[chore] media and emoji refactoring (#3000)

* start updating media manager interface ready for storing attachments / emoji right away

* store emoji and media as uncached immediately, then (re-)cache on Processing{}.Load()

* remove now unused media workers

* fix tests and issues

* fix another test!

* fix emoji activitypub uri setting behaviour, fix remainder of test compilation issues

* fix more tests

* fix (most of) remaining tests, add debouncing to repeatedly failing media / emojis

* whoops, rebase issue

* remove kim's whacky experiments

* do some reshuffling, ensure emoji uri gets set

* ensure marked as not cached on cleanup

* tweaks to media / emoji processing to handle context canceled better

* ensure newly fetched emojis actually get set in returned slice

* use different varnames to be a bit more obvious

* move emoji refresh rate limiting to dereferencer

* add exported dereferencer functions for remote media, use these for recaching in processor

* add check for nil attachment in updateAttachment()

* remove unused emoji and media fields + columns

* see previous commit

* fix old migrations expecting image_updated_at to exists (from copies of old models)

* remove freshness checking code (seems to be broken...)

* fix error arg causing nil ptr exception

* finish documentating functions with comments, slight tweaks to media / emoji deref error logic

* remove some extra unneeded boolean checking

* finish writing documentation (code comments) for exported media manager methods

* undo changes to migration snapshot gtsmodels, updated failing migration to have its own snapshot

* move doesColumnExist() to util.go in migrations package

1 files changed, 20 insertions, 12 deletions

diff --git a/internal/gtsmodel/mediaattachment.go b/internal/gtsmodel/mediaattachment.go
index f18589f85..471a5abd1 100644
--- a/internal/gtsmodel/mediaattachment.go
+++ b/internal/gtsmodel/mediaattachment.go
@@ -30,8 +30,8 @@ type MediaAttachment struct {
 	StatusID          string           `bun:"type:CHAR(26),nullzero"`                                      // ID of the status to which this is attached
 	URL               string           `bun:",nullzero"`                                                   // Where can the attachment be retrieved on *this* server
 	RemoteURL         string           `bun:",nullzero"`                                                   // Where can the attachment be retrieved on a remote server (empty for local media)
-	Type              FileType         `bun:",nullzero,notnull"`                                           // Type of file (image/gifv/audio/video/unknown)
-	FileMeta          FileMeta         `bun:",embed:,nullzero,notnull"`                                    // Metadata about the file
+	Type              FileType         `bun:",notnull"`                                                    // Type of file (image/gifv/audio/video/unknown)
+	FileMeta          FileMeta         `bun:",embed:,notnull"`                                             // Metadata about the file
 	AccountID         string           `bun:"type:CHAR(26),nullzero,notnull"`                              // To which account does this attachment belong
 	Description       string           `bun:""`                                                            // Description of the attachment (for screenreaders)
 	ScheduledStatusID string           `bun:"type:CHAR(26),nullzero"`                                      // To which scheduled status does this attachment belong
@@ -44,22 +44,30 @@ type MediaAttachment struct {
 	Cached            *bool            `bun:",nullzero,notnull,default:false"`                             // Is this attachment currently cached by our instance?
 }
 
+// IsLocal returns whether media attachment is local.
+func (m *MediaAttachment) IsLocal() bool {
+	return m.RemoteURL == ""
+}
+
+// IsRemote returns whether media attachment is remote.
+func (m *MediaAttachment) IsRemote() bool {
+	return m.RemoteURL != ""
+}
+
 // File refers to the metadata for the whole file
 type File struct {
-	Path        string    `bun:",nullzero,notnull"`                                           // Path of the file in storage.
-	ContentType string    `bun:",nullzero,notnull"`                                           // MIME content type of the file.
-	FileSize    int       `bun:",notnull"`                                                    // File size in bytes
-	UpdatedAt   time.Time `bun:"type:timestamptz,nullzero,notnull,default:current_timestamp"` // When was the file last updated.
+	Path        string `bun:",notnull"` // Path of the file in storage.
+	ContentType string `bun:",notnull"` // MIME content type of the file.
+	FileSize    int    `bun:",notnull"` // File size in bytes
 }
 
 // Thumbnail refers to a small image thumbnail derived from a larger image, video, or audio file.
 type Thumbnail struct {
-	Path        string    `bun:",nullzero,notnull"`                                           // Path of the file in storage.
-	ContentType string    `bun:",nullzero,notnull"`                                           // MIME content type of the file.
-	FileSize    int       `bun:",notnull"`                                                    // File size in bytes
-	UpdatedAt   time.Time `bun:"type:timestamptz,nullzero,notnull,default:current_timestamp"` // When was the file last updated.
-	URL         string    `bun:",nullzero"`                                                   // What is the URL of the thumbnail on the local server
-	RemoteURL   string    `bun:",nullzero"`                                                   // What is the remote URL of the thumbnail (empty for local media)
+	Path        string `bun:",notnull"`  // Path of the file in storage.
+	ContentType string `bun:",notnull"`  // MIME content type of the file.
+	FileSize    int    `bun:",notnull"`  // File size in bytes
+	URL         string `bun:",nullzero"` // What is the URL of the thumbnail on the local server
+	RemoteURL   string `bun:",nullzero"` // What is the remote URL of the thumbnail (empty for local media)
 }
 
 // ProcessingStatus refers to how far along in the processing stage the attachment is.