// Copyright 2017 Vector Creations Ltd
// Copyright 2018 New Vector Ltd
// Copyright 2019-2020 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 database

import (
	"context"

	"github.com/matrix-org/dendrite/roomserver/types"
)

// A RoomStateDatabase has the storage APIs needed to load state from the database
type RoomStateDatabase interface {
	// Store the room state at an event in the database
	AddState(
		ctx context.Context,
		roomNID types.RoomNID,
		stateBlockNIDs []types.StateBlockNID,
		state []types.StateEntry,
	) (types.StateSnapshotNID, error)
	// Look up the state of a room at each event for a list of string event IDs.
	// Returns an error if there is an error talking to the database
	// Returns a types.MissingEventError if the room state for the event IDs aren't in the database
	StateAtEventIDs(ctx context.Context, eventIDs []string) ([]types.StateAtEvent, error)
	// Look up the numeric IDs for a list of string event types.
	// Returns a map from string event type to numeric ID for the event type.
	EventTypeNIDs(ctx context.Context, eventTypes []string) (map[string]types.EventTypeNID, error)
	// Look up the numeric IDs for a list of string event state keys.
	// Returns a map from string state key to numeric ID for the state key.
	EventStateKeyNIDs(ctx context.Context, eventStateKeys []string) (map[string]types.EventStateKeyNID, error)
	// Look up the numeric state data IDs for each numeric state snapshot ID
	// The returned slice is sorted by numeric state snapshot ID.
	StateBlockNIDs(ctx context.Context, stateNIDs []types.StateSnapshotNID) ([]types.StateBlockNIDList, error)
	// Look up the state data for each numeric state data ID
	// The returned slice is sorted by numeric state data ID.
	StateEntries(ctx context.Context, stateBlockNIDs []types.StateBlockNID) ([]types.StateEntryList, error)
	// Look up the state data for the state key tuples for each numeric state block ID
	// This is used to fetch a subset of the room state at a snapshot.
	// If a block doesn't contain any of the requested tuples then it can be discarded from the result.
	// The returned slice is sorted by numeric state block ID.
	StateEntriesForTuples(
		ctx context.Context,
		stateBlockNIDs []types.StateBlockNID,
		stateKeyTuples []types.StateKeyTuple,
	) ([]types.StateEntryList, error)
	// Look up the Events for a list of numeric event IDs.
	// Returns a sorted list of events.
	Events(ctx context.Context, eventNIDs []types.EventNID) ([]types.Event, error)
	// Look up snapshot NID for an event ID string
	SnapshotNIDFromEventID(ctx context.Context, eventID string) (types.StateSnapshotNID, error)
}