use std::marker::PhantomData;

#[derive(Clone)]
pub enum ColumnType {
    Float(Vec<f32>),
    Boolean(Vec<bool>),
}

#[derive(Clone)]
pub struct ColumnData {
    pub data: ColumnType,
    pub data_len: usize,
}

// TODO - Add in Ref for ColumnType
#[derive(Clone)]
pub struct ColumnView<'a, T> {
    pub data: &'a ColumnData,
    pub indices_len: usize,
    pub indices: Vec<usize>,
    pub index: usize,
    pub phantom: PhantomData<T>,
}

macro_rules! impl_view {
    ($e:ty, $f:path) => {
        impl<'a> Iterator for ColumnView<'a, $e> {
    type Item = $e;
    fn next(&mut self) -> Option<Self::Item> {
        if self.index >= self.indices_len {
            None
        } else {
            self.index += 1_usize;
            Some(unsafe {
                match &self.data.data {
                    $f(column) => column.get_unchecked(self.indices[self.index - 1]).clone(),
                    _ => unreachable!()
                }
            })
        }
    }
    }
    }
}

impl_view!(f32, ColumnType::Float);
impl_view!(bool, ColumnType::Boolean);

fn main() {
    let data: ColumnData = ColumnData {
        data: ColumnType::Float(vec![0.0, 1.0, 2.0, 3.0]),
        data_len: 4_usize,
    };
    let c = ColumnView::<f32> {
        data: &data,
        indices_len: 3,
        indices: vec![0_usize, 1, 2],
        index: 0,
        phantom: PhantomData::<f32>,
    };
    for x in c {
        dbg!(x);
    }
}