// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"context"
	"os"
	"path/filepath"
	"sort"
	"time"

	"github.com/minio/dperf/pkg/dperf"
	"github.com/minio/madmin-go"
)

var dperfUUID = mustGetUUID()

type speedTestOpts struct {
	throughputSize   int
	concurrencyStart int
	duration         time.Duration
	autotune         bool
	storageClass     string
}

// Get the max throughput and iops numbers.
func objectSpeedTest(ctx context.Context, opts speedTestOpts) chan madmin.SpeedTestResult {
	ch := make(chan madmin.SpeedTestResult, 1)
	go func() {
		defer close(ch)

		concurrency := opts.concurrencyStart

		throughputHighestGet := uint64(0)
		throughputHighestPut := uint64(0)
		var throughputHighestResults []SpeedtestResult

		sendResult := func() {
			var result madmin.SpeedTestResult

			durationSecs := opts.duration.Seconds()

			result.GETStats.ThroughputPerSec = throughputHighestGet / uint64(durationSecs)
			result.GETStats.ObjectsPerSec = throughputHighestGet / uint64(opts.throughputSize) / uint64(durationSecs)
			result.PUTStats.ThroughputPerSec = throughputHighestPut / uint64(durationSecs)
			result.PUTStats.ObjectsPerSec = throughputHighestPut / uint64(opts.throughputSize) / uint64(durationSecs)
			for i := 0; i < len(throughputHighestResults); i++ {
				errStr := ""
				if throughputHighestResults[i].Error != "" {
					errStr = throughputHighestResults[i].Error
				}
				result.PUTStats.Servers = append(result.PUTStats.Servers, madmin.SpeedTestStatServer{
					Endpoint:         throughputHighestResults[i].Endpoint,
					ThroughputPerSec: throughputHighestResults[i].Uploads / uint64(durationSecs),
					ObjectsPerSec:    throughputHighestResults[i].Uploads / uint64(opts.throughputSize) / uint64(durationSecs),
					Err:              errStr,
				})
				result.GETStats.Servers = append(result.GETStats.Servers, madmin.SpeedTestStatServer{
					Endpoint:         throughputHighestResults[i].Endpoint,
					ThroughputPerSec: throughputHighestResults[i].Downloads / uint64(durationSecs),
					ObjectsPerSec:    throughputHighestResults[i].Downloads / uint64(opts.throughputSize) / uint64(durationSecs),
					Err:              errStr,
				})
			}

			result.Size = opts.throughputSize
			result.Disks = globalEndpoints.NEndpoints()
			result.Servers = len(globalNotificationSys.peerClients) + 1
			result.Version = Version
			result.Concurrent = concurrency

			ch <- result
		}

		for {
			select {
			case <-ctx.Done():
				// If the client got disconnected stop the speedtest.
				return
			default:
			}

			results := globalNotificationSys.Speedtest(ctx,
				opts.throughputSize, concurrency,
				opts.duration, opts.storageClass)
			sort.Slice(results, func(i, j int) bool {
				return results[i].Endpoint < results[j].Endpoint
			})

			totalPut := uint64(0)
			totalGet := uint64(0)
			for _, result := range results {
				totalPut += result.Uploads
				totalGet += result.Downloads
			}

			if totalGet < throughputHighestGet {
				// Following check is for situations
				// when Writes() scale higher than Reads()
				// - practically speaking this never happens
				// and should never happen - however it has
				// been seen recently due to hardware issues
				// causes Reads() to go slower than Writes().
				//
				// Send such results anyways as this shall
				// expose a problem underneath.
				if totalPut > throughputHighestPut {
					throughputHighestResults = results
					throughputHighestPut = totalPut
					// let the client see lower value as well
					throughputHighestGet = totalGet
				}
				sendResult()
				break
			}

			doBreak := float64(totalGet-throughputHighestGet)/float64(totalGet) < 0.025

			throughputHighestGet = totalGet
			throughputHighestResults = results
			throughputHighestPut = totalPut

			if doBreak {
				sendResult()
				break
			}

			for _, result := range results {
				if result.Error != "" {
					// Break out on errors.
					sendResult()
					return
				}
			}

			sendResult()
			if !opts.autotune {
				break
			}

			// Try with a higher concurrency to see if we get better throughput
			concurrency += (concurrency + 1) / 2
		}
	}()
	return ch
}

// speedTest - Deprecated. See objectSpeedTest
func speedTest(ctx context.Context, opts speedTestOpts) chan madmin.SpeedTestResult {
	return objectSpeedTest(ctx, opts)
}

func driveSpeedTest(ctx context.Context, opts madmin.DriveSpeedTestOpts) madmin.DriveSpeedTestResult {
	perf := &dperf.DrivePerf{
		Serial:    opts.Serial,
		BlockSize: opts.BlockSize,
		FileSize:  opts.FileSize,
	}
	paths := func() []string {
		toRet := []string{}
		paths := globalEndpoints.LocalDisksPaths()
		for _, p := range paths {
			dperfFilename := filepath.Join(p, ".minio.sys", "tmp", dperfUUID)
			if _, err := os.Stat(dperfFilename); err == nil {
				// file exists, so remove it
				os.Remove(dperfFilename)
			}
			toRet = append(toRet, dperfFilename)
		}
		return toRet
	}()

	perfs, err := perf.Run(ctx, paths...)
	return madmin.DriveSpeedTestResult{
		Endpoint: globalLocalNodeName,
		Version:  Version,
		DrivePerf: func() []madmin.DrivePerf {
			results := []madmin.DrivePerf{}
			for _, r := range perfs {
				result := madmin.DrivePerf{
					Path:            r.Path,
					ReadThroughput:  r.ReadThroughput,
					WriteThroughput: r.WriteThroughput,
					Error: func() string {
						if r.Error != nil {
							return r.Error.Error()
						}
						return ""
					}(),
				}
				results = append(results, result)
			}
			return results
		}(),
		Error: func() string {
			if err != nil {
				return err.Error()
			}
			return ""
		}(),
	}
}