use crate::download::Downloader;
use anyhow::{Context, Result};
use std::{
    collections::{HashMap, HashSet},
    sync::Arc,
};
use weareshared::{
    Affine3A,
    packets::{ReadWrite, Resource},
    resources::{Attribute, Part, Prefab},
};
use wgpu::Buffer;

pub struct ScenePreparer {
    index_buffers: HashMap<Resource, (Arc<Buffer>, u32)>,
    index_buffers_needed: HashSet<Resource>,
    vertex_buffers: HashMap<Resource, Arc<Buffer>>,
    vertex_buffers_needed: HashSet<Resource>,
    parts: HashMap<Resource, Arc<RPart>>,
    parts_needed: HashSet<Resource>,
    pub prefabs: HashMap<Resource, RPrefab>,
    pub prefabs_needed: HashSet<Resource>,
}

pub struct RPrefab(pub Vec<(Affine3A, Arc<RPart>)>);
pub struct RPart {
    pub index_count: u32,
    pub index: Arc<Buffer>,
    pub position: [Arc<Buffer>; 3],
    pub normal: [Arc<Buffer>; 3],
    pub texcoord: [Arc<Buffer>; 2],
}

impl ScenePreparer {
    pub fn new() -> Self {
        Self {
            index_buffers: HashMap::new(),
            vertex_buffers: HashMap::new(),
            vertex_buffers_needed: HashSet::new(),
            parts: HashMap::new(),
            parts_needed: HashSet::new(),
            prefabs: HashMap::new(),
            prefabs_needed: HashSet::new(),
            index_buffers_needed: HashSet::new(),
        }
    }
    pub fn update(&mut self, dls: &mut Downloader) -> Result<()> {
        let mut done = Vec::new();
        for pres in &self.prefabs_needed {
            if let Some(buf) = dls.try_get(*pres)? {
                let prefab = Prefab::read(&mut buf.as_slice()).context("parsing prefab")?;
                let mut rprefab = RPrefab(Vec::new());
                for (aff, partres) in &prefab.0 {
                    if let Some(part) = self.parts.get(partres) {
                        rprefab.0.push((*aff, part.clone()));
                    } else {
                        self.parts_needed.insert(*partres);
                    }
                }
                if rprefab.0.len() == prefab.0.len() {
                    self.prefabs.insert(*pres, rprefab);
                    done.push(*pres);
                }
            }
        }
        for pres in &self.index_buffers_needed {
            if let Some(buf) = dls.try_get(*pres)? {}
        }
        for pres in &self.parts_needed {
            if let Some(buf) = dls.try_get(*pres)? {
                let part = Part::read(&mut buf.as_slice()).context("parsing part")?;
                if let (Some(indexres), Some(positionres), Some(normalres), Some(texcoordres)) = (
                    part.index,
                    part.va_position,
                    part.va_normal,
                    part.va_texcoord,
                ) {
                    let Some((index, index_count)) = self.index_buffers.get(&indexres).cloned()
                    else {
                        self.index_buffers_needed.insert(indexres);
                        continue;
                    };
                    let mut positions = Vec::new();
                    for vr in positionres {
                        match vr {
                            Attribute::Constant(_) => todo!(),
                            Attribute::Vertex(resource) => {
                                let Some(vertex) = self.vertex_buffers.get(&resource).cloned()
                                else {
                                    self.vertex_buffers_needed.insert(indexres);
                                    continue;
                                };
                                positions.push(vertex);
                            }
                            Attribute::Texture(_resource) => todo!(),
                        }
                    }
                    let mut normals = Vec::new();
                    for vr in normalres {
                        match vr {
                            Attribute::Constant(_) => todo!(),
                            Attribute::Vertex(resource) => {
                                let Some(vertex) = self.vertex_buffers.get(&resource).cloned()
                                else {
                                    self.vertex_buffers_needed.insert(indexres);
                                    continue;
                                };
                                normals.push(vertex);
                            }
                            Attribute::Texture(_resource) => todo!(),
                        }
                    }
                    let mut texcoords = Vec::new();
                    for vr in texcoordres {
                        match vr {
                            Attribute::Constant(_) => todo!(),
                            Attribute::Vertex(resource) => {
                                let Some(vertex) = self.vertex_buffers.get(&resource).cloned()
                                else {
                                    self.vertex_buffers_needed.insert(indexres);
                                    continue;
                                };
                                texcoords.push(vertex);
                            }
                            Attribute::Texture(_resource) => todo!(),
                        }
                    }
                    self.parts.insert(
                        *pres,
                        Arc::new(RPart {
                            index_count,
                            index,
                            texcoord: texcoords.try_into().unwrap(),
                            normal: normals.try_into().unwrap(),
                            position: positions.try_into().unwrap(),
                        }),
                    );
                }
            }
        }
        Ok(())
    }
}