use crate::number::Number;
use std::cmp;
use std::iter::{Zip, Take};

pub struct Iter {
    index: usize,
    data: Vec<Number>,
    degree: usize
}

impl Iter {
    pub fn new(data: Vec<Number>, degree: usize) -> Iter {
        Iter { index: 0, data, degree }
    }

    pub fn zip(self, other: Self) -> Zip<Take<Iter>, Take<Iter>> {
        let deg = cmp::max(self.degree, other.degree) + 1;
        let a = self.take(deg);
        let b = other.take(deg);
        a.zip(b)
    }
}

impl Iterator for Iter {
    type Item = Number;

    fn next(&mut self) -> Option<Number> {
        self.index += 1;
        if self.index <= self.data.len() {
            Some(self.data[self.index - 1])
        } else {
            Some(0.0)
        }
    }
}