// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Also licensed under MIT license, at your choice.

//! Load rendering shaders.

mod preprocess;

use std::{collections::HashSet, fs, path::Path};

use wgpu::Device;

use crate::engine::{BindType, Engine, Error, ShaderId};

pub const PATHTAG_REDUCE_WG: u32 = 256;
pub const PATH_COARSE_WG: u32 = 256;

pub struct Shaders {
    pub pathtag_reduce: ShaderId,
    pub pathtag_scan: ShaderId,
    pub path_coarse: ShaderId,
    pub backdrop: ShaderId,
    pub fine: ShaderId,
}

pub fn init_shaders(device: &Device, engine: &mut Engine) -> Result<Shaders, Error> {
    let shader_dir = Path::new(concat!(env!("CARGO_MANIFEST_DIR"), "/shader"));
    let imports = preprocess::get_imports(shader_dir);
    let read_shader =
        |path: &str| fs::read_to_string(shader_dir.join(path.to_string() + ".wgsl")).unwrap();
    let empty = HashSet::new();
    let pathtag_reduce = engine.add_shader(
        device,
        preprocess::preprocess(&read_shader("pathtag_reduce"), &empty, &imports).into(),
        &[BindType::BufReadOnly, BindType::Buffer],
    )?;
    let pathtag_scan = engine.add_shader(
        device,
        preprocess::preprocess(&read_shader("pathtag_scan"), &empty, &imports).into(),
        &[
            BindType::BufReadOnly,
            BindType::BufReadOnly,
            BindType::Buffer,
        ],
    )?;
    let path_coarse_config = HashSet::new();
    // path_coarse_config.add("cubics_out");

    let path_coarse = engine.add_shader(
        device,
        preprocess::preprocess(&read_shader("path_coarse"), &path_coarse_config, &imports).into(),
        &[
            BindType::BufReadOnly,
            BindType::BufReadOnly,
            BindType::BufReadOnly,
            BindType::BufReadOnly,
            BindType::Buffer,
            BindType::Buffer,
        ],
    )?;
    let backdrop = engine.add_shader(
        device,
        preprocess::preprocess(&read_shader("backdrop"), &empty, &imports).into(),
        &[BindType::BufReadOnly, BindType::Buffer],
    )?;
    let fine = engine.add_shader(
        device,
        preprocess::preprocess(&read_shader("fine"), &empty, &imports).into(),
        &[
            BindType::BufReadOnly,
            BindType::BufReadOnly,
            BindType::BufReadOnly,
            BindType::Buffer,
        ],
    )?;
    Ok(Shaders {
        pathtag_reduce,
        pathtag_scan,
        path_coarse,
        backdrop,
        fine,
    })
}