package databag

import (
	"databag/internal/store"
	"errors"
	"github.com/gorilla/mux"
	"gorm.io/gorm"
	"net/http"
)

func RemoveChannelTopic(w http.ResponseWriter, r *http.Request) {

	// scan parameters
	params := mux.Vars(r)
	channelID := params["channelID"]
	topicID := params["topicID"]

	channelSlot, guid, code, err := getChannelSlot(r, true)
	if err != nil {
		ErrResponse(w, code, err)
		return
	}
	act := &channelSlot.Account

	// load topic
	var topicSlot store.TopicSlot
	if ret := store.DB.Preload("Topic.Channel.ChannelSlot").Where("account_id = ? AND topic_slot_id = ?", act.ID, topicID).First(&topicSlot).Error; ret != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			ErrResponse(w, http.StatusNotFound, ret)
		} else {
			ErrResponse(w, http.StatusInternalServerError, ret)
		}
	}
	if topicSlot.Topic == nil {
		ErrResponse(w, http.StatusNotFound, errors.New("referenced empty topic"))
		return
	}
	if topicSlot.Topic.Channel.ChannelSlot.ChannelSlotID != channelID {
		ErrResponse(w, http.StatusNotFound, errors.New("channel topic not found"))
		return
	}

	// check permission
	if act.GUID != guid && topicSlot.Topic.GUID != guid {
		ErrResponse(w, http.StatusUnauthorized, errors.New("not creator of topic or host"))
		return
	}

	err = store.DB.Transaction(func(tx *gorm.DB) error {

		if res := tx.Where("topic_id = ?", topicSlot.Topic.ID).Delete(&store.Tag{}).Error; res != nil {
			return res
		}
		if res := tx.Where("topic_id = ?", topicSlot.Topic.ID).Delete(&store.TagSlot{}).Error; res != nil {
			return res
		}
		if res := tx.Where("topic_id = ?", topicSlot.Topic.ID).Delete(&store.Asset{}).Error; res != nil {
			return res
		}
		if res := tx.Delete(&topicSlot.Topic).Error; res != nil {
			return res
		}
		topicSlot.Topic = nil
		if res := tx.Model(&topicSlot).Update("revision", act.ChannelRevision+1).Error; res != nil {
			return res
		}
		if res := tx.Model(&channelSlot.Channel).Update("topic_revision", act.ChannelRevision+1).Error; res != nil {
			return res
		}
		if res := tx.Model(&channelSlot).Update("revision", act.ChannelRevision+1).Error; res != nil {
			return res
		}
		if res := tx.Model(act).Update("channel_revision", act.ChannelRevision+1).Error; res != nil {
			return res
		}
		return nil
	})
	if err != nil {
		ErrResponse(w, http.StatusInternalServerError, err)
		return
	}

	// cleanup file assets
	go garbageCollect(act)

	// determine affected contact list
	cards := make(map[string]store.Card)
	for _, card := range channelSlot.Channel.Cards {
		cards[card.GUID] = card
	}
	for _, group := range channelSlot.Channel.Groups {
		for _, card := range group.Cards {
			cards[card.GUID] = card
		}
	}

	SetStatus(act)
	for _, card := range cards {
		SetContactChannelNotification(act, &card)
	}
	WriteResponse(w, nil)
}