use std::borrow::{Borrow, Cow};
use std::error::Error;
use std::fmt;
use std::fs;
use std::os::unix::fs::MetadataExt;
use std::path::Path;

use users::get_user_by_name;

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

pub struct Owner<'a, C: 'a + CommandRunner, D>
where
  D: AsRef<str>,
{
  path: D,
  user_name: Cow<'a, str>,
  command_runner: &'a C,
}

impl<'a, C: CommandRunner, D> Owner<'a, C, D>
where
  D: AsRef<str>,
{
  pub fn new(path: D, user_name: Cow<'a, str>, command_runner: &'a C) -> Self {
    Owner {
      path,
      user_name,
      command_runner,
    }
  }
}

impl<'a, C: CommandRunner, D> Symbol for Owner<'a, C, D>
where
  D: AsRef<str>,
{
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    if !Path::new(self.path.as_ref()).exists() {
      return Ok(false);
    }
    let actual_uid = fs::metadata(self.path.as_ref()).unwrap().uid();
    let target_uid = get_user_by_name(self.user_name.borrow()).unwrap().uid();
    Ok(actual_uid == target_uid)
  }

  fn execute(&self) -> Result<(), Box<dyn Error>> {
    self.command_runner.run_successfully(
      "chown",
      &["-R", self.user_name.borrow(), self.path.as_ref()],
    )
  }

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

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

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

impl<'a, C: CommandRunner, D> fmt::Display for Owner<'a, C, D>
where
  D: AsRef<str>,
{
  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
    write!(f, "Owner {} for {}", self.user_name, self.path.as_ref())
  }
}