package ui

import (
	"crypto/subtle"

	"gioui.org/layout"
	"gioui.org/unit"
	"gioui.org/widget"
	"gioui.org/widget/material"

	"git.wxccs.org/iceking2nd/winauth-go/internal/i18n"
)

// changePasswordDialog asks for the current passphrase, then a new
// passphrase + confirmation. The dialog refuses to submit unless the
// current passphrase matches what the store already holds (via a
// constant-time compare to avoid leaking length / prefix information).
type changePasswordDialog struct {
	oldEd     widget.Editor
	newEd     widget.Editor
	confirmEd widget.Editor
	okBtn     widget.Clickable
	cancelBtn widget.Clickable
	errorMsg  string
}

func newChangePasswordDialog() *changePasswordDialog {
	d := &changePasswordDialog{}
	d.oldEd.SingleLine = true
	d.oldEd.Mask = '*'
	d.newEd.SingleLine = true
	d.newEd.Mask = '*'
	d.confirmEd.SingleLine = true
	d.confirmEd.Mask = '*'
	return d
}

// changePasswordResult tells the caller what to do. cancel skips any
// state change. ok=true means commit newPw via store.SetPassword.
type changePasswordResult struct {
	cancel bool
	newPw  []byte
}

// Layout takes a verify callback that returns true when oldPw matches
// what the store believes the current passphrase is. The caller is
// responsible for that comparison so the dialog itself never has to
// hold a copy of the live passphrase.
func (d *changePasswordDialog) Layout(
	gtx layout.Context, th *material.Theme,
	verifyOld func(oldPw []byte) bool,
	onDone func(changePasswordResult),
) layout.Dimensions {
	if d.cancelBtn.Clicked(gtx) {
		onDone(changePasswordResult{cancel: true})
		return layout.Dimensions{Size: gtx.Constraints.Max}
	}
	if d.okBtn.Clicked(gtx) {
		oldPw := []byte(d.oldEd.Text())
		newPw := []byte(d.newEd.Text())
		confirm := []byte(d.confirmEd.Text())
		switch {
		case !verifyOld(oldPw):
			// Use the constant-length wrong-password string so the
			// presence of an error is not itself a side channel.
			d.errorMsg = i18n.T("msg_password_wrong")
		case subtle.ConstantTimeCompare(newPw, confirm) != 1:
			d.errorMsg = i18n.T("msg_password_mismatch")
		default:
			onDone(changePasswordResult{newPw: newPw})
			return layout.Dimensions{Size: gtx.Constraints.Max}
		}
	}

	body := func(gtx layout.Context) layout.Dimensions {
		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
			layout.Rigid(labeledEditor(th, i18n.T("label_password_current"), &d.oldEd, "")),
			layout.Rigid(labeledEditor(th, i18n.T("label_password_new"), &d.newEd, "")),
			layout.Rigid(labeledEditor(th, i18n.T("label_password_confirm"), &d.confirmEd, "")),
			layout.Rigid(layout.Spacer{Height: unit.Dp(4)}.Layout),
			layout.Rigid(material.Caption(th, i18n.T("hint_password_empty_disables")).Layout),
			layout.Rigid(errorLabel(th, d.errorMsg)),
		)
	}
	return modalCard(gtx, th, i18n.T("dialog_change_password_title"),
		i18n.T("btn_ok"), i18n.T("btn_cancel"),
		&d.okBtn, &d.cancelBtn, body)
}