package story

import (
	"sort"
	"strings"

	"github.com/globalsign/mgo/bson"
)

// A Tag associates a story with other content, like other stories, logs and more.
type Tag struct {
	Kind string `bson:"kind"`
	Name string `bson:"name"`
}

// Equal returns true if the tags match one another.
func (tag *Tag) Equal(other Tag) bool {
	return tag.Kind == other.Kind && tag.Name == other.Name
}

// ListTags lists all tags
func ListTags() ([]Tag, error) {
	tags := make([]Tag, 0, 64)
	err := storyCollection.Find(bson.M{"listed": true, "tags": bson.M{"$ne": nil}}).Distinct("tags", &tags)

	sort.Slice(tags, func(i, j int) bool {
		kindCmp := strings.Compare(tags[i].Kind, tags[j].Kind)
		if kindCmp != 0 {
			return kindCmp < 0
		}

		return strings.Compare(tags[i].Name, tags[j].Name) < 0
	})

	return tags, err
}