package api

import (
	"encoding/json"
	"net/http"
	"net/url"

	"github.com/ponzischeme89/memby/server/internal/cache"
	"github.com/ponzischeme89/memby/server/internal/store"
)

type seriesEpisodesResponse struct {
	Items []json.RawMessage `json:"items"`
}

type flagRequest struct {
	Value bool `json:"value"`
}

// handleItem serves full metadata for one item. The TV asks for this only after D-pad
// focus settles, so it is worth caching for longer than a home row.
func (s *Server) handleItem(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
	}
	// Version the entry when the detail contract grows so older cached payloads cannot
	// hide newly requested fields such as People.
	key := cache.UserKey(sess.EmbyUserID, "item:v2:"+itemID)

	if raw, err := s.cache.Get(ctx, key); err == nil {
		w.Header().Set("X-Memby-Cache", "hit")
		writeRaw(w, http.StatusOK, raw)
		return
	}

	item, err := s.emby.Item(ctx, credentials(sess), itemID, fieldsDetail)
	if err != nil {
		s.writeUpstreamError(w, err, "could not load the item")
		return
	}
	if err := s.cache.Set(ctx, key, item, s.cfg.ItemTTL); err != nil {
		s.log.Warn("item cache write failed", "error", err)
	}
	w.Header().Set("X-Memby-Cache", "miss")
	writeRaw(w, http.StatusOK, item)
}

// handleSeriesEpisodes supplies the complete episode browser in one cached response.
// The TV groups by ParentIndexNumber locally, so changing seasons never reaches Emby.
func (s *Server) handleSeriesEpisodes(w http.ResponseWriter, r *http.Request, sess store.Session) {
	ctx := r.Context()
	seriesID := r.PathValue("id")
	if seriesID == "" {
		writeError(w, http.StatusBadRequest, "series id is required")
		return
	}
	key := cache.UserKey(sess.EmbyUserID, "series-episodes:"+seriesID)
	if raw, err := s.cache.Get(ctx, key); err == nil {
		w.Header().Set("X-Memby-Cache", "hit")
		writeRaw(w, http.StatusOK, raw)
		return
	}

	result, err := s.emby.Episodes(ctx, credentials(sess), seriesID, url.Values{
		"UserId":           {sess.EmbyUserID},
		"Fields":           {"Overview,RunTimeTicks,SeriesName,PrimaryImageAspectRatio"},
		"EnableUserData":   {"true"},
		"EnableImages":     {"true"},
		"EnableImageTypes": {"Primary,Thumb,Backdrop"},
		"ImageTypeLimit":   {"1"},
		"Limit":            {"1000"},
	})
	if err != nil {
		s.writeUpstreamError(w, err, "could not load series episodes")
		return
	}
	items := result.Items
	if items == nil {
		items = []json.RawMessage{}
	}
	body, err := json.Marshal(seriesEpisodesResponse{Items: items})
	if err != nil {
		writeError(w, http.StatusInternalServerError, "could not encode series episodes")
		return
	}
	if err := s.cache.Set(ctx, key, body, s.cfg.ItemTTL); err != nil {
		s.log.Warn("series episodes cache write failed", "error", err)
	}
	w.Header().Set("X-Memby-Cache", "miss")
	writeRaw(w, http.StatusOK, body)
}

// handleTrailer answers with the item's first local trailer, or 404 when it has none.
// The screensaver's Play action uses this before asking for a playback URL.
func (s *Server) handleTrailer(w http.ResponseWriter, r *http.Request, sess store.Session) {
	itemID := r.PathValue("id")
	if itemID == "" {
		writeError(w, http.StatusBadRequest, "item id is required")
		return
	}
	result, err := s.emby.LocalTrailers(r.Context(), credentials(sess), itemID)
	if err != nil {
		s.writeUpstreamError(w, err, "could not load trailers")
		return
	}
	if len(result.Items) == 0 {
		writeError(w, http.StatusNotFound, "no trailer available")
		return
	}
	writeRaw(w, http.StatusOK, result.Items[0])
}

func (s *Server) handleFavorite(w http.ResponseWriter, r *http.Request, sess store.Session) {
	s.setFlag(w, r, sess, func(itemID string, value bool) (json.RawMessage, error) {
		return s.emby.SetFavorite(r.Context(), credentials(sess), itemID, value)
	})
}

func (s *Server) handlePlayed(w http.ResponseWriter, r *http.Request, sess store.Session) {
	s.setFlag(w, r, sess, func(itemID string, value bool) (json.RawMessage, error) {
		return s.emby.SetPlayed(r.Context(), credentials(sess), itemID, value)
	})
}

// setFlag applies a user-data mutation and drops this user's cached views, so the next
// home request reflects it rather than serving the row it just contradicted.
func (s *Server) setFlag(
	w http.ResponseWriter,
	r *http.Request,
	sess store.Session,
	apply func(itemID string, value bool) (json.RawMessage, error),
) {
	itemID := r.PathValue("id")
	if itemID == "" {
		writeError(w, http.StatusBadRequest, "item id is required")
		return
	}
	var req flagRequest
	if err := json.NewDecoder(http.MaxBytesReader(w, r.Body, 4<<10)).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "malformed request body")
		return
	}

	userData, err := apply(itemID, req.Value)
	if err != nil {
		s.writeUpstreamError(w, err, "could not update the item")
		return
	}
	if err := s.cache.InvalidateUser(r.Context(), sess.EmbyUserID); err != nil {
		s.log.Warn("cache invalidation failed", "error", err)
	}
	if s.forYou != nil {
		s.forYou.MarkDirty(r.Context(), sess)
		s.forYou.RefreshAsync(sess, true)
	}
	writeRaw(w, http.StatusOK, userData)
}