package chartjs

import (
	"sync"
	"time"
)

const (
	Minute = "minute"
	Hour   = "hour"
	Day    = "day"
	Method = "method"
)

// 时间序列值, 实现了按时间进行分组的值计算
type TimeSeries struct {
	mutex  sync.Mutex
	step   string
	values []*TimeseriesValue
}

func (s *TimeSeries) cutTimeSeries(tm time.Time) int64 {
	switch s.step {
	case Method:
		return time.Date(tm.Year(), tm.Month(), 0, 0, 0, 0, 0, time.Local).Unix()
	case Day:
		return time.Date(tm.Year(), tm.Month(), tm.Day(), 0, 0, 0, 0, time.Local).Unix()
	case Hour:
		return time.Date(tm.Year(), tm.Month(), tm.Day(), tm.Hour(), 0, 0, 0, time.Local).Unix()
	default:
		return time.Date(tm.Year(), tm.Month(), tm.Day(), tm.Hour(), tm.Minute(), 0, 0, time.Local).Unix()
	}
}

func (s *TimeSeries) truncateTime(ts int64) int64 {
	tm := time.Unix(ts, 0)
	switch s.step {
	case Method:
		return time.Date(tm.Year(), tm.Month(), 0, 0, 0, 0, 0, time.Local).Unix()
	case Day:
		return time.Date(tm.Year(), tm.Month(), tm.Day(), 0, 0, 0, 0, time.Local).Unix()
	case Hour:
		return time.Date(tm.Year(), tm.Month(), tm.Day(), tm.Hour(), 0, 0, 0, time.Local).Unix()
	default:
		return time.Date(tm.Year(), tm.Month(), tm.Day(), tm.Hour(), tm.Minute(), 0, 0, time.Local).Unix()
	}
	return tm.Unix()
}

func (s *TimeSeries) nextTimestamp(ts int64) int64 {
	tm := time.Unix(ts, 0)
	switch s.step {
	case Method:
		return tm.AddDate(0, 1, 0).Unix()
	case Day:
		return tm.AddDate(0, 0, 1).Unix()
	case Hour:
		return ts + 3600
	default:
		return ts + 60
	}
}

func (s *TimeSeries) Inc(tm time.Time, value float64) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	ts := s.cutTimeSeries(tm)
	for _, v := range s.values {
		if v.Timestamp == ts {
			v.Value += value
			return
		}
	}
	s.values = append(s.values, &TimeseriesValue{
		Timestamp: ts,
		Value:     value,
	})
}

func (s *TimeSeries) Dec(tm time.Time, value float64) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	ts := s.cutTimeSeries(tm)
	for _, v := range s.values {
		if v.Timestamp == ts {
			v.Value -= value
			return
		}
	}
}

func (s *TimeSeries) Values(sts, ets int64) []*TimeseriesValue {
	var (
		nextStamp int64
	)
	sts = s.truncateTime(sts)
	ets = s.truncateTime(ets)
	series := make([]*TimeseriesValue, 0, len(s.values))
	nextStamp = sts
	for _, row := range s.values {
		for row.Timestamp > nextStamp {
			series = append(series, &TimeseriesValue{
				Timestamp: nextStamp,
				Value:     0,
			})
			nextStamp = s.nextTimestamp(nextStamp)
		}
		series = append(series, row)
		nextStamp = s.nextTimestamp(nextStamp)
	}
	for ets > nextStamp {
		series = append(series, &TimeseriesValue{
			Timestamp: nextStamp,
			Value:     0,
		})
		nextStamp = s.nextTimestamp(nextStamp)
	}
	return series
}

func NewTimeSeries(step string) *TimeSeries {
	return &TimeSeries{
		step:   step,
		values: make([]*TimeseriesValue, 0, 64),
	}
}