// Copyright 2021 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 !nocpu
// +build !nocpu

package collector

import (
	"io"
	"log/slog"
	"reflect"
	"testing"

	"github.com/prometheus/procfs"
)

func copyStats(d, s map[int64]procfs.CPUStat) {
	for k := range s {
		v := s[k]
		d[k] = v
	}
}

func makeTestCPUCollector(s map[int64]procfs.CPUStat) *cpuCollector {
	dup := make(map[int64]procfs.CPUStat, len(s))
	copyStats(dup, s)
	return &cpuCollector{
		logger:   slog.New(slog.NewTextHandler(io.Discard, nil)),
		cpuStats: dup,
	}
}

func TestCPU(t *testing.T) {
	firstCPUStat := map[int64]procfs.CPUStat{
		0: {
			User:      100.0,
			Nice:      100.0,
			System:    100.0,
			Idle:      100.0,
			Iowait:    100.0,
			IRQ:       100.0,
			SoftIRQ:   100.0,
			Steal:     100.0,
			Guest:     100.0,
			GuestNice: 100.0,
		}}

	c := makeTestCPUCollector(firstCPUStat)
	want := map[int64]procfs.CPUStat{
		0: {
			User:      101.0,
			Nice:      101.0,
			System:    101.0,
			Idle:      101.0,
			Iowait:    101.0,
			IRQ:       101.0,
			SoftIRQ:   101.0,
			Steal:     101.0,
			Guest:     101.0,
			GuestNice: 101.0,
		}}
	c.updateCPUStats(want)
	got := c.cpuStats
	if !reflect.DeepEqual(want, got) {
		t.Fatalf("should have %v CPU Stat: got %v", want, got)
	}

	c = makeTestCPUCollector(firstCPUStat)
	jumpBack := map[int64]procfs.CPUStat{
		0: {
			User:      99.9,
			Nice:      99.9,
			System:    99.9,
			Idle:      99.9,
			Iowait:    99.9,
			IRQ:       99.9,
			SoftIRQ:   99.9,
			Steal:     99.9,
			Guest:     99.9,
			GuestNice: 99.9,
		}}
	c.updateCPUStats(jumpBack)
	got = c.cpuStats
	if reflect.DeepEqual(jumpBack, got) {
		t.Fatalf("should have %v CPU Stat: got %v", firstCPUStat, got)
	}

	c = makeTestCPUCollector(firstCPUStat)
	resetIdle := map[int64]procfs.CPUStat{
		0: {
			User:      102.0,
			Nice:      102.0,
			System:    102.0,
			Idle:      1.0,
			Iowait:    102.0,
			IRQ:       102.0,
			SoftIRQ:   102.0,
			Steal:     102.0,
			Guest:     102.0,
			GuestNice: 102.0,
		}}
	c.updateCPUStats(resetIdle)
	got = c.cpuStats
	if !reflect.DeepEqual(resetIdle, got) {
		t.Fatalf("should have %v CPU Stat: got %v", resetIdle, got)
	}
}

func TestCPUOffline(t *testing.T) {
	// CPU 1 goes offline.
	firstCPUStat := map[int64]procfs.CPUStat{
		0: {
			User:      100.0,
			Nice:      100.0,
			System:    100.0,
			Idle:      100.0,
			Iowait:    100.0,
			IRQ:       100.0,
			SoftIRQ:   100.0,
			Steal:     100.0,
			Guest:     100.0,
			GuestNice: 100.0,
		},
		1: {
			User:      101.0,
			Nice:      101.0,
			System:    101.0,
			Idle:      101.0,
			Iowait:    101.0,
			IRQ:       101.0,
			SoftIRQ:   101.0,
			Steal:     101.0,
			Guest:     101.0,
			GuestNice: 101.0,
		},
	}

	c := makeTestCPUCollector(firstCPUStat)
	want := map[int64]procfs.CPUStat{
		0: {
			User:      100.0,
			Nice:      100.0,
			System:    100.0,
			Idle:      100.0,
			Iowait:    100.0,
			IRQ:       100.0,
			SoftIRQ:   100.0,
			Steal:     100.0,
			Guest:     100.0,
			GuestNice: 100.0,
		},
	}
	c.updateCPUStats(want)
	got := c.cpuStats
	if !reflect.DeepEqual(want, got) {
		t.Fatalf("should have %v CPU Stat: got %v", want, got)
	}

	// CPU 1 comes back online.
	want = map[int64]procfs.CPUStat{
		0: {
			User:      100.0,
			Nice:      100.0,
			System:    100.0,
			Idle:      100.0,
			Iowait:    100.0,
			IRQ:       100.0,
			SoftIRQ:   100.0,
			Steal:     100.0,
			Guest:     100.0,
			GuestNice: 100.0,
		},
		1: {
			User:      101.0,
			Nice:      101.0,
			System:    101.0,
			Idle:      101.0,
			Iowait:    101.0,
			IRQ:       101.0,
			SoftIRQ:   101.0,
			Steal:     101.0,
			Guest:     101.0,
			GuestNice: 101.0,
		},
	}
	c.updateCPUStats(want)
	got = c.cpuStats
	if !reflect.DeepEqual(want, got) {
		t.Fatalf("should have %v CPU Stat: got %v", want, got)
	}

}