package timefmt

import (
	"bytes"
	"git.swzry.com/zry/YAGTF/yagtf/tfelem"
	"time"
)

type TimeElement interface {
	PrintElement(t time.Time) string
	ExpectedSize() int
}

const bufSizeRedunt = 64

type TimePrinter struct {
	elementList  []TimeElement
	expectedSize int
	forceTz      bool
	forceUTC     bool
	forceLocal   bool
	forceTzVal   *time.Location
}

func (this *TimePrinter) UseArgumentSpecifiedTimezone() {
	this.forceTz = false
}

func (this *TimePrinter) UseTimezone(tz *time.Location) {
	this.forceTz = true
	this.forceLocal = false
	this.forceUTC = false
	this.forceTzVal = tz
}

func (this *TimePrinter) UseLocalTimezone() {
	this.forceTz = true
	this.forceLocal = true
	this.forceUTC = false
}

func (this *TimePrinter) UseUTC() {
	this.forceTz = true
	this.forceLocal = false
	this.forceUTC = true
}

func (this *TimePrinter) AddPureText(text string) {
	e := &tfelem.PureTextElement{
		PureText: text,
	}
	this.AddElement(e)
}

func (this *TimePrinter) AddElement(e TimeElement) {
	this.elementList = append(this.elementList, e)
	this.expectedSize += e.ExpectedSize()
}

func (this *TimePrinter) PrintTime(t time.Time) string {
	bsl := make([]byte, 0, this.expectedSize+bufSizeRedunt)
	buf := bytes.NewBuffer(bsl)
	ttz := t
	if this.forceTz {
		if this.forceLocal {
			ttz = t.Local()
		} else if this.forceUTC {
			ttz = t.UTC()
		} else {
			ttz = t.In(this.forceTzVal)
		}
	}
	for _, v := range this.elementList {
		buf.WriteString(v.PrintElement(ttz))
	}
	return buf.String()
}

func NewTimePrinter() *TimePrinter {
	tp := &TimePrinter{}
	tp.elementList = make([]TimeElement, 0)
	tp.expectedSize = 0
	return tp
}