package business

import (
	"math/big"
	"time"
)

func GoalMetric(goal *PerformanceGoal, key string) *int64 {
	if goal == nil {
		return nil
	}
	switch key {
	case "open":
		return goal.Open
	case "effective":
		return goal.Effective
	case "pay":
		return goal.Amount
	}
	return nil
}
func GoalPeriodTarget(goal *PerformanceGoal, key, period, grain string) *string {
	if len(period) < 7 {
		return nil
	}
	value := GoalMetric(goal, key)
	if value == nil {
		return nil
	}
	target := big.NewRat(*value, 1)
	if grain == "day" {
		month, err := time.Parse("2006-01", period[:7])
		if err != nil {
			return nil
		}
		target.Quo(target, big.NewRat(int64(month.AddDate(0, 1, -1).Day()), 1))
	}
	return stringPointer(portraitDecimal(target, 2))
}
func GoalCompletion(periods map[string]PerformanceMetrics, goals map[string]*PerformanceGoal, key string) *string {
	actual, target := new(big.Rat), new(big.Rat)
	months := map[string]bool{}
	for period, value := range periods {
		if len(period) < 7 {
			continue
		}
		month := period[:7]
		goal := GoalMetric(goals[month], key)
		if goal == nil {
			continue
		}
		if !months[month] {
			target.Add(target, big.NewRat(*goal, 1))
			months[month] = true
		}
		switch key {
		case "open":
			actual.Add(actual, big.NewRat(value.Open, 1))
		case "effective":
			actual.Add(actual, big.NewRat(value.Effective, 1))
		case "pay":
			amount, err := portraitNumber(value.Pay)
			if err == nil {
				actual.Add(actual, amount)
			}
		}
	}
	if target.Sign() <= 0 {
		return nil
	}
	return stringPointer(portraitDecimal(actual.Quo(actual, target).Mul(actual, big.NewRat(100, 1)), 1))
}
func PerformanceChange(current, previous PerformanceMetrics, key string) *string {
	var a, b *big.Rat
	switch key {
	case "open":
		a, b = big.NewRat(current.Open, 1), big.NewRat(previous.Open, 1)
	case "effective":
		a, b = big.NewRat(current.Effective, 1), big.NewRat(previous.Effective, 1)
	case "pay":
		a, _ = portraitNumber(current.Pay)
		b, _ = portraitNumber(previous.Pay)
	}
	if a == nil || b == nil || b.Sign() == 0 {
		return nil
	}
	return stringPointer(portraitDecimal(a.Sub(a, b).Quo(a, b).Mul(a, big.NewRat(100, 1)), 1))
}
func PerformanceRate(value PerformanceMetrics) *string { return performanceRate(value) }