package models

import (
	"fmt"
	"io"
	"strconv"
)

// ChangeModel describes a model related to the change.
type ChangeModel string

const (
	// ChangeModelCharacter is a value of ChangeModel
	ChangeModelCharacter ChangeModel = "Character"
	// ChangeModelChannel is a value of ChangeModel
	ChangeModelChannel ChangeModel = "Channel"
	// ChangeModelLog is a value of ChangeModel
	ChangeModelLog ChangeModel = "Log"
	// ChangeModelPost is a value of ChangeModel
	ChangeModelPost ChangeModel = "Post"
	// ChangeModelStory is a value of ChangeModel
	ChangeModelStory ChangeModel = "Story"
	// ChangeModelTag is a value of ChangeModel
	ChangeModelTag ChangeModel = "Tag"
	// ChangeModelChapter is a value of ChangeModel
	ChangeModelChapter ChangeModel = "Chapter"
)

// IsValid returns true if the underlying string is one of the correct values.
func (e ChangeModel) IsValid() bool {
	switch e {
	case ChangeModelCharacter, ChangeModelChannel, ChangeModelLog, ChangeModelPost, ChangeModelStory, ChangeModelTag, ChangeModelChapter:
		return true
	}
	return false
}

func (e ChangeModel) String() string {
	return string(e)
}

// UnmarshalGQL unmarshals the underlying graphql value.
func (e *ChangeModel) UnmarshalGQL(v interface{}) error {
	str, ok := v.(string)
	if !ok {
		return fmt.Errorf("enums must be strings")
	}

	*e = ChangeModel(str)
	if !e.IsValid() {
		return fmt.Errorf("%s is not a valid ChangeModel", str)
	}
	return nil
}

// MarshalGQL marshals the underlying graphql value.
func (e ChangeModel) MarshalGQL(w io.Writer) {
	fmt.Fprint(w, strconv.Quote(e.String()))
}