use std::error::Error;
use std::fmt;

use resources::Resource;
use symbols::{Action, Symbol, SymbolRunner};

pub struct List<'a> {
  symbols: Vec<Box<dyn Symbol + 'a>>,
}

impl<'a> List<'a> {
  pub fn new(symbols: Vec<Box<dyn Symbol + 'a>>) -> Self {
    List { symbols }
  }
}

impl<'a> Symbol for List<'a> {
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    for symbol in &self.symbols {
      if !symbol.target_reached()? {
        return Ok(false);
      }
    }
    Ok(true)
  }

  fn execute(&self) -> Result<(), Box<dyn Error>> {
    for symbol in &self.symbols {
      symbol.execute()?;
    }
    Ok(())
  }

  fn get_prerequisites(&self) -> Vec<Resource> {
    let mut r = vec![];
    for symbol in &self.symbols {
      for req in symbol.get_prerequisites() {
        if self.provides().map_or(true, |p| !p.contains(&req)) {
          r.push(req)
        }
      }
    }
    r
  }

  fn provides(&self) -> Option<Vec<Resource>> {
    let mut r = vec![];
    for symbol in &self.symbols {
      if let Some(provides) = symbol.provides() {
        r.extend(provides.into_iter());
      }
    }
    if r.is_empty() {
      None
    } else {
      Some(r)
    }
  }

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

  fn into_action<'b>(self: Box<Self>, runner: &'b dyn SymbolRunner) -> Box<dyn Action + 'b>
  where
    Self: 'b,
  {
    Box::new(ListAction::new(
      self
        .symbols
        .into_iter()
        .map(|s| s.into_action(runner))
        .collect(),
    ))
  }
}

macro_rules! from_tuple {
    ( $($name:ident)* ) => (
        #[allow(non_snake_case)]
        impl<'a, $($name: 'a + Symbol,)*> From<($($name,)*)> for List<'a> {
            fn from(($($name,)*): ($($name,)*)) -> Self {
                Self::new(vec![$(Box::new($name),)*])
            }
        }
    );
}

for_each_tuple!(from_tuple);

struct SymbolListAction<'a> {
  runner: &'a dyn SymbolRunner,
  symbols: &'a [Box<dyn Symbol + 'a>],
}

impl<'a> SymbolListAction<'a> {
  fn new(runner: &'a dyn SymbolRunner, symbols: &'a [Box<dyn Symbol + 'a>]) -> Self {
    Self { runner, symbols }
  }
}

impl<'a> Action for SymbolListAction<'a> {
  fn run(&self) -> Result<(), Box<dyn Error>> {
    for symbol in self.symbols {
      symbol.as_action(self.runner).run()?;
    }
    Ok(())
  }
}

pub struct ListAction<'a> {
  actions: Vec<Box<dyn Action + 'a>>,
}

impl<'a> ListAction<'a> {
  pub fn new(actions: Vec<Box<dyn Action + 'a>>) -> Self {
    Self { actions }
  }
}

impl<'a> Action for ListAction<'a> {
  fn run(&self) -> Result<(), Box<dyn Error>> {
    for action in &self.actions {
      action.run()?;
    }
    Ok(())
  }
}

impl<'a> fmt::Display for List<'a> {
  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
    write!(f, "List [ ")?;
    for symbol in &self.symbols {
      write!(f, "{} ", symbol)?;
    }
    write!(f, "]")
  }
}

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

  use symbols::{Action, OwnedSymbolAction, Symbol, SymbolAction, SymbolRunner};
  use symbols::hook::List;

  struct ErrSymbol(String);
  impl Symbol for ErrSymbol {
    fn target_reached(&self) -> Result<bool, Box<Error>> { Err(self.0.clone().into()) }
    fn execute(&self) -> Result<(), Box<Error>> { Err(self.0.clone().into()) }
  }
  impl fmt::Display for ErrSymbol { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error>{ write!(f, "") } }

  struct OkSymbol(bool);
  impl Symbol for OkSymbol {
    fn target_reached(&self) -> Result<bool, Box<Error>> { Ok(self.0) }
    fn execute(&self) -> Result<(), Box<Error>> { Ok(()) }
  }
  impl fmt::Display for OkSymbol { fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error>{ write!(f, "") } }

  #[test]
  fn first_target_reached_fails() {
    let res = List::new(ErrSymbol("first".into()), ErrSymbol("second".into())).target_reached();
    assert_eq!(res.unwrap_err().description(), "first");
  }

  #[test]
  fn first_target_not_reached() {
    let res = List::new(OkSymbol(false), ErrSymbol("second".into())).target_reached();
    assert_eq!(res.unwrap(), false);
  }

  #[test]
  fn second_target_reached_fails() {
    let res = List::new(OkSymbol(true), ErrSymbol("second".into())).target_reached();
    assert_eq!(res.unwrap_err().description(), "second");
  }

  #[test]
  fn second_target_not_reached() {
    let res = List::new(OkSymbol(true), OkSymbol(false)).target_reached();
    assert_eq!(res.unwrap(), false);
  }

  #[test]
  fn everything_reached() {
    let res = List::new(OkSymbol(true), OkSymbol(true)).target_reached();
    assert_eq!(res.unwrap(), true);
  }

  #[test]
  fn first_execute_fails() {
    let res = List::new(ErrSymbol("first".into()), ErrSymbol("second".into())).execute();
    assert_eq!(res.unwrap_err().description(), "first");
  }

  #[test]
  fn second_execute_fails() {
    let res = List::new(OkSymbol(true), ErrSymbol("second".into())).execute();
    assert_eq!(res.unwrap_err().description(), "second");
  }

  #[test]
  fn everything_executes() {
    let res = List::new(OkSymbol(true), OkSymbol(true)).execute();
    assert_eq!(res.unwrap(), ());
  }
}
*/