use std::error::Error;
use std::fmt;
use std::ops::Deref;

use command_runner::CommandRunner;
use resources::Resource;
use symbols::{Action, OwnedSymbolAction, Symbol, SymbolAction, SymbolRunner};

pub struct Cron<'r, C, U, R: 'r + CommandRunner>
where
  C: Deref<Target = str>,
  U: Deref<Target = str>,
{
  user: U,
  content: C,
  command_runner: &'r R,
}

impl<'r, U, R: 'r + CommandRunner> Cron<'r, String, U, R>
where
  U: Deref<Target = str>,
{
  pub fn new<C: Deref<Target = str>>(user: U, content: C, command_runner: &'r R) -> Self {
    Cron {
      user,
      content: String::from(&*content) + "\n",
      command_runner,
    }
  }
}

impl<'r, C, U, R: 'r + CommandRunner> Symbol for Cron<'r, C, U, R>
where
  C: Deref<Target = str>,
  U: Deref<Target = str>,
{
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    let tab = try!(self
      .command_runner
      .get_output("crontab", &["-l", "-u", &self.user]));
    return Ok(tab == self.content.bytes().collect::<Vec<u8>>());
  }

  fn execute(&self) -> Result<(), Box<dyn Error>> {
    self.command_runner.run_with_args_and_stdin(
      "crontab",
      &["-u", &self.user, "-"],
      &self.content,
    )?;
    Ok(())
  }

  fn get_prerequisites(&self) -> Vec<Resource> {
    vec![]
  }

  fn as_action<'a>(&'a self, runner: &'a dyn SymbolRunner) -> Box<dyn Action + 'a> {
    Box::new(SymbolAction::new(runner, self))
  }

  fn into_action<'a>(self: Box<Self>, runner: &'a dyn SymbolRunner) -> Box<dyn Action + 'a>
  where
    Self: 'a,
  {
    Box::new(OwnedSymbolAction::new(runner, *self))
  }
}

impl<'r, C, U, R: 'r + CommandRunner> fmt::Display for Cron<'r, C, U, R>
where
  C: Deref<Target = str>,
  U: Deref<Target = str>,
{
  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
    write!(f, "Cron {}", &*self.user)
  }
}