package dashboard

import (
	"fmt"
	"time"
)

func PeriodWindows(eventTime time.Time, statZone *time.Location) []PeriodWindow {
	localDate := startOfDay(timeInLocation(eventTime, statZone))
	dayEnd := localDate.AddDate(0, 0, 1)

	weekday := int(localDate.Weekday())
	if weekday == 0 {
		weekday = 7
	}
	weekStart := localDate.AddDate(0, 0, -(weekday - 1))
	weekEnd := weekStart.AddDate(0, 0, 7)

	monthStart := time.Date(localDate.Year(), localDate.Month(), 1, 0, 0, 0, 0, statZone)
	monthEnd := monthStart.AddDate(0, 1, 0)

	_, isoWeek := localDate.ISOWeek()
	isoYear, _ := localDate.ISOWeek()

	return []PeriodWindow{
		{
			Type:      PeriodDay,
			Key:       localDate.Format("2006-01-02"),
			Name:      localDate.Format("2006-01-02"),
			StartDate: ptrTime(localDate),
			EndDate:   ptrTime(dayEnd),
		},
		{
			Type:      PeriodWeek,
			Key:       fmt.Sprintf("%04d-W%02d", isoYear, isoWeek),
			Name:      fmt.Sprintf("%04d-W%02d", isoYear, isoWeek),
			StartDate: ptrTime(weekStart),
			EndDate:   ptrTime(weekEnd),
		},
		{
			Type:      PeriodMonth,
			Key:       localDate.Format("2006-01"),
			Name:      localDate.Format("2006-01"),
			StartDate: ptrTime(monthStart),
			EndDate:   ptrTime(monthEnd),
		},
		{
			Type: PeriodAll,
			Key:  PeriodAll,
			Name: "全部",
		},
	}
}

func SamePeriod(left time.Time, right time.Time, window PeriodWindow, statZone *time.Location) bool {
	if left.IsZero() || right.IsZero() {
		return false
	}
	if window.Type == PeriodAll {
		return true
	}
	leftLocal := timeInLocation(left, statZone)
	rightLocal := timeInLocation(right, statZone)
	switch window.Type {
	case PeriodDay:
		return startOfDay(leftLocal).Equal(startOfDay(rightLocal))
	case PeriodWeek:
		leftYear, leftWeek := leftLocal.ISOWeek()
		rightYear, rightWeek := rightLocal.ISOWeek()
		return leftYear == rightYear && leftWeek == rightWeek
	case PeriodMonth:
		return leftLocal.Year() == rightLocal.Year() && leftLocal.Month() == rightLocal.Month()
	default:
		return false
	}
}

func DailyDate(eventTime time.Time, storageZone *time.Location) time.Time {
	return startOfDay(timeInLocation(eventTime, storageZone))
}

func DateNumber(day time.Time) int {
	year, month, date := day.Date()
	return year*10000 + int(month)*100 + date
}

func ptrTime(value time.Time) *time.Time {
	v := value
	return &v
}

func startOfDay(value time.Time) time.Time {
	year, month, date := value.Date()
	return time.Date(year, month, date, 0, 0, 0, 0, value.Location())
}

func timeInLocation(value time.Time, location *time.Location) time.Time {
	if value.IsZero() {
		return value
	}
	if location == nil {
		location = time.UTC
	}
	return value.In(location)
}