Files
memby/server/internal/api/related.go
T

87 lines
2.7 KiB
Go

package api
import (
"encoding/json"
"net/http"
"github.com/ponzischeme89/memby/server/internal/cache"
"github.com/ponzischeme89/memby/server/internal/recommend"
"github.com/ponzischeme89/memby/server/internal/store"
)
// fieldsRelated adds Studios to the detail set: the explanation layer names the studio a
// viewer keeps returning to, and Emby omits it unless asked.
const fieldsRelated = fieldsDetail + ",Studios"
// relatedResponse is what the detail page renders: a strip of short reasons under the
// description, and the carousel beneath the page.
type relatedResponse struct {
Reasons []string `json:"reasons"`
Items []json.RawMessage `json:"items"`
}
// handleRelated explains one title to one viewer and lists what resembles it.
//
// Building the taste profile costs the same Emby fan-out the home rows pay for, so the
// whole answer is cached per user and item. It is deliberately *not* folded into
// `/v1/items/{id}`: that response is shared with the screensaver and the player, and this
// one is only ever needed once a detail page is open.
func (s *Server) handleRelated(w http.ResponseWriter, r *http.Request, sess store.Session) {
ctx := r.Context()
itemID := r.PathValue("id")
if itemID == "" {
writeError(w, http.StatusBadRequest, "item id is required")
return
}
key := cache.UserKey(sess.EmbyUserID, "related:v1:"+itemID)
if raw, err := s.cache.Get(ctx, key); err == nil {
w.Header().Set("X-Memby-Cache", "hit")
writeRaw(w, http.StatusOK, raw)
return
}
raw, err := s.emby.Item(ctx, credentials(sess), itemID, fieldsRelated)
if err != nil {
s.writeUpstreamError(w, err, "could not load the item")
return
}
decoded := recommend.Decode([]json.RawMessage{raw})
if len(decoded) == 0 {
writeError(w, http.StatusNotFound, "item not found")
return
}
reasons, related, err := s.recommender.RelatedTo(
ctx, credentials(sess), decoded[0], relatedRowSize,
)
if err != nil {
s.writeUpstreamError(w, err, "could not load related titles")
return
}
body, err := json.Marshal(relatedResponse{
Reasons: nonNilStrings(reasons),
Items: nonNilRaws(recommend.Raws(related)),
})
if err != nil {
writeError(w, http.StatusInternalServerError, "could not encode related titles")
return
}
if err := s.cache.Set(ctx, key, body, s.cfg.ItemTTL); err != nil {
s.log.Warn("related cache write failed", "error", err)
}
w.Header().Set("X-Memby-Cache", "miss")
writeRaw(w, http.StatusOK, body)
}
// relatedRowSize is a carousel's worth. The strip scrolls, but a viewer who reaches the
// twelfth card has stopped looking for something like this one.
const relatedRowSize = 12
func nonNilRaws(values []json.RawMessage) []json.RawMessage {
if values == nil {
return []json.RawMessage{}
}
return values
}