package calculate

import (
	"electricity_bill_calc/model"
	"electricity_bill_calc/types"
	"errors"
	"fmt"
	"time"
)

// 确定指定非商户表计的起始读数
func DeterminePublicMeterStartReading(meterId string, periodStart time.Time,
	attachedAt time.Time, meterReadings []model.MeterReading) (*model.MeterReading, error) {
	periodBeginning := types.Date{Time: periodStart}.ToBeginningOfDate()

	if len(meterReadings) <= 0 {
		return nil, errors.New(fmt.Sprintf("表计的抄表记录数据不足%s", meterId))
	}

	var minReading types.DateTime
	for _, reading := range meterReadings {
		if reading.ReadAt.Before(minReading.Time) {
			minReading = reading.ReadAt
		}
	}
	startTimes := []time.Time{
		minReading.Time,
		periodBeginning.Time,
		ShiftToAsiaShanghai(attachedAt),
	}
	if len(startTimes) < 0 {
		return nil, errors.New(fmt.Sprintf("无法确定表计 {%s} 的计量的起始时间", meterId))
	}

	var startReading []model.MeterReading
	for _, reading := range meterReadings {
		readingAt := ShiftToAsiaShanghai(reading.ReadAt.UTC())
		for _, startTime := range startTimes {
			if reading.Meter == meterId && readingAt.After(startTime) || readingAt.Equal(startTime) {
				startReading = append(startReading, reading)
				break
			}
		}
	}

	if len(startReading) <= 0 {
		return nil, errors.New(fmt.Sprintf("无法确定表计 %s 的计量的起始读数", meterId))
	}

	var startReadings *model.MeterReading
	for _, readings := range startReading {
		if startReadings == nil || readings.ReadAt.Before(startReadings.ReadAt.Time) {
			startReadings = &readings
		}
	}
	return startReadings, nil
}

// 确定指定非商户表计的结束读数
func DeterminePublicMeterEndReading(meterId string, periodEnd time.Time,
	detachedAt time.Time, meterReadings []model.MeterReading) (*model.MeterReading, error) {
	periodEnding := types.Date{Time: periodEnd}.ToEndingOfDate()

	if len(meterReadings) <= 0 {
		return nil, errors.New(fmt.Sprintf("表计的抄表记录数据不足%s", meterId))
	}

	var minReading types.DateTime
	for _, reading := range meterReadings {
		if reading.ReadAt.Before(minReading.Time) {
			minReading = reading.ReadAt
		}
	}
	startTimes := []time.Time{
		minReading.Time,
		periodEnding.Time,
		ShiftToAsiaShanghai(detachedAt),
	}
	if len(startTimes) < 0 {
		return nil, errors.New(fmt.Sprintf("无法确定表计 {%s} 的计量的终止时间", meterId))
	}

	var startReading []model.MeterReading
	for _, reading := range meterReadings {
		readingAt := ShiftToAsiaShanghai(reading.ReadAt.UTC())
		for _, startTime := range startTimes {
			if reading.Meter == meterId && readingAt.After(startTime) || readingAt.Equal(startTime) {
				startReading = append(startReading, reading)
				break
			}
		}
	}

	if len(startReading) <= 0 {
		return nil, errors.New(fmt.Sprintf("无法确定表计 %s 的计量的终止读数", meterId))
	}

	var startReadings *model.MeterReading
	for _, readings := range startReading {
		if startReadings == nil || readings.ReadAt.Before(startReadings.ReadAt.Time) {
			startReadings = &readings
		}
	}
	return startReadings, nil
}