package profile

import (
	"context"
	"encoding/json"
	"errors"
	"os"
	"runtime"
	"strings"
	"testing"
	"time"
)

// The parsing layer, with the machine's files given (novox/hq ADR 0017 allows a fake here and only here);
// the real machine is asked below.

var files = map[string]string{
	"/proc/sys/kernel/osrelease": "7.2.8-arch1-2\n",
	"/etc/os-release":            "NAME=\"Arch Linux\"\nPRETTY_NAME=\"Arch Linux\"\nID=arch\nBUILD_ID=rolling\n",
	"/proc/cpuinfo": "processor\t: 0\nmodel name\t: AMD Ryzen 9 5900HS\nphysical id\t: 0\ncore id\t\t: 0\n\n" +
		"processor\t: 1\nmodel name\t: AMD Ryzen 9 5900HS\nphysical id\t: 0\ncore id\t\t: 0\n\n" +
		"processor\t: 2\nmodel name\t: AMD Ryzen 9 5900HS\nphysical id\t: 0\ncore id\t\t: 1\n",
	"/proc/meminfo": "MemTotal:       32000000 kB\nMemFree: 1 kB\n",
	"/proc/stat":    "cpu 1 2 3\nbtime 1791800000\n",
	"/proc/self/mounts": "/dev/nvme0n1p2 / btrfs rw 0 0\n/dev/nvme0n1p2 /home btrfs rw 0 0\n" +
		"proc /proc proc rw 0 0\ntank/data /srv/my\\040data zfs rw 0 0\n" +
		"server:/x /mnt/x nfs4 rw 0 0\n/dev/loop3 /snap/core/1 squashfs ro 0 0\n",
}

func given(read map[string]string) Sources {
	return Sources{
		Read: func(p string) ([]byte, error) {
			if s, ok := read[p]; ok {
				return []byte(s), nil
			}
			return nil, &os.PathError{Op: "open", Path: p, Err: os.ErrNotExist}
		},
		Readlink: func(string) (string, error) { return "/usr/share/zoneinfo/Europe/Brussels", nil },
		Run:      func(context.Context, string, ...string) (string, error) { return "none\n", errors.New("exited 1") },
		Statfs:   func(p string) (int64, int64, error) { return 1000, 400, nil },
		Now:      func() time.Time { return time.Date(2026, 10, 12, 15, 0, 0, 0, time.UTC) },
	}
}

func TestMachine_saysEveryFactItCanRead(t *testing.T) {
	m := DescribeMachine(context.Background(), given(files))

	if m.KernelRelease != "7.2.8-arch1-2" || m.Distribution != "Arch Linux" || m.Version != "rolling" {
		t.Errorf("kernel %q, distribution %q %q", m.KernelRelease, m.Distribution, m.Version)
	}
	if m.Processor != "AMD Ryzen 9 5900HS" || m.Cores != 2 || m.Threads != 3 {
		t.Errorf("processor %q, %d cores, %d threads", m.Processor, m.Cores, m.Threads)
	}
	if m.MemoryBytes != 32000000*1024 {
		t.Errorf("memory %d", m.MemoryBytes)
	}
	if m.Virtual != "physical" {
		t.Errorf("systemd-detect-virt said none and exited 1; read as %q", m.Virtual)
	}
	if m.BootedAt == nil || m.BootedAt.Unix() != 1791800000 {
		t.Errorf("booted at %v", m.BootedAt)
	}
	if m.Timezone != "Europe/Brussels" {
		t.Errorf("timezone %q", m.Timezone)
	}
	// One btrfs device under its shortest mount, the zfs dataset with its escaped space, and no network or
	// read-only image filesystem.
	var mounts []string
	for _, f := range m.Filesystems {
		mounts = append(mounts, f.Mount)
		if f.SizeBytes != 1000 || f.FreeBytes != 400 {
			t.Errorf("%s: size %d free %d", f.Mount, f.SizeBytes, f.FreeBytes)
		}
	}
	if got := strings.Join(mounts, ","); got != "/,/srv/my data" {
		t.Errorf("filesystems %q", got)
	}
	// Everything read is not unknown; the public address is, with why.
	for fact := range m.Unknown {
		if fact != FactPublicAddress {
			t.Errorf("%s said unknown though it was readable: %s", fact, m.Unknown[fact])
		}
	}
	if m.Unknown[FactPublicAddress] == "" {
		t.Error("the public address is not said, and not said unknown either")
	}
}

// The acceptance of issue 160: a machine that cannot determine a fact says so rather than reporting a zero.
func TestMachine_aFactItCannotReadIsSaidUnknownNeverZero(t *testing.T) {
	src := given(map[string]string{})
	src.Readlink = func(string) (string, error) { return "", os.ErrNotExist }
	src.Run = func(context.Context, string, ...string) (string, error) { return "", errors.New("not found") }
	m := DescribeMachine(context.Background(), src)

	raw, _ := json.Marshal(m)
	var said map[string]any
	_ = json.Unmarshal(raw, &said)
	for key, v := range said {
		if key == "observed_at" || key == "unknown" {
			continue
		}
		t.Errorf("%s is said as %v from a machine where nothing could be read", key, v)
	}
	for _, fact := range MachineFacts {
		if strings.TrimSpace(m.Unknown[fact]) == "" {
			t.Errorf("%s is neither said nor said unknown with why", fact)
		}
	}
}

func TestMachine_aHungFilesystemCannotHangTheReport(t *testing.T) {
	src := given(files)
	block := make(chan struct{})
	defer close(block)
	src.Statfs = func(string) (int64, int64, error) { <-block; return 0, 0, nil }
	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
	defer cancel()
	m := DescribeMachine(ctx, src)
	if len(m.Filesystems) != 0 || !strings.Contains(m.Unknown[FactFilesystems], "did not finish") {
		t.Errorf("filesystems %v, unknown %q", m.Filesystems, m.Unknown[FactFilesystems])
	}
}

func TestMachine_coresUnsaidAreUnknownNotGuessed(t *testing.T) {
	p := processorOf("processor\t: 0\nModel\t: Raspberry Pi 4\nprocessor\t: 1\n")
	if p.model != "Raspberry Pi 4" || p.threads != 2 || p.cores != 0 || p.unknown[FactCores] == "" {
		t.Errorf("%+v", p)
	}
}

// Against the real machine (ADR 0017): what it says agrees with what this process sees.
func TestAgainstThisMachine_machineSaysWhatItIs(t *testing.T) {
	if runtime.GOOS != "linux" {
		t.Skip("the facts are read from Linux's own files")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	m := DescribeMachine(ctx, RealSources())
	if m.MemoryBytes <= 0 && m.Unknown[FactMemory] == "" {
		t.Error("memory neither said nor unknown")
	}
	if m.Threads != 0 && m.Threads < runtime.NumCPU() {
		t.Errorf("%d threads said, and this process alone may use %d", m.Threads, runtime.NumCPU())
	}
	if m.BootedAt != nil && m.BootedAt.After(time.Now()) {
		t.Errorf("booted in the future: %v", m.BootedAt)
	}
	for _, f := range m.Filesystems {
		if f.SizeBytes <= 0 || f.FreeBytes > f.SizeBytes {
			t.Errorf("%s: size %d free %d", f.Mount, f.SizeBytes, f.FreeBytes)
		}
	}
	for _, fact := range MachineFacts {
		if why, unknown := m.Unknown[fact]; unknown && strings.TrimSpace(why) == "" {
			t.Errorf("%s unknown with no why", fact)
		}
	}
	raw, _ := json.MarshalIndent(m, "", "  ")
	t.Logf("%s", raw)
}