use std::fmt::Write as FmtWrite;

use super::{Repl, InterpreterDirectiveOutput};
use crate::repl::command_tree::CommandTree;

pub fn help(repl: &mut Repl, arguments: &[&str]) -> InterpreterDirectiveOutput {
  let mut buf = String::new();
  let directives = match repl.get_directives() {
    CommandTree::Top(children) => children,
    _ => panic!("Top-level CommandTree not Top")
  };

  match arguments {
    [] =>  return global_help(repl, &directives),
    _ => {
      writeln!(buf, "Command-specific help not available yet").unwrap();
    }
  };
  Some(buf)
}

fn global_help(repl: &mut Repl, directives: &Vec<CommandTree>) -> InterpreterDirectiveOutput {
  let mut buf = String::new();

  writeln!(buf, "MetaInterpreter options").unwrap();
  writeln!(buf, "-----------------------").unwrap();

  for directive in directives {
    let trailer = " ";
    writeln!(buf, "{}{}- {}", directive.get_cmd(), trailer, directive.get_help()).unwrap();
  }

  let ref lang = repl.get_cur_language_state();
  writeln!(buf, "").unwrap();
  writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
  writeln!(buf, "-----------------------").unwrap();
  Some(buf)
}