// Package fees ports fee calculation from legacy/scripts/attendance.py.
package fees

const (
	AdultFeeDefault = 600 // CZK fallback for 2+ practices when month not in AdultFeeMonthlyRate
	AdultFeeSingle  = 200 // CZK for exactly 1 practice
)

// AdultFeeMonthlyRate mirrors ADULT_FEE_MONTHLY_RATE in legacy/scripts/attendance.py.
// Months absent from this map fall back to AdultFeeDefault.
var AdultFeeMonthlyRate = map[string]int{
	"2025-09": 750, "2025-10": 750, "2025-11": 750, "2025-12": 750,
	"2026-01": 750, "2026-02": 750, "2026-03": 350,
	"2026-04": 700, "2026-05": 450, "2026-06": 600, "2026-07": 0, "2026-08": 0,
	"2026-09": 600, "2026-10": 600, "2026-11": 600, "2026-12": 600,
}

// CalculateFee returns the adult fee in CZK for attendanceCount practices in
// the given monthKey (format "YYYY-MM").
//
//	0 practices → 0
//	1 practice  → AdultFeeSingle (200), capped at the month's rate so a
//	              0-rate month is free for everyone
//	2+          → AdultFeeMonthlyRate[monthKey] or AdultFeeDefault
func CalculateFee(attendanceCount int, monthKey string) int {
	if attendanceCount == 0 {
		return 0
	}
	rate, ok := AdultFeeMonthlyRate[monthKey]
	if !ok {
		rate = AdultFeeDefault
	}
	if attendanceCount == 1 {
		return min(AdultFeeSingle, rate)
	}
	return rate
}