feat(alerting): add alert history api endpoint

ref #5850

pkg/services/sqlstore/annotation.go

@@ -1,6 +1,9 @@
 package sqlstore
 
 import (
+	"bytes"
+	"fmt"
+
 	"github.com/go-xorm/xorm"
 	"github.com/grafana/grafana/pkg/services/annotations"
 )
@@ -17,5 +20,39 @@ func (r *SqlAnnotationRepo) Save(item *annotations.Item) error {
 
 		return nil
 	})
+}
 
+func (r *SqlAnnotationRepo) Find(query *annotations.ItemQuery) ([]*annotations.Item, error) {
+	var sql bytes.Buffer
+	params := make([]interface{}, 0)
+
+	sql.WriteString(`SELECT *
+						from annotation
+						`)
+
+	sql.WriteString(`WHERE org_id = ?`)
+	params = append(params, query.OrgId)
+
+	if query.AlertId != 0 {
+		sql.WriteString(` AND alert_id = ?`)
+		params = append(params, query.AlertId)
+	}
+
+	if query.Type != "" {
+		sql.WriteString(` AND type = ?`)
+		params = append(params, string(query.Type))
+	}
+
+	if query.Limit == 0 {
+		query.Limit = 10
+	}
+
+	sql.WriteString(fmt.Sprintf("ORDER BY timestamp DESC LIMIT %v", query.Limit))
+
+	items := make([]*annotations.Item, 0)
+	if err := x.Sql(sql.String(), params...).Find(&items); err != nil {
+		return nil, err
+	}
+
+	return items, nil
 }