ferret/pkg/stdlib/datetime/daysinmonth.go

package datetime

import (
	"context"
	"time"

	"github.com/MontFerret/ferret/pkg/runtime/core"
	"github.com/MontFerret/ferret/pkg/runtime/values"
	"github.com/MontFerret/ferret/pkg/runtime/values/types"
)

var daysCount = map[time.Month]int{
	time.January:   31,
	time.February:  28,
	time.March:     31,
	time.April:     30,
	time.May:       31,
	time.June:      30,
	time.July:      30,
	time.August:    31,
	time.September: 30,
	time.October:   31,
	time.November:  30,
	time.December:  31,
}

// DateDaysInMonth returns the number of days in the month of date.
// @params date (DateTime) - source DateTime.
// @return (Int) - number of the days.
func DateDaysInMonth(_ context.Context, args ...core.Value) (core.Value, error) {
	err := core.ValidateArgs(args, 1, 1)
	if err != nil {
		return values.None, err
	}

	err = core.ValidateType(args[0], types.DateTime)
	if err != nil {
		return values.None, err
	}

	dt := args[0].(values.DateTime)
	month := dt.Month()
	count := daysCount[month]

	if month == time.February && isLeap(dt.Year()) {
		count++
	}

	return values.NewInt(count), nil
}