package main

import (
	"time"
)

const dailySupplyCharge = 105.750 / 100

var (
	solarFeedInTariff = fixedTariff(8.471 / 100)
	tariff93          = &onOffPeakTariff{
		onPeak:  32.137 / 100,
		offPeak: 14.963 / 100,
		isPeak: (&weekdayHours{
			zone: time.FixedZone("UTC+10", +10*60*60),
			on: [24]bool{
				7:  true,
				8:  true,
				9:  true,
				16: true,
				17: true,
				18: true,
				19: true,
				20: true,
			},
		}).isPeak,
	}
)

type tariff interface {
	pricePerKWh(time.Time) float64
}

type fixedTariff float64

func (f fixedTariff) pricePerKWh(time.Time) float64 { return float64(f) }

type onOffPeakTariff struct {
	onPeak, offPeak float64
	isPeak          func(time.Time) bool
}

func (o *onOffPeakTariff) pricePerKWh(t time.Time) float64 {
	if o.isPeak(t) {
		return o.onPeak
	}
	return o.offPeak
}

type weekdayHours struct {
	zone *time.Location
	on   [24]bool
}

func (w *weekdayHours) isPeak(t time.Time) bool {
	t = t.In(w.zone)
	switch t.Weekday() {
	case time.Saturday, time.Sunday:
		return false
	default:
		return w.on[t.Hour()]
	}
}