// Copyright 2021 TiKV Authors
//
// 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.

// NOTE: The code in this file is based on code from the
// TiDB project, licensed under the Apache License v 2.0
//
// https://github.com/pingcap/tidb/tree/cc5e161ac06827589c4966674597c137cc9e809c/store/tikv/util/pd_interceptor.go
//

// Copyright 2020 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 util

import (
	"context"
	"sync/atomic"
	"time"

	"github.com/pingcap/kvproto/pkg/metapb"
	pd "github.com/tikv/pd/client"
	"github.com/tikv/pd/client/clients/router"
	"github.com/tikv/pd/client/clients/tso"
	"github.com/tikv/pd/client/opt"
	"github.com/tikv/pd/client/pkg/caller"
)

var (
	_ pd.Client    = &InterceptedPDClient{}
	_ tso.TSFuture = &interceptedTsFuture{}
)

func recordPDWaitTime(ctx context.Context, start time.Time) {
	stmtExec := ctx.Value(ExecDetailsKey)
	if stmtExec != nil {
		detail := stmtExec.(*ExecDetails)
		atomic.AddInt64(&detail.WaitPDRespDuration, int64(time.Since(start)))
	}
}

// InterceptedPDClient is a PD's wrapper client to record stmt detail.
type InterceptedPDClient struct {
	pd.Client
}

func NewInterceptedPDClient(client pd.Client) *InterceptedPDClient {
	return &InterceptedPDClient{client.WithCallerComponent("intercepted-pd-client")}
}

// interceptedTsFuture is a PD's wrapper future to record stmt detail.
type interceptedTsFuture struct {
	tso.TSFuture
	ctx context.Context
}

// Wait implements pd.Client#Wait.
func (m interceptedTsFuture) Wait() (int64, int64, error) {
	start := time.Now()
	physical, logical, err := m.TSFuture.Wait()
	recordPDWaitTime(m.ctx, start)
	return physical, logical, err
}

// GetTS implements pd.Client#GetTS.
func (m InterceptedPDClient) GetTS(ctx context.Context) (int64, int64, error) {
	start := time.Now()
	physical, logical, err := m.Client.GetTS(ctx)
	recordPDWaitTime(ctx, start)
	return physical, logical, err
}

// GetTSAsync implements pd.Client#GetTSAsync.
func (m InterceptedPDClient) GetTSAsync(ctx context.Context) tso.TSFuture {
	start := time.Now()
	f := m.Client.GetTSAsync(ctx)
	recordPDWaitTime(ctx, start)
	return interceptedTsFuture{
		ctx:      ctx,
		TSFuture: f,
	}
}

// GetRegion implements pd.Client#GetRegion.
func (m InterceptedPDClient) GetRegion(ctx context.Context, key []byte, opts ...opt.GetRegionOption) (*router.Region, error) {
	start := time.Now()
	r, err := m.Client.GetRegion(ctx, key, opts...)
	recordPDWaitTime(ctx, start)
	return r, err
}

// GetPrevRegion implements pd.Client#GetPrevRegion.
func (m InterceptedPDClient) GetPrevRegion(ctx context.Context, key []byte, opts ...opt.GetRegionOption) (*router.Region, error) {
	start := time.Now()
	r, err := m.Client.GetPrevRegion(ctx, key, opts...)
	recordPDWaitTime(ctx, start)
	return r, err
}

// GetRegionByID implements pd.Client#GetRegionByID.
func (m InterceptedPDClient) GetRegionByID(ctx context.Context, regionID uint64, opts ...opt.GetRegionOption) (*router.Region, error) {
	start := time.Now()
	r, err := m.Client.GetRegionByID(ctx, regionID, opts...)
	recordPDWaitTime(ctx, start)
	return r, err
}

// ScanRegions implements pd.Client#ScanRegions.
func (m InterceptedPDClient) ScanRegions(ctx context.Context, key, endKey []byte, limit int, opts ...opt.GetRegionOption) ([]*router.Region, error) {
	start := time.Now()
	// TODO: ScanRegions has been deprecated in favor of BatchScanRegions.
	r, err := m.Client.ScanRegions(ctx, key, endKey, limit, opts...)
	recordPDWaitTime(ctx, start)
	return r, err
}

// GetStore implements pd.Client#GetStore.
func (m InterceptedPDClient) GetStore(ctx context.Context, storeID uint64) (*metapb.Store, error) {
	start := time.Now()
	s, err := m.Client.GetStore(ctx, storeID)
	recordPDWaitTime(ctx, start)
	return s, err
}

// WithCallerComponent implements pd.Client#WithCallerComponent.
func (m InterceptedPDClient) WithCallerComponent(component caller.Component) pd.Client {
	return NewInterceptedPDClient(m.Client.WithCallerComponent(component))
}