feat(core): score by distance from target size (#63)

crates/arr-core/src/lib.rs

@@ -6,8 +6,10 @@ use std::{collections::BTreeMap, path::PathBuf, time::SystemTime};
 
 pub mod lang;
 pub mod policy;
+pub mod score;
 
 pub use arr_parse::NameClaims as ParsedRelease;
+pub use score::{Score, ScoreWeights};
 
 macro_rules! id_type {
     ($name:ident) => {
@@ -124,10 +126,19 @@ pub struct HdrRules {
     pub rejected_dolby_vision_profiles: Vec<DolbyVisionProfile>,
 }
 
+/// One resolution's size band (`DESIGN.md` §5.5). Below the floor is a hard
+/// filter; the target is where the score peaks; above it the penalty grows
+/// with every gibibyte.
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct SizeBand {
     pub floor_bytes: u64,
     pub target_bytes: u64,
+    /// Points lost per gibibyte above `target_bytes`, on the scale set by
+    /// [`ScoreWeights::size_at_target`] — 1000 points at target means one
+    /// point is a tenth of a percent, fine enough to tune by hand without a
+    /// fractional type. Applied per byte over, so a partial gibibyte costs
+    /// its fraction.
+    pub penalty_points_per_gib_over: i32,
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -140,6 +151,7 @@ pub struct Policy {
     pub size_bands: BTreeMap<Resolution, SizeBand>,
     pub resolution_preference: Vec<Resolution>,
     pub source_weights: BTreeMap<Source, i32>,
+    pub score_weights: ScoreWeights,
 }
 
 #[derive(Clone, Debug, Default, Eq, PartialEq)]