package dehub

import (
	"errors"
	"fmt"
	"strings"

	"dehub.dev/src/dehub.git/yamlutil"
)

// CommitComment describes the structure of a comment commit message.
type CommitComment struct {
	Message     string        `yaml:"message"`
	MessageHash yamlutil.Blob `yaml:"message_hash"`
}

var _ CommitInterface = CommitComment{}

// NewCommitComment constructs and returns a Commit populated with a
// CommitComment encompassing the given message. The Credentials of the returned
// Commit will _not_ be filled in.
func (r *Repo) NewCommitComment(msg string) (Commit, error) {
	cc := CommitComment{Message: msg}
	var err error
	if cc.MessageHash, err = cc.ExpectedHash(nil); err != nil {
		return Commit{}, fmt.Errorf("calculating comment hash: %w", err)
	}
	return Commit{Comment: &cc}, nil
}

// MessageHead implements the method for the CommitInterface interface.
func (cc CommitComment) MessageHead(common CommitCommon) (string, error) {
	msgAbbrev := abbrevCommitMessage(cc.Message)
	credIDs := strings.Join(common.credIDs(), ", ")
	return fmt.Sprintf("Comment by %s: %s", credIDs, msgAbbrev), nil
}

// ExpectedHash implements the method for the CommitInterface.
func (cc CommitComment) ExpectedHash(changes []ChangedFile) ([]byte, error) {
	if len(changes) > 0 {
		return nil, errors.New("CommitComment cannot have any changed files")
	}
	return genCommentHash(nil, cc.Message), nil
}

// StoredHash implements the method for the CommitInterface.
func (cc CommitComment) StoredHash() []byte {
	return cc.MessageHash
}