// SPDX-License-Identifier: Apache-2.0
//
// Copyright The Prometheus 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.

//go:build windows

package pdh

import (
	"fmt"
	"log/slog"
	"math"
	"reflect"
	"runtime"
	"slices"
	"testing"
	"unsafe"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/stretchr/testify/require"
	"golang.org/x/sys/windows"
)

type rowSetValues struct {
	Name     string
	A        float64 `perfdata:"A"`
	B        float64 `perfdata:"B"`
	BSecond  float64 `perfdata:"B,secondvalue"`
	Optional float64 `perfdata:"Optional"`
}

// newRowSetTestCollector returns a collector with the counters A and B, which
// have instances, and Optional, which was skipped at Build and has none.
func newRowSetTestCollector(partialRows bool) *Collector[rowSetValues] {
	return &Collector[rowSetValues]{
		partialRows: partialRows,
		logger:      slog.New(slog.DiscardHandler),
		rows: rowAccessor[rowSetValues]{
			newRow: func(instance string) rowSetValues {
				return rowSetValues{Name: instance}
			},
			setName: func(row *rowSetValues, instance string) {
				row.Name = instance
			},
			setValue: func(row *rowSetValues, field int, value float64) {
				reflect.ValueOf(row).Elem().Field(field).SetFloat(value)
			},
		},
		counters: []Counter{
			{Name: "A", Instances: map[string]pdhCounterHandle{"*": 1}, FieldIndexValue: 1, FieldIndexSecondValue: -1},
			{Name: "B", Instances: map[string]pdhCounterHandle{"*": 2}, FieldIndexValue: 2, FieldIndexSecondValue: 3},
			{Name: "Optional", Instances: map[string]pdhCounterHandle{}, FieldIndexValue: 4, FieldIndexSecondValue: -1},
		},
	}
}

// fillRows adds the instance "complete" with valid values for A and B, and the
// instance "partial" with a valid value for A only, as if its item for B had an
// invalid status.
func fillRows(t *testing.T, c *Collector[rowSetValues]) []rowSetValues {
	t.Helper()

	var dst []rowSetValues

	rows := rowSet[rowSetValues]{
		c:           c,
		dst:         &dst,
		index:       map[instanceKey]int{},
		nameCache:   map[string]string{},
		occurrences: map[string]int{},
		seen:        map[string]int{},
	}

	for _, name := range []string{"complete", "partial"} {
		row, ok := rows.row(&c.counters[0], windows.StringToUTF16Ptr(name), CstatusValidData)
		require.True(t, ok)
		require.True(t, c.setRawValue(&dst[row], &c.counters[0], RawCounter{FirstValue: 1}))
		rows.setValid(row, 0)
	}

	clear(rows.seen)

	_, ok := rows.row(&c.counters[1], windows.StringToUTF16Ptr("partial"), CstatusInvalidData)
	require.False(t, ok)

	row, ok := rows.row(&c.counters[1], windows.StringToUTF16Ptr("complete"), CstatusNewData)
	require.True(t, ok)
	require.True(t, c.setRawValue(&dst[row], &c.counters[1], RawCounter{FirstValue: 2, SecondValue: 3}))
	rows.setValid(row, 1)

	rows.finish()

	return dst
}

func TestRowSetOmitsIncompleteInstances(t *testing.T) {
	t.Parallel()

	rows := fillRows(t, newRowSetTestCollector(false))

	// "partial" has no valid value for B. Without partial rows, it must be left
	// out instead of reporting B as zero. Optional has no instances, so it is
	// not required.
	require.Equal(t, []rowSetValues{{Name: "complete", A: 1, B: 2, BSecond: 3}}, rows)
}

func TestRowSetPartialRows(t *testing.T) {
	t.Parallel()

	rows := fillRows(t, newRowSetTestCollector(true))
	require.Len(t, rows, 2)

	require.Equal(t, rowSetValues{Name: "complete", A: 1, B: 2, BSecond: 3}, rows[0])

	require.Equal(t, "partial", rows[1].Name)
	require.InDelta(t, 1, rows[1].A, 0)
	require.True(t, math.IsNaN(rows[1].B), "B: %v", rows[1].B)
	require.True(t, math.IsNaN(rows[1].BSecond), "BSecond: %v", rows[1].BSecond)
	require.Zero(t, rows[1].Optional)
}

func TestRowSetDuplicateInstances(t *testing.T) {
	t.Parallel()

	nan := math.NaN()

	for _, tc := range []struct {
		name        string
		names       []string
		secondNames []string
		a           []float64
		b           []float64
		repeatArray bool
		want        []rowSetValues
	}{
		{
			name:  "duplicates",
			names: []string{"A", "A", "A"},
			a:     []float64{1, 2, 3},
			b:     []float64{10, 20, 30},
			want: []rowSetValues{
				{Name: "A", A: 1, B: 10},
				{Name: "A#1", A: 2, B: 20},
				{Name: "A#2", A: 3, B: 30},
			},
		},
		{
			name:        "interleaved_names",
			names:       []string{"A", "B", "A"},
			secondNames: []string{"B", "A", "A"},
			a:           []float64{1, 2, 3},
			b:           []float64{20, 10, 30},
			want: []rowSetValues{
				{Name: "A", A: 1, B: 10},
				{Name: "B", A: 2, B: 20},
				{Name: "A#1", A: 3, B: 30},
			},
		},
		{
			name:        "literal_suffix",
			names:       []string{"A", "A", "A#1"},
			secondNames: []string{"A#1", "A", "A"},
			a:           []float64{1, 2, 3},
			b:           []float64{30, 10, 20},
			want: []rowSetValues{
				{Name: "A", A: 1, B: 10},
				{Name: "A#2", A: 2, B: 20},
				{Name: "A#1", A: 3, B: 30},
			},
		},
		{
			name:  "invalid_middle_item",
			names: []string{"A", "A", "A"},
			a:     []float64{1, nan, 3},
			b:     []float64{10, 20, 30},
			want: []rowSetValues{
				{Name: "A", A: 1, B: 10},
				{Name: "A#1", A: nan, B: 20},
				{Name: "A#2", A: 3, B: 30},
			},
		},
		{
			name:  "invalid_first_item",
			names: []string{"A", "A", "A"},
			a:     []float64{1, 2, 3},
			b:     []float64{nan, 20, 30},
			want: []rowSetValues{
				{Name: "A", A: 1, B: nan},
				{Name: "A#1", A: 2, B: 20},
				{Name: "A#2", A: 3, B: 30},
			},
		},
		{
			name:  "invalid_literal_suffix",
			names: []string{"A", "A", "A#1"},
			a:     []float64{1, 2, nan},
			b:     []float64{10, 20, nan},
			want: []rowSetValues{
				{Name: "A", A: 1, B: 10},
				{Name: "A#2", A: 2, B: 20},
			},
		},
		{
			name:        "overlapping_counter_arrays",
			names:       []string{"A", "A"},
			a:           []float64{1, 2},
			b:           []float64{10, 20},
			repeatArray: true,
			want: []rowSetValues{
				{Name: "A", A: 1, B: 10},
				{Name: "A#1", A: 2, B: 20},
			},
		},
	} {
		for _, resultType := range []CounterType{CounterTypeRaw, CounterTypeFormatted} {
			for _, partialRows := range []bool{false, true} {
				t.Run(fmt.Sprintf("%s/%s/partial=%t", tc.name, resultType, partialRows), func(t *testing.T) {
					t.Parallel()

					c := newRowSetTestCollector(partialRows)
					c.counters[1].FieldIndexSecondValue = -1

					var dst []rowSetValues

					rows := rowSet[rowSetValues]{
						c:           c,
						dst:         &dst,
						index:       map[instanceKey]int{},
						nameCache:   map[string]string{},
						occurrences: map[string]int{},
						seen:        map[string]int{},
					}

					addDuplicateTestItems(
						&rows,
						resultType,
						0,
						tc.names,
						tc.a,
					)

					if tc.repeatArray {
						addDuplicateTestItems(
							&rows,
							resultType,
							0,
							tc.names,
							tc.a,
						)
					}

					secondNames := tc.secondNames
					if secondNames == nil {
						secondNames = tc.names
					}

					addDuplicateTestItems(
						&rows,
						resultType,
						1,
						secondNames,
						tc.b,
					)
					rows.finish()

					want := slices.DeleteFunc(slices.Clone(tc.want), func(row rowSetValues) bool {
						return !partialRows && (math.IsNaN(row.A) || math.IsNaN(row.B))
					})
					require.Len(t, dst, len(want))

					for _, expected := range want {
						i := slices.IndexFunc(dst, func(row rowSetValues) bool { return row.Name == expected.Name })
						require.NotEqual(t, -1, i, "missing instance %s", expected.Name)

						for field, value := range map[string]float64{"A": expected.A, "B": expected.B} {
							got := reflect.ValueOf(dst[i]).FieldByName(field).Float()
							if math.IsNaN(value) {
								require.True(t, math.IsNaN(got), "%s/%s: %v", expected.Name, field, got)

								continue
							}

							require.InDelta(t, value, got, 0, "%s/%s", expected.Name, field)
						}
					}
				})
			}
		}
	}
}

// addDuplicateTestItems supplies counter arrays without querying PDH. NaN marks an invalid item.
func addDuplicateTestItems(
	rows *rowSet[rowSetValues],
	resultType CounterType,
	counterIndex int,
	names []string,
	values []float64,
) {
	if resultType == CounterTypeRaw {
		items := make([]RawCounterItem, len(names))
		for i, name := range names {
			status := CstatusValidData
			if math.IsNaN(values[i]) {
				status = CstatusInvalidData
			}

			items[i] = RawCounterItem{
				SzName: windows.StringToUTF16Ptr(name),
				RawValue: RawCounter{
					CStatus:    status,
					FirstValue: int64(values[i]),
				},
			}
		}

		itemSize := int(unsafe.Sizeof(RawCounterItem{}))
		buf := unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(items))), len(items)*itemSize)
		rows.addRawItems(counterIndex, buf, uint32(len(items)))
		runtime.KeepAlive(items)

		return
	}

	items := make([]FmtCounterValueItemDouble, len(names))
	for i, name := range names {
		status := CstatusNewData
		if math.IsNaN(values[i]) {
			status = CstatusInvalidData
		}

		items[i] = FmtCounterValueItemDouble{
			SzName: windows.StringToUTF16Ptr(name),
			FmtValue: FmtCounterValueDouble{
				CStatus:     status,
				DoubleValue: values[i],
			},
		}
	}

	itemSize := int(unsafe.Sizeof(FmtCounterValueItemDouble{}))
	buf := unsafe.Slice((*byte)(unsafe.Pointer(unsafe.SliceData(items))), len(items)*itemSize)
	rows.addFormattedItems(counterIndex, buf, uint32(len(items)))
	runtime.KeepAlive(items)
}

func TestSetRawValueElapsedTime(t *testing.T) {
	t.Parallel()

	c := newRowSetTestCollector(false)

	var values rowSetValues

	counter := &Counter{Type: PERF_ELAPSED_TIME, Frequency: 10_000_000, FieldIndexValue: 1, FieldIndexSecondValue: -1}

	// 2.5 s at 10 MHz. Integer division truncated this to 2.
	require.True(t, c.setRawValue(&values, counter, RawCounter{FirstValue: 100_000_000, SecondValue: 125_000_000}))
	require.InDelta(t, 2.5, values.A, 0)

	// A zero frequency panicked with an integer divide by zero.
	counter.Frequency = 0
	require.False(t, c.setRawValue(&values, counter, RawCounter{FirstValue: 1, SecondValue: 2}))

	// A counter with only a second value field must not set field -1.
	counter = &Counter{Type: PERF_ELAPSED_TIME, Frequency: 1, FieldIndexValue: -1, FieldIndexSecondValue: 3}
	require.True(t, c.setRawValue(&values, counter, RawCounter{FirstValue: 1, SecondValue: 2}))
}

func TestMetricTypeForCounterType(t *testing.T) {
	t.Parallel()

	require.Equal(t, prometheus.GaugeValue, metricType(CounterTypeRaw, PERF_COUNTER_RAWCOUNT))
	require.Equal(t, prometheus.CounterValue, metricType(CounterTypeRaw, PERF_COUNTER_BULK_COUNT))
	require.Equal(t, prometheus.GaugeValue, metricType(CounterTypeRaw, 0xFFFFFFFF))
	require.Equal(t, prometheus.GaugeValue, metricType(CounterTypeFormatted, PERF_COUNTER_BULK_COUNT))
}

type processThreads struct {
	Name        string
	ThreadCount float64 `perfdata:"Thread Count"`
}

// TestCollectRecoversPanic checks that a panic while collecting is returned as an error.
func TestCollectRecoversPanic(t *testing.T) {
	t.Parallel()

	c, err := NewCollector[processThreads](slog.New(slog.DiscardHandler), CounterTypeRaw, "Process", InstancesAll)
	require.NoError(t, err)

	t.Cleanup(c.Close)

	var dst []processThreads

	require.NoError(t, c.Collect(&dst))

	// Point the counter at a field that does not exist, so that reflect panics.
	c.mu.Lock()
	c.counters[0].FieldIndexValue = 42
	c.mu.Unlock()

	err = c.Collect(&dst)
	require.ErrorContains(t, err, "panic while collecting performance counters of Process")

	// Collection still works after the panic.
	c.mu.Lock()
	c.counters[0].FieldIndexValue = 1
	c.mu.Unlock()

	require.NoError(t, c.Collect(&dst))
	require.NotEmpty(t, dst)
}