// +build windows

package win_perf_counters

import (
	"errors"
	"fmt"
	"strings"
	"syscall"
	"unsafe"

	"os"
	"os/signal"

	"github.com/influxdata/telegraf"
	"github.com/influxdata/telegraf/plugins/inputs"
	"github.com/lxn/win"
)

var sampleConfig string = `
  # By default this plugin returns basic CPU and Disk statistics.
  # See the README file for more examples.
  # Uncomment examples below or write your own as you see fit. If the system
  # being polled for data does not have the Object at startup of the Telegraf
  # agent, it will not be gathered.
  # Settings:
  # PrintValid = false # Print All matching performance counters

  [[inputs.win_perf_counters.object]]
    # Processor usage, alternative to native, reports on a per core.
    ObjectName = "Processor"
    Instances = ["*"]
    Counters = [
      "%% Idle Time", "%% Interrupt Time",
      "%% Privileged Time", "%% User Time",
      "%% Processor Time"
    ]
    Measurement = "win_cpu"
    # Set to true to include _Total instance when querying for all (*).
    # IncludeTotal=false
    # Print out when the performance counter is missing from object, counter or instance.
    # WarnOnMissing = false

  [[inputs.win_perf_counters.object]]
    # Disk times and queues
    ObjectName = "LogicalDisk"
    Instances = ["*"]
    Counters = [
      "%% Idle Time", "%% Disk Time","%% Disk Read Time",
      "%% Disk Write Time", "%% User Time", "Current Disk Queue Length"
    ]
    Measurement = "win_disk"

  [[inputs.win_perf_counters.object]]
    ObjectName = "System"
    Counters = ["Context Switches/sec","System Calls/sec"]
    Instances = ["------"]
    Measurement = "win_system"

  [[inputs.win_perf_counters.object]]
    # Example query where the Instance portion must be removed to get data back,
    # such as from the Memory object.
    ObjectName = "Memory"
    Counters = [
      "Available Bytes", "Cache Faults/sec", "Demand Zero Faults/sec",
      "Page Faults/sec", "Pages/sec", "Transition Faults/sec",
      "Pool Nonpaged Bytes", "Pool Paged Bytes"
    ]
    Instances = ["------"] # Use 6 x - to remove the Instance bit from the query.
    Measurement = "win_mem"
`

// Valid queries end up in this map.
var gItemList = make(map[int]*item)

var configParsed bool
var testConfigParsed bool
var testObject string

type Win_PerfCounters struct {
	PrintValid bool
	TestName   string
	Object     []perfobject
}

type perfobject struct {
	ObjectName    string
	Counters      []string
	Instances     []string
	Measurement   string
	WarnOnMissing bool
	FailOnMissing bool
	IncludeTotal  bool
}

// Parsed configuration ends up here after it has been validated for valid
// Performance Counter paths
type itemList struct {
	items map[int]*item
}

type item struct {
	query         string
	objectName    string
	counter       string
	instance      string
	measurement   string
	include_total bool
	handle        win.PDH_HQUERY
	counterHandle win.PDH_HCOUNTER
}

func (m *Win_PerfCounters) AddItem(metrics *itemList, query string, objectName string, counter string, instance string,
	measurement string, include_total bool) {

	var handle win.PDH_HQUERY
	var counterHandle win.PDH_HCOUNTER
	ret := win.PdhOpenQuery(0, 0, &handle)
	ret = win.PdhAddEnglishCounter(handle, query, 0, &counterHandle)

	_ = ret

	temp := &item{query, objectName, counter, instance, measurement,
		include_total, handle, counterHandle}
	index := len(gItemList)
	gItemList[index] = temp

	if metrics.items == nil {
		metrics.items = make(map[int]*item)
	}
	metrics.items[index] = temp
}

func (m *Win_PerfCounters) InvalidObject(exists uint32, query string, PerfObject perfobject, instance string, counter string) error {
	if exists == 3221228472 { // win.PDH_CSTATUS_NO_OBJECT
		if PerfObject.FailOnMissing {
			err := errors.New("Performance object does not exist")
			return err
		} else if PerfObject.WarnOnMissing {
			fmt.Printf("Performance Object '%s' does not exist in query: %s\n", PerfObject.ObjectName, query)
		}
	} else if exists == 3221228473 { //win.PDH_CSTATUS_NO_COUNTER

		if PerfObject.FailOnMissing {
			err := errors.New("Counter in Performance object does not exist")
			return err
		} else if PerfObject.WarnOnMissing {
			fmt.Printf("Counter '%s' does not exist in query: %s\n", counter, query)
		}
	} else if exists == 2147485649 { //win.PDH_CSTATUS_NO_INSTANCE
		if PerfObject.FailOnMissing {
			err := errors.New("Instance in Performance object does not exist")
			return err
		} else if PerfObject.WarnOnMissing {
			fmt.Printf("Instance '%s' does not exist in query: %s\n", instance, query)

		}
	} else {
		fmt.Printf("Invalid result: %v, query: %s\n", exists, query)
		if PerfObject.FailOnMissing {
			err := errors.New("Invalid query for Performance Counters")
			return err
		}
	}
	return nil
}

func (m *Win_PerfCounters) Description() string {
	return "Input plugin to query Performance Counters on Windows operating systems"
}

func (m *Win_PerfCounters) SampleConfig() string {
	return sampleConfig
}

func (m *Win_PerfCounters) ParseConfig(metrics *itemList) error {
	var query string

	configParsed = true

	if len(m.Object) > 0 {
		for _, PerfObject := range m.Object {
			for _, counter := range PerfObject.Counters {
				for _, instance := range PerfObject.Instances {
					objectname := PerfObject.ObjectName

					if instance == "------" {
						query = "\\" + objectname + "\\" + counter
					} else {
						query = "\\" + objectname + "(" + instance + ")\\" + counter
					}

					var exists uint32 = win.PdhValidatePath(query)

					if exists == win.ERROR_SUCCESS {
						if m.PrintValid {
							fmt.Printf("Valid: %s\n", query)
						}
						m.AddItem(metrics, query, objectname, counter, instance,
							PerfObject.Measurement, PerfObject.IncludeTotal)
					} else {
						err := m.InvalidObject(exists, query, PerfObject, instance, counter)
						return err
					}
				}
			}
		}

		return nil
	} else {
		err := errors.New("No performance objects configured!")
		return err
	}
}

func (m *Win_PerfCounters) Cleanup(metrics *itemList) {
	// Cleanup

	for _, metric := range metrics.items {
		ret := win.PdhCloseQuery(metric.handle)
		_ = ret
	}
}

func (m *Win_PerfCounters) CleanupTestMode() {
	// Cleanup for the testmode.

	for _, metric := range gItemList {
		ret := win.PdhCloseQuery(metric.handle)
		_ = ret
	}
}

func (m *Win_PerfCounters) Gather(acc telegraf.Accumulator) error {
	metrics := itemList{}

	// Both values are empty in normal use.
	if m.TestName != testObject {
		// Cleanup any handles before emptying the global variable containing valid queries.
		m.CleanupTestMode()
		gItemList = make(map[int]*item)
		testObject = m.TestName
		testConfigParsed = true
		configParsed = false
	}

	// We only need to parse the config during the init, it uses the global variable after.
	if configParsed == false {

		err := m.ParseConfig(&metrics)
		if err != nil {
			return err
		}
	}

	// When interrupt or terminate is called.
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt)
	signal.Notify(c, syscall.SIGTERM)
	go func() error {
		<-c
		m.Cleanup(&metrics)
		return nil
	}()

	var bufSize uint32
	var bufCount uint32
	var size uint32 = uint32(unsafe.Sizeof(win.PDH_FMT_COUNTERVALUE_ITEM_DOUBLE{}))
	var emptyBuf [1]win.PDH_FMT_COUNTERVALUE_ITEM_DOUBLE // need at least 1 addressable null ptr.

	// For iterate over the known metrics and get the samples.
	for _, metric := range gItemList {
		// collect
		ret := win.PdhCollectQueryData(metric.handle)
		if ret == win.ERROR_SUCCESS {
			ret = win.PdhGetFormattedCounterArrayDouble(metric.counterHandle, &bufSize,
				&bufCount, &emptyBuf[0]) // uses null ptr here according to MSDN.
			if ret == win.PDH_MORE_DATA {
				filledBuf := make([]win.PDH_FMT_COUNTERVALUE_ITEM_DOUBLE, bufCount*size)
				ret = win.PdhGetFormattedCounterArrayDouble(metric.counterHandle,
					&bufSize, &bufCount, &filledBuf[0])
				for i := 0; i < int(bufCount); i++ {
					c := filledBuf[i]
					var s string = win.UTF16PtrToString(c.SzName)

					var add bool

					if metric.include_total {
						// If IncludeTotal is set, include all.
						add = true
					} else if metric.instance == "*" && !strings.Contains(s, "_Total") {
						// Catch if set to * and that it is not a '*_Total*' instance.
						add = true
					} else if metric.instance == s {
						// Catch if we set it to total or some form of it
						add = true
					} else if metric.instance == "------" {
						add = true
					}

					if add {
						fields := make(map[string]interface{})
						tags := make(map[string]string)
						if s != "" {
							tags["instance"] = s
						}
						tags["objectname"] = metric.objectName
						fields[string(metric.counter)] = float32(c.FmtValue.DoubleValue)

						var measurement string
						if metric.measurement == "" {
							measurement = "win_perf_counters"
						} else {
							measurement = metric.measurement
						}
						acc.AddFields(measurement, fields, tags)
					}
				}

				filledBuf = nil
				// Need to at least set bufSize to zero, because if not, the function will not
				// return PDH_MORE_DATA and will not set the bufSize.
				bufCount = 0
				bufSize = 0
			}

		}
	}

	return nil
}

func init() {
	inputs.Add("win_perf_counters", func() telegraf.Input { return &Win_PerfCounters{} })
}