get interface at {}",
                                    AC_INPUT_OBJECT_PATH
                                );
                            }
                        });
                    }
                    Err(_) => {
                        warn!("Signal emission backpressure: dropping signal for AcInputPower");
                    }
                }
            }
        }
        PropertyType::AcLoadPower => {
            let mut guard = state.ac_load_power.write().await;
            if (*guard - value).abs() > f64::EPSILON {
                *guard = value;
                let object_server_clone = object_server.clone();
                match state.signal_semaphore.clone().try_acquire_owned() {
                    Ok(permit) => {
                        tokio::spawn(async move {
                            let _permit = permit;
                            if let Ok(iface_ref) = object_server_clone
                                .interface::<_, AcLoadInterface>(AC_LOAD_OBJECT_PATH)
                                .await
                            {
                                let iface = iface_ref.get_mut().await;
                                if let Err(e) =
                                    iface.power_changed(iface_ref.signal_emitter()).await
                                {
                                    error!("AcLoadPower: Failed to emit signal: {}", e);
                                }
                            } else {
                                error!(
                                    "AcLoadPower: Failed to get interface at {}",
                                    AC_LOAD_OBJECT_PATH
                                );
                            }
                        });
                    }
                    Err(_) => {
                        warn!("Signal emission backpressure: dropping signal for AcLoadPower");
                    }
                }
            }
        }
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_shared_state_initialization() {
        let state = SharedState::default();
        assert!(!(*state.connected.read().await));
        assert_eq!(*state.battery_soc.read().await, 0.0);
        assert_eq!(*state.battery_power.read().await, 0.0);
        assert_eq!(*state.battery_state.read().await, "idle");
        assert_eq!(*state.solar_power.read().await, 0.0);
        assert_eq!(*state.ac_input_power.read().await, 0.0);
        assert_eq!(*state.ac_load_power.read().await, 0.0);
    }

    #[tokio::test]
    async fn test_property_updates() {
        let state = SharedState::default();

        // Test connected status update
        {
            let mut guard = state.connected.write().await;
            *guard = true;
        }
        assert!(*state.connected.read().await);

        // Test battery property updates
        {
            let mut soc_guard = state.battery_soc.write().await;
            *soc_guard = 75.0;
        }
        {
            let mut power_guard = state.battery_power.write().await;
            *power_guard = -15.0;
        }
        {
            let mut state_guard = state.battery_state.write().await;
            *state_guard = "discharging".to_string();
        }

        assert_eq!(*state.battery_soc.read().await, 75.0);
        assert_eq!(*state.battery_power.read().await, -15.0);
        assert_eq!(*state.battery_state.read().await, "discharging");

        // Test solar power update
        {
            let mut solar_guard = state.solar_power.write().await;
            *solar_guard = 120.0;
        }
        assert_eq!(*state.solar_power.read().await, 120.0);

        // Test AC input power update
        {
            let mut ac_input_guard = state.ac_input_power.write().await;
            *ac_input_guard = 82.0;
        }
        assert_eq!(*state.ac_input_power.read().await, 82.0);

        // Test AC load power update
        {
            let mut ac_load_guard = state.ac_load_power.write().await;
            *ac_load_guard = 77.0;
        }
        assert_eq!(*state.ac_load_power.read().await, 77.0);
    }

    #[tokio::test]
    async fn test_interface_creation() {
        let state = SharedState::default();

        let _status_interface = StatusInterface::new(state.clone());
        let _battery_interface = BatteryInterface::new(state.clone());
        let _solar_interface = SolarInterface::new(state.clone());
        let _ac_input_interface = AcInputInterface::new(state.clone());
        let _ac_load_interface = AcLoadInterface::new(state.clone());
        let _config_interface = ConfigInterface::new(state.clone());

        // Test that interfaces can be created without panicking
        // If we get here, creation succeeded
    }

    #[test]
    fn test_property_change_detection() {
        // Test floating point comparison logic without async
        let value1: f64 = 50.0;
        let value2: f64 = 50.1;

        assert!((value1 - 50.0_f64).abs() < f64::EPSILON);
        assert!((value2 - 50.1_f64).abs() < f64::EPSILON);
        assert!((value1 - value2).abs() > f64::EPSILON);
    }

    #[tokio::test]
    async fn test_battery_state_mapping() {
        // Test the battery state mapping logic from main.rs
        let test_cases = vec![
            (10.0, "charging"),
            (-10.0, "discharging"),
            (0.0, "idle"),
            (3.0, "idle"),  // Below threshold
            (-3.0, "idle"), // Above negative threshold
        ];

        for (power, expected_state) in test_cases {
            let direction = if power > 5.0 {
                "charging".to_string()
            } else if power < -5.0 {
                "discharging".to_string()
            } else {
                "idle".to_string()
            };

            assert_eq!(
                direction, expected_state,
                "Power {power} should map to {expected_state}"
            );
        }
    }
}