use crate::buffer::Buffer;
use crate::color::Color;
use crate::draw::{draw_bar, draw_text, draw_box, ROBOTO_REGULAR};
use crate::module::{Input, ModuleImpl};

use std::thread;
use std::sync::{Arc, Mutex};
use std::sync::mpsc::Sender;

use dbus;
use chrono::{DateTime, Local};

fn get_upower_property(con: &dbus::Connection, device_path: &str, property: &str) -> Result<dbus::Message, ::std::io::Error> {
    let msg = dbus::Message::new_method_call(
        "org.freedesktop.UPower",
        device_path,
        "org.freedesktop.DBus.Properties",
        "Get",
    ).map_err(|_| ::std::io::Error::new(::std::io::ErrorKind::Other, "could not send make dbus method call"))?
        .append2(
            dbus::MessageItem::Str("org.freedesktop.UPower.Device".to_string()),
            dbus::MessageItem::Str(property.to_string()),
        );;

    con.send_with_reply_and_block(msg, 1000).map_err(|_| {::std::io::Error::new(::std::io::ErrorKind::Other, "could not send dbus message")})
}

pub struct UpowerBattery {
    device_path: String,
    inner: Arc<Mutex<UpowerBatteryInner>>
}

pub struct UpowerBatteryInner {
    state: UpowerBatteryState,
    capacity: f64,
    dirty: bool,
}

enum UpowerBatteryState {
    Charging,
    Discharging,
    Empty,
    Full,
    NotCharging,
    Unknown,
}

impl UpowerBattery {
    pub fn from_device(device: &str) -> Result<Self, ::std::io::Error> {
        let device_path = format!("/org/freedesktop/UPower/devices/battery_{}", device);
        let con = dbus::Connection::get_private(dbus::BusType::System)
            .map_err(|_| ::std::io::Error::new(::std::io::ErrorKind::Other, "could not get dbus connection"))?;

        let upower_type: dbus::arg::Variant<u32> = match get_upower_property(&con, &device_path, "Type")?.get1() {
            Some(v) => v,
            None => {
                return Err(::std::io::Error::new(::std::io::ErrorKind::Other, "no such upower device"));
            }
        };

        // https://upower.freedesktop.org/docs/Device.html#Device:Type
        if upower_type.0 != 2 {
            return Err(::std::io::Error::new(
                ::std::io::ErrorKind::Other,
                "UPower device is not a battery.",
            ));
        }

        let capacity: f64 = match get_upower_property(&con, &device_path, "Percentage")?.get1::<dbus::arg::Variant<f64>>() {
            Some(v) => v.0,
            None => {
                return Err(::std::io::Error::new(::std::io::ErrorKind::Other, "no such upower device"));
            }
        };
        let state: UpowerBatteryState = match get_upower_property(&con, &device_path, "State")?.get1::<dbus::arg::Variant<u32>>() {
            Some(v) => match v.0 {
                1 => UpowerBatteryState::Charging,
                2 => UpowerBatteryState::Discharging,
                3 => UpowerBatteryState::Empty,
                4 => UpowerBatteryState::Full,
                5 => UpowerBatteryState::NotCharging,
                6 => UpowerBatteryState::Discharging,
                _ => UpowerBatteryState::Unknown,
            },
            None => {
                return Err(::std::io::Error::new(::std::io::ErrorKind::Other, "no such upower device"));
            }
        };

        Ok(UpowerBattery {
            device_path,
            inner: Arc::new(Mutex::new(UpowerBatteryInner{
                capacity: capacity,
                state: state,
                dirty: true
            })),
        })
    }

    pub fn new(listener: Sender<bool>) -> Result<Self, ::std::io::Error> {
        let d = UpowerBattery::from_device("BAT0")?;
        let path = d.device_path.clone();
        let inner = d.inner.clone();
        thread::spawn(move || {
            let con = dbus::Connection::get_private(dbus::BusType::System)
                .expect("Failed to establish D-Bus connection.");
            let rule = format!(
                "type='signal',\
                 path='{}',\
                 interface='org.freedesktop.DBus.Properties',\
                 member='PropertiesChanged'",
                path
            );

            // First we're going to get an (irrelevant) NameAcquired event.
            con.incoming(10_000).next();

            con.add_match(&rule)
                .expect("Failed to add D-Bus match rule.");

            loop {
                if con.incoming(10_000).next().is_some() {
                    let capacity = get_upower_property(&con, &path, "Percentage").unwrap().get1::<dbus::arg::Variant<f64>>().unwrap().0;
                    let state = match get_upower_property(&con, &path, "State").unwrap().get1::<dbus::arg::Variant<u32>>().unwrap().0 {
                        1 => UpowerBatteryState::Charging,
                        2 => UpowerBatteryState::Discharging,
                        3 => UpowerBatteryState::Empty,
                        4 => UpowerBatteryState::Full,
                        5 => UpowerBatteryState::NotCharging,
                        6 => UpowerBatteryState::Discharging,
                        _ => UpowerBatteryState::Unknown,
                    };
                    let mut inner = inner.lock().unwrap();
                    inner.state = state;
                    inner.capacity = capacity;
                    inner.dirty = true;
                    listener.send(true).unwrap();
                }
            }
        });

        Ok(d)

    }

}

impl ModuleImpl for UpowerBattery {
    fn draw(
        &self,
        buf: &mut Buffer,
        bg: &Color,
        _time: &DateTime<Local>,
    ) -> Result<Vec<(i32, i32, i32, i32)>, ::std::io::Error> {
        buf.memset(bg);
        let c = Color::new(1.0, 1.0, 1.0, 1.0);
        let inner = self.inner.lock().unwrap();
        draw_text(
            ROBOTO_REGULAR,
            &mut buf.subdimensions((0, 0, 128, 24))?,
            bg,
            &c,
            24.0,
            "battery",
        )?;
        draw_bar(
            &mut buf.subdimensions((128, 0, 432, 24))?,
            &c,
            432,
            24,
            (inner.capacity as f32) / 100.0,
        )?;

        draw_box(
            &mut buf.subdimensions((128, 0, 432, 24))?,
            &c,
            (432, 24),
        )?;
        Ok(vec![buf.get_signed_bounds()])
    }

    fn update(&mut self, _time: &DateTime<Local>, force: bool) -> Result<bool, ::std::io::Error> {
        let mut inner = self.inner.lock().unwrap();
        if inner.dirty || force {
            inner.dirty = false;
            Ok(true)
        } else {
            Ok(false)
        }
    }

    fn input(&mut self, _input: Input) {}
}