// 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"
	"encoding/json"
	"fmt"
	"strings"

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

type CurrentStateInternalAPI interface {
	QueryCurrentState(ctx context.Context, req *QueryCurrentStateRequest, res *QueryCurrentStateResponse) error
}

type QueryCurrentStateRequest struct {
	RoomID      string
	StateTuples []gomatrixserverlib.StateKeyTuple
}

type QueryCurrentStateResponse struct {
	StateEvents map[gomatrixserverlib.StateKeyTuple]gomatrixserverlib.HeaderedEvent
}

// MarshalJSON stringifies the StateKeyTuple keys so they can be sent over the wire in HTTP API mode.
func (r *QueryCurrentStateResponse) MarshalJSON() ([]byte, error) {
	se := make(map[string]gomatrixserverlib.HeaderedEvent, len(r.StateEvents))
	for k, v := range r.StateEvents {
		// use 0x1F (unit separator) as the delimiter between type/state key,
		se[fmt.Sprintf("%s\x1F%s", k.EventType, k.StateKey)] = v
	}
	return json.Marshal(se)
}

func (r *QueryCurrentStateResponse) UnmarshalJSON(data []byte) error {
	res := make(map[string]gomatrixserverlib.HeaderedEvent)
	err := json.Unmarshal(data, &res)
	if err != nil {
		return err
	}
	r.StateEvents = make(map[gomatrixserverlib.StateKeyTuple]gomatrixserverlib.HeaderedEvent, len(res))
	for k, v := range res {
		fields := strings.Split(k, "\x1F")
		r.StateEvents[gomatrixserverlib.StateKeyTuple{
			EventType: fields[0],
			StateKey:  fields[1],
		}] = v
	}
	return nil
}