[feature] Add List functionality (#1802)

* start working on lists

* further list work

* test list db functions nicely

* more work on lists

* peepoopeepoo

* poke

* start list timeline func

* we're getting there lads

* couldn't be me working on stuff... could it?

* hook up handlers

* fiddling

* weeee

* woah

* screaming, pissing

* fix streaming being a whiny baby

* lint, small test fix, swagger

* tidying up, testing

* fucked! by the linter

* move timelines to state like a boss

* add timeline start to tests using state

* invalidate lists

1 files changed, 157 insertions, 0 deletions

diff --git a/internal/processing/timeline/list.go b/internal/processing/timeline/list.go
new file mode 100644
index 000000000..adad35197
--- /dev/null
+++ b/internal/processing/timeline/list.go
@@ -0,0 +1,157 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// 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 timeline
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+	"github.com/superseriousbusiness/gotosocial/internal/state"
+	"github.com/superseriousbusiness/gotosocial/internal/timeline"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+	"github.com/superseriousbusiness/gotosocial/internal/visibility"
+)
+
+// ListTimelineGrab returns a function that satisfies GrabFunction for list timelines.
+func ListTimelineGrab(state *state.State) timeline.GrabFunction {
+	return func(ctx context.Context, listID string, maxID string, sinceID string, minID string, limit int) ([]timeline.Timelineable, bool, error) {
+		statuses, err := state.DB.GetListTimeline(ctx, listID, maxID, sinceID, minID, limit)
+		if err != nil {
+			if errors.Is(err, db.ErrNoEntries) {
+				return nil, true, nil // we just don't have enough statuses left in the db so return stop = true
+			}
+			return nil, false, fmt.Errorf("ListTimelineGrab: error getting statuses from db: %w", err)
+		}
+
+		items := make([]timeline.Timelineable, len(statuses))
+		for i, s := range statuses {
+			items[i] = s
+		}
+
+		return items, false, nil
+	}
+}
+
+// HomeTimelineFilter returns a function that satisfies FilterFunction for list timelines.
+func ListTimelineFilter(state *state.State, filter *visibility.Filter) timeline.FilterFunction {
+	return func(ctx context.Context, listID string, item timeline.Timelineable) (shouldIndex bool, err error) {
+		status, ok := item.(*gtsmodel.Status)
+		if !ok {
+			return false, errors.New("ListTimelineFilter: could not convert item to *gtsmodel.Status")
+		}
+
+		list, err := state.DB.GetListByID(ctx, listID)
+		if err != nil {
+			return false, fmt.Errorf("ListTimelineFilter: error getting list with id %s: %w", listID, err)
+		}
+
+		requestingAccount, err := state.DB.GetAccountByID(ctx, list.AccountID)
+		if err != nil {
+			return false, fmt.Errorf("ListTimelineFilter: error getting account with id %s: %w", list.AccountID, err)
+		}
+
+		timelineable, err := filter.StatusHomeTimelineable(ctx, requestingAccount, status)
+		if err != nil {
+			return false, fmt.Errorf("ListTimelineFilter: error checking hometimelineability of status %s for account %s: %w", status.ID, list.AccountID, err)
+		}
+
+		return timelineable, nil
+	}
+}
+
+// ListTimelineStatusPrepare returns a function that satisfies PrepareFunction for list timelines.
+func ListTimelineStatusPrepare(state *state.State, tc typeutils.TypeConverter) timeline.PrepareFunction {
+	return func(ctx context.Context, listID string, itemID string) (timeline.Preparable, error) {
+		status, err := state.DB.GetStatusByID(ctx, itemID)
+		if err != nil {
+			return nil, fmt.Errorf("ListTimelineStatusPrepare: error getting status with id %s: %w", itemID, err)
+		}
+
+		list, err := state.DB.GetListByID(ctx, listID)
+		if err != nil {
+			return nil, fmt.Errorf("ListTimelineStatusPrepare: error getting list with id %s: %w", listID, err)
+		}
+
+		requestingAccount, err := state.DB.GetAccountByID(ctx, list.AccountID)
+		if err != nil {
+			return nil, fmt.Errorf("ListTimelineStatusPrepare: error getting account with id %s: %w", list.AccountID, err)
+		}
+
+		return tc.StatusToAPIStatus(ctx, status, requestingAccount)
+	}
+}
+
+func (p *Processor) ListTimelineGet(ctx context.Context, authed *oauth.Auth, listID string, maxID string, sinceID string, minID string, limit int) (*apimodel.PageableResponse, gtserror.WithCode) {
+	// Ensure list exists + is owned by this account.
+	list, err := p.state.DB.GetListByID(ctx, listID)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, gtserror.NewErrorNotFound(err)
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	if list.AccountID != authed.Account.ID {
+		err = fmt.Errorf("list with id %s does not belong to account %s", list.ID, authed.Account.ID)
+		return nil, gtserror.NewErrorNotFound(err)
+	}
+
+	statuses, err := p.state.Timelines.List.GetTimeline(ctx, listID, maxID, sinceID, minID, limit, false)
+	if err != nil {
+		err = fmt.Errorf("ListTimelineGet: error getting statuses: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	count := len(statuses)
+	if count == 0 {
+		return util.EmptyPageableResponse(), nil
+	}
+
+	var (
+		items          = make([]interface{}, count)
+		nextMaxIDValue string
+		prevMinIDValue string
+	)
+
+	for i, item := range statuses {
+		if i == count-1 {
+			nextMaxIDValue = item.GetID()
+		}
+
+		if i == 0 {
+			prevMinIDValue = item.GetID()
+		}
+
+		items[i] = item
+	}
+
+	return util.PackagePageableResponse(util.PageableResponseParams{
+		Items:          items,
+		Path:           "api/v1/timelines/list/" + listID,
+		NextMaxIDValue: nextMaxIDValue,
+		PrevMinIDValue: prevMinIDValue,
+		Limit:          limit,
+	})
+}