use std::{
    fs::{self, File},
    io::{BufRead, BufReader},
    path::Path,
};

pub fn main() {
    let proto_file = "nap.proto";
    if Path::new(&proto_file).exists() {
        println!("cargo:rerun-if-changed={proto_file}");
        let _ = fs::create_dir("out/");

        prost_build::Config::new()
            .out_dir("out/")
            .type_attribute(".", "#[derive(proto_gen::CmdID)]")
            .type_attribute(".", "#[derive(proto_gen::XorFields)]")
            .compile_protos(&[proto_file], &["."])
            .unwrap();
        apply_xor(Path::new("out/_.rs")).unwrap();
    }

    let proto_file = "bin.server.proto";
    if Path::new(&proto_file).exists() {
        println!("cargo:rerun-if-changed={proto_file}");
        let _ = fs::create_dir("out/");

        prost_build::Config::new()
            .out_dir("out/")
            .compile_protos(&[proto_file], &["bin"])
            .unwrap();
    }
}

fn apply_xor(path: &Path) -> std::io::Result<()> {
    let file = File::open(path)?;
    let reader = BufReader::new(file);
    let mut output = Vec::new();

    let mut cmd_id_attr = None;
    for line in reader.lines() {
        let line = line?;
        if line.contains("xor const: ") {
            if !line.contains("xor const: 0") {
                output.push(make_xor_attr(&line).unwrap());
            }
        } else if line.contains("CmdID: ") {
            cmd_id_attr = Some(make_cmd_id_attr(&line).unwrap());
        } else {
            output.push(line);
            if let Some(attr) = cmd_id_attr.take() {
                output.push(attr);
            }
        }
    }

    fs::write(path, output.join("\n").as_bytes())?;
    Ok(())
}

fn make_xor_attr(line: &str) -> Option<String> {
    let xor_value = line.split("xor const: ").nth(1)?.parse::<u32>().ok()?;
    Some(format!("    #[xor({xor_value})]"))
}

fn make_cmd_id_attr(line: &str) -> Option<String> {
    let cmd_id = line.split("CmdID: ").nth(1)?.parse::<u16>().ok()?;
    Some(format!("#[cmdid({cmd_id})]"))
}