use std::cell::RefCell;
use std::collections::{HashMap, HashSet};

use symbols::Symbol;
use resources::Resource;

pub trait SymbolRepository<'a> {
  fn get_symbol(&self, resource: &Resource) -> Option<Box<Symbol + 'a>>;
}

impl<'a, C> SymbolRepository<'a> for C where C: Fn(&Resource) -> Option<Box<Symbol + 'a>> {
  fn get_symbol(&self, resource: &Resource) -> Option<Box<Symbol + 'a>> {
    self(resource)
  }
}

pub struct DispatchingSymbolRepository<'a> {
  repositories: HashMap<&'static str, Box<SymbolRepository<'a>>>
}

impl<'a> DispatchingSymbolRepository<'a> {
  pub fn new(repositories: HashMap<&'static str, Box<SymbolRepository<'a>>>) -> DispatchingSymbolRepository<'a> {
    DispatchingSymbolRepository { repositories: repositories }
  }
}

impl<'a> SymbolRepository<'a> for DispatchingSymbolRepository<'a> {
  fn get_symbol(&self, resource: &Resource) -> Option<Box<Symbol + 'a>> {
    self.repositories.get(resource.get_type()).and_then(|repo| repo.get_symbol(resource))
  }
}

use std::marker::PhantomData;

pub struct NonRepeatingSymbolRepository<'a, R> where R: SymbolRepository<'a> {
  upstream: R,
  done: RefCell<HashSet<Resource>>,
  d: PhantomData<Box<Symbol + 'a>>
}

impl<'a, R> NonRepeatingSymbolRepository<'a, R> where R: SymbolRepository<'a> {
  pub fn new(repository: R) -> Self {
    NonRepeatingSymbolRepository { upstream: repository, done: RefCell::new(HashSet::new()), d: PhantomData }
  }
}

impl<'a, R> SymbolRepository<'a> for NonRepeatingSymbolRepository<'a, R> where R: SymbolRepository<'a> {
  fn get_symbol(&self, resource: &Resource) -> Option<Box<Symbol + 'a>> {
    let mut done = self.done.borrow_mut();
    if done.contains(&resource) {
      None
    } else {
      done.insert(resource.clone());
      self.upstream.get_symbol(resource)
    }
  }
}