use std::env::VarError;
use std::ffi::{OsStr, OsString};
use std::path::PathBuf;
use std::{env, io};

pub trait Environment {
  fn args_os(&self) -> Vec<OsString>;
  fn var<K>(&self, key: K) -> Result<String, VarError>
  where
    K: AsRef<OsStr>;
  fn set_var<K, V>(&mut self, key: K, value: V)
  where
    K: AsRef<OsStr>,
    V: AsRef<OsStr>;
  fn get_home_directory(&self) -> Option<PathBuf>;
  fn read_line(&mut self) -> Result<String, io::Error>;
}

#[derive(Debug, Default)]
pub struct Prod;

impl Environment for Prod {
  fn args_os(&self) -> Vec<OsString> {
    env::args_os().collect()
  }

  fn var<K>(&self, key: K) -> Result<String, VarError>
  where
    K: AsRef<OsStr>,
  {
    env::var(key)
  }

  fn set_var<K, V>(&mut self, key: K, value: V)
    where
      K: AsRef<OsStr>,
      V: AsRef<OsStr>
  {
    env::set_var(key, value);
  }

  fn get_home_directory(&self) -> Option<PathBuf> {
    homedir::my_home().ok().flatten()
  }

  fn read_line(&mut self) -> Result<String, io::Error> {
    let mut buffer = String::new();
    io::stdin().read_line(&mut buffer)?;
    Ok(buffer.trim().to_string())
  }
}