/// lowercase `a` to `z` have priorities 1 to 26, uppercase `A` through `Z` have priority 27 through 52.
fn priority(item: char) -> u32 {
    let value: u32;
    if item.is_lowercase() {
        value = item as u32 - 96;
    } else {
        value = item as u32 - 64 + 26;
    }
    value
}

pub fn sum_priorities_items_both_compartiments(sacks: &str) -> u32 {
    let mut sum: u32 = 0;
    for sack in sacks.lines() {
        let middle_index: usize = sack.len() / 2;
        let first_compartiment: &str = &sack[..middle_index];
        let second_compartiment: &str = &sack[middle_index..];
        for item in first_compartiment.chars() {
            if second_compartiment.contains(item) {
                sum += priority(item);
                break;
            }
        }
    }
    sum
}

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

    #[test]
    fn test_priority() {
        assert_eq!(priority('a'), 1);
        assert_eq!(priority('z'), 26);
        assert_eq!(priority('A'), 27);
        assert_eq!(priority('Z'), 52);
    }

    #[test]
    fn test_sum_priorities_items_both_compartiments() {
        assert_eq!(sum_priorities_items_both_compartiments("aAa"), 1);
        assert_eq!(sum_priorities_items_both_compartiments("AbilABC"), 27);
    }
}