package timex

import (
	"fmt"
	"time"
)

type Interval struct {
	intervalDuration time.Duration
	periodType       PeriodType
}

type PeriodType string

const (
	PeriodHourly  PeriodType = "hourly"
	PeriodDaily   PeriodType = "daily"
	PeriodMonthly PeriodType = "monthly"
	PeriodYearly  PeriodType = "yearly"
)

func NewInterval(intervalDuration time.Duration, periodType PeriodType) *Interval {
	return &Interval{
		intervalDuration: intervalDuration,
		periodType:       periodType,
	}
}

func (i *Interval) GetCurrent() int {
	return i.GetIntervalForTime(time.Now().UTC())
}

func (i *Interval) GetIntervalForTime(t time.Time) int {
	t = t.UTC()
	periodStart := i.getPeriodStart(t)
	elapsed := t.Sub(periodStart)

	intervalIndex := int(elapsed / i.intervalDuration)

	// S'assurer que l'index n'est pas négatif
	if intervalIndex < 0 {
		intervalIndex = 0
	}

	return intervalIndex
}

func (i *Interval) getPeriodStart(t time.Time) time.Time {
	t = t.UTC()
	switch i.periodType {
	case PeriodHourly:
		return time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), 0, 0, 0, time.UTC)
	case PeriodDaily:
		return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, time.UTC)
	case PeriodMonthly:
		return time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, time.UTC)
	case PeriodYearly:
		return time.Date(t.Year(), 1, 1, 0, 0, 0, 0, time.UTC)
	default:
		return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, time.UTC)
	}
}

func (i *Interval) GetTotalIntervalsInPeriod(referenceTime time.Time) int {
	referenceTime = referenceTime.UTC()
	periodStart := i.getPeriodStart(referenceTime)
	periodEnd := i.getPeriodEnd(referenceTime)

	totalDuration := periodEnd.Sub(periodStart)
	return int(totalDuration / i.intervalDuration)
}

func (i *Interval) getPeriodEnd(t time.Time) time.Time {
	t = t.UTC()
	switch i.periodType {
	case PeriodHourly:
		return time.Date(t.Year(), t.Month(), t.Day(), t.Hour()+1, 0, 0, 0, time.UTC)
	case PeriodDaily:
		return time.Date(t.Year(), t.Month(), t.Day()+1, 0, 0, 0, 0, time.UTC)
	case PeriodMonthly:
		return time.Date(t.Year(), t.Month()+1, 1, 0, 0, 0, 0, time.UTC)
	case PeriodYearly:
		return time.Date(t.Year()+1, 1, 1, 0, 0, 0, 0, time.UTC)
	default:
		return time.Date(t.Year(), t.Month(), t.Day()+1, 0, 0, 0, 0, time.UTC)
	}
}

func (i *Interval) GetIntervalBounds(index int, referenceTime time.Time) (time.Time, time.Time) {
	referenceTime = referenceTime.UTC()
	periodStart := i.getPeriodStart(referenceTime)

	intervalStart := periodStart.Add(time.Duration(index) * i.intervalDuration)
	intervalEnd := intervalStart.Add(i.intervalDuration)

	return intervalStart.UTC(), intervalEnd.UTC()
}

func (i *Interval) GetIntervalInfo(t time.Time) IntervalInfo {
	t = t.UTC()
	index := i.GetIntervalForTime(t)
	start, end := i.GetIntervalBounds(index, t)

	return IntervalInfo{
		Index:     index,
		Start:     start,
		End:       end,
		Duration:  i.intervalDuration,
		Reference: t,
	}
}

type IntervalInfo struct {
	Index     int
	Start     time.Time
	End       time.Time
	Duration  time.Duration
	Reference time.Time
}

func (ii IntervalInfo) String() string {
	return fmt.Sprintf("Interval %d: %s -> %s (Duration: %v)",
		ii.Index,
		ii.Start.Format("2006-01-02 15:04:05"),
		ii.End.Format("2006-01-02 15:04:05"),
		ii.Duration)
}