use gl::types::{GLenum, GLint, GLuint};
use rustc_hash::FxHashMap;
use librashader_common::{FilterMode, WrapMode};
use crate::error::Result;

pub struct SamplerSet {
    // todo: may need to deal with differences in mip filter.
    samplers: FxHashMap<(WrapMode, FilterMode, FilterMode), GLuint>
}

impl SamplerSet {
    pub fn get(&self, wrap: WrapMode, filter: FilterMode, mip: FilterMode) -> GLuint {
        // eprintln!("{wrap}, {filter}, {mip}");
        *self.samplers.get(&(wrap, filter, mip))
            .unwrap()
    }

    fn make_sampler(sampler: GLuint, wrap: WrapMode, filter: FilterMode, mip: FilterMode) {
        unsafe {
            gl::SamplerParameteri(
                sampler,
                gl::TEXTURE_WRAP_S,
                GLenum::from(wrap) as GLint,
            );
            gl::SamplerParameteri(
                sampler,
                gl::TEXTURE_WRAP_T,
                GLenum::from(wrap) as GLint,
            );
            gl::SamplerParameteri(
                sampler,
                gl::TEXTURE_MAG_FILTER,
                GLenum::from(filter) as GLint,
            );
            gl::SamplerParameteri(
                sampler,
                gl::TEXTURE_MIN_FILTER,
                GLenum::from(filter.gl_mip(mip)) as GLint,
            );
        }
    }

    pub fn new() -> SamplerSet {
        let mut samplers = FxHashMap::default();
        let wrap_modes =
            &[WrapMode::ClampToBorder, WrapMode::ClampToEdge, WrapMode::Repeat, WrapMode::MirroredRepeat];
        for wrap_mode in wrap_modes {
            unsafe {
                let mut linear_linear = 0;
                let mut nearest_nearest = 0;
                let mut linear_nearest = 0;
                let mut nearest_linear = 0;
                gl::GenSamplers(1, &mut linear_linear);
                gl::GenSamplers(1, &mut linear_nearest);
                gl::GenSamplers(1, &mut nearest_linear);
                gl::GenSamplers(1, &mut nearest_nearest);

                SamplerSet::make_sampler(linear_linear, *wrap_mode, FilterMode::Linear, FilterMode::Linear);
                SamplerSet::make_sampler(linear_nearest, *wrap_mode, FilterMode::Linear, FilterMode::Linear);
                SamplerSet::make_sampler(nearest_linear, *wrap_mode, FilterMode::Nearest, FilterMode::Linear);
                SamplerSet::make_sampler(nearest_linear, *wrap_mode, FilterMode::Nearest, FilterMode::Nearest);

                samplers.insert((*wrap_mode, FilterMode::Linear, FilterMode::Linear), linear_linear);
                samplers.insert((*wrap_mode, FilterMode::Linear, FilterMode::Nearest), linear_nearest);

                samplers.insert((*wrap_mode, FilterMode::Nearest, FilterMode::Nearest), nearest_nearest);
                samplers.insert((*wrap_mode, FilterMode::Nearest, FilterMode::Linear), nearest_linear);
            }
        }

        SamplerSet {
            samplers
        }
    }
}