package launcher

import (
	"context"
	"errors"
	"testing"
	"time"

	"code.nochebuena.dev/go/logz"
)

// ---- test helpers -------------------------------------------------------

type mockComponent struct {
	name        string
	initErr     error
	startErr    error
	stopErr     error
	initCalled  bool
	startCalled bool
	stopCalled  bool
	stopDelay   time.Duration
}

func (m *mockComponent) OnInit() error  { m.initCalled = true; return m.initErr }
func (m *mockComponent) OnStart() error { m.startCalled = true; return m.startErr }
func (m *mockComponent) OnStop() error {
	m.stopCalled = true
	if m.stopDelay > 0 {
		time.Sleep(m.stopDelay)
	}
	return m.stopErr
}

func newLogger() logz.Logger {
	return logz.New(logz.Options{})
}

func fastOpts() Options {
	return Options{ComponentStopTimeout: 100 * time.Millisecond}
}

// runAndShutdown starts Run in a goroutine, waits shutdownAfter, then calls Shutdown.
// Returns the error returned by Run.
func runAndShutdown(t *testing.T, lc Launcher, shutdownAfter time.Duration) error {
	t.Helper()
	errCh := make(chan error, 1)
	go func() { errCh <- lc.Run() }()
	time.Sleep(shutdownAfter)
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	lc.Shutdown(ctx) //nolint:errcheck
	select {
	case err := <-errCh:
		return err
	case <-time.After(2 * time.Second):
		t.Fatal("Run() did not return after Shutdown")
		return nil
	}
}

// ---- tests ---------------------------------------------------------------

func TestNew_Defaults(t *testing.T) {
	lc := New(newLogger())
	if lc == nil {
		t.Fatal("expected non-nil Launcher")
	}
	impl := lc.(*launcher)
	if impl.opts.ComponentStopTimeout != defaultComponentStopTimeout {
		t.Errorf("default timeout = %v, want %v", impl.opts.ComponentStopTimeout, defaultComponentStopTimeout)
	}
}

func TestNew_WithOptions(t *testing.T) {
	want := 42 * time.Millisecond
	lc := New(newLogger(), Options{ComponentStopTimeout: want})
	impl := lc.(*launcher)
	if impl.opts.ComponentStopTimeout != want {
		t.Errorf("timeout = %v, want %v", impl.opts.ComponentStopTimeout, want)
	}
}

func TestLauncher_Append(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	c1 := &mockComponent{name: "c1"}
	c2 := &mockComponent{name: "c2"}
	lc.Append(c1, c2)

	err := runAndShutdown(t, lc, 10*time.Millisecond)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !c1.initCalled || !c2.initCalled {
		t.Error("OnInit not called on all components")
	}
}

func TestLauncher_BeforeStart(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	c := &mockComponent{name: "c"}
	lc.Append(c)

	hookRan := false
	var hookOrder, startOrder int
	counter := 0

	lc.BeforeStart(func() error {
		counter++
		hookOrder = counter
		hookRan = true
		return nil
	})

	origStart := c.OnStart
	_ = origStart // ensure c.startCalled is set by OnStart

	// Track order by inspecting startCalled after hook
	lc2 := New(newLogger(), fastOpts())
	c2 := &mockComponent{name: "c2"}
	var afterHookStartCalled bool

	lc2.Append(c2)
	lc2.BeforeStart(func() error {
		// At hook time, OnInit has run but OnStart has not
		if c2.initCalled && !c2.startCalled {
			afterHookStartCalled = true
		}
		return nil
	})

	err := runAndShutdown(t, lc2, 10*time.Millisecond)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !afterHookStartCalled {
		t.Error("hook ran but init/start order was wrong")
	}

	_ = hookRan
	_ = hookOrder
	_ = startOrder
}

func TestLauncher_Run_Success(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	c := &mockComponent{name: "c"}
	lc.Append(c)

	err := runAndShutdown(t, lc, 10*time.Millisecond)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if !c.initCalled || !c.startCalled || !c.stopCalled {
		t.Errorf("lifecycle incomplete: init=%v start=%v stop=%v", c.initCalled, c.startCalled, c.stopCalled)
	}
}

func TestLauncher_Run_OnInitFails(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	initErr := errors.New("init failure")
	c := &mockComponent{name: "c", initErr: initErr}
	lc.Append(c)

	errCh := make(chan error, 1)
	go func() { errCh <- lc.Run() }()

	select {
	case err := <-errCh:
		if !errors.Is(err, initErr) {
			t.Errorf("got %v, want %v", err, initErr)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("Run() did not return")
	}

	if c.startCalled {
		t.Error("OnStart should not be called when OnInit fails")
	}
}

func TestLauncher_Run_HookFails(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	c := &mockComponent{name: "c"}
	lc.Append(c)
	hookErr := errors.New("hook failure")
	lc.BeforeStart(func() error { return hookErr })

	errCh := make(chan error, 1)
	go func() { errCh <- lc.Run() }()

	select {
	case err := <-errCh:
		if !errors.Is(err, hookErr) {
			t.Errorf("got %v, want %v", err, hookErr)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("Run() did not return")
	}

	if c.startCalled {
		t.Error("OnStart should not be called when hook fails")
	}
}

func TestLauncher_Run_OnStartFails(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	c1 := &mockComponent{name: "c1"}
	startErr := errors.New("start failure")
	c2 := &mockComponent{name: "c2", startErr: startErr}
	lc.Append(c1, c2)

	errCh := make(chan error, 1)
	go func() { errCh <- lc.Run() }()

	select {
	case err := <-errCh:
		if !errors.Is(err, startErr) {
			t.Errorf("got %v, want %v", err, startErr)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("Run() did not return")
	}

	if !c1.stopCalled {
		t.Error("c1 OnStop should be called when c2 OnStart fails")
	}
}

func TestLauncher_Shutdown_ReverseOrder(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	var stopOrder []string
	makeComponent := func(name string) *mockComponent {
		return &mockComponent{name: name}
	}

	c1 := makeComponent("c1")
	c2 := makeComponent("c2")
	c3 := makeComponent("c3")

	// Wrap OnStop to capture order
	type stoppable struct {
		*mockComponent
		recordStop func(string)
	}
	type recordingComponent struct {
		inner      *mockComponent
		name       string
		recordStop func(string)
	}
	rc := func(c *mockComponent, name string) Component {
		return &recordingWrapper{mockComponent: c, name: name, record: &stopOrder}
	}

	lc.Append(rc(c1, "c1"), rc(c2, "c2"), rc(c3, "c3"))

	err := runAndShutdown(t, lc, 10*time.Millisecond)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	if len(stopOrder) != 3 {
		t.Fatalf("expected 3 stops, got %v", stopOrder)
	}
	if stopOrder[0] != "c3" || stopOrder[1] != "c2" || stopOrder[2] != "c1" {
		t.Errorf("stop order = %v, want [c3 c2 c1]", stopOrder)
	}

	_ = stoppable{}
	_ = recordingComponent{}
}

type recordingWrapper struct {
	*mockComponent
	name   string
	record *[]string
}

func (r *recordingWrapper) OnStop() error {
	*r.record = append(*r.record, r.name)
	return r.mockComponent.OnStop()
}

func TestLauncher_Shutdown_ComponentTimeout(t *testing.T) {
	opts := Options{ComponentStopTimeout: 50 * time.Millisecond}
	lc := New(newLogger(), opts)
	// Component takes 200ms to stop — longer than the 50ms timeout.
	slow := &mockComponent{name: "slow", stopDelay: 200 * time.Millisecond}
	lc.Append(slow)

	start := time.Now()
	err := runAndShutdown(t, lc, 10*time.Millisecond)
	elapsed := time.Since(start)

	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	// Should not block for the full 200ms stop delay.
	if elapsed > 500*time.Millisecond {
		t.Errorf("Run took %v, expected less than 500ms (timeout should have fired)", elapsed)
	}
}

func TestLauncher_Shutdown_Idempotent(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	lc.Append(&mockComponent{name: "c"})

	errCh := make(chan error, 1)
	go func() { errCh <- lc.Run() }()
	time.Sleep(10 * time.Millisecond)

	ctx := context.Background()
	// Call Shutdown twice — must not panic.
	lc.Shutdown(ctx) //nolint:errcheck
	lc.Shutdown(ctx) //nolint:errcheck

	select {
	case err := <-errCh:
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("Run() did not return")
	}
}

func TestLauncher_Shutdown_ContextCancelled(t *testing.T) {
	lc := New(newLogger(), Options{ComponentStopTimeout: 500 * time.Millisecond})
	slow := &mockComponent{name: "slow", stopDelay: 300 * time.Millisecond}
	lc.Append(slow)

	errCh := make(chan error, 1)
	go func() { errCh <- lc.Run() }()
	time.Sleep(10 * time.Millisecond)

	// Very short timeout — Shutdown should return ctx.Err() before Run completes.
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond)
	defer cancel()
	shutdownErr := lc.Shutdown(ctx)
	if !errors.Is(shutdownErr, context.DeadlineExceeded) {
		t.Errorf("Shutdown returned %v, want DeadlineExceeded", shutdownErr)
	}

	// Wait for Run to finish eventually.
	select {
	case <-errCh:
	case <-time.After(3 * time.Second):
		t.Fatal("Run() did not return")
	}
}

func TestLauncher_Run_MultipleComponents(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	components := make([]*mockComponent, 5)
	for i := range components {
		components[i] = &mockComponent{}
		lc.Append(components[i])
	}

	err := runAndShutdown(t, lc, 10*time.Millisecond)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	for i, c := range components {
		if !c.initCalled || !c.startCalled || !c.stopCalled {
			t.Errorf("component[%d] lifecycle incomplete: init=%v start=%v stop=%v",
				i, c.initCalled, c.startCalled, c.stopCalled)
		}
	}
}

func TestLauncher_OnStop_ErrorLogged(t *testing.T) {
	lc := New(newLogger(), fastOpts())
	stopErr := errors.New("stop error")
	c := &mockComponent{name: "c", stopErr: stopErr}
	lc.Append(c)

	// Run should still return nil even when OnStop returns an error.
	err := runAndShutdown(t, lc, 10*time.Millisecond)
	if err != nil {
		t.Fatalf("Run() returned error %v, want nil", err)
	}
	if !c.stopCalled {
		t.Error("OnStop was not called")
	}
}