// Copyright 2019 PingCAP, Inc.
//
// 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 bindinfo

import (
	"time"

	"github.com/pingcap/tidb/pkg/sessionctx/vardef"
	"github.com/pingcap/tidb/pkg/sessionctx/variable"
	"github.com/pingcap/tidb/pkg/util"
)

// Lease influences the duration of loading bind info and handling invalid bind.
var Lease = 3 * time.Second

const (
	// OwnerKey is the bindinfo owner path that is saved to etcd.
	OwnerKey = "/tidb/bindinfo/owner"
	// Prompt is the prompt for bindinfo owner manager.
	Prompt = "bindinfo"
	// BuiltinPseudoSQL4BindLock is used to simulate LOCK TABLE for mysql.bind_info.
	BuiltinPseudoSQL4BindLock = "builtin_pseudo_sql_for_bind_lock"

	// LockBindInfoSQL simulates LOCK TABLE by updating a same row in each pessimistic transaction.
	LockBindInfoSQL = `UPDATE mysql.bind_info SET source= 'builtin' WHERE original_sql= 'builtin_pseudo_sql_for_bind_lock'`

	// StmtRemoveDuplicatedPseudoBinding is used to remove duplicated pseudo binding.
	// After using BR to sync bind_info between two clusters, the pseudo binding may be duplicated, and
	// BR use this statement to remove duplicated rows, and this SQL should only be executed by BR.
	StmtRemoveDuplicatedPseudoBinding = `DELETE FROM mysql.bind_info
       WHERE original_sql='builtin_pseudo_sql_for_bind_lock' AND
       _tidb_rowid NOT IN ( -- keep one arbitrary pseudo binding
         SELECT _tidb_rowid FROM mysql.bind_info WHERE original_sql='builtin_pseudo_sql_for_bind_lock' limit 1)`
)

// BindingHandle is used to handle all sql bind operations.
type BindingHandle interface {
	BindingCacheUpdater

	BindingOperator

	BindingPlanEvolution

	variable.Statistics
}

// bindingHandle is used to handle all sql bind operations.
type bindingHandle struct {
	BindingCacheUpdater
	BindingOperator
	BindingPlanEvolution
}

// NewBindingHandle creates a new BindingHandle.
func NewBindingHandle(sPool util.DestroyableSessionPool) BindingHandle {
	cache := NewBindingCacheUpdater(sPool)
	op := newBindingOperator(sPool, cache)
	auto := newBindingAuto(sPool)
	h := &bindingHandle{BindingOperator: op, BindingCacheUpdater: cache, BindingPlanEvolution: auto}
	variable.RegisterStatistics(h)
	return h
}

var (
	lastPlanBindingUpdateTime = "last_plan_binding_update_time"
)

// GetScope gets the status variables scope.
func (*bindingHandle) GetScope(_ string) vardef.ScopeFlag {
	return vardef.ScopeSession
}

// Stats returns the server statistics.
func (h *bindingHandle) Stats(_ *variable.SessionVars) (map[string]any, error) {
	m := make(map[string]any)
	m[lastPlanBindingUpdateTime] = h.LastUpdateTime().String()
	return m, nil
}