1 files changed, 104 insertions, 0 deletions
diff --git a/internal/util/timeline.go b/internal/util/timeline.go
new file mode 100644
index 000000000..929464add
--- /dev/null
+++ b/internal/util/timeline.go
@@ -0,0 +1,104 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package util
+
+import (
+	"fmt"
+	"net/url"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/timeline"
+)
+
+// TimelineableResponseParams models the parameters to pass to PackageTimelineableResponse.
+//
+// The given items will be provided in the timeline response.
+//
+// The other values are all used to create the Link header so that callers know
+// which endpoint to query next and previously in order to do paging.
+type TimelineableResponseParams struct {
+	Items            []timeline.Timelineable // Sorted slice of Timelineables (statuses, notifications, etc)
+	Path             string                  // path to use for next/prev queries in the link header
+	NextMaxIDKey     string                  // key to use for the next max id query param in the link header, defaults to 'max_id'
+	NextMaxIDValue   string                  // value to use for next max id
+	PrevMinIDKey     string                  // key to use for the prev min id query param in the link header, defaults to 'min_id'
+	PrevMinIDValue   string                  // value to use for prev min id
+	Limit            int                     // limit number of entries to return
+	ExtraQueryParams []string                // any extra query parameters to provide in the link header, should be in the format 'example=value'
+}
+
+// PackageTimelineableResponse is a convenience function for returning
+// a bunch of timelineable items (notifications, statuses, etc), as well
+// as a Link header to inform callers of where to find next/prev items.
+func PackageTimelineableResponse(params TimelineableResponseParams) (*apimodel.TimelineResponse, gtserror.WithCode) {
+	if params.NextMaxIDKey == "" {
+		params.NextMaxIDKey = "max_id"
+	}
+
+	if params.PrevMinIDKey == "" {
+		params.PrevMinIDKey = "min_id"
+	}
+
+	timelineResponse := &apimodel.TimelineResponse{
+		Items: params.Items,
+	}
+
+	// prepare the next and previous links
+	if len(params.Items) != 0 {
+		protocol := config.GetProtocol()
+		host := config.GetHost()
+
+		nextRaw := fmt.Sprintf("limit=%d&%s=%s", params.Limit, params.NextMaxIDKey, params.NextMaxIDValue)
+		for _, p := range params.ExtraQueryParams {
+			nextRaw = nextRaw + "&" + p
+		}
+		nextLink := &url.URL{
+			Scheme:   protocol,
+			Host:     host,
+			Path:     params.Path,
+			RawQuery: nextRaw,
+		}
+		next := fmt.Sprintf("<%s>; rel=\"next\"", nextLink.String())
+
+		prevRaw := fmt.Sprintf("limit=%d&%s=%s", params.Limit, params.PrevMinIDKey, params.PrevMinIDValue)
+		for _, p := range params.ExtraQueryParams {
+			prevRaw = prevRaw + "&" + p
+		}
+		prevLink := &url.URL{
+			Scheme:   protocol,
+			Host:     host,
+			Path:     params.Path,
+			RawQuery: prevRaw,
+		}
+		prev := fmt.Sprintf("<%s>; rel=\"prev\"", prevLink.String())
+		timelineResponse.LinkHeader = next + ", " + prev
+	}
+
+	return timelineResponse, nil
+}
+
+// EmptyTimelineResponse just returns an empty
+// TimelineResponse with no link header or items.
+func EmptyTimelineResponse() *apimodel.TimelineResponse {
+	return &apimodel.TimelineResponse{
+		Items: []timeline.Timelineable{},
+	}
+}