package dehub

import (
	"errors"
	"fmt"
	"strings"
)

// PayloadComment describes the structure of a comment payload.
type PayloadComment struct {
	Comment string `yaml:"comment"`
}

var _ Payload = PayloadComment{}

// NewPayloadComment constructs a PayloadUnion populated with a PayloadComment.
// The Credentials of the returned PayloadUnion will _not_ be filled in.
func (proj *Project) NewPayloadComment(comment string) (PayloadUnion, error) {
	payCom := PayloadComment{Comment: comment}
	fingerprint, err := payCom.Fingerprint(nil)
	if err != nil {
		return PayloadUnion{}, err
	}
	return PayloadUnion{
		Comment: &payCom,
		Common:  PayloadCommon{Fingerprint: fingerprint},
	}, nil
}

// MessageHead implements the method for the Payload interface.
func (payCom PayloadComment) MessageHead(common PayloadCommon) (string, error) {
	credIDs := strings.Join(common.credIDs(), ", ")
	fullMsgHead := fmt.Sprintf("Comment by %s: %s", credIDs, payCom.Comment)
	return abbrevCommitMessage(fullMsgHead), nil
}

// Fingerprint implements the method for the Payload interface.
func (payCom PayloadComment) Fingerprint(changes []ChangedFile) ([]byte, error) {
	if len(changes) > 0 {
		return nil, errors.New("PayloadComment cannot have any changed files")
	}
	return genCommentFingerprint(nil, payCom.Comment), nil
}