package hotline

import (
	"encoding/binary"
	"slices"
	"time"
)

type Time [8]byte

// NewTime converts a time.Time to the 8 byte Hotline time format:
// Year (2 bytes), milliseconds (2 bytes) and seconds (4 bytes)
func NewTime(t time.Time) (b Time) {
	yearBytes := make([]byte, 2)
	secondBytes := make([]byte, 4)

	// Get a time.Time for January 1st 00:00 from t so we can calculate the difference in seconds from t
	startOfYear := time.Date(t.Year(), time.January, 1, 0, 0, 0, 0, time.Local)

	binary.BigEndian.PutUint16(yearBytes, uint16(t.Year()))
	binary.BigEndian.PutUint32(secondBytes, uint32(t.Sub(startOfYear).Seconds()))

	return [8]byte(slices.Concat(
		yearBytes,
		[]byte{0, 0},
		secondBytes,
	))
}

// Time converts the Hotline Time format to a Go time.Time.
// The Hotline format stores: Year (2 bytes) + milliseconds (2 bytes, unused) + seconds since Jan 1 (4 bytes)
func (t Time) Time() time.Time {
	year := binary.BigEndian.Uint16(t[0:2])
	seconds := binary.BigEndian.Uint32(t[4:8])

	// Create start of year, then add seconds
	startOfYear := time.Date(int(year), time.January, 1, 0, 0, 0, 0, time.Local)
	return startOfYear.Add(time.Duration(seconds) * time.Second)
}

// Format returns the time formatted according to the layout string.
// This is a convenience wrapper around Time().Format().
func (t Time) Format(layout string) string {
	return t.Time().Format(layout)
}