package api

import (
	"encoding/json"
	"net/http"
	"strconv"
)

func (h *apiHandler) addReaction(w http.ResponseWriter, r *http.Request) {
	userID, _ := userIDFrom(r.Context())
	convID, msgID, ok := h.parseMessagePath(w, r)
	if !ok {
		return
	}
	var req struct {
		Emoji string `json:"emoji"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	if len(req.Emoji) == 0 || len(req.Emoji) > 32 {
		writeError(w, http.StatusBadRequest, "emoji must be 1-32 chars")
		return
	}

	if err := h.store.AddReaction(r.Context(), msgID, userID, req.Emoji); err != nil {
		writeError(w, http.StatusInternalServerError, "internal server error")
		return
	}
	h.hub.PublishReactionChanged(convID, msgID, userID, req.Emoji, true)
	h.writeMessageWithReactions(w, r, convID, msgID)
}

func (h *apiHandler) removeReaction(w http.ResponseWriter, r *http.Request) {
	userID, _ := userIDFrom(r.Context())
	convID, msgID, ok := h.parseMessagePath(w, r)
	if !ok {
		return
	}
	emoji := r.PathValue("emoji")
	if emoji == "" {
		writeError(w, http.StatusBadRequest, "emoji is required")
		return
	}

	if err := h.store.RemoveReaction(r.Context(), msgID, userID, emoji); err != nil {
		writeError(w, http.StatusInternalServerError, "internal server error")
		return
	}
	h.hub.PublishReactionChanged(convID, msgID, userID, emoji, false)
	h.writeMessageWithReactions(w, r, convID, msgID)
}

func (h *apiHandler) parseMessagePath(w http.ResponseWriter, r *http.Request) (convID, msgID int64, ok bool) {
	userID, _ := userIDFrom(r.Context())
	convID, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil || convID <= 0 {
		writeError(w, http.StatusBadRequest, "invalid conversation id")
		return 0, 0, false
	}
	msgID, err = strconv.ParseInt(r.PathValue("msg_id"), 10, 64)
	if err != nil || msgID <= 0 {
		writeError(w, http.StatusBadRequest, "invalid message id")
		return 0, 0, false
	}
	if member, err := h.store.IsMember(r.Context(), convID, userID); err != nil || !member {
		writeError(w, http.StatusForbidden, "not a member")
		return 0, 0, false
	}
	belongs, err := h.store.MessageBelongsToConversation(r.Context(), convID, msgID)
	if err != nil || !belongs {
		writeError(w, http.StatusNotFound, "message not found")
		return 0, 0, false
	}
	return convID, msgID, true
}

func (h *apiHandler) writeMessageWithReactions(w http.ResponseWriter, r *http.Request, convID, msgID int64) {
	msg, err := h.store.GetMessageByID(r.Context(), msgID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal server error")
		return
	}
	msgs := []messageJSON{toMessageJSON(msg)}
	reactions, err := h.store.ReactionsForMessages(r.Context(), []int64{msgID})
	if err != nil {
		writeError(w, http.StatusInternalServerError, "internal server error")
		return
	}
	attachReactions(msgs, reactions)
	writeJSON(w, http.StatusOK, msgs[0])
}