[feature] Federate pinned posts (aka `featuredCollection`) in and out (#1560)

* start fiddling

* the ol' fiddle + update

* start working on fetching statuses

* poopy doopy doo where r u uwu

* further adventures in featuring statuses

* finishing up

* fmt

* simply status unpin loop

* move empty featured check back to caller function

* remove unnecessary log.WithContext calls

* remove unnecessary IsIRI() checks

* add explanatory comment about status URIs

* change log level to error

* better test names

1 files changed, 78 insertions, 120 deletions

diff --git a/internal/processing/fedi/collections.go b/internal/processing/fedi/collections.go
index 33d1b64e9..78a65bebe 100644
--- a/internal/processing/fedi/collections.go
+++ b/internal/processing/fedi/collections.go
@@ -20,6 +20,7 @@ package fedi
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -27,38 +28,85 @@ import (
 	"github.com/superseriousbusiness/activity/streams"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
-	"github.com/superseriousbusiness/gotosocial/internal/transport"
 )
 
-// FollowersGet handles the getting of a fedi/activitypub representation of a user/account's followers, performing appropriate
-// authentication before returning a JSON serializable interface to the caller.
-func (p *Processor) FollowersGet(ctx context.Context, requestedUsername string, requestURL *url.URL) (interface{}, gtserror.WithCode) {
-	// get the account the request is referring to
-	requestedAccount, err := p.db.GetAccountByUsernameDomain(ctx, requestedUsername, "")
-	if err != nil {
-		return nil, gtserror.NewErrorNotFound(fmt.Errorf("database error getting account with username %s: %s", requestedUsername, err))
-	}
+// InboxPost handles POST requests to a user's inbox for new activitypub messages.
+//
+// InboxPost returns true if the request was handled as an ActivityPub POST to an actor's inbox.
+// If false, the request was not an ActivityPub request and may still be handled by the caller in another way, such as serving a web page.
+//
+// If the error is nil, then the ResponseWriter's headers and response has already been written. If a non-nil error is returned, then no response has been written.
+//
+// If the Actor was constructed with the Federated Protocol enabled, side effects will occur.
+//
+// If the Federated Protocol is not enabled, writes the http.StatusMethodNotAllowed status code in the response. No side effects occur.
+func (p *Processor) InboxPost(ctx context.Context, w http.ResponseWriter, r *http.Request) (bool, error) {
+	return p.federator.FederatingActor().PostInbox(ctx, w, r)
+}
 
-	// authenticate the request
-	requestingAccountURI, errWithCode := p.federator.AuthenticateFederatedRequest(ctx, requestedUsername)
+// OutboxGet returns the activitypub representation of a local user's outbox.
+// This contains links to PUBLIC posts made by this user.
+func (p *Processor) OutboxGet(ctx context.Context, requestedUsername string, page bool, maxID string, minID string) (interface{}, gtserror.WithCode) {
+	requestedAccount, _, errWithCode := p.authenticate(ctx, requestedUsername)
 	if errWithCode != nil {
 		return nil, errWithCode
 	}
 
-	requestingAccount, err := p.federator.GetAccountByURI(
-		transport.WithFastfail(ctx), requestedUsername, requestingAccountURI, false,
-	)
-	if err != nil {
-		return nil, gtserror.NewErrorUnauthorized(err)
+	var data map[string]interface{}
+	// There are two scenarios:
+	// 1. we're asked for the whole collection and not a page -- we can just return the collection, with no items, but a link to 'first' page.
+	// 2. we're asked for a specific page; this can be either the first page or any other page
+
+	if !page {
+		/*
+			scenario 1: return the collection with no items
+			we want something that looks like this:
+			{
+				"@context": "https://www.w3.org/ns/activitystreams",
+				"id": "https://example.org/users/whatever/outbox",
+				"type": "OrderedCollection",
+				"first": "https://example.org/users/whatever/outbox?page=true",
+				"last": "https://example.org/users/whatever/outbox?min_id=0&page=true"
+			}
+		*/
+		collection, err := p.tc.OutboxToASCollection(ctx, requestedAccount.OutboxURI)
+		if err != nil {
+			return nil, gtserror.NewErrorInternalError(err)
+		}
+
+		data, err = streams.Serialize(collection)
+		if err != nil {
+			return nil, gtserror.NewErrorInternalError(err)
+		}
+
+		return data, nil
 	}
 
-	blocked, err := p.db.IsBlocked(ctx, requestedAccount.ID, requestingAccount.ID, true)
+	// scenario 2 -- get the requested page
+	// limit pages to 30 entries per page
+	publicStatuses, err := p.db.GetAccountStatuses(ctx, requestedAccount.ID, 30, true, true, maxID, minID, false, true)
+	if err != nil && err != db.ErrNoEntries {
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	outboxPage, err := p.tc.StatusesToASOutboxPage(ctx, requestedAccount.OutboxURI, maxID, minID, publicStatuses)
 	if err != nil {
 		return nil, gtserror.NewErrorInternalError(err)
 	}
+	data, err = streams.Serialize(outboxPage)
+	if err != nil {
+		return nil, gtserror.NewErrorInternalError(err)
+	}
+
+	return data, nil
+}
 
-	if blocked {
-		return nil, gtserror.NewErrorUnauthorized(fmt.Errorf("block exists between accounts %s and %s", requestedAccount.ID, requestingAccount.ID))
+// FollowersGet handles the getting of a fedi/activitypub representation of a user/account's followers, performing appropriate
+// authentication before returning a JSON serializable interface to the caller.
+func (p *Processor) FollowersGet(ctx context.Context, requestedUsername string) (interface{}, gtserror.WithCode) {
+	requestedAccount, _, errWithCode := p.authenticate(ctx, requestedUsername)
+	if errWithCode != nil {
+		return nil, errWithCode
 	}
 
 	requestedAccountURI, err := url.Parse(requestedAccount.URI)
@@ -81,35 +129,12 @@ func (p *Processor) FollowersGet(ctx context.Context, requestedUsername string,
 
 // FollowingGet handles the getting of a fedi/activitypub representation of a user/account's following, performing appropriate
 // authentication before returning a JSON serializable interface to the caller.
-func (p *Processor) FollowingGet(ctx context.Context, requestedUsername string, requestURL *url.URL) (interface{}, gtserror.WithCode) {
-	// get the account the request is referring to
-	requestedAccount, err := p.db.GetAccountByUsernameDomain(ctx, requestedUsername, "")
-	if err != nil {
-		return nil, gtserror.NewErrorNotFound(fmt.Errorf("database error getting account with username %s: %s", requestedUsername, err))
-	}
-
-	// authenticate the request
-	requestingAccountURI, errWithCode := p.federator.AuthenticateFederatedRequest(ctx, requestedUsername)
+func (p *Processor) FollowingGet(ctx context.Context, requestedUsername string) (interface{}, gtserror.WithCode) {
+	requestedAccount, _, errWithCode := p.authenticate(ctx, requestedUsername)
 	if errWithCode != nil {
 		return nil, errWithCode
 	}
 
-	requestingAccount, err := p.federator.GetAccountByURI(
-		transport.WithFastfail(ctx), requestedUsername, requestingAccountURI, false,
-	)
-	if err != nil {
-		return nil, gtserror.NewErrorUnauthorized(err)
-	}
-
-	blocked, err := p.db.IsBlocked(ctx, requestedAccount.ID, requestingAccount.ID, true)
-	if err != nil {
-		return nil, gtserror.NewErrorInternalError(err)
-	}
-
-	if blocked {
-		return nil, gtserror.NewErrorUnauthorized(fmt.Errorf("block exists between accounts %s and %s", requestedAccount.ID, requestingAccount.ID))
-	}
-
 	requestedAccountURI, err := url.Parse(requestedAccount.URI)
 	if err != nil {
 		return nil, gtserror.NewErrorInternalError(fmt.Errorf("error parsing url %s: %s", requestedAccount.URI, err))
@@ -128,97 +153,30 @@ func (p *Processor) FollowingGet(ctx context.Context, requestedUsername string,
 	return data, nil
 }
 
-// OutboxGet returns the activitypub representation of a local user's outbox.
-// This contains links to PUBLIC posts made by this user.
-func (p *Processor) OutboxGet(ctx context.Context, requestedUsername string, page bool, maxID string, minID string, requestURL *url.URL) (interface{}, gtserror.WithCode) {
-	// get the account the request is referring to
-	requestedAccount, err := p.db.GetAccountByUsernameDomain(ctx, requestedUsername, "")
-	if err != nil {
-		return nil, gtserror.NewErrorNotFound(fmt.Errorf("database error getting account with username %s: %s", requestedUsername, err))
-	}
-
-	// authenticate the request
-	requestingAccountURI, errWithCode := p.federator.AuthenticateFederatedRequest(ctx, requestedUsername)
+// FeaturedCollectionGet returns an ordered collection of the requested username's Pinned posts.
+// The returned collection have an `items` property which contains an ordered list of status URIs.
+func (p *Processor) FeaturedCollectionGet(ctx context.Context, requestedUsername string) (interface{}, gtserror.WithCode) {
+	requestedAccount, _, errWithCode := p.authenticate(ctx, requestedUsername)
 	if errWithCode != nil {
 		return nil, errWithCode
 	}
 
-	requestingAccount, err := p.federator.GetAccountByURI(
-		transport.WithFastfail(ctx), requestedUsername, requestingAccountURI, false,
-	)
+	statuses, err := p.db.GetAccountPinnedStatuses(ctx, requestedAccount.ID)
 	if err != nil {
-		return nil, gtserror.NewErrorUnauthorized(err)
-	}
-
-	// authorize the request:
-	// 1. check if a block exists between the requester and the requestee
-	blocked, err := p.db.IsBlocked(ctx, requestedAccount.ID, requestingAccount.ID, true)
-	if err != nil {
-		return nil, gtserror.NewErrorInternalError(err)
-	}
-	if blocked {
-		return nil, gtserror.NewErrorUnauthorized(fmt.Errorf("block exists between accounts %s and %s", requestedAccount.ID, requestingAccount.ID))
-	}
-
-	var data map[string]interface{}
-	// now there are two scenarios:
-	// 1. we're asked for the whole collection and not a page -- we can just return the collection, with no items, but a link to 'first' page.
-	// 2. we're asked for a specific page; this can be either the first page or any other page
-
-	if !page {
-		/*
-			scenario 1: return the collection with no items
-			we want something that looks like this:
-			{
-				"@context": "https://www.w3.org/ns/activitystreams",
-				"id": "https://example.org/users/whatever/outbox",
-				"type": "OrderedCollection",
-				"first": "https://example.org/users/whatever/outbox?page=true",
-				"last": "https://example.org/users/whatever/outbox?min_id=0&page=true"
-			}
-		*/
-		collection, err := p.tc.OutboxToASCollection(ctx, requestedAccount.OutboxURI)
-		if err != nil {
+		if !errors.Is(err, db.ErrNoEntries) {
 			return nil, gtserror.NewErrorInternalError(err)
 		}
-
-		data, err = streams.Serialize(collection)
-		if err != nil {
-			return nil, gtserror.NewErrorInternalError(err)
-		}
-
-		return data, nil
-	}
-
-	// scenario 2 -- get the requested page
-	// limit pages to 30 entries per page
-	publicStatuses, err := p.db.GetAccountStatuses(ctx, requestedAccount.ID, 30, true, true, maxID, minID, false, true)
-	if err != nil && err != db.ErrNoEntries {
-		return nil, gtserror.NewErrorInternalError(err)
 	}
 
-	outboxPage, err := p.tc.StatusesToASOutboxPage(ctx, requestedAccount.OutboxURI, maxID, minID, publicStatuses)
+	collection, err := p.tc.StatusesToASFeaturedCollection(ctx, requestedAccount.FeaturedCollectionURI, statuses)
 	if err != nil {
 		return nil, gtserror.NewErrorInternalError(err)
 	}
-	data, err = streams.Serialize(outboxPage)
+
+	data, err := streams.Serialize(collection)
 	if err != nil {
 		return nil, gtserror.NewErrorInternalError(err)
 	}
 
 	return data, nil
 }
-
-// InboxPost handles POST requests to a user's inbox for new activitypub messages.
-//
-// InboxPost returns true if the request was handled as an ActivityPub POST to an actor's inbox.
-// If false, the request was not an ActivityPub request and may still be handled by the caller in another way, such as serving a web page.
-//
-// If the error is nil, then the ResponseWriter's headers and response has already been written. If a non-nil error is returned, then no response has been written.
-//
-// If the Actor was constructed with the Federated Protocol enabled, side effects will occur.
-//
-// If the Federated Protocol is not enabled, writes the http.StatusMethodNotAllowed status code in the response. No side effects occur.
-func (p *Processor) InboxPost(ctx context.Context, w http.ResponseWriter, r *http.Request) (bool, error) {
-	return p.federator.FederatingActor().PostInbox(ctx, w, r)
-}