use std::{collections::HashMap, fmt::Display, sync::{Arc, Mutex}};

use bevy_ecs::system::Resource;
use image::EncodableLayout;
use poll_promise::Promise;
use resvg::{tiny_skia, usvg};

#[derive(Debug, Clone)]
pub enum AssetError {
    AssetNotFound,
    ResponseNotOk(u16),
}
impl Display for AssetError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            AssetError::AssetNotFound => write!(f, "Asset not found"),
            AssetError::ResponseNotOk(code) => write!(f, "Server response was not ok {}", code),
        }
    }
}
impl std::error::Error for AssetError {}

#[derive(Debug, Clone)]
pub struct ImgData {
    pub bytes: Vec<u8>,
    pub width: u32,
    pub height: u32,
}

#[derive(Resource)]
pub struct Assets {
    texture_promises: Arc<Mutex<HashMap<String, Promise<ImgData>>>>,
    textures: Arc<Mutex<HashMap<String, ImgData>>>,
}

impl Assets {
    pub fn new() -> Self {
        Assets {
            textures: Arc::new(Mutex::new(HashMap::new())),
            texture_promises: Arc::new(Mutex::new(HashMap::new())),
        }
    }
    pub fn get(&self, local_path: impl Into<String>) -> Option<ImgData> {
        let local_path = local_path.into();
        let contains_texture = {
            self.textures.lock().unwrap().contains_key(&local_path)
        };
        let contains_texture_promise = {
            self.texture_promises.lock().unwrap().contains_key(&local_path)
        };
        if !contains_texture && !contains_texture_promise {
            let local_path_clone = local_path.clone();
            let request_promise = poll_promise::Promise::spawn_local(async move {
                let window = web_sys::window().unwrap();
                let request = ehttp::Request::get(format!("{}/src/assets/{}", window.location().origin().unwrap(), local_path_clone));
                let response = match ehttp::fetch_async(request).await {
                    Ok(resp) => resp,
                    Err(e) => {
                        panic!("{}", e);
                    },
                };
                if local_path_clone.ends_with(".svg") {
                    let opt = usvg::Options {
                        default_size: usvg::Size::from_wh(20.0, 20.0).unwrap(),
                        ..Default::default()
                    };
                    let tree = usvg::Tree::from_data(&response.bytes, &opt).expect(&format!("Couldn't parse svg {}", local_path_clone));
                    let tree_size = tree.size().to_int_size();
                    let size = usvg::Size::from_wh(500.0, 500.0).unwrap().to_int_size();
                    assert!(size.width() > 0 && size.height() > 0);
                    let mut pixmap = tiny_skia::Pixmap::new(size.width(), size.height()).expect("Failed to construct pixmap");
                    resvg::render(&tree, tiny_skia::Transform::from_scale((size.width() as f32)/(tree_size.height() as f32), (size.height() as f32)/(tree_size.height() as f32)), &mut pixmap.as_mut());
                    let data = ImgData {
                        bytes: pixmap.data().to_vec(),
                        width: size.width(),
                        height: size.height(),
                    };
                    
                    data
                } else if local_path_clone.ends_with(".png") {
                    let img = image::load_from_memory(&response.bytes).unwrap();
                    let rgba = img.to_rgba8();
                    let data = ImgData {
                        bytes: rgba.as_bytes().to_vec(),
                        width: rgba.width(),
                        height: rgba.height(),
                    };
                    data
                } else {
                    panic!("Unsupported sprite type");
                }
            });
            {
                self.texture_promises.lock().unwrap().insert(local_path.clone(), request_promise);
            }
            None
        } else if !contains_texture {
            let mut texture_promises = self.texture_promises.lock().unwrap();
            let promise = texture_promises.get_mut(&local_path).unwrap();
            let mut returned_value = None;
            if let Some(texture) = promise.ready() {
                self.textures.lock().unwrap().insert(local_path.clone(), texture.clone());
                returned_value = Some(texture.clone());
                texture_promises.remove(&local_path);
            }
            return returned_value
        } else {
            self.textures.lock().unwrap().get(&local_path).cloned()
        }
    }
}