Add collectible fish quality tiers

fish/fish_quality.gd

@@ -0,0 +1,91 @@
+class_name FishQuality
+extends RefCounted
+
+enum Tier {
+	BORING,
+	AVERAGE,
+	IMPRESSIVE,
+	EXCEPTIONAL,
+	SHINY,
+}
+
+const TIER_COUNT: int = 5
+const ALL_TIERS_MASK: int = (1 << TIER_COUNT) - 1
+
+# Starting distribution. Equipment and tackle can supply per-tier
+# multipliers later without changing catch serialization or tier identity.
+const BASE_ROLL_WEIGHTS: Array[float] = [40.0, 32.0, 18.0, 8.0, 2.0]
+const SALE_MULTIPLIERS: Array[float] = [1.0, 1.1, 1.25, 1.5, 2.0]
+const DISPLAY_NAMES: PackedStringArray = [
+	"boring",
+	"average",
+	"impressive",
+	"exceptional",
+	"shiny",
+]
+
+
+static func is_valid(quality: int) -> bool:
+	return quality >= 0 and quality < TIER_COUNT
+
+
+static func display_name(quality: int) -> String:
+	return DISPLAY_NAMES[quality] if is_valid(quality) else "unknown"
+
+
+static func bit_for(quality: int) -> int:
+	return 1 << quality if is_valid(quality) else 0
+
+
+static func sale_multiplier(quality: int) -> float:
+	return SALE_MULTIPLIERS[quality] if is_valid(quality) else 1.0
+
+
+static func apply_sale_value(base_value: int, quality: int) -> int:
+	if base_value <= 0 or not is_valid(quality):
+		return maxi(base_value, 0)
+	if quality == Tier.BORING:
+		return base_value
+	return maxi(
+		base_value + quality,
+		ceili(float(base_value) * sale_multiplier(quality)),
+	)
+
+
+static func roll(
+	rng: RandomNumberGenerator,
+	weight_multipliers: Array[float] = [],
+) -> int:
+	if rng == null:
+		return Tier.BORING
+	var weights: Array[float] = []
+	var total_weight: float = 0.0
+	for quality: int in TIER_COUNT:
+		var multiplier: float = 1.0
+		if quality < weight_multipliers.size():
+			multiplier = maxf(weight_multipliers[quality], 0.0)
+		var weight: float = BASE_ROLL_WEIGHTS[quality] * multiplier
+		weights.append(weight)
+		total_weight += weight
+	if total_weight <= 0.0:
+		return Tier.BORING
+	var rolled_weight: float = rng.randf() * total_weight
+	var accumulated_weight: float = 0.0
+	for quality: int in TIER_COUNT:
+		accumulated_weight += weights[quality]
+		if rolled_weight <= accumulated_weight:
+			return quality
+	return Tier.SHINY
+
+
+static func qualified_name(fish_name: String, quality: int) -> String:
+	return "%s %s" % [display_name(quality), fish_name]
+
+
+static func qualified_name_with_article(
+	fish_name: String,
+	quality: int,
+) -> String:
+	var quality_name: String = display_name(quality)
+	var article: String = "an" if quality_name[0] in ["a", "e", "i", "o", "u"] else "a"
+	return "%s %s %s" % [article, quality_name, fish_name]