use std::cell::RefCell;

// Wrapper holding (amoung other things) a vec of entries
// as well as some values that are constant for all entries
struct Wrapper {
    entries: Vec<Entry>,
    some_values_constant_for_all_entries: Vec<usize>
}

impl Wrapper {
    pub fn new() -> Self {
        let mut entries = Vec::with_capacity(3);
        for val in 0..3 {
            entries.push(Entry { val });
        }
        Wrapper {
            entries,
            some_values_constant_for_all_entries: vec![1,2,4]
        }
    }

    pub fn entries_mut(&mut self) -> &mut Vec<Entry> {
        &mut self.entries
    }

    pub fn constant_values(&self) -> &Vec<usize> {
        &self.some_values_constant_for_all_entries
    }
}

// Entry holding a value (and various other things)
struct Entry {
    val: usize
}

impl Entry {
    pub fn update_val(&mut self, update_value: usize, constant_values: &Vec<usize>) {
        //update value based off the update_value and constant_values
    }

    pub fn val(&self) -> usize {
        self.val
    }
}

// implementations of the trait define how the values get updated
trait MyTrait {
    fn calculate_update_value(&self, wrapper: &RefCell<Wrapper>);
}

struct SomeImpl {
    some_val: usize
}

impl MyTrait for SomeImpl {
    fn calculate_update_value(&self, wrapper: &RefCell<Wrapper>) {
        for entry in wrapper.borrow_mut().entries_mut().iter_mut() {
            let val = entry.val % self.some_val;
            entry.update_val(val, wrapper.borrow().constant_values());
        }
    }
}

struct Algorithm<T> where T: MyTrait {
    wrapper: RefCell<Wrapper>,
    implementation: T
}

impl<T> Algorithm<T> where T: MyTrait {
    fn update(&mut self) {
        self.implementation.calculate_update_value(&self.wrapper);
    }
}



fn main() {
    let wrapper = Wrapper::new();
    let implementation = SomeImpl { some_val: 5 };
    let mut algorithm = Algorithm {wrapper: RefCell::new(wrapper), implementation};
    algorithm.update();
}