use super::*;
use std::{
    hash::Hash,
    collections::{HashSet, HashMap},
    mem,
};

pub trait DedupFullExt
{
     fn dedup_full(&mut self);
}

impl<T> DedupFullExt for Vec<T>
where T: Hash + Default + Eq
{
     fn dedup_full(&mut self)
    {
	let mut set: HashMap<T, usize> = HashMap::new();
	for (i,x) in (0..).zip(self.iter_mut())
	{
	    if !set.contains_key(x) {
		let us = mem::replace(x, Default::default());
		set.insert(us, i);
	    }
	}
	// To preserve order:
	let mut tmp = Vec::with_capacity(self.len());
	for item in set.into_iter()
	{
	    tmp.push(item);
	}
	tmp.sort_by(move |a, b| a.1.partial_cmp(&b.1).unwrap());
	self.truncate(tmp.len());
	for (d,s) in self.iter_mut().zip(tmp.into_iter())
	{
	    *d = s.0;
	}
    }
}

#[cfg(test)]
mod test
{
    use super::*;

    #[test]
    fn dedup_full()
    {
	let mut vec = vec![
	    "hello",
	    "how",
	    "are",
	    "you",
	    "hello",
	    "hello",
	    "today",
	    "today",
	    "you",
	    "how",
	    "hello",
	];

	vec.dedup_full();
	
	assert_eq!(vec.len(), 5);
	assert_eq!(&vec[..], &["hello","how", "are", "you", "today"]);
    }
}