calendarheatmap/charts/dayiter.go

package charts

import (
	"image"
	"time"
)

// DayIterator has data for updating image based on a day
type DayIterator struct {
	Year     int
	Row      int
	Col      int
	offset   image.Point
	time     time.Time
	counts   map[string]int
	maxCount int
	boxSize  int
	margin   int
}

// NewDayIterator initializes iterator for a year
func NewDayIterator(counts map[string]int, offset image.Point, boxSize int, margin int) *DayIterator {
	year := 1972
	for dateStr := range counts {
		date, err := time.Parse("2006-01-02", dateStr)
		if err != nil {
			panic(err)
		}
		year = date.Year()
		break
	}

	row := 0
	yearStartDate := time.Date(year, 1, 1, 1, 1, 1, 1, time.UTC)
	for i, w := range weekdayOrder {
		if w == yearStartDate.Weekday() {
			row = i
		}
	}

	// in case CountByDay is empty, we need to make Value 0/1 -> 0
	maxCount := 1
	for _, q := range counts {
		if q > maxCount {
			maxCount = q
		}
	}

	return &DayIterator{
		Year:     year,
		Col:      0,
		Row:      row,
		counts:   counts,
		time:     yearStartDate,
		offset:   offset,
		maxCount: maxCount,
		boxSize:  boxSize,
		margin:   margin,
	}
}

// Next will update current iterator to next value
func (d *DayIterator) Next() {
	if d.Row == 6 {
		d.Row = 0
		d.Col++
	} else {
		d.Row++
	}
	d.time = d.time.Add(time.Hour * 24)
}

// Done returns true if no entries left, else false
func (d *DayIterator) Done() bool {
	return d.time.Year() > d.Year
}

// Point returns position of top left corner of box for drawing
func (d *DayIterator) Point() image.Point {
	return image.Point{
		X: d.offset.X + d.Col*(d.boxSize+d.margin),
		Y: d.offset.Y + d.Row*(d.boxSize+d.margin),
	}
}

// Time returns time representation of iterator
func (d *DayIterator) Time() time.Time {
	return d.time
}

// Value returns relative value in range 0 ~ 1
func (d *DayIterator) Value() float64 {
	return float64(d.counts[d.time.Format("2006-01-02")]) / float64(d.maxCount)
}

// Count returns count value
func (d *DayIterator) Count() int {
	return d.counts[d.time.Format("2006-01-02")]
}