/*
 * Copyright (c) 2020 Baidu, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package flag

import (
	"fmt"
	"strconv"
)

// Tristate is a flag compatible with flags and pflags that
// keeps track of whether it had a value supplied or not.
type Tristate int

const (
	Unset Tristate = iota // 0
	True
	False
)

func (f *Tristate) Default(value bool) {
	*f = triFromBool(value)
}

func (f Tristate) String() string {
	b := boolFromTri(f)
	return fmt.Sprintf("%t", b)
}

func (f Tristate) Value() bool {
	b := boolFromTri(f)
	return b
}

func (f *Tristate) Set(value string) error {
	boolVal, err := strconv.ParseBool(value)
	if err != nil {
		return err
	}

	*f = triFromBool(boolVal)
	return nil
}

func (f Tristate) Provided() bool {
	if f != Unset {
		return true
	}
	return false
}

func (f *Tristate) Type() string {
	return "tristate"
}

func boolFromTri(t Tristate) bool {
	if t == True {
		return true
	} else {
		return false
	}
}

func triFromBool(b bool) Tristate {
	if b {
		return True
	} else {
		return False
	}
}
