// Copyright 2017-2018 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 cosmosdb

import (
	"context"
	"database/sql"
	"fmt"
	"time"

	"github.com/matrix-org/dendrite/internal/cosmosdbapi"
	"github.com/matrix-org/dendrite/roomserver/storage/tables"
	"github.com/matrix-org/dendrite/roomserver/types"
)

// const stateSnapshotSchema = `
//   CREATE TABLE IF NOT EXISTS roomserver_state_snapshots (
//     state_snapshot_nid INTEGER PRIMARY KEY AUTOINCREMENT,
//     room_nid INTEGER NOT NULL,
//     state_block_nids TEXT NOT NULL DEFAULT '[]'
//   );
// `

type StateSnapshotCosmos struct {
	StateSnapshotNID int64   `json:"state_snapshot_nid"`
	RoomNID          int64   `json:"room_nid"`
	StateBlockNIDs   []int64 `json:"state_block_nids"`
}

type StateSnapshotCosmosData struct {
	Id            string              `json:"id"`
	Pk            string              `json:"_pk"`
	Cn            string              `json:"_cn"`
	ETag          string              `json:"_etag"`
	Timestamp     int64               `json:"_ts"`
	StateSnapshot StateSnapshotCosmos `json:"mx_roomserver_state_snapshot"`
}

// const insertStateSQL = `
// 	INSERT INTO roomserver_state_snapshots (room_nid, state_block_nids)
// 	  VALUES ($1, $2);`

// Bulk state data NID lookup.
// Sorting by state_snapshot_nid means we can use binary search over the result
// to lookup the state data NIDs for a state snapshot NID.
// 	"SELECT state_snapshot_nid, state_block_nids FROM roomserver_state_snapshots" +
// 	" WHERE state_snapshot_nid IN ($1) ORDER BY state_snapshot_nid ASC"
const bulkSelectStateBlockNIDsSQL = "" +
	"select * from c where c._cn = @x1 " +
	"and ARRAY_CONTAINS(@x2, c.mx_roomserver_state_snapshot.state_snapshot_nid) " +
	"order by c.mx_roomserver_state_snapshot.state_snapshot_nid asc"

type stateSnapshotStatements struct {
	db *Database
	// insertStateStmt              *sql.Stmt
	bulkSelectStateBlockNIDsStmt string
	tableName                    string
}

func mapFromStateBlockNIDArray(stateBlockNIDs []types.StateBlockNID) []int64 {
	result := []int64{}
	for i := 0; i < len(stateBlockNIDs); i++ {
		result = append(result, int64(stateBlockNIDs[i]))
	}
	return result
}

func mapToStateBlockNIDArray(stateBlockNIDs []int64) []types.StateBlockNID {
	result := []types.StateBlockNID{}
	for i := 0; i < len(stateBlockNIDs); i++ {
		result = append(result, types.StateBlockNID(stateBlockNIDs[i]))
	}
	return result
}

func NewCosmosDBStateSnapshotTable(db *Database) (tables.StateSnapshot, error) {
	s := &stateSnapshotStatements{
		db: db,
	}

	// return s, shared.StatementList{
	// 	{&s.insertStateStmt, insertStateSQL},
	s.bulkSelectStateBlockNIDsStmt = bulkSelectStateBlockNIDsSQL
	// }.Prepare(db)
	s.tableName = "state_snapshots"
	return s, nil
}

func (s *stateSnapshotStatements) InsertState(
	ctx context.Context, txn *sql.Tx, roomNID types.RoomNID, stateBlockNIDs []types.StateBlockNID,
) (stateNID types.StateSnapshotNID, err error) {

	// INSERT INTO roomserver_state_snapshots (room_nid, state_block_nids)
	// VALUES ($1, $2);`
	stateSnapshotNIDSeq, seqErr := GetNextStateSnapshotNID(s, ctx)
	if seqErr != nil {
		return 0, seqErr
	}

	data := StateSnapshotCosmos{
		RoomNID:          int64(roomNID),
		StateBlockNIDs:   mapFromStateBlockNIDArray(stateBlockNIDs),
		StateSnapshotNID: int64(stateSnapshotNIDSeq),
	}

	var dbCollectionName = cosmosdbapi.GetCollectionName(s.db.databaseName, s.tableName)

	//     state_snapshot_nid INTEGER PRIMARY KEY AUTOINCREMENT,
	docId := fmt.Sprintf("%d", stateSnapshotNIDSeq)
	cosmosDocId := cosmosdbapi.GetDocumentId(s.db.cosmosConfig.ContainerName, dbCollectionName, docId)
	pk := cosmosdbapi.GetPartitionKey(s.db.cosmosConfig.ContainerName, dbCollectionName)

	var dbData = StateSnapshotCosmosData{
		Id:            cosmosDocId,
		Cn:            dbCollectionName,
		Pk:            pk,
		Timestamp:     time.Now().Unix(),
		StateSnapshot: data,
	}

	var options = cosmosdbapi.GetCreateDocumentOptions(dbData.Pk)
	_, _, err = cosmosdbapi.GetClient(s.db.connection).CreateDocument(
		ctx,
		s.db.cosmosConfig.DatabaseName,
		s.db.cosmosConfig.ContainerName,
		&dbData,
		options)

	if err != nil {
		return 0, err
	}

	stateNID = types.StateSnapshotNID(stateSnapshotNIDSeq)
	return
}

func (s *stateSnapshotStatements) BulkSelectStateBlockNIDs(
	ctx context.Context, stateNIDs []types.StateSnapshotNID,
) ([]types.StateBlockNIDList, error) {

	// "SELECT state_snapshot_nid, state_block_nids FROM roomserver_state_snapshots" +
	// " WHERE state_snapshot_nid IN ($1) ORDER BY state_snapshot_nid ASC"
	var dbCollectionName = cosmosdbapi.GetCollectionName(s.db.databaseName, s.tableName)
	var pk = cosmosdbapi.GetPartitionKey(s.db.cosmosConfig.ContainerName, dbCollectionName)
	var response []StateSnapshotCosmosData
	params := map[string]interface{}{
		"@x1": dbCollectionName,
		"@x2": stateNIDs,
	}

	var optionsQry = cosmosdbapi.GetQueryDocumentsOptions(pk)
	var query = cosmosdbapi.GetQuery(s.bulkSelectStateBlockNIDsStmt, params)
	var _, err = cosmosdbapi.GetClient(s.db.connection).QueryDocuments(
		ctx,
		s.db.cosmosConfig.DatabaseName,
		s.db.cosmosConfig.ContainerName,
		query,
		&response,
		optionsQry)
	if err != nil {
		return nil, err
	}

	results := make([]types.StateBlockNIDList, len(stateNIDs))
	i := 0
	for _, item := range response {
		result := &results[i]
		result.StateSnapshotNID = types.StateSnapshotNID(item.StateSnapshot.StateSnapshotNID)
		result.StateBlockNIDs = mapToStateBlockNIDArray(item.StateSnapshot.StateBlockNIDs)
		i++
	}
	if i != len(stateNIDs) {
		return nil, fmt.Errorf("storage: state NIDs missing from the database (%d != %d)", i, len(stateNIDs))
	}
	return results, nil
}