// client/src/input/mouse.rs

use evdev::{AbsoluteAxisCode, Device, EventType, InputEvent, KeyCode, RelativeAxisCode};
use std::time::{Duration, Instant};
use tokio::sync::broadcast::{self, Sender};
use tracing::{debug, error, trace, warn};

use lesavka_common::lesavka::MouseReport;

const SEND_INTERVAL: Duration = Duration::from_millis(1);

pub struct MouseAggregator {
    dev: Device,
    tx: Sender<MouseReport>,
    dev_mode: bool,
    sending_disabled: bool,
    next_send: Instant,

    buttons: u8,
    last_buttons: u8,
    dx: i8,
    dy: i8,
    wheel: i8,
    last_abs_x: Option<i32>,
    last_abs_y: Option<i32>,
    abs_scale: i32,
    abs_jump_x: i32,
    abs_jump_y: i32,
    has_touch_state: bool,
    touch_guarded: bool,
    touch_active: bool,
}

impl MouseAggregator {
    pub fn new(dev: Device, dev_mode: bool, tx: Sender<MouseReport>) -> Self {
        let abs_scale = std::env::var("LESAVKA_TOUCHPAD_SCALE")
            .ok()
            .and_then(|v| v.parse::<i32>().ok())
            .unwrap_or(8)
            .max(1);
        let has_touch_state = dev
            .supported_keys()
            .map(|keys| keys.contains(KeyCode::BTN_TOUCH))
            .unwrap_or(false)
            || dev
                .supported_absolute_axes()
                .map(|abs| abs.contains(AbsoluteAxisCode::ABS_MT_TRACKING_ID))
                .unwrap_or(false);
        let abs_jump_x = Self::abs_jump_threshold(
            &dev,
            &[AbsoluteAxisCode::ABS_X, AbsoluteAxisCode::ABS_MT_POSITION_X],
            abs_scale,
        );
        let abs_jump_y = Self::abs_jump_threshold(
            &dev,
            &[AbsoluteAxisCode::ABS_Y, AbsoluteAxisCode::ABS_MT_POSITION_Y],
            abs_scale,
        );
        Self {
            dev,
            tx,
            dev_mode,
            sending_disabled: false,
            next_send: Instant::now(),
            buttons: 0,
            last_buttons: 0,
            dx: 0,
            dy: 0,
            wheel: 0,
            last_abs_x: None,
            last_abs_y: None,
            abs_scale,
            abs_jump_x,
            abs_jump_y,
            has_touch_state,
            touch_guarded: false,
            touch_active: true,
        }
    }

    #[inline]
    #[allow(dead_code)]
    fn slog(&self, f: impl FnOnce()) {
        if self.dev_mode {
            f()
        }
    }
    pub fn set_grab(&mut self, grab: bool) {
        let _ = if grab {
            self.dev.grab()
        } else {
            self.dev.ungrab()
        };
    }

    pub fn set_send(&mut self, send: bool) {
        self.sending_disabled = !send;
    }

    pub fn process_events(&mut self) {
        let evts: Vec<InputEvent> = match self.dev.fetch_events() {
            Ok(it) => it.collect(),
            Err(e) if e.kind() == std::io::ErrorKind::WouldBlock => return,
            Err(e) => {
                if self.dev_mode {
                    error!("🖱️❌ mouse read err: {e}");
                }
                return;
            }
        };

        if self.dev_mode && !evts.is_empty() {
            trace!(
                "🖱️ {} evts from {}",
                evts.len(),
                self.dev.name().unwrap_or("?")
            );
        }

        for e in evts {
            match e.event_type() {
                EventType::KEY => match e.code() {
                    c if c == KeyCode::BTN_LEFT.0 => self.set_btn(0, e.value()),
                    c if c == KeyCode::BTN_RIGHT.0 => self.set_btn(1, e.value()),
                    c if c == KeyCode::BTN_MIDDLE.0 => self.set_btn(2, e.value()),
                    c if c == KeyCode::BTN_TOUCH.0 => {
                        self.touch_guarded = true;
                        self.touch_active = e.value() != 0;
                        if !self.touch_active {
                            self.last_abs_x = None;
                            self.last_abs_y = None;
                        }
                        self.set_btn(0, e.value());
                    }
                    _ => {}
                },
                EventType::RELATIVE => match e.code() {
                    c if c == RelativeAxisCode::REL_X.0 => {
                        self.dx = self.dx.saturating_add(e.value().clamp(-127, 127) as i8)
                    }
                    c if c == RelativeAxisCode::REL_Y.0 => {
                        self.dy = self.dy.saturating_add(e.value().clamp(-127, 127) as i8)
                    }
                    c if c == RelativeAxisCode::REL_WHEEL.0 => {
                        self.wheel = self.wheel.saturating_add(e.value().clamp(-1, 1) as i8)
                    }
                    _ => {}
                },
                EventType::ABSOLUTE => match e.code() {
                    c if c == AbsoluteAxisCode::ABS_X.0
                        || c == AbsoluteAxisCode::ABS_MT_POSITION_X.0 =>
                    {
                        if self.touch_guarded && !self.touch_active {
                            self.last_abs_x = Some(e.value());
                            continue;
                        }
                        if let Some(prev) = self.last_abs_x {
                            if !self.has_touch_state {
                                let delta = (e.value() - prev).abs();
                                if delta > self.abs_jump_x {
                                    self.last_abs_x = Some(e.value());
                                    continue;
                                }
                            }
                            let delta = (e.value() - prev) / self.abs_scale;
                            if delta != 0 {
                                self.dx = self.dx.saturating_add(delta.clamp(-127, 127) as i8);
                            }
                        }
                        self.last_abs_x = Some(e.value());
                    }
                    c if c == AbsoluteAxisCode::ABS_Y.0
                        || c == AbsoluteAxisCode::ABS_MT_POSITION_Y.0 =>
                    {
                        if self.touch_guarded && !self.touch_active {
                            self.last_abs_y = Some(e.value());
                            continue;
                        }
                        if let Some(prev) = self.last_abs_y {
                            if !self.has_touch_state {
                                let delta = (e.value() - prev).abs();
                                if delta > self.abs_jump_y {
                                    self.last_abs_y = Some(e.value());
                                    continue;
                                }
                            }
                            let delta = (e.value() - prev) / self.abs_scale;
                            if delta != 0 {
                                self.dy = self.dy.saturating_add(delta.clamp(-127, 127) as i8);
                            }
                        }
                        self.last_abs_y = Some(e.value());
                    }
                    c if c == AbsoluteAxisCode::ABS_MT_TRACKING_ID.0 => {
                        if e.value() < 0 {
                            self.touch_guarded = true;
                            self.touch_active = false;
                            self.last_abs_x = None;
                            self.last_abs_y = None;
                        } else {
                            self.touch_guarded = true;
                            self.touch_active = true;
                        }
                    }
                    _ => {}
                },
                EventType::SYNCHRONIZATION => self.flush(),
                _ => {}
            }
        }
    }

    pub fn reset_state(&mut self) {
        self.buttons = 0;
        self.last_buttons = 0;
        self.dx = 0;
        self.dy = 0;
        self.wheel = 0;
        self.last_abs_x = None;
        self.last_abs_y = None;
        if !self.sending_disabled {
            let _ = self.tx.send(MouseReport {
                data: [0; 4].into(),
            });
        }
    }

    fn flush(&mut self) {
        if self.buttons == self.last_buttons && Instant::now() < self.next_send {
            return;
        }
        self.next_send = Instant::now() + SEND_INTERVAL;

        let pkt = [
            self.buttons,
            self.dx.clamp(-127, 127) as u8,
            self.dy.clamp(-127, 127) as u8,
            self.wheel as u8,
        ];

        if !self.sending_disabled {
            if let Err(broadcast::error::SendError(_)) =
                self.tx.send(MouseReport { data: pkt.to_vec() })
            {
                if self.dev_mode {
                    warn!("❌🖱️ no HID receiver (mouse)");
                }
            } else if self.dev_mode {
                debug!("📤🖱️ mouse {:?}", pkt);
            }
        }

        self.dx = 0;
        self.dy = 0;
        self.wheel = 0;
        self.last_buttons = self.buttons;
    }

    #[inline]
    fn set_btn(&mut self, bit: u8, val: i32) {
        if val != 0 {
            self.buttons |= 1 << bit
        } else {
            self.buttons &= !(1 << bit)
        }
    }

    fn abs_jump_threshold(dev: &Device, codes: &[AbsoluteAxisCode], abs_scale: i32) -> i32 {
        let mut range: Option<i32> = None;
        if let Ok(iter) = dev.get_absinfo() {
            for (code, info) in iter {
                if codes.iter().any(|c| *c == code) {
                    range = Some(info.maximum() - info.minimum());
                    break;
                }
            }
        }
        let mut threshold = range.unwrap_or(0).abs() / 3;
        let min = (abs_scale * 40).max(50);
        if threshold < min {
            threshold = min;
        }
        if threshold == 0 {
            threshold = min;
        }
        threshold
    }
}

impl Drop for MouseAggregator {
    fn drop(&mut self) {
        let _ = self.dev.ungrab();
        let _ = self.tx.send(MouseReport {
            data: [0; 8].into(),
        });
    }
}