use super::CodePiece;
use crate::impl_code_piece;
use glsl::parser::Parse;
use glsl::syntax::ShaderStage;
use glsl::syntax::TranslationUnit;
use glsl::transpiler::glsl::show_translation_unit;

pub struct ColorMap(pub ShaderStage);

impl ColorMap {
    pub fn new() -> Self {
        let raw = {
            "
            uniform sampler1D colormap;
            uniform vec4 colormap_conf;

            float find_idx(float ratio) {
                float i = 0;
                float count = colormap_conf.z - 1.0;
                float sum = 0.0;

                while (ratio > sum) {
                    sum += texture(colormap, float(i++) / count).w;
                }
                return i / count;
            }

            vec4 linear_colormap(float value)
            {
                float vmin = colormap_conf.x;
                float vmax = colormap_conf.y;
                float count = colormap_conf.z - 1.0;

                float invalid = colormap_conf.w;

                if (abs(value - invalid) < 0.0001 || value < vmin || value > vmax) {
                    return vec4(0.0, 0.0, 0.0, 0.0);
                }

                float v = clamp((value - vmin), vmin, vmax) / (vmax - vmin);
                float idx = find_idx(v);
                vec4 result = texture(colormap, idx);
                return vec4(result.rgb, 1.0);
            }
        "
        };

        Self(ShaderStage::parse(raw).unwrap())
    }
}

impl_code_piece!(ColorMap, 0);