use error::Error;
use std::io;
use std::io::prelude::*;

#[macro_use] extern crate lalrpop_util;

lalrpop_mod!(pub commandline);
pub mod error;
pub mod path;


pub type Result<T> = std::result::Result<T, Error>;

pub enum Input {
    String(String),
    End,
}


fn main() -> Result<()> {
    std::process::exit(match repl() {
        Ok(()) => 0,
        Err(ref e) => {
            eprintln!("{}", e);
            1
        }
    })
}


fn repl() -> Result<()> {
    println!("Hello, terminal!");

    loop {
        prompt()?;

        let input = read()?;
        match input {
            Input::String(string) => execute(&string)?,
            Input::End => break,
        }
    }

    Ok(())
}


fn prompt() -> Result<()> {
    print!("$ ");
    io::stdout().flush()?;

    Ok(())
}


fn read() -> Result<Input> {
    let mut input = String::new();
    let n_bytes = io::stdin().read_line(&mut input)?;

    if n_bytes == 0 {
        Ok(Input::End)
    } else {
        Ok(Input::String(input))
    }
}


fn execute(input: &str) -> Result<()> {
    let invocation = commandline::InvocationParser::new().parse(input)?;

    println!("{}", input);

    match invocation.as_slice() {
      ["paths", path_list, ..] => {
        println!("{:?}", path_list);
        match path::parser::PathListParser::new().parse(path_list) {
          Ok(parsed_paths) => {
            println!("paths '{:?}'", parsed_paths);
          },
          Err(_) => {
            match path::parser::PathListAllowingEmptyPathsParser::new()
              .parse(path_list)
            {
              Ok(parsed) => {
                println!("path list has empty component");
                println!("{:?}", parsed);
              },
              Err(error) => {
                println!("path list is okay, does not have empty component");
                println!("{:?}", error);
              },
            }
          },
        }
      },
      _ => {
        println!("invocation '{:?}'", invocation);
      }
    }

    Ok(())
}