#![forbid(unsafe_code)]
use crate::error::*;

use std::collections::HashMap;
use std::ops::Deref;


pub struct Command<M: Mode + ?Sized> {
  name: String,
  pub implementation: fn(mode: Box<M>, params: &[&str])
    -> Result<Option<Box<dyn Mode>>>,
}


pub struct CommandMap<M: Mode + ?Sized>(HashMap<String, Command<M>>);

impl<M: Mode> CommandMap<M> {
  pub fn new() -> CommandMap<M> {
    CommandMap(HashMap::new())
  }

  pub fn get(self: &Self, name: &str) -> Option<&Command<M>> {
    self.0.get(name)
  }

  pub fn insert(self: &mut Self, command: Command<M>)
    -> Result<()>
  {
    let name = command.name.to_string();

    let _ = self.0.insert(name, command);

    Ok(())
  }
}


pub trait Mode {
  fn prompt_text(&self) -> Result<&str>;
  fn dispatch(self: Box<Self>, params: &[&str])
    -> Result<Option<Box<dyn Mode>>>;
}

impl<M: Mode> Command<M> {
  pub fn new(name: impl Deref<Target=str>,
             implementation: fn(mode: Box<M>, params: &[&str])
                               -> Result<Option<Box<dyn Mode>>>)
    -> Self
  {
    Command {
      name: name.to_string(),
      implementation: implementation,
    }
  }
}