previous_tag.go

package git

import (
	"errors"

	"github.com/apex/log"
	"github.com/go-git/go-git/v5/plumbing"
)

var (
	// ErrPrevTagNotAvailable is returned when no previous tag is found.
	ErrPrevTagNotAvailable = errors.New("previous tag is not available")
)

// PreviousTag sorts tags based on when their commit happened and returns the one previous
// to the current.
func (g *Git) PreviousTag(currentHash plumbing.Hash) (*Tag, error) {
	tags, err := g.getTags()

	if err != nil {
		log.Debugf("[ERR] getting previous tag failed: %v", err)
		return nil, err
	}

	// If there are fewer than two tags assume that the currentCommit is the newest tag
	if len(tags) < 2 {
		log.Debug("[ERR] previous tag not available")
		return nil, ErrPrevTagNotAvailable
	}

	if tags[0].Hash != currentHash {
		log.Debug("[ERR] current commit does not have a tag attached, building from this commit")
		return tags[0], nil
	}

	log.Debugf("success: previous tag found at %v", tags[1].Hash)

	return tags[1], nil
}