package transform

import (
	"errors"
	"fmt"
	"io"
	"time"

	"gordenko.dev/dima/diploma"
	"gordenko.dev/dima/diploma/bin"
	"gordenko.dev/dima/diploma/timeutil"
)

// INSTANT

type InstantPeriodsWriterOptions struct {
	Dst            io.Writer
	GroupBy        diploma.GroupBy
	AggregateFuncs byte
	FirstHourOfDay int
}

type InstantPeriodsWriter struct {
	aggregateFuncs byte
	arr            []byte
	responder      *ChunkedResponder
	groupBy        diploma.GroupBy
	firstHourOfDay int
	time2period    func(uint32) time.Time
	currentPeriod  time.Time
	lastTimestamp  uint32
	endTimestamp   uint32
	min            float64
	max            float64
	total          float64
	entries        int
}

func NewInstantPeriodsWriter(opt InstantPeriodsWriterOptions) (*InstantPeriodsWriter, error) {
	if opt.Dst == nil {
		return nil, errors.New("Dst option is required")
	}
	if opt.FirstHourOfDay < 0 || opt.FirstHourOfDay > 23 {
		return nil, fmt.Errorf("wrong FirstHourOfDay option: %d", opt.FirstHourOfDay)
	}
	var q int
	if (opt.AggregateFuncs & diploma.AggregateMin) == diploma.AggregateMin {
		q++
	}
	if (opt.AggregateFuncs & diploma.AggregateMax) == diploma.AggregateMax {
		q++
	}
	if (opt.AggregateFuncs & diploma.AggregateAvg) == diploma.AggregateAvg {
		q++
	}

	if q == 0 {
		return nil, errors.New("AggregateFuncs option is required")
	}

	s := &InstantPeriodsWriter{
		aggregateFuncs: opt.AggregateFuncs,
		arr:            make([]byte, 12+q*8),
		responder:      NewChunkedResponder(opt.Dst),
		groupBy:        opt.GroupBy,
		firstHourOfDay: opt.FirstHourOfDay,
	}

	switch opt.GroupBy {
	case diploma.GroupByHour:
		s.time2period = groupByHour

	case diploma.GroupByDay:
		if s.firstHourOfDay > 0 {
			s.time2period = s.groupByDayUsingFHD
		} else {
			s.time2period = groupByDay
		}

	case diploma.GroupByMonth:
		if s.firstHourOfDay > 0 {
			s.time2period = s.groupByMonthUsingFHD
		} else {
			s.time2period = groupByMonth
		}

	default:
		return nil, fmt.Errorf("unknown groupBy %d option", opt.GroupBy)
	}
	return s, nil
}

func (s *InstantPeriodsWriter) groupByDayUsingFHD(timestamp uint32) time.Time {
	tm := timeutil.FirstSecondInPeriod(time.Unix(int64(timestamp), 0), "d")
	if tm.Hour() < s.firstHourOfDay {
		tm = tm.AddDate(0, 0, -1)
	}
	return tm
}

func (s *InstantPeriodsWriter) groupByMonthUsingFHD(timestamp uint32) time.Time {
	tm := timeutil.FirstSecondInPeriod(time.Unix(int64(timestamp), 0), "m")
	if tm.Hour() < s.firstHourOfDay {
		tm = tm.AddDate(0, 0, -1)
	}
	return tm
}

func (s *InstantPeriodsWriter) Feed(timestamp uint32, value float64) {
	s.feed(timestamp, value, false)
}

func (s *InstantPeriodsWriter) FeedNoSend(timestamp uint32, value float64) {
	s.feed(timestamp, value, true)
}

func (s *InstantPeriodsWriter) feed(timestamp uint32, value float64, isBuffer bool) {
	if s.entries > 0 {
		period := s.time2period(timestamp)
		if period != s.currentPeriod {
			s.packPeriod(timestamp)
			if isBuffer {
				s.responder.BufferRecord(s.arr)
			} else {
				s.responder.AppendRecord(s.arr)
			}
			s.decrementPeriod()
			for period.Before(s.currentPeriod) {
				s.packBlankPeriod()
				if isBuffer {
					s.responder.BufferRecord(s.arr)
				} else {
					s.responder.AppendRecord(s.arr)
				}
				s.decrementPeriod()
			}
			s.endTimestamp = timestamp
			s.min = value
			s.max = value
			s.total = value
			s.entries = 1
		} else {
			if value < s.min {
				s.min = value
			} else if value > s.max {
				s.max = value
			}
			s.total += value
			s.entries++
		}
	} else {
		s.endTimestamp = timestamp
		s.min = value
		s.max = value
		s.total = value
		s.entries = 1
		s.currentPeriod = s.time2period(timestamp)
	}
	s.lastTimestamp = timestamp
}

func (s *InstantPeriodsWriter) decrementPeriod() {
	switch s.groupBy {
	case diploma.GroupByHour:
		s.currentPeriod = s.currentPeriod.Add(-1 * time.Hour)
	case diploma.GroupByDay:
		s.currentPeriod = s.currentPeriod.AddDate(0, 0, -1)
	case diploma.GroupByMonth:
		s.currentPeriod = s.currentPeriod.AddDate(0, -1, 0)
	}
}

func (s *InstantPeriodsWriter) packBlankPeriod() {
	bin.PutUint32(s.arr[0:], uint32(s.currentPeriod.Unix()))
	for i := 4; i < len(s.arr); i++ {
		s.arr[i] = 0
	}
}

func (s *InstantPeriodsWriter) Close() (err error) {
	if s.entries > 0 {
		s.packPeriod(s.lastTimestamp)
		s.responder.AppendRecord(s.arr)
	}
	return s.responder.Flush()
}

func (s *InstantPeriodsWriter) packPeriod(timestamp uint32) {
	bin.PutUint32(s.arr[0:], uint32(s.currentPeriod.Unix()))
	bin.PutUint32(s.arr[4:], timestamp)
	bin.PutUint32(s.arr[8:], s.endTimestamp)

	pos := 12
	if (s.aggregateFuncs & diploma.AggregateMin) == diploma.AggregateMin {
		bin.PutFloat64(s.arr[pos:], s.min)
		pos += 8
	}
	if (s.aggregateFuncs & diploma.AggregateMax) == diploma.AggregateMax {
		bin.PutFloat64(s.arr[pos:], s.max)
		pos += 8
	}
	if (s.aggregateFuncs & diploma.AggregateAvg) == diploma.AggregateAvg {
		bin.PutFloat64(s.arr[pos:], s.total/float64(s.entries))
	}
}

type CumulativePeriodsWriter struct {
	arr            []byte
	responder      *ChunkedResponder
	since          uint32
	firstHourOfDay int
	currentPeriod  time.Time
	groupBy        diploma.GroupBy
	time2period    func(uint32) time.Time
	endTimestamp   uint32
	endValue       float64
	lastTimestamp  uint32
	lastValue      float64
}

type CumulativePeriodsWriterOptions struct {
	Dst            io.Writer
	GroupBy        diploma.GroupBy
	Since          uint32
	FirstHourOfDay int
}

func NewCumulativePeriodsWriter(opt CumulativePeriodsWriterOptions) (*CumulativePeriodsWriter, error) {
	if opt.Dst == nil {
		return nil, errors.New("Dst option is required")
	}
	if opt.FirstHourOfDay < 0 || opt.FirstHourOfDay > 23 {
		return nil, fmt.Errorf("wrong firstHourOfDay option: %d", opt.FirstHourOfDay)
	}

	s := &CumulativePeriodsWriter{
		arr:            make([]byte, 28),
		responder:      NewChunkedResponder(opt.Dst),
		since:          opt.Since,
		firstHourOfDay: opt.FirstHourOfDay,
		groupBy:        opt.GroupBy,
	}

	s.time2period = func(timestamp uint32) time.Time {
		return timeutil.FirstSecondInPeriod(time.Unix(int64(timestamp), 0), "h")
	}

	switch opt.GroupBy {
	case diploma.GroupByHour:
		s.time2period = groupByHour

	case diploma.GroupByDay:
		if s.firstHourOfDay > 0 {
			s.time2period = s.groupByDayUsingFHD
		} else {
			s.time2period = groupByDay
		}

	case diploma.GroupByMonth:
		if s.firstHourOfDay > 0 {
			s.time2period = s.groupByMonthUsingFHD
		} else {
			s.time2period = groupByMonth
		}

	default:
		return nil, fmt.Errorf("unknown groupBy %d option", opt.GroupBy)
	}
	return s, nil
}

func (s *CumulativePeriodsWriter) groupByDayUsingFHD(timestamp uint32) time.Time {
	tm := timeutil.FirstSecondInPeriod(time.Unix(int64(timestamp), 0), "d")
	if tm.Hour() < s.firstHourOfDay {
		tm = tm.AddDate(0, 0, -1)
	}
	return tm
}

func (s *CumulativePeriodsWriter) groupByMonthUsingFHD(timestamp uint32) time.Time {
	tm := timeutil.FirstSecondInPeriod(time.Unix(int64(timestamp), 0), "m")
	if tm.Hour() < s.firstHourOfDay {
		tm = tm.AddDate(0, 0, -1)
	}
	return tm
}

func (s *CumulativePeriodsWriter) Feed(timestamp uint32, value float64) {
	s.feed(timestamp, value, false)
}

func (s *CumulativePeriodsWriter) FeedNoSend(timestamp uint32, value float64) {
	s.feed(timestamp, value, true)
}

func (s *CumulativePeriodsWriter) feed(timestamp uint32, value float64, isBuffer bool) {
	if s.endTimestamp > 0 {
		period := s.time2period(timestamp)
		if period != s.currentPeriod {
			s.packPeriod(timestamp, value)
			if isBuffer {
				s.responder.BufferRecord(s.arr)
			} else {
				s.responder.AppendRecord(s.arr)
			}
			s.decrementPeriod()
			for period.Before(s.currentPeriod) {
				// вставляю пустышку
				s.packBlankPeriod()
				if isBuffer {
					s.responder.BufferRecord(s.arr)
				} else {
					s.responder.AppendRecord(s.arr)
				}
				s.decrementPeriod()
			}
			s.endTimestamp = timestamp
			s.endValue = value
		}
	} else {
		s.endTimestamp = timestamp
		s.endValue = value
		s.currentPeriod = s.time2period(timestamp)
	}
	s.lastTimestamp = timestamp
	s.lastValue = value
}

func (s *CumulativePeriodsWriter) decrementPeriod() {
	switch s.groupBy {
	case diploma.GroupByHour:
		s.currentPeriod = s.currentPeriod.Add(-1 * time.Hour)
	case diploma.GroupByDay:
		s.currentPeriod = s.currentPeriod.AddDate(0, 0, -1)
	case diploma.GroupByMonth:
		s.currentPeriod = s.currentPeriod.AddDate(0, -1, 0)
	}
}

func (s *CumulativePeriodsWriter) packBlankPeriod() {
	bin.PutUint32(s.arr[0:], uint32(s.currentPeriod.Unix()))
	for i := 4; i < len(s.arr); i++ {
		s.arr[i] = 0
	}
}

func (s *CumulativePeriodsWriter) packPeriod(start uint32, startValue float64) {
	bin.PutUint32(s.arr[0:], uint32(s.currentPeriod.Unix()))
	bin.PutUint32(s.arr[4:], start)
	bin.PutUint32(s.arr[8:], s.endTimestamp)
	bin.PutFloat64(s.arr[12:], startValue)
	bin.PutFloat64(s.arr[20:], s.endValue)
}

func (s *CumulativePeriodsWriter) Close() error {
	if s.endTimestamp > 0 {
		if s.endTimestamp >= s.since {
			if s.lastTimestamp != s.endTimestamp {
				s.packPeriod(s.lastTimestamp, s.lastValue)
			} else {
				s.packPeriod(s.endTimestamp, s.endValue)
			}
			s.responder.AppendRecord(s.arr)
		}
	}
	return s.responder.Flush()
}