FEAT: Discovery Video Service Subscription

discovery/internal/handlers/videos.go

@@ -0,0 +1,49 @@
+package handlers
+
+import (
+	"errors"
+	"log"
+	"net/http"
+	"thamanyah/discovery/internal/api"
+	"thamanyah/discovery/internal/db/repositories"
+)
+
+// GetVideo serves the catalogue's copy of one video.
+//
+//	@Summary		Get a catalogued video
+//	@Description	Returns the catalogue's copy of a video: what a reader needs to show and play it. A video appears here only after the CMS has announced it as ready, so a video that is still transcoding — or one the CMS never made ready — is a 404.
+//	@Tags			videos
+//	@Produce		json
+//	@Param			id	path		string	true	"Video id, as issued by the CMS"
+//	@Success		200	{object}	api.Video
+//	@Failure		404	{object}	api.ProblemDetails
+//	@Failure		500	{object}	api.ProblemDetails
+//	@Router			/api/videos/{id} [get]
+func GetVideo(w http.ResponseWriter, r *http.Request) {
+	id := r.PathValue("id")
+
+	video, err := repositories.VideoRepo.GetVideoByID(r.Context(), id)
+	if errors.Is(err, repositories.ErrVideoNotFound) {
+		writeProblem(w, http.StatusNotFound, "Video Not In The Catalogue",
+			"No video with that id is in the catalogue. A video appears here once the CMS announces it as ready, so one that is still being transcoded is not here yet.")
+		return
+	}
+	if err != nil {
+		log.Printf("Something Went Wrong Loading A Catalogued Video: id=%q: %s", id, err)
+		writeProblem(w, http.StatusInternalServerError, "Something Went Wrong Loading The Catalogue",
+			"The video could not be read from the database. This is a server-side fault and the request was not processed; retrying in a few moments may succeed.")
+		return
+	}
+
+	// Translated field by field rather than returned as-is: models.Video is the
+	// row, api.Video is the published schema, and neither should drag the other
+	// along when it changes.
+	writeJSON(w, http.StatusOK, api.Video{
+		ID:          video.ID,
+		Title:       video.Title,
+		PlaybackURL: video.PlaybackURL,
+		// Never null on the wire: a video with no categories has an empty
+		// list, which is a different thing from "unknown".
+		Categories: append([]string{}, video.Categories...),
+	})
+}