feat: doc direct purchase cost

internal/common/service/common.depreciation.service.go

@@ -0,0 +1,88 @@
+package service
+
+import (
+	"strings"
+	"time"
+)
+
+const (
+	depreciationStartAgeDayCloseHouse = 155
+	depreciationStartAgeDayOpenHouse  = 176
+)
+
+func NormalizeDepreciationHouseType(raw string) string {
+	return strings.TrimSpace(strings.ToLower(raw))
+}
+
+func DepreciationStartAgeDay(houseType string) int {
+	switch NormalizeDepreciationHouseType(houseType) {
+	case "close_house":
+		return depreciationStartAgeDayCloseHouse
+	case "open_house":
+		return depreciationStartAgeDayOpenHouse
+	default:
+		return 0
+	}
+}
+
+func FlockAgeDay(originDate time.Time, periodDate time.Time) int {
+	origin := time.Date(originDate.Year(), originDate.Month(), originDate.Day(), 0, 0, 0, 0, originDate.Location())
+	period := time.Date(periodDate.Year(), periodDate.Month(), periodDate.Day(), 0, 0, 0, 0, periodDate.Location())
+	if period.Before(origin) {
+		return 0
+	}
+	return int(period.Sub(origin).Hours()/24) + 1
+}
+
+func DepreciationScheduleDay(originDate time.Time, periodDate time.Time, houseType string) int {
+	ageDay := FlockAgeDay(originDate, periodDate)
+	startAgeDay := DepreciationStartAgeDay(houseType)
+	if ageDay <= 0 || startAgeDay <= 0 || ageDay < startAgeDay {
+		return 0
+	}
+	return ageDay - startAgeDay + 1
+}
+
+func CalculateDepreciationAtDayN(
+	initialPulletCost float64,
+	dayN int,
+	houseType string,
+	percentByHouseType map[string]map[int]float64,
+) (float64, float64, float64) {
+	if initialPulletCost <= 0 || dayN <= 0 {
+		return 0, 0, 0
+	}
+
+	normalizedHouseType := NormalizeDepreciationHouseType(houseType)
+	housePercent, exists := percentByHouseType[normalizedHouseType]
+	if !exists {
+		return 0, 0, 0
+	}
+
+	current := initialPulletCost
+	pulletCostDayN := 0.0
+	depreciationValue := 0.0
+	depreciationPercent := 0.0
+	for day := 1; day <= dayN; day++ {
+		pct := housePercent[day]
+		dep := current * (pct / 100)
+		if day == dayN {
+			pulletCostDayN = current
+			depreciationValue = dep
+			depreciationPercent = pct
+		}
+		current -= dep
+		if current < 0 {
+			current = 0
+		}
+	}
+
+	return pulletCostDayN, depreciationValue, depreciationPercent
+}
+
+func CalculateEffectiveDepreciationPercent(totalDepreciationValue, totalPulletCostDayN float64) float64 {
+	if totalPulletCostDayN <= 0 {
+		return 0
+	}
+	return (totalDepreciationValue / totalPulletCostDayN) * 100
+}