Add topic support (#3711)

* add topic models and unit tests

* fix comments

* fix comment

* add the UI to show or add topics for a repo

* show topics on repositories list

* fix test

* don't show manage topics link when no permission

* use green basic as topic label

* fix topic label color

* remove trace content

* remove debug function

5 files changed, 274 insertions, 0 deletions

diff --git a/models/fixtures/repo_topic.yml b/models/fixtures/repo_topic.yml
new file mode 100644
index 0000000000..58937031cd
--- /dev/null
+++ b/models/fixtures/repo_topic.yml
@@ -0,0 +1,11 @@
+-
+  repo_id: 1
+  topic_id: 1
+
+-
+  repo_id: 1
+  topic_id: 2
+
+-
+  repo_id: 1
+  topic_id: 3
diff --git a/models/fixtures/topic.yml b/models/fixtures/topic.yml
new file mode 100644
index 0000000000..b6b94ff4d9
--- /dev/null
+++ b/models/fixtures/topic.yml
@@ -0,0 +1,13 @@
+-
+  id: 1
+  name: golang
+  repo_count: 1
+
+-
+  id: 2
+  name: database
+  repo_count: 1
+
+- id: 3
+  name: SQL
+  repo_count: 1
diff --git a/models/repo.go b/models/repo.go
index 300bdbe875..a7e8bd2a52 100644
--- a/models/repo.go
+++ b/models/repo.go
@@ -199,6 +199,7 @@ type Repository struct {
 	Size          int64              `xorm:"NOT NULL DEFAULT 0"`
 	IndexerStatus *RepoIndexerStatus `xorm:"-"`
 	IsFsckEnabled bool               `xorm:"NOT NULL DEFAULT true"`
+	Topics        []string           `xorm:"TEXT JSON"`
 
 	CreatedUnix util.TimeStamp `xorm:"INDEX created"`
 	UpdatedUnix util.TimeStamp `xorm:"INDEX updated"`
diff --git a/models/topic.go b/models/topic.go
new file mode 100644
index 0000000000..3b1737f8af
--- /dev/null
+++ b/models/topic.go
@@ -0,0 +1,192 @@
+// Copyright 2018 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package models
+
+import (
+	"fmt"
+	"strings"
+
+	"code.gitea.io/gitea/modules/util"
+
+	"github.com/go-xorm/builder"
+)
+
+func init() {
+	tables = append(tables,
+		new(Topic),
+		new(RepoTopic),
+	)
+}
+
+// Topic represents a topic of repositories
+type Topic struct {
+	ID          int64
+	Name        string `xorm:"unique"`
+	RepoCount   int
+	CreatedUnix util.TimeStamp `xorm:"INDEX created"`
+	UpdatedUnix util.TimeStamp `xorm:"INDEX updated"`
+}
+
+// RepoTopic represents associated repositories and topics
+type RepoTopic struct {
+	RepoID  int64 `xorm:"unique(s)"`
+	TopicID int64 `xorm:"unique(s)"`
+}
+
+// ErrTopicNotExist represents an error that a topic is not exist
+type ErrTopicNotExist struct {
+	Name string
+}
+
+// IsErrTopicNotExist checks if an error is an ErrTopicNotExist.
+func IsErrTopicNotExist(err error) bool {
+	_, ok := err.(ErrTopicNotExist)
+	return ok
+}
+
+// Error implements error interface
+func (err ErrTopicNotExist) Error() string {
+	return fmt.Sprintf("topic is not exist [name: %s]", err.Name)
+}
+
+// GetTopicByName retrieves topic by name
+func GetTopicByName(name string) (*Topic, error) {
+	var topic Topic
+	if has, err := x.Where("name = ?", name).Get(&topic); err != nil {
+		return nil, err
+	} else if !has {
+		return nil, ErrTopicNotExist{name}
+	}
+	return &topic, nil
+}
+
+// FindTopicOptions represents the options when fdin topics
+type FindTopicOptions struct {
+	RepoID  int64
+	Keyword string
+	Limit   int
+	Page    int
+}
+
+func (opts *FindTopicOptions) toConds() builder.Cond {
+	var cond = builder.NewCond()
+	if opts.RepoID > 0 {
+		cond = cond.And(builder.Eq{"repo_topic.repo_id": opts.RepoID})
+	}
+
+	if opts.Keyword != "" {
+		cond = cond.And(builder.Like{"topic.name", opts.Keyword})
+	}
+
+	return cond
+}
+
+// FindTopics retrieves the topics via FindTopicOptions
+func FindTopics(opts *FindTopicOptions) (topics []*Topic, err error) {
+	sess := x.Select("topic.*").Where(opts.toConds())
+	if opts.RepoID > 0 {
+		sess.Join("INNER", "repo_topic", "repo_topic.topic_id = topic.id")
+	}
+	if opts.Limit > 0 {
+		sess.Limit(opts.Limit, opts.Page*opts.Limit)
+	}
+	return topics, sess.Desc("topic.repo_count").Find(&topics)
+}
+
+// SaveTopics save topics to a repository
+func SaveTopics(repoID int64, topicNames ...string) error {
+	topics, err := FindTopics(&FindTopicOptions{
+		RepoID: repoID,
+	})
+	if err != nil {
+		return err
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	var addedTopicNames []string
+	for _, topicName := range topicNames {
+		if strings.TrimSpace(topicName) == "" {
+			continue
+		}
+
+		var found bool
+		for _, t := range topics {
+			if strings.EqualFold(topicName, t.Name) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			addedTopicNames = append(addedTopicNames, topicName)
+		}
+	}
+
+	var removeTopics []*Topic
+	for _, t := range topics {
+		var found bool
+		for _, topicName := range topicNames {
+			if strings.EqualFold(topicName, t.Name) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			removeTopics = append(removeTopics, t)
+		}
+	}
+
+	for _, topicName := range addedTopicNames {
+		var topic Topic
+		if has, err := sess.Where("name = ?", topicName).Get(&topic); err != nil {
+			return err
+		} else if !has {
+			topic.Name = topicName
+			topic.RepoCount = 1
+			if _, err := sess.Insert(&topic); err != nil {
+				return err
+			}
+		} else {
+			topic.RepoCount++
+			if _, err := sess.ID(topic.ID).Cols("repo_count").Update(&topic); err != nil {
+				return err
+			}
+		}
+
+		if _, err := sess.Insert(&RepoTopic{
+			RepoID:  repoID,
+			TopicID: topic.ID,
+		}); err != nil {
+			return err
+		}
+	}
+
+	for _, topic := range removeTopics {
+		topic.RepoCount--
+		if _, err := sess.ID(topic.ID).Cols("repo_count").Update(topic); err != nil {
+			return err
+		}
+
+		if _, err := sess.Delete(&RepoTopic{
+			RepoID:  repoID,
+			TopicID: topic.ID,
+		}); err != nil {
+			return err
+		}
+	}
+
+	if _, err := sess.ID(repoID).Cols("topics").Update(&Repository{
+		Topics: topicNames,
+	}); err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}
diff --git a/models/topic_test.go b/models/topic_test.go
new file mode 100644
index 0000000000..472f4e52d9
--- /dev/null
+++ b/models/topic_test.go
@@ -0,0 +1,57 @@
+// Copyright 2018 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package models
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAddTopic(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	topics, err := FindTopics(&FindTopicOptions{})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 3, len(topics))
+
+	topics, err = FindTopics(&FindTopicOptions{
+		Limit: 2,
+	})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 2, len(topics))
+
+	topics, err = FindTopics(&FindTopicOptions{
+		RepoID: 1,
+	})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 3, len(topics))
+
+	assert.NoError(t, SaveTopics(2, "golang"))
+	topics, err = FindTopics(&FindTopicOptions{})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 3, len(topics))
+
+	topics, err = FindTopics(&FindTopicOptions{
+		RepoID: 2,
+	})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, len(topics))
+
+	assert.NoError(t, SaveTopics(2, "golang", "gitea"))
+	topic, err := GetTopicByName("gitea")
+	assert.NoError(t, err)
+	assert.EqualValues(t, 1, topic.RepoCount)
+
+	topics, err = FindTopics(&FindTopicOptions{})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 4, len(topics))
+
+	topics, err = FindTopics(&FindTopicOptions{
+		RepoID: 2,
+	})
+	assert.NoError(t, err)
+	assert.EqualValues(t, 2, len(topics))
+}