use radix_trie::{Trie, TrieCommon, TrieKey};
use super::FullyQualifiedSymbolName;
use std::hash::{Hasher, Hash};
use std::collections::hash_map::DefaultHasher;

#[derive(Debug)]
pub struct SymbolTrie(Trie<FullyQualifiedSymbolName, ()>);

impl TrieKey for FullyQualifiedSymbolName {
  fn encode_bytes(&self) -> Vec<u8> {
    let mut hasher = DefaultHasher::new();
    let mut output = vec![];
    let FullyQualifiedSymbolName(scopes) = self;
    for segment in scopes.iter() {
      segment.name.as_bytes().hash(&mut hasher);
      output.extend_from_slice(&hasher.finish().to_be_bytes());
    }
    output
  }
}

impl SymbolTrie {
  pub fn new() -> SymbolTrie {
    SymbolTrie(Trie::new())
  }

  pub fn insert(&mut self, fqsn: &FullyQualifiedSymbolName) {
    self.0.insert(fqsn.clone(), ());
  }

  pub fn get_children(&self, fqsn: &FullyQualifiedSymbolName) -> Vec<FullyQualifiedSymbolName> {
    let subtrie = match self.0.subtrie(fqsn) {
      Some(s) => s,
      None => return vec![]
    };
    let output: Vec<FullyQualifiedSymbolName> = subtrie.keys().filter(|cur_key| **cur_key != *fqsn).map(|fqsn| fqsn.clone()).collect();
    output
  }
}

#[test]
fn test_trie_insertion() {
  let mut trie = SymbolTrie::new();

  trie.insert(&fqsn!("unrelated"; ty, "thing"; tr));
  trie.insert(&fqsn!("outer"; ty, "inner"; tr));
  trie.insert(&fqsn!("outer"; ty, "inner"; ty, "still_inner"; tr));

  let children = trie.get_children(&fqsn!("outer"; ty, "inner"; tr));
  assert_eq!(children.len(), 1);
}