// Copyright 2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package api

import (
	"context"

	"github.com/matrix-org/gomatrixserverlib"
	"github.com/matrix-org/util"
)

// GetEvent returns the current state event in the room or nil.
func GetEvent(ctx context.Context, stateAPI CurrentStateInternalAPI, roomID string, tuple gomatrixserverlib.StateKeyTuple) *gomatrixserverlib.HeaderedEvent {
	var res QueryCurrentStateResponse
	err := stateAPI.QueryCurrentState(ctx, &QueryCurrentStateRequest{
		RoomID:      roomID,
		StateTuples: []gomatrixserverlib.StateKeyTuple{tuple},
	}, &res)
	if err != nil {
		util.GetLogger(ctx).WithError(err).Error("Failed to QueryCurrentState")
		return nil
	}
	ev, ok := res.StateEvents[tuple]
	if ok {
		return ev
	}
	return nil
}

// PopulatePublicRooms extracts PublicRoom information for all the provided room IDs. The IDs are not checked to see if they are visible in the
// published room directory.
// due to lots of switches
// nolint:gocyclo
func PopulatePublicRooms(ctx context.Context, roomIDs []string, stateAPI CurrentStateInternalAPI) ([]gomatrixserverlib.PublicRoom, error) {
	avatarTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.avatar", StateKey: ""}
	nameTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.name", StateKey: ""}
	canonicalTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomCanonicalAlias, StateKey: ""}
	topicTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.topic", StateKey: ""}
	guestTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.guest_access", StateKey: ""}
	visibilityTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomHistoryVisibility, StateKey: ""}
	joinRuleTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomJoinRules, StateKey: ""}

	var stateRes QueryBulkStateContentResponse
	err := stateAPI.QueryBulkStateContent(ctx, &QueryBulkStateContentRequest{
		RoomIDs:        roomIDs,
		AllowWildcards: true,
		StateTuples: []gomatrixserverlib.StateKeyTuple{
			nameTuple, canonicalTuple, topicTuple, guestTuple, visibilityTuple, joinRuleTuple, avatarTuple,
			{EventType: gomatrixserverlib.MRoomMember, StateKey: "*"},
		},
	}, &stateRes)
	if err != nil {
		util.GetLogger(ctx).WithError(err).Error("QueryBulkStateContent failed")
		return nil, err
	}
	chunk := make([]gomatrixserverlib.PublicRoom, len(roomIDs))
	i := 0
	for roomID, data := range stateRes.Rooms {
		pub := gomatrixserverlib.PublicRoom{
			RoomID: roomID,
		}
		joinCount := 0
		var joinRule, guestAccess string
		for tuple, contentVal := range data {
			if tuple.EventType == gomatrixserverlib.MRoomMember && contentVal == "join" {
				joinCount++
				continue
			}
			switch tuple {
			case avatarTuple:
				pub.AvatarURL = contentVal
			case nameTuple:
				pub.Name = contentVal
			case topicTuple:
				pub.Topic = contentVal
			case canonicalTuple:
				pub.CanonicalAlias = contentVal
			case visibilityTuple:
				pub.WorldReadable = contentVal == "world_readable"
			// need both of these to determine whether guests can join
			case joinRuleTuple:
				joinRule = contentVal
			case guestTuple:
				guestAccess = contentVal
			}
		}
		if joinRule == gomatrixserverlib.Public && guestAccess == "can_join" {
			pub.GuestCanJoin = true
		}
		pub.JoinedMembersCount = joinCount
		chunk[i] = pub
		i++
	}
	return chunk, nil
}