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use serde::{Deserialize, Serialize};
use std::collections::VecDeque;

static DEFAULT_SIZE: usize = 20;

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Frame<T> {
    size: usize,
    frame: VecDeque<T>,
}

impl<T> Default for Frame<T> {
    fn default() -> Self {
        Self::new(DEFAULT_SIZE)
    }
}

impl<T> Frame<T> {
    pub fn new(size: usize) -> Self {
        Self {
            size,
            frame: VecDeque::with_capacity(size),
        }
    }

    /// Returns a reference to the inserted element.
    pub fn insert(&mut self, item: T) -> &T {
        if self.frame.len() > self.size {
            self.frame.pop_front();
        }
        self.frame.push_back(item);
        self.frame.back().unwrap()
    }

    pub fn iter(&self) -> impl Iterator<Item = &T> {
        self.frame.iter()
    }
}