use futures::future::join_all;
use once_cell::sync::OnceCell;
use paris::{error, info};
use serde::{Deserialize, Serialize};

use std::{
    collections::{HashMap, HashSet},
    sync::Arc,
    time::Duration,
};
use tauri::async_runtime::RwLock;
use tokio::{
    sync::mpsc,
    time::{sleep, Instant},
};
use tracing::warn;

use crate::{
    picker::{
        self, config::DisplayConfig, display_picker::DisplayPicker, led_color::LedColor,
        screenshot::Screenshot,
    },
    rpc,
};

#[derive(Debug, Serialize, Deserialize, Clone, Copy)]
pub enum AmbientLightMode {
    None,
    Follow,
    Flowing,
}

pub struct CoreManager {
    ambient_light_mode: Arc<RwLock<AmbientLightMode>>,
}

impl CoreManager {
    pub fn global() -> &'static CoreManager {
        static CORE_MANAGER: OnceCell<CoreManager> = OnceCell::new();

        let core = CORE_MANAGER.get_or_init(|| CoreManager {
            ambient_light_mode: Arc::new(RwLock::new(AmbientLightMode::None)),
        });

        core
    }

    pub async fn set_ambient_light(&self, target_mode: AmbientLightMode) {
        let mut mode = self.ambient_light_mode.write().await;
        *mode = target_mode;

        drop(mode);

        match target_mode {
            AmbientLightMode::Flowing => self.play_flowing_light().await,
            AmbientLightMode::None => {}
            AmbientLightMode::Follow => match self.play_follow().await {
                Ok(_) => {}
                Err(error) => {
                    warn!("Can not following displays. {}", error);
                }
            },
        };
    }

    pub async fn play_flowing_light(&self) {
        let mut hue = 0f64;
        let step_length = 2.0;
        loop {
            let lock = self.ambient_light_mode.read().await;
            if let AmbientLightMode::Flowing = *lock {
                let mut colors = Vec::<LedColor>::new();
                for i in 0..60 {
                    let color =
                        LedColor::from_hsv((hue + i as f64 * step_length) % 360.0, 1.0, 0.5);
                    colors.push(color);
                }
                hue = (hue + 1.0) % 360.0;
                match rpc::manager::Manager::global()
                    .publish_led_colors(&colors)
                    .await
                {
                    Ok(_) => {}
                    Err(error) => {
                        warn!("publish led colors failed. {}", error);
                    }
                }
            } else {
                break;
            }
            sleep(Duration::from_millis(50)).await;
        }
    }

    pub async fn play_follow(&self) -> anyhow::Result<()> {
        let mut futs = vec![];
        let configs = picker::config::Manager::global().reload_config().await;
        let configs = match configs {
            Ok(c) => c.display_configs,
            Err(err) => anyhow::bail!("can not get display configs. {:?}", err),
        };
        info!("piker display configs: {:?}", configs);

        let (tx, mut rx) = mpsc::channel(10);

        for config in configs.clone() {
            let tx = tx.clone();
            let fut = tokio::spawn(async move {
                match Self::follow_display_by_config(config, tx).await {
                    Ok(_) => {}
                    Err(error) => {
                        warn!("following failed. {}", error);
                    }
                }
            });
            futs.push(fut);
        }

        let total_colors_count = configs
            .iter()
            .flat_map(|c| {
                vec![
                    c.led_strip_of_borders.top,
                    c.led_strip_of_borders.bottom,
                    c.led_strip_of_borders.left,
                    c.led_strip_of_borders.right,
                ]
            })
            .flat_map(|l| match l {
                Some(l) => (l.global_start_position.min(l.global_end_position)
                    ..l.global_start_position.max(l.global_end_position))
                    .collect(),
                None => {
                    vec![]
                }
            })
            .collect::<HashSet<_>>()
            .len();
        tokio::spawn(async move {
            let mut global_sub_pixels = HashMap::new();
            while let Some(screenshot) = rx.recv().await {
                let start_at = Instant::now();
                let colors = screenshot.get_colors();
                let config = screenshot.get_config();
                for (colors, config) in vec![
                    (colors.top, config.led_strip_of_borders.top),
                    (colors.right, config.led_strip_of_borders.right),
                    (colors.bottom, config.led_strip_of_borders.bottom),
                    (colors.left, config.led_strip_of_borders.left),
                ] {
                    match config {
                        Some(config) => {
                            let (sign, start) =
                                if config.global_start_position <= config.global_end_position {
                                    (1, config.global_start_position as isize * 3)
                                } else {
                                    (-1, (config.global_start_position as isize + 1) * 3 - 1)
                                };
                            for (index, color) in colors.into_iter().enumerate() {
                                let pixel_index = index / 3;
                                let sub_pixel_index = index % 3;
                                let offset = if sign < 0 {
                                    2 - sub_pixel_index
                                } else {
                                    sub_pixel_index
                                };
                                let global_sub_pixel_index =
                                    (sign * (pixel_index as isize * 3 + offset as isize) + start ) as usize;
                                global_sub_pixels.insert(global_sub_pixel_index, color);
                            }
                        }
                        None => {}
                    }
                }

                // info!(
                //     "led count: {}, spend: {:?}",
                //     global_sub_pixels.len(),
                //     start_at.elapsed()
                // );

                if global_sub_pixels.len() >= total_colors_count * 3 {
                    let mut colors = vec![];
                    for index in 0..global_sub_pixels.len() {
                        colors.push(*global_sub_pixels.get(&index).unwrap());
                    }
                    // info!("{:?}", colors);
                    global_sub_pixels = HashMap::new();
                    match rpc::manager::Manager::global()
                        .publish_led_sub_pixels(colors)
                        .await
                    {
                        Ok(_) => {
                            // info!("publish successful",);
                        }
                        Err(error) => {
                            warn!("publish led colors failed. {}", error);
                        }
                    }
                }
            }
        });

        join_all(futs).await;

        Ok(())
    }

    async fn follow_display_by_config(
        config: DisplayConfig,
        tx: mpsc::Sender<Screenshot>,
    ) -> anyhow::Result<()> {
        let mut picker = DisplayPicker::from_config(config)?;
        info!("width: {}", picker.config.display_width);

        loop {
            let start = Instant::now();
            let next_tick = start + Duration::from_millis(16);
            let lock = Self::global().ambient_light_mode.read().await;
            if let AmbientLightMode::Follow = *lock {
                drop(lock);
                let screenshot = picker.take_screenshot()?;
                info!("Take Screenshot Spend: {:?}", start.elapsed());
                match tx.send(screenshot).await {
                    Ok(_) => {}
                    Err(err) => {
                        error!("send screenshot to main thread was failed. {:?}", err);
                    }
                };
            } else {
                break;
            }
            tokio::time::sleep_until(next_tick).await;
        }
        Ok(())
    }
}