package cmd

import (
	"bytes"
	"errors"
	"io"
	"path/filepath"
	"reflect"
	"sort"
	"strings"
	"sync"
	"testing"
	"time"

	"github.com/warkanum/unitdore/config"
	"github.com/warkanum/unitdore/initsys"
)

// fakeInit records calls and simulates installed files in memory.
type fakeInit struct {
	mu        sync.Mutex
	installed map[string]bool
	calls     []string
	failOn    map[string]bool // "op:name" -> error
}

func newFake(installed ...string) *fakeInit {
	f := &fakeInit{installed: map[string]bool{}, failOn: map[string]bool{}}
	for _, n := range installed {
		f.installed[n] = true
	}
	return f
}

func (f *fakeInit) rec(op string, u config.Unit) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.calls = append(f.calls, op+":"+u.Name)
	if f.failOn[op+":"+u.Name] {
		return errors.New("boom")
	}
	return nil
}

func (f *fakeInit) Name() string                                  { return "fake" }
func (f *fakeInit) ServiceName(u config.Unit, p, s string) string { return p + u.Name + s }
func (f *fakeInit) UnitPath(u config.Unit, p, s string) (string, error) {
	return "/fake/" + f.ServiceName(u, p, s), nil
}
func (f *fakeInit) Generate(u config.Unit, p, s string) (string, error) {
	return "content-" + u.Name, nil
}
func (f *fakeInit) Install(u config.Unit, p, s string) error {
	if err := f.rec("install", u); err != nil {
		return err
	}
	f.mu.Lock()
	f.installed[u.Name] = true
	f.mu.Unlock()
	return nil
}
func (f *fakeInit) Uninstall(u config.Unit, p, s string) error {
	if err := f.rec("uninstall", u); err != nil {
		return err
	}
	f.mu.Lock()
	delete(f.installed, u.Name)
	f.mu.Unlock()
	return nil
}
func (f *fakeInit) Enable(u config.Unit, p, s string) error  { return f.rec("enable", u) }
func (f *fakeInit) Disable(u config.Unit, p, s string) error { return f.rec("disable", u) }
func (f *fakeInit) Start(u config.Unit, p, s string) error   { return f.rec("start", u) }
func (f *fakeInit) Stop(u config.Unit, p, s string) error    { return f.rec("stop", u) }
func (f *fakeInit) Status(u config.Unit, p, s string) string { return "active" }
func (f *fakeInit) IsInstalled(u config.Unit, p, s string) bool {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.installed[u.Name]
}
func (f *fakeInit) SupportsLinger() bool { return false }

func unit(name string, order int, delay string, enabled bool) config.Unit {
	return config.Unit{Name: name, Runtime: "podman", Order: order, Delay: delay, Enabled: enabled}
}

func TestSortUnits(t *testing.T) {
	in := []config.Unit{unit("b", 2, "", true), unit("a", 2, "", true), unit("c", 1, "", true)}
	names := func(us []config.Unit) (n []string) {
		for _, u := range us {
			n = append(n, u.Name)
		}
		return
	}
	if got := names(sortUnits(in, false)); !reflect.DeepEqual(got, []string{"c", "a", "b"}) {
		t.Errorf("forward = %v", got)
	}
	if got := names(sortUnits(in, true)); !reflect.DeepEqual(got, []string{"b", "a", "c"}) {
		t.Errorf("reverse = %v", got)
	}
	if in[0].Name != "b" {
		t.Error("input was mutated")
	}
}

// grouped reports calls with each parallel group sorted, so order within a group is irrelevant.
func grouped(calls []string, sizes ...int) [][]string {
	var out [][]string
	i := 0
	for _, n := range sizes {
		g := append([]string(nil), calls[i:i+n]...)
		sort.Strings(g)
		out = append(out, g)
		i += n
	}
	return out
}

func TestStartAllOrder(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{
		unit("db", 1, "", true),
		unit("web", 2, "3s", true),
		unit("web2", 2, "5s", true),
		unit("off", 2, "", false),
		unit("app", 3, "1s", true),
		unit("missing", 3, "", true),
	}}
	f := newFake("db", "web", "web2", "off", "app")

	var out bytes.Buffer
	bulkStart(cfg, f, &out, initsys.Init.Start, "started")

	want := [][]string{{"start:db"}, {"start:web", "start:web2"}, {"start:app"}}
	if got := grouped(f.calls, 1, 2, 1); !reflect.DeepEqual(got, want) {
		t.Errorf("calls = %v", f.calls)
	}
	o := out.String()
	for _, s := range []string{"! missing: not installed", "Done. Started: 4  Failed: 0"} {
		if !strings.Contains(o, s) {
			t.Errorf("output missing %q:\n%s", s, o)
		}
	}
	if strings.Contains(o, "off") {
		t.Errorf("disabled unit should be skipped:\n%s", o)
	}
}

func TestStartAllParallelWithinGroup(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true), unit("b", 1, "", true)}}
	f := newFake("a", "b")
	started := make(chan string, 2)
	release := make(chan struct{})
	act := func(_ initsys.Init, u config.Unit, _, _ string) error {
		started <- u.Name
		<-release // blocks until both have started: fails (deadlocks) if sequential
		return nil
	}
	done := make(chan struct{})
	go func() { bulkStart(cfg, f, &bytes.Buffer{}, act, "started"); close(done) }()
	for i := 0; i < 2; i++ {
		select {
		case <-started:
		case <-time.After(2 * time.Second):
			t.Fatal("units in the same order did not start in parallel")
		}
	}
	close(release)
	<-done
}

func TestEnableAllUsesEnable(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true)}}
	f := newFake("a")
	var out bytes.Buffer
	bulkStart(cfg, f, &out, initsys.Init.Enable, "enabled")
	if !reflect.DeepEqual(f.calls, []string{"enable:a"}) || !strings.Contains(out.String(), "Done. Enabled: 1") {
		t.Errorf("calls=%v out=%s", f.calls, out.String())
	}
}

func TestStartAllFailureCounted(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true), unit("b", 2, "", true)}}
	f := newFake("a", "b")
	f.failOn["start:a"] = true
	var out bytes.Buffer
	bulkStart(cfg, f, &out, initsys.Init.Start, "started")
	if !strings.Contains(out.String(), "Done. Started: 1  Failed: 1") {
		t.Errorf("out=%s", out.String())
	}
}

func TestStopAllReverseOrder(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true), unit("b", 2, "", false), unit("c", 3, "", true), unit("d", 3, "", true)}}
	f := newFake("a", "b", "c", "d")
	var out bytes.Buffer
	stopAll(cfg, f, &out)
	if want := []string{"stop:d", "stop:c", "stop:b", "stop:a"}; !reflect.DeepEqual(f.calls, want) {
		t.Errorf("calls = %v", f.calls)
	}
	if !strings.Contains(out.String(), "Stopped: 4") {
		t.Errorf("out=%s", out.String())
	}
}

func TestUninstallAllReverseOrderAndFailure(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true), unit("b", 2, "", true), unit("c", 3, "", true)}}
	f := newFake("a", "b") // c not installed
	f.failOn["disable:b"] = true
	var out bytes.Buffer
	uninstallAll(cfg, f, &out)
	if want := []string{"disable:b", "disable:a", "uninstall:a"}; !reflect.DeepEqual(f.calls, want) {
		t.Errorf("calls = %v", f.calls)
	}
	if !f.installed["b"] {
		t.Error("b must stay installed when disable fails")
	}
	if !strings.Contains(out.String(), "Uninstalled: 1  Failed: 1") {
		t.Errorf("out=%s", out.String())
	}
}

func TestInstallAll(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{
		unit("on", 1, "", true),
		unit("off-installed", 2, "", false),
		unit("off-absent", 3, "", false),
	}}
	f := newFake("off-installed")
	var out bytes.Buffer
	installAll(cfg, f, false, &out)

	// a disabled unit must be stopped before its file is removed
	if want := []string{"install:on", "disable:off-installed", "uninstall:off-installed"}; !reflect.DeepEqual(f.calls, want) {
		t.Errorf("calls = %v", f.calls)
	}
	if !strings.Contains(out.String(), "Installed: 1  Removed: 1  Skipped: 1") {
		t.Errorf("out=%s", out.String())
	}
}

func TestInstallAllDisableFailureKeepsFile(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("x", 1, "", false)}}
	f := newFake("x")
	f.failOn["disable:x"] = true
	installAll(cfg, f, false, &bytes.Buffer{})
	if !f.installed["x"] || len(f.calls) != 1 {
		t.Errorf("file must be kept when disable fails; calls=%v", f.calls)
	}
}

func TestInstallAllDryRunWritesNothing(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("on", 1, "", true), unit("off", 2, "", false)}}
	f := newFake("off")
	var out bytes.Buffer
	installAll(cfg, f, true, &out)
	if len(f.calls) != 0 {
		t.Errorf("dry run touched system: %v", f.calls)
	}
	for _, s := range []string{"--- /fake/on ---", "content-on", "would remove: off", "Would install: 1"} {
		if !strings.Contains(out.String(), s) {
			t.Errorf("output missing %q:\n%s", s, out.String())
		}
	}
}

func updateCfg(t *testing.T) (*config.Config, string) {
	t.Helper()
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true)}}
	return cfg, filepath.Join(t.TempDir(), "units.yaml")
}

func TestUpdateOrderReinstallsInstalled(t *testing.T) {
	cfg, path := updateCfg(t)
	f := newFake("a")
	order := 7
	if err := applyUpdate(cfg, f, "a", &order, false, false, path, &bytes.Buffer{}); err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(f.calls, []string{"install:a"}) {
		t.Errorf("calls = %v", f.calls)
	}
	saved, err := config.Load(path)
	if err != nil || saved.Units[0].Order != 7 {
		t.Errorf("saved = %+v, %v", saved, err)
	}
}

func TestUpdateDisableStopsAndRemoves(t *testing.T) {
	cfg, path := updateCfg(t)
	f := newFake("a")
	if err := applyUpdate(cfg, f, "a", nil, false, true, path, &bytes.Buffer{}); err != nil {
		t.Fatal(err)
	}
	if want := []string{"disable:a", "uninstall:a"}; !reflect.DeepEqual(f.calls, want) {
		t.Errorf("calls = %v", f.calls)
	}
	saved, _ := config.Load(path)
	if saved.Units[0].Enabled {
		t.Error("unit should be saved as disabled")
	}
}

func TestUpdateNotInstalledOnlySaves(t *testing.T) {
	cfg, path := updateCfg(t)
	f := newFake()
	if err := applyUpdate(cfg, f, "a", nil, false, true, path, &bytes.Buffer{}); err != nil {
		t.Fatal(err)
	}
	if len(f.calls) != 0 {
		t.Errorf("calls = %v", f.calls)
	}
}

func TestUpdateEnableClearsReason(t *testing.T) {
	cfg, path := updateCfg(t)
	cfg.Units[0].Enabled = false
	cfg.Units[0].DisabledReason = "container not found"
	if err := applyUpdate(cfg, newFake(), "a", nil, true, false, path, &bytes.Buffer{}); err != nil {
		t.Fatal(err)
	}
	saved, _ := config.Load(path)
	if !saved.Units[0].Enabled || saved.Units[0].DisabledReason != "" {
		t.Errorf("saved = %+v", saved.Units[0])
	}
}

func TestUpdateUnknownUnit(t *testing.T) {
	cfg, path := updateCfg(t)
	if err := applyUpdate(cfg, newFake(), "nope", nil, false, false, path, &bytes.Buffer{}); err == nil {
		t.Error("expected not found error")
	}
}

func TestUpdateOrderRefreshesNeighbours(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true), unit("b", 2, "", true), unit("off", 3, "", false)}}
	path := filepath.Join(t.TempDir(), "units.yaml")
	f := newFake("a", "b", "off")
	order := 5
	if err := applyUpdate(cfg, f, "a", &order, false, false, path, &bytes.Buffer{}); err != nil {
		t.Fatal(err)
	}
	// b's After= changes when a moves behind it; disabled units are left alone
	if want := []string{"install:a", "install:b"}; !reflect.DeepEqual(f.calls, want) {
		t.Errorf("calls = %v", f.calls)
	}
	if got := cfg.Units[0].After; len(got) != 1 || got[0] != "b" {
		t.Errorf("a.After = %v, want [b]", got)
	}
}

func TestInstallOneOnlyNamedUnit(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true), unit("b", 2, "", true), unit("off", 3, "", false)}}
	f := newFake("off")
	var out bytes.Buffer
	if err := installOne(cfg, f, "b", false, &out); err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(f.calls, []string{"install:b"}) {
		t.Errorf("calls = %v", f.calls)
	}
	if !strings.Contains(out.String(), "installed: /fake/b") {
		t.Errorf("out=%s", out.String())
	}
}

func TestInstallOneDryRun(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true)}}
	f := newFake()
	var out bytes.Buffer
	if err := installOne(cfg, f, "a", true, &out); err != nil {
		t.Fatal(err)
	}
	if len(f.calls) != 0 || !strings.Contains(out.String(), "content-a") {
		t.Errorf("calls=%v out=%s", f.calls, out.String())
	}
}

func TestInstallOneErrors(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("off", 1, "", false), unit("bad", 2, "", true)}}
	f := newFake("off")
	if err := installOne(cfg, f, "nope", false, &bytes.Buffer{}); err == nil {
		t.Error("unknown unit must error")
	}
	if err := installOne(cfg, f, "off", false, &bytes.Buffer{}); err == nil {
		t.Error("disabled unit must error")
	}
	f.failOn["install:bad"] = true
	if err := installOne(cfg, f, "bad", false, &bytes.Buffer{}); err == nil {
		t.Error("install failure must be returned")
	}
	if len(f.calls) != 1 || !f.installed["off"] {
		t.Errorf("disabled unit must be left untouched; calls=%v", f.calls)
	}
}

func TestNameOrAll(t *testing.T) {
	cases := []struct {
		all  bool
		args []string
		ok   bool
	}{
		{false, nil, false},
		{false, []string{"a", "b"}, false},
		{false, []string{"a"}, true},
		{true, nil, true},
		{true, []string{"a"}, false},
	}
	for _, c := range cases {
		all := c.all
		if err := nameOrAll(&all)(nil, c.args); (err == nil) != c.ok {
			t.Errorf("all=%v args=%v: err=%v", c.all, c.args, err)
		}
	}
}

func TestSingleUnitCommands(t *testing.T) {
	cfg := &config.Config{Units: []config.Unit{unit("a", 1, "", true), unit("b", 2, "", true), unit("gone", 3, "", true)}}
	f := newFake("a", "b")
	var out bytes.Buffer

	for _, step := range []struct {
		op   string
		run  func(*config.Config, initsys.Init, string, io.Writer) error
		want string
	}{
		{"start", startOne, "start:a"},
		{"enable", enableOne, "enable:a"},
		{"stop", stopOne, "stop:a"},
		{"uninstall", uninstallOne, "uninstall:a"},
	} {
		f.calls = nil
		f.installed["a"] = true
		if err := step.run(cfg, f, "a", &out); err != nil {
			t.Fatalf("%s: %v", step.op, err)
		}
		// only the named unit is touched
		for _, c := range f.calls {
			if strings.HasSuffix(c, ":b") {
				t.Errorf("%s touched b: %v", step.op, f.calls)
			}
		}
		if got := f.calls[len(f.calls)-1]; got != step.want {
			t.Errorf("%s last call = %s, want %s", step.op, got, step.want)
		}
		if step.op == "uninstall" && !reflect.DeepEqual(f.calls, []string{"disable:a", "uninstall:a"}) {
			t.Errorf("uninstall calls = %v", f.calls)
		}

		f.calls = nil
		if err := step.run(cfg, f, "gone", &out); err == nil {
			t.Errorf("%s: not-installed unit must error", step.op)
		}
		if err := step.run(cfg, f, "nope", &out); err == nil {
			t.Errorf("%s: unknown unit must error", step.op)
		}
		if len(f.calls) != 0 {
			t.Errorf("%s: errors must not act: %v", step.op, f.calls)
		}
	}
}