use std::process::Command;
use std::path::Path;
use std::ffi::OsStr;
use std::fs::File;
use std::io::Write;
use std::io::prelude::*;

fn main() -> std::io::Result<()> {
    println!("building shaders...");
    //shaders path
    let shaders = Path::new("./src/shaders");
    //shader target path
    let out = Command::new("mkdir")
        .arg("target/shaders/")
        .output();
     
    let shader_target = Path::new("./target/shaders/");
    //compile all glsl shaders
    for entry in shaders.read_dir().expect("reading shader directory failed") {
        if let Ok(entry) = entry {
            let shader_path = entry.path();
            println!("compiling shader: {:?}", shader_path);
            let shader_path_string: String = "./target/shaders/".to_string() + shader_path.file_name().unwrap().to_str().unwrap() + ".spv";
            let shader_file: &OsStr = OsStr::new::<str>(shader_path_string.as_str()); 
            let out = Command::new("glslc")
                .arg("-c")
                .arg(shader_path)
                .arg("-o")
                .arg(shader_file)
                .output();
        }
    }
    //include all compiled shaders in shaders.rs file in src dir
    let mut txt: String = String::new();
    for entry in shader_target.read_dir().expect("reading compiled shader target directory failed") {
        if let Ok(entry) = entry {
            let bin_path = entry.path();
            let bin_path_string = bin_path.file_name().unwrap().to_str().unwrap().to_string();
            txt += &("const ".to_owned() + 
                &bin_path_string.replace(".spv", "").replace(".", "_").to_uppercase() + 
                " = include_bytes!(\"../target/shaders/" + 
                &bin_path_string +
                "\");\n");
        }
    }
    let mut file = File::create("./src/shaders.rs")?;
    file.write_all(txt.as_bytes())?;
    Ok(())
}