use std::borrow::Cow;
use std::error::Error;
use std::fmt;

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

#[derive(Debug)]
pub enum UserAdderError {
  AlreadyExists,
  UnknownError,
  ImplError(Box<Error>)
}

impl Error for UserAdderError {
  fn description(&self) -> &str {
    match self {
      UserAdderError::AlreadyExists => "User already exists",
      UserAdderError::UnknownError => "Unknown error",
      UserAdderError::ImplError(_) => "User adding error"
    }
  }
  fn cause(&self) -> Option<&Error> {
    match self {
      UserAdderError::ImplError(ref e) => Some(e.as_ref()),
      _ => None
    }
  }
}

impl fmt::Display for UserAdderError {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    match self.cause() {
      Some(e) => write!(f, "{} (cause: {})", self.description(), e),
      None => write!(f, "{}", self.description())
    }
  }
}

pub trait UserAdder {
  fn add_user(&self, user_name: &str) -> Result<(), UserAdderError>;
}

#[derive(Debug, PartialEq)]
pub enum UserError {
  GenericError
}

impl Error for UserError {
  fn description(&self) -> &str {
    match self {
      UserError::GenericError => "Could not find out if user exists"
    }
  }
  fn cause(&self) -> Option<&Error> {
    match self {
      _ => None
    }
  }
}

impl fmt::Display for UserError {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    match self.cause() {
      Some(e) => write!(f, "{} (cause: {})", self.description(), e),
      None => write!(f, "{}", self.description())
    }
  }
}

pub struct User<'a, C: 'a + CommandRunner, A: 'a + UserAdder> {
  user_name: Cow<'a, str>,
  command_runner: &'a C,
  user_adder: &'a A
}

impl<'a, C: CommandRunner, A: 'a + UserAdder> User<'a, C, A> {
  pub fn new(user_name: Cow<'a, str>, command_runner: &'a C, user_adder: &'a A) -> Self {
    User { user_name, command_runner, user_adder }
  }
}

impl<'a, C: CommandRunner, A: 'a + UserAdder> fmt::Display for User<'a, C, A> {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    write!(f, "User {}", self.user_name)
  }
}

impl<'a, C: CommandRunner, A: 'a + UserAdder> Symbol for User<'a, C, A> {
  fn target_reached(&self) -> Result<bool, Box<Error>> {
    let output = try!(self.command_runner.run_with_args("getent", &["passwd", &*self.user_name]));
    match output.status.code() {
      Some(2) => Ok(false),
      Some(0) => Ok(true),
      _ => Err(Box::new(UserError::GenericError))
    }
  }

  fn execute(&self) -> Result<(), Box<Error>> {
    self.user_adder.add_user(&*self.user_name).map_err(|e| Box::new(e) as Box<Error>)
  }

  fn provides(&self) -> Option<Vec<Resource>> {
    Some(vec![Resource::new("user", self.user_name.to_string())])
  }

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

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

pub struct SystemUserAdder<'a, C: 'a + CommandRunner> {
  command_runner: &'a C
}

impl<'a, C: CommandRunner> SystemUserAdder<'a, C> {
  pub fn new(command_runner: &'a C) -> Self {
    SystemUserAdder { command_runner }
  }
}

impl<'a, C: CommandRunner> UserAdder for SystemUserAdder<'a, C> {
  fn add_user(&self, user_name: &str) -> Result<(), UserAdderError> {
    let output = self.command_runner.run_with_args(
      "adduser",
      &[
        // "-m", // Necessary for Fedora, not accepted in Debian
        "--system",
        user_name
      ]);
    match output {
      Ok(output) => match output.status.code() {
        Some(0) => Ok(()),
        Some(1) =>
{
      println!("{:?}", output);
Err(UserAdderError::AlreadyExists)},
        Some(_) =>
{
      println!("{:?}", output);
Err(UserAdderError::UnknownError)
},
        None => {
      println!("{:?}", output);
Err(UserAdderError::UnknownError)
},
      },
      Err(e) => Err(UserAdderError::ImplError(Box::new(e)))
    }
  }
}

#[cfg(test)]
mod test {
  use std::error::Error;
  use std::fmt;

  use command_runner::StdCommandRunner;
  use symbols::Symbol;
  use symbols::user::User;
  use symbols::user::UserAdder;
  use symbols::user::UserAdderError;

  #[derive(Debug, PartialEq)]
  struct DummyError;
  impl Error for DummyError {
    fn description(&self) -> &str {
      "DummyError"
    }
  }

  impl fmt::Display for DummyError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
      write!(f, "DummyError")
    }
  }

  struct DummyUserAdder;

  impl UserAdder for DummyUserAdder {
    fn add_user(&self, user_name: &str) -> Result<(), UserAdderError> {
      Ok(())
    }
  }

  #[test]
  fn test_target_reached_nonexisting() {
    let symbol = User { user_name: "nonexisting".into(), command_runner: &StdCommandRunner, user_adder: &DummyUserAdder };
    assert_eq!(symbol.target_reached().unwrap(), false);
  }

  #[test]
  fn test_target_reached_root() {
    let symbol = User { user_name: "root".into(), command_runner: &StdCommandRunner, user_adder: &DummyUserAdder };
    assert_eq!(symbol.target_reached().unwrap(), true);
  }
}