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use proc_macro::TokenStream;
use std::path::PathBuf;
use walkdir::WalkDir;

fn proc_macro_caller_crate_root() -> PathBuf {
    let crate_name =
        std::env::var("CARGO_PKG_NAME").expect("failed to read ENV var `CARGO_PKG_NAME`!");
    let current_dir = std::env::current_dir().expect("failed to unwrap env::current_dir()!");
    let search_entry = format!("name=\"{crate_name}\"");
    for entry in WalkDir::new(&current_dir)
        .into_iter()
        .filter_entry(|e| !e.file_name().eq_ignore_ascii_case("target"))
    {
        let Ok(entry) = entry else { continue };
        if !entry.file_type().is_file() {
            continue;
        }
        let Some(file_name) = entry.path().file_name() else { continue };
        if !file_name.eq_ignore_ascii_case("Cargo.toml") {
            continue;
        }
        let Ok(cargo_toml) = std::fs::read_to_string(&entry.path()) else {
            continue
        };
        if cargo_toml
            .chars()
            .filter(|&c| !c.is_whitespace())
            .collect::<String>()
            .contains(search_entry.as_str())
        {
            return entry.path().parent().unwrap().to_path_buf();
        }
    }
    current_dir
}

#[proc_macro]
pub fn my_macro(_tokens: TokenStream) -> TokenStream {
    let crate_name = std::env::var("CARGO_PKG_NAME").unwrap();
    let working_dir = std::env::current_dir().unwrap().display().to_string();
    let root = proc_macro_caller_crate_root()
        .as_path()
        .to_str()
        .unwrap()
        .to_string();
    println!("CRATE_NAME: {}", crate_name);
    println!("WORKING_DIR: {}", working_dir);
    println!("CRATE_ROOT: {}", root);
    format!("(\"{crate_name}\", \"{working_dir}\", \"{root}\")")
        .parse()
        .unwrap()
}