//! What is left to vote in a document — the line of « Décisions ».
//!
//! A module is an article (a unit). It stays **to vote** as long as no version
//! of it was adopted by a vote: its version in force is a seed a minima not yet
//! confirmed, or it has no version in force and at least one open version.
//! Variants of an article count once. For a person who votes, a module is
//! **without their vote** when they hold no valid vote (one not « to
//! reconfirm ») on any of its versions.

/// One article, as one person sees it.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct Module {
    /// The version in force, if any: `Some(true)` when a vote adopted or
    /// confirmed it, `Some(false)` for a seed a minima.
    pub in_force: Option<bool>,
    /// Open versions of the article (proposals to replace, add or remove it).
    pub open: u32,
    /// The person holds a valid vote on one of its versions, in force or open.
    pub voted: bool,
}

impl Module {
    pub fn to_vote(&self) -> bool {
        match self.in_force {
            Some(adopted) => !adopted,
            None => self.open > 0,
        }
    }
}

#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct Pending {
    /// Modules not yet adopted by a vote.
    pub to_vote: u32,
    /// Among them, those where the person has no valid vote.
    pub without_my_vote: u32,
}

pub fn pending(modules: &[Module]) -> Pending {
    modules.iter().filter(|m| m.to_vote()).fold(Pending::default(), |acc, m| Pending {
        to_vote: acc.to_vote + 1,
        without_my_vote: acc.without_my_vote + u32::from(!m.voted),
    })
}

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

    const SEED: Option<bool> = Some(false);
    const ADOPTED: Option<bool> = Some(true);

    fn m(in_force: Option<bool>, open: u32, voted: bool) -> Module {
        Module { in_force, open, voted }
    }

    #[test]
    fn a_seed_a_minima_stays_to_vote_until_a_vote_confirms_it() {
        assert!(m(SEED, 0, false).to_vote());
        assert!(m(SEED, 2, true).to_vote());
        assert!(!m(ADOPTED, 0, false).to_vote());
    }

    #[test]
    fn an_adopted_article_is_no_longer_to_vote_even_with_rivals() {
        assert!(!m(ADOPTED, 3, false).to_vote());
    }

    #[test]
    fn an_empty_slot_is_to_vote_only_with_an_open_version() {
        assert!(m(None, 1, false).to_vote());
        assert!(!m(None, 0, false).to_vote());
    }

    #[test]
    fn variants_count_once_and_my_vote_on_any_version_counts() {
        // Seed of the certification act: 3 seeds a minima, 30 open articles (two with a variant).
        let mut modules = vec![m(SEED, 0, false); 3];
        modules.extend(vec![m(None, 1, false); 28]);
        modules.extend(vec![m(None, 2, false); 2]);
        assert_eq!(pending(&modules), Pending { to_vote: 33, without_my_vote: 33 });
        modules[0].voted = true;
        modules[31].voted = true;
        assert_eq!(pending(&modules), Pending { to_vote: 33, without_my_vote: 31 });
        // Once adopted, an article leaves both counts, voted or not.
        modules[1].in_force = ADOPTED;
        modules[31].in_force = ADOPTED;
        assert_eq!(pending(&modules), Pending { to_vote: 31, without_my_vote: 30 });
    }

    #[test]
    fn nothing_to_vote_in_an_empty_document() {
        assert_eq!(pending(&[]), Pending::default());
    }
}