use std::collections::HashMap;
use std::error::Error;
use std::path::Path;
use gl::types::{GLenum, GLuint};
use rustc_hash::FxHashMap;

use librashader::ShaderSource;
use librashader_presets::ShaderPassConfig;
use librashader_reflect::back::CompileShader;
use librashader_reflect::back::cross::GlVersion;
use librashader_reflect::back::targets::{FromCompilation, GLSL};
use librashader_reflect::front::shaderc::GlslangCompilation;
use librashader_reflect::reflect::cross::CrossReflect;
use librashader_reflect::reflect::{ReflectSemantics, ReflectShader, UniformSemantic};
use librashader_reflect::reflect::semantics::{SemanticMap, TextureSemantics, VariableSemantics};
use librashader_reflect::reflect::{TextureSemanticMap, VariableSemanticMap};

pub fn load_pass_semantics(uniform_semantics: &mut FxHashMap<String, UniformSemantic>, texture_semantics: &mut FxHashMap<String, SemanticMap<TextureSemantics>>,
                           config: &ShaderPassConfig) {
    let Some(alias) = &config.alias else {
        return;
    };

    // Ignore empty aliases
    if alias.trim().is_empty() {
        return;
    }

    let index = config.id as u32;

    // PassOutput
    texture_semantics.insert(alias.clone(), SemanticMap {
        semantics: TextureSemantics::PassOutput,
        index
    });
    uniform_semantics.insert(format!("{alias}Size"), UniformSemantic::Texture(SemanticMap {
        semantics: TextureSemantics::PassOutput,
        index
    }));

    // PassFeedback
    texture_semantics.insert(format!("{alias}Feedback"), SemanticMap {
        semantics: TextureSemantics::PassFeedback,
        index
    });
    uniform_semantics.insert(format!("{alias}FeedbackSize"), UniformSemantic::Texture(SemanticMap {
        semantics: TextureSemantics::PassFeedback,
        index
    }));

}


// todo: init gl

pub fn load(path: impl AsRef<Path>) -> Result<(), Box<dyn Error>>{
    let preset = librashader_presets::ShaderPreset::try_parse(path)?;
    let mut passes: Vec<(&ShaderPassConfig, ShaderSource, _)> = preset.shaders.iter()
        .map(|shader| {
            let source = librashader_preprocess::load_shader_source(&shader.name)
                .unwrap();
            let spirv = librashader_reflect::front::shaderc::compile_spirv(&source)
                .unwrap();
            let mut reflect = GLSL::from_compilation(spirv).unwrap();
            (shader, source, reflect)
        }).collect();

    // todo: this can probably be extracted out.
    let mut uniform_semantics: FxHashMap<String, UniformSemantic> = Default::default();
    let mut texture_semantics: FxHashMap<String, SemanticMap<TextureSemantics>> = Default::default();

    for details in &passes {
        load_pass_semantics(&mut uniform_semantics, &mut texture_semantics, details.0)
    }

    // add float params
    for (index, parameter) in preset.parameters.iter().enumerate() {
        uniform_semantics.insert(parameter.name.clone(), UniformSemantic::Variable(SemanticMap {
            semantics: VariableSemantics::FloatParameter,
            index: index as u32
        }));
    }

    // add lut params
    for (index, texture) in preset.textures.iter().enumerate() {
        texture_semantics.insert(texture.name.clone(), SemanticMap {
            semantics: TextureSemantics::User,
            index: index as u32
        });
    }

    let semantics = ReflectSemantics {
        uniform_semantics,
        non_uniform_semantics: texture_semantics
    };

    let mut reflections = Vec::new();
    let mut compiled = Vec::new();

    for (index, (config, source, reflect)) in passes.iter_mut().enumerate() {
        let reflection = reflect.reflect(index as u32, &semantics)?;
        let glsl = reflect.compile(GlVersion::V4_60)?;


        // shader_gl3: 1375
        reflection.meta.texture_meta.get(&SemanticMap {
            semantics: TextureSemantics::Source,
            index: 0
        }).unwrap().binding;

        // unsafe {
        //     let vertex = gl_compile_shader(gl::VERTEX_SHADER, glsl.vertex.as_str());
        //     let fragment = gl_compile_shader(gl::FRAGMENT_SHADER, glsl.fragment.as_str());
        //
        //     let program = gl::CreateProgram();
        //     gl::AttachShader(program, vertex);
        //     gl::AttachShader(program, fragment);
        //
        // }


        compiled.push(glsl);
        reflections.push(reflection);
    }

    let mut glprogram: Vec<GLuint> = Vec::new();
    for compilation in &compiled {
        // compilation.context.compiler.vertex
    }

    eprintln!("{:#?}", reflections);

    // eprintln!("{:#?}", compiled./);
    // eprintln!("{:?}", preset);
    // eprintln!("{:?}", reflect.reflect(&ReflectOptions {
    //     pass_number: i as u32,
    //     uniform_semantics,
    //     non_uniform_semantics: Default::default(),
    // }));

    Ok(())
}

unsafe fn gl_compile_shader(stage: GLenum, source: &str) -> GLuint {
    let shader = gl::CreateShader(stage);
    gl::ShaderSource(shader, 1, &source.as_bytes().as_ptr().cast(), std::ptr::null());
    gl::CompileShader(shader);

    let mut compile_status = 0;
    gl::GetShaderiv(shader, gl::COMPILE_STATUS, &mut compile_status);

    if compile_status == 0 {
        panic!("failed to compile")
    }
    shader
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn load_preset() {

        load("../test/basic.slangp")
            .unwrap();
    }
}