[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

internal/processing/list/get.go

@@ -0,0 +1,155 @@
+// 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 list
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+// Get returns the api model of one list with the given ID.
+func (p *Processor) Get(ctx context.Context, account *gtsmodel.Account, id string) (*apimodel.List, gtserror.WithCode) {
+	list, errWithCode := p.getList(
+		// Use barebones ctx; no embedded
+		// structs necessary for this call.
+		gtscontext.SetBarebones(ctx),
+		account.ID,
+		id,
+	)
+	if errWithCode != nil {
+		return nil, errWithCode
+	}
+
+	return p.apiList(ctx, list)
+}
+
+// GetMultiple returns multiple lists created by the given account, sorted by list ID DESC (newest first).
+func (p *Processor) GetAll(ctx context.Context, account *gtsmodel.Account) ([]*apimodel.List, gtserror.WithCode) {
+	lists, err := p.state.DB.GetListsForAccountID(
+		// Use barebones ctx; no embedded
+		// structs necessary for simple GET.
+		gtscontext.SetBarebones(ctx),
+		account.ID,
+	)
+	if err != nil {
+		if errors.Is(err, db.ErrNoEntries) {
+			return nil, nil
+		}
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	apiLists := make([]*apimodel.List, 0, len(lists))
+	for _, list := range lists {
+		apiList, errWithCode := p.apiList(ctx, list)
+		if errWithCode != nil {
+			return nil, errWithCode
+		}
+
+		apiLists = append(apiLists, apiList)
+	}
+
+	return apiLists, nil
+}
+
+// GetListAccounts returns accounts that are in the given list, owned by the given account.
+// The additional parameters can be used for paging.
+func (p *Processor) GetListAccounts(
+	ctx context.Context,
+	account *gtsmodel.Account,
+	listID string,
+	maxID string,
+	sinceID string,
+	minID string,
+	limit int,
+) (*apimodel.PageableResponse, gtserror.WithCode) {
+	// Ensure list exists + is owned by requesting account.
+	if _, errWithCode := p.getList(ctx, account.ID, listID); errWithCode != nil {
+		return nil, errWithCode
+	}
+
+	// To know which accounts are in the list,
+	// we need to first get requested list entries.
+	listEntries, err := p.state.DB.GetListEntries(ctx, listID, maxID, sinceID, minID, limit)
+	if err != nil && !errors.Is(err, db.ErrNoEntries) {
+		err = fmt.Errorf("GetListAccounts: error getting list entries: %w", err)
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	count := len(listEntries)
+	if count == 0 {
+		// No list entries means no accounts.
+		return util.EmptyPageableResponse(), nil
+	}
+
+	var (
+		items          = make([]interface{}, count)
+		nextMaxIDValue string
+		prevMinIDValue string
+	)
+
+	// For each list entry, we want the account it points to.
+	// To get this, we need to first get the follow that the
+	// list entry pertains to, then extract the target account
+	// from that follow.
+	//
+	// We do paging not by account ID, but by list entry ID.
+	for i, listEntry := range listEntries {
+		if i == count-1 {
+			nextMaxIDValue = listEntry.ID
+		}
+
+		if i == 0 {
+			prevMinIDValue = listEntry.ID
+		}
+
+		if err := p.state.DB.PopulateListEntry(ctx, listEntry); err != nil {
+			log.Debugf(ctx, "skipping list entry because of error populating it: %q", err)
+			continue
+		}
+
+		if err := p.state.DB.PopulateFollow(ctx, listEntry.Follow); err != nil {
+			log.Debugf(ctx, "skipping list entry because of error populating follow: %q", err)
+			continue
+		}
+
+		apiAccount, err := p.tc.AccountToAPIAccountPublic(ctx, listEntry.Follow.TargetAccount)
+		if err != nil {
+			log.Debugf(ctx, "skipping list entry because of error converting follow target account: %q", err)
+			continue
+		}
+
+		items[i] = apiAccount
+	}
+
+	return util.PackagePageableResponse(util.PageableResponseParams{
+		Items:          items,
+		Path:           "api/v1/lists/" + listID + "/accounts",
+		NextMaxIDValue: nextMaxIDValue,
+		PrevMinIDValue: prevMinIDValue,
+		Limit:          limit,
+	})
+}