Add post video storage (#21)

post_images.kind is image or video. A post can keep one video alongside up to four images.

Reviewed-on: #21
Co-authored-by: codegirl-007 <s.raide@gmail.com>

internal/store/migrate.go

@@ -158,6 +158,32 @@ CREATE UNIQUE INDEX IF NOT EXISTS discord_post_links_thread_uidx
 	return nil
 }
 
+func migratePostImageVideo(ctx context.Context, exec execContext) error {
+	steps := []struct {
+		name string
+		sql  string
+	}{
+		{"add kind", `ALTER TABLE post_images ADD COLUMN IF NOT EXISTS kind TEXT NOT NULL DEFAULT 'image'`},
+		{"drop kind check", `ALTER TABLE post_images DROP CONSTRAINT IF EXISTS post_images_kind_check`},
+		{"add kind check", `ALTER TABLE post_images ADD CONSTRAINT post_images_kind_check CHECK (kind IN ('image', 'video'))`},
+		{"drop width check", `ALTER TABLE post_images DROP CONSTRAINT IF EXISTS post_images_width_check`},
+		{"drop height check", `ALTER TABLE post_images DROP CONSTRAINT IF EXISTS post_images_height_check`},
+		{"add width check", `ALTER TABLE post_images ADD CONSTRAINT post_images_width_check CHECK (width >= 0)`},
+		{"add height check", `ALTER TABLE post_images ADD CONSTRAINT post_images_height_check CHECK (height >= 0)`},
+		{"drop image dims check", `ALTER TABLE post_images DROP CONSTRAINT IF EXISTS post_images_image_dims_check`},
+		{"add image dims check", `ALTER TABLE post_images ADD CONSTRAINT post_images_image_dims_check CHECK (kind <> 'image' OR (width > 0 AND height > 0))`},
+		{"drop position check", `ALTER TABLE post_images DROP CONSTRAINT IF EXISTS post_images_position_check`},
+		{"add position check", `ALTER TABLE post_images ADD CONSTRAINT post_images_position_check CHECK (position BETWEEN 0 AND 4)`},
+		{"one video index", `CREATE UNIQUE INDEX IF NOT EXISTS post_images_one_video_uidx ON post_images (post_id) WHERE kind = 'video'`},
+	}
+	for _, step := range steps {
+		if _, err := exec.ExecContext(ctx, step.sql); err != nil {
+			return fmt.Errorf("%s: %w", step.name, err)
+		}
+	}
+	return nil
+}
+
 func migratePostDate(ctx context.Context, exec execContext) error {
 	steps := []struct {
 		name string
@@ -351,6 +377,7 @@ CREATE TABLE IF NOT EXISTS schema_migrations (
 		{"009_drop_legacy_post_tables", migrateDropLegacyPostTables},
 		{"010_post_images", migratePostImages},
 		{"011_discord_post_links", migrateDiscordPostLinks},
+		{"012_post_image_video", migratePostImageVideo},
 	}
 	for _, m := range migrations {
 		if applied[m.version] {