solverforge-core 0.8.1

// HardSoftScore - Two-level score with hard and soft constraints

use std::cmp::Ordering;
use std::fmt;

use super::traits::Score;
use super::ScoreLevel;

/* A score with separate hard and soft constraint levels.

Hard constraints must be satisfied for a solution to be feasible.
Soft constraints are optimization objectives.

When comparing scores:
1. Hard scores are compared first
2. Soft scores are only compared when hard scores are equal

# Examples

```
use solverforge_core::HardSoftScore;

let score1 = HardSoftScore::of(-1, -100);  // 1 hard constraint broken
let score2 = HardSoftScore::of(0, -200);   // Feasible but poor soft score

// Feasible solutions are always better than infeasible ones
assert!(score2 > score1);

let score3 = HardSoftScore::of(0, -50);    // Better soft score
assert!(score3 > score2);
```
*/
#[derive(Clone, Copy, PartialEq, Eq, Hash, Default)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct HardSoftScore {
    hard: i64,
    soft: i64,
}

impl HardSoftScore {
    /// The zero score.
    pub const ZERO: HardSoftScore = HardSoftScore { hard: 0, soft: 0 };

    /// One hard constraint penalty.
    pub const ONE_HARD: HardSoftScore = HardSoftScore { hard: 1, soft: 0 };

    /// One soft constraint penalty.
    pub const ONE_SOFT: HardSoftScore = HardSoftScore { hard: 0, soft: 1 };

    #[inline]
    pub const fn of(hard: i64, soft: i64) -> Self {
        HardSoftScore { hard, soft }
    }

    #[inline]
    pub const fn of_hard(hard: i64) -> Self {
        HardSoftScore { hard, soft: 0 }
    }

    #[inline]
    pub const fn of_soft(soft: i64) -> Self {
        HardSoftScore { hard: 0, soft }
    }

    #[inline]
    pub const fn hard(&self) -> i64 {
        self.hard
    }

    #[inline]
    pub const fn soft(&self) -> i64 {
        self.soft
    }

    pub const fn hard_score(&self) -> HardSoftScore {
        HardSoftScore::of_hard(self.hard)
    }

    pub const fn soft_score(&self) -> HardSoftScore {
        HardSoftScore::of_soft(self.soft)
    }
}

impl Score for HardSoftScore {
    #[inline]
    fn is_feasible(&self) -> bool {
        self.hard >= 0
    }

    #[inline]
    fn zero() -> Self {
        HardSoftScore::ZERO
    }

    #[inline]
    fn levels_count() -> usize {
        2
    }

    fn to_level_numbers(&self) -> Vec<i64> {
        vec![self.hard, self.soft]
    }

    fn from_level_numbers(levels: &[i64]) -> Self {
        assert_eq!(levels.len(), 2, "HardSoftScore requires exactly 2 levels");
        HardSoftScore::of(levels[0], levels[1])
    }

    impl_score_scale!(HardSoftScore { hard, soft } => of);

    fn level_label(index: usize) -> ScoreLevel {
        match index {
            0 => ScoreLevel::Hard,
            1 => ScoreLevel::Soft,
            _ => panic!("HardSoftScore has 2 levels, got index {}", index),
        }
    }

    #[inline]
    fn to_scalar(&self) -> f64 {
        self.hard as f64 * 1_000_000.0 + self.soft as f64
    }
}

impl Ord for HardSoftScore {
    fn cmp(&self, other: &Self) -> Ordering {
        match self.hard.cmp(&other.hard) {
            Ordering::Equal => self.soft.cmp(&other.soft),
            other => other,
        }
    }
}

impl_score_ops!(HardSoftScore { hard, soft } => of);

impl fmt::Debug for HardSoftScore {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "HardSoftScore({}, {})", self.hard, self.soft)
    }
}

impl fmt::Display for HardSoftScore {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}hard/{}soft", self.hard, self.soft)
    }
}

impl_score_parse!(HardSoftScore { hard => "hard", soft => "soft" } => of);