extern crate proc_macro;

use proc_macro::TokenStream;
use std::{collections::HashMap, fs::File, io::BufReader};
use std::io::prelude::*;



fn readds100() -> HashMap<String, String> {
    // who needs obvious filepaths, anyways?
    let filename = "./DBNetz-Betriebsstellenverzeichnis-Stand2021-10.csv";
    let file = File::open(filename).unwrap();
    let reader = BufReader::new(file);

    reader.lines()
          .filter_map(|l| l.ok())
        .skip(1)
          .map(|l| {
              let segments: Vec<&str> = l
                  .split(";")
                  .collect();
              (segments[1].to_owned(),segments[2].to_owned())
          })
          .collect::<HashMap<String,String>>()
}


// rust macros are a strange kind of horrible, tbh
#[proc_macro]
pub fn make_ds100(_item: TokenStream) -> TokenStream {
    let symbols = readds100();

    format!(
        "pub fn ds100(key: &str) -> Option<&str> {{
          match key {{
             {}
             _ => None
          }}
        }}",
        symbols.iter()
               .map(|(k,v)| format!("\"{}\" => Some(\"{}\"),",k,v))
               .collect::<Vec<_>>()
               .join("\n")
    ).parse().unwrap()
}