// 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 cosmosdb

import (
	"context"
	"database/sql"

	"github.com/matrix-org/dendrite/internal/sqlutil"
)

// const txnIDSchema = `
// -- Keeps a count of the current transaction ID
// CREATE TABLE IF NOT EXISTS appservice_counters (
//   name TEXT PRIMARY KEY NOT NULL,
//   last_id INTEGER DEFAULT 1
// );
// INSERT OR IGNORE INTO appservice_counters (name, last_id) VALUES('txn_id', 1);
// `

// const selectTxnIDSQL = `
//   SELECT last_id FROM appservice_counters WHERE name='txn_id';
//   UPDATE appservice_counters SET last_id=last_id+1 WHERE name='txn_id';
// `

type txnStatements struct {
	db              *Database
	writer          sqlutil.Writer
	selectTxnIDStmt *sql.Stmt
	tableName string
}

func (s *txnStatements) prepare(db *Database, writer sqlutil.Writer) (err error) {
	s.db = db
	s.writer = writer
	//Only used for the seq generation
	s.tableName = "counters"
	return
}

// selectTxnID selects the latest ascending transaction ID
func (s *txnStatements) selectTxnID(
	ctx context.Context,
) (txnID int, err error) {
	return GetNextCounterTXNID(s, ctx)
}