[feature] Conversations API (#3013)

* Implement conversations API

* Sort and page conversations by last status ID

* Appease linter

* Fix deleting conversations and statuses

* Refactor to make migrations automatic

* Lint

* Update tests post-merge

* Fixes from live-fire testing

* Linter caught a format problem

* Refactor tests, fix cache

* Negative test for non-DMs

* Run conversations advanced migration on testrig startup as well as regular server startup

* Document (lack of) side effects of API method for deleting a conversation

* Make not-found check less nested for readability

* Rename PutConversation to UpsertConversation

* Use util.Ptr instead of IIFE

* Reduce cache used by conversations

* Remove unnecessary TableExpr/ColumnExpr

* Use struct tags for both unique constraints on Conversation

* Make it clear how paging with GetDirectStatusIDsBatch should be used

* Let conversation paging skip conversations it can't render

* Use Bun NewDropTable

* Convert delete raw query to Bun

* Convert update raw query to Bun

* Convert latestConversationStatusesTempTable raw query partially to Bun

* Convert conversationStatusesTempTable raw query partially to Bun

* Rename field used to store result of MaxDirectStatusID

* Move advanced migrations to their own tiny processor

* Catch up util function name with main

* Remove json.… wrappers

* Remove redundant check

* Combine error checks

* Replace map with slice of structs

* Address processor/type converter comments

- Add context info for errors
- Extract some common processor code into shared methods
- Move conversation eligibility check ahead of populating conversation

* Add error context when dropping temp tables

1 files changed, 126 insertions, 0 deletions

diff --git a/internal/processing/conversations/conversations.go b/internal/processing/conversations/conversations.go
new file mode 100644
index 000000000..d95740605
--- /dev/null
+++ b/internal/processing/conversations/conversations.go
@@ -0,0 +1,126 @@
+// 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 conversations
+
+import (
+	"context"
+	"errors"
+
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/filter/usermute"
+	"github.com/superseriousbusiness/gotosocial/internal/filter/visibility"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/state"
+	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
+)
+
+type Processor struct {
+	state     *state.State
+	converter *typeutils.Converter
+	filter    *visibility.Filter
+}
+
+func New(
+	state *state.State,
+	converter *typeutils.Converter,
+	filter *visibility.Filter,
+) Processor {
+	return Processor{
+		state:     state,
+		converter: converter,
+		filter:    filter,
+	}
+}
+
+const conversationNotFoundHelpText = "conversation not found"
+
+// getConversationOwnedBy gets a conversation by ID and checks that it is owned by the given account.
+func (p *Processor) getConversationOwnedBy(
+	ctx context.Context,
+	id string,
+	requestingAccount *gtsmodel.Account,
+) (*gtsmodel.Conversation, gtserror.WithCode) {
+	// Get the conversation so that we can check its owning account ID.
+	conversation, err := p.state.DB.GetConversationByID(ctx, id)
+	if err != nil && !errors.Is(err, db.ErrNoEntries) {
+		return nil, gtserror.NewErrorInternalError(
+			gtserror.Newf(
+				"DB error getting conversation %s for account %s: %w",
+				id,
+				requestingAccount.ID,
+				err,
+			),
+		)
+	}
+	if conversation == nil {
+		return nil, gtserror.NewErrorNotFound(
+			gtserror.Newf(
+				"conversation %s not found: %w",
+				id,
+				err,
+			),
+			conversationNotFoundHelpText,
+		)
+	}
+	if conversation.AccountID != requestingAccount.ID {
+		return nil, gtserror.NewErrorNotFound(
+			gtserror.Newf(
+				"conversation %s not owned by account %s: %w",
+				id,
+				requestingAccount.ID,
+				err,
+			),
+			conversationNotFoundHelpText,
+		)
+	}
+
+	return conversation, nil
+}
+
+// getFiltersAndMutes gets the given account's filters and compiled mute list.
+func (p *Processor) getFiltersAndMutes(
+	ctx context.Context,
+	requestingAccount *gtsmodel.Account,
+) ([]*gtsmodel.Filter, *usermute.CompiledUserMuteList, gtserror.WithCode) {
+	filters, err := p.state.DB.GetFiltersForAccountID(ctx, requestingAccount.ID)
+	if err != nil {
+		return nil, nil, gtserror.NewErrorInternalError(
+			gtserror.Newf(
+				"DB error getting filters for account %s: %w",
+				requestingAccount.ID,
+				err,
+			),
+		)
+	}
+
+	mutes, err := p.state.DB.GetAccountMutes(gtscontext.SetBarebones(ctx), requestingAccount.ID, nil)
+	if err != nil {
+		return nil, nil, gtserror.NewErrorInternalError(
+			gtserror.Newf(
+				"DB error getting mutes for account %s: %w",
+				requestingAccount.ID,
+				err,
+			),
+		)
+	}
+	compiledMutes := usermute.NewCompiledUserMuteList(mutes)
+
+	return filters, compiledMutes, nil
+}