//go:build linux

package collector

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"

	"mfd-monitor-agent/internal/status"
)

// TestParseAddressIPv4 验证 Linux IPv4 套接字地址解码。
func TestParseAddressIPv4(t *testing.T) {
	ip, port, err := parseAddress("0100007F:1F90", "ipv4")
	if err != nil {
		t.Fatal(err)
	}
	if ip != "127.0.0.1" || port != 8080 {
		t.Fatalf("address = %s:%d", ip, port)
	}
}

// TestParseAddressIPv6 验证 Linux IPv6 套接字地址解码。
func TestParseAddressIPv6(t *testing.T) {
	ip, port, err := parseAddress("00000000000000000000000001000000:1F90", "ipv6")
	if err != nil {
		t.Fatal(err)
	}
	if ip != "::1" || port != 8080 {
		t.Fatalf("address = %s:%d", ip, port)
	}
}

// TestParseProcessStatStartTime 验证从 /proc/<pid>/stat 解析第 22 字段。
func TestParseProcessStatStartTime(t *testing.T) {
	raw := "1234 (agent worker) S 1 2 3 4 5 0 0 0 0 0 11 22 0 0 20 0 1 0 987654 0 0"

	startTime, err := parseProcessStatStartTime(raw)
	if err != nil {
		t.Fatal(err)
	}
	if startTime != 987654 {
		t.Fatalf("start time = %d", startTime)
	}
}

// TestCPUUsageFromProcStatSamples 验证由两次 /proc/stat 采样计算 CPU 使用率。
func TestCPUUsageFromProcStatSamples(t *testing.T) {
	prevIdle, prevTotal, err := parseCPUTimes("cpu  100 0 100 800 0 0 0 0 0 0\n")
	if err != nil {
		t.Fatal(err)
	}
	nextIdle, nextTotal, err := parseCPUTimes("cpu  150 0 150 900 0 0 0 0 0 0\n")
	if err != nil {
		t.Fatal(err)
	}

	got := cpuUsagePercent(prevIdle, prevTotal, nextIdle, nextTotal)
	if got != 50 {
		t.Fatalf("usage percent = %f", got)
	}
}

// TestReadProcessStatReturnsStartTime 验证进程启动时间被暴露。
func TestReadProcessStatReturnsStartTime(t *testing.T) {
	path := filepath.Join(t.TempDir(), "stat")
	raw := "1234 (agent worker) S 1 2 3 4 5 0 0 0 0 0 11 22 0 0 20 0 1 0 987654 0 0"
	if err := os.WriteFile(path, []byte(raw), 0o600); err != nil {
		t.Fatal(err)
	}

	got, err := readProcessStat(path)
	if err != nil {
		t.Fatal(err)
	}
	if got.StartTime != 987654 {
		t.Fatalf("start time = %d", got.StartTime)
	}
}

// TestReadMemoryReturnsBytesWithUnit 验证内存容量字段以字节暴露。
func TestReadMemoryReturnsBytesWithUnit(t *testing.T) {
	meminfo, err := os.ReadFile("/proc/meminfo")
	if err != nil {
		t.Fatal(err)
	}
	var totalKiB uint64
	for _, line := range strings.Split(string(meminfo), "\n") {
		fields := strings.Fields(line)
		if len(fields) >= 2 && fields[0] == "MemTotal:" {
			totalKiB, err = strconv.ParseUint(fields[1], 10, 64)
			if err != nil {
				t.Fatal(err)
			}
			break
		}
	}
	if totalKiB == 0 {
		t.Fatal("MemTotal not found")
	}

	got := readMemory()

	if got.Total != totalKiB*1024 {
		t.Fatalf("total memory = %d bytes, want %d bytes", got.Total, totalKiB*1024)
	}
	if got.Unit != "byte" {
		t.Fatalf("unit = %q, want byte", got.Unit)
	}
}

// TestShouldIncludeDiskMount 保留物理盘与网络盘并排除伪挂载。
func TestShouldIncludeDiskMount(t *testing.T) {
	tests := []struct {
		name   string
		device string
		fsType string
		total  uint64
		want   bool
	}{
		{name: "physical block device", device: "/dev/mapper/pve-vm--103--disk--1", fsType: "ext4", total: 1024, want: true},
		{name: "nfs mount", device: "server:/export/data", fsType: "nfs4", total: 1024, want: true},
		{name: "lxcfs pseudo mount", device: "lxcfs", fsType: "fuse.lxcfs", total: 0, want: false},
		{name: "proc pseudo mount", device: "proc", fsType: "proc", total: 0, want: false},
		{name: "tmpfs memory mount", device: "tmpfs", fsType: "tmpfs", total: 1024, want: false},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			got := shouldIncludeDiskMount(test.device, test.fsType, test.total)
			if got != test.want {
				t.Fatalf("include = %t, want %t", got, test.want)
			}
		})
	}
}

// TestCollectSocketsMarksPartialWhenProcessFDsUnreadable 验证进程 fd 不可读时套接字映射降级。
func TestCollectSocketsMarksPartialWhenProcessFDsUnreadable(t *testing.T) {
	oldSocketInodes := socketInodesFunc
	oldReadTCPListeners := readTCPListenersFunc
	t.Cleanup(func() {
		socketInodesFunc = oldSocketInodes
		readTCPListenersFunc = oldReadTCPListeners
	})
	socketInodesFunc = func() (map[string]status.ProcessInfo, error) {
		return map[string]status.ProcessInfo{}, fmt.Errorf("1 process fd directory could not be read")
	}
	readTCPListenersFunc = func(path string, family string, inodes map[string]status.ProcessInfo) ([]status.TCPListenerInfo, error) {
		return []status.TCPListenerInfo{{IP: "127.0.0.1", Port: 8080, Family: family}}, nil
	}

	var got status.HostStatus
	err := collectSockets(context.Background(), &got)
	if err == nil {
		t.Fatal("expected partial mapping error")
	}
	if got.TCPListeners.Status != "partial" {
		t.Fatalf("status = %q", got.TCPListeners.Status)
	}
	if len(got.TCPListeners.Items) != 2 {
		t.Fatalf("listener count = %d", len(got.TCPListeners.Items))
	}
}