package monitor

import (
	"context"
	"database/sql"
	"log/slog"
	"os"
	"path/filepath"
	"testing"
	"time"

	"git.wntrmute.dev/mc/mcp/internal/config"
	"git.wntrmute.dev/mc/mcp/internal/registry"
	"git.wntrmute.dev/mc/mcp/internal/runtime"
)

func openTestDB(t *testing.T) *sql.DB {
	t.Helper()
	db, err := registry.Open(filepath.Join(t.TempDir(), "test.db"))
	if err != nil {
		t.Fatalf("open db: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })
	return db
}

func testLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
}

func testMonitorConfig() config.MonitorConfig {
	return config.MonitorConfig{
		Interval:      config.Duration{Duration: 1 * time.Second},
		Cooldown:      config.Duration{Duration: 1 * time.Minute},
		FlapThreshold: 3,
		FlapWindow:    config.Duration{Duration: 10 * time.Minute},
		Retention:     config.Duration{Duration: 24 * time.Hour},
	}
}

// fakeRuntime implements runtime.Runtime for testing.
type fakeRuntime struct {
	containers []runtime.ContainerInfo
}

func (f *fakeRuntime) Pull(_ context.Context, _ string) error               { return nil }
func (f *fakeRuntime) Run(_ context.Context, _ runtime.ContainerSpec) error { return nil }
func (f *fakeRuntime) Stop(_ context.Context, _ string) error               { return nil }
func (f *fakeRuntime) Remove(_ context.Context, _ string) error             { return nil }
func (f *fakeRuntime) Build(_ context.Context, _, _, _ string) error        { return nil }
func (f *fakeRuntime) Push(_ context.Context, _ string) error               { return nil }

func (f *fakeRuntime) ImageExists(_ context.Context, _ string) (bool, error) { return true, nil }

func (f *fakeRuntime) Inspect(_ context.Context, _ string) (runtime.ContainerInfo, error) {
	return runtime.ContainerInfo{}, nil
}

func (f *fakeRuntime) List(_ context.Context) ([]runtime.ContainerInfo, error) {
	return f.containers, nil
}

func TestAlerterDriftDetection(t *testing.T) {
	db := openTestDB(t)
	logger := testLogger()
	cfg := testMonitorConfig()

	al := NewAlerter(cfg, "test-node", db, logger)

	// Set up a service and component so CountEvents works.
	if err := registry.CreateService(db, "metacrypt", true); err != nil {
		t.Fatalf("create service: %v", err)
	}
	if err := registry.CreateComponent(db, &registry.Component{
		Name: "api", Service: "metacrypt", Image: "img:v1",
		Restart: "unless-stopped", DesiredState: "running", ObservedState: "running",
	}); err != nil {
		t.Fatalf("create component: %v", err)
	}

	// Desired is "running" but observed is "exited" -- drift should fire.
	al.Evaluate("metacrypt", "api", "running", "exited", "running")

	// Verify alert was recorded (lastAlert should be set).
	key := "metacrypt/api"
	if _, ok := al.lastAlert[key]; !ok {
		t.Fatal("expected drift alert to be recorded in lastAlert")
	}
}

func TestAlerterIgnoreState(t *testing.T) {
	db := openTestDB(t)
	logger := testLogger()
	cfg := testMonitorConfig()

	al := NewAlerter(cfg, "test-node", db, logger)

	// Components with desired_state "ignore" should not trigger alerts.
	al.Evaluate("metacrypt", "api", "ignore", "exited", "running")

	key := "metacrypt/api"
	if _, ok := al.lastAlert[key]; ok {
		t.Fatal("expected no alert for ignored component")
	}
}

func TestAlerterCooldownSuppression(t *testing.T) {
	db := openTestDB(t)
	logger := testLogger()
	cfg := testMonitorConfig()
	cfg.Cooldown.Duration = 1 * time.Hour // long cooldown

	al := NewAlerter(cfg, "test-node", db, logger)

	if err := registry.CreateService(db, "metacrypt", true); err != nil {
		t.Fatalf("create service: %v", err)
	}
	if err := registry.CreateComponent(db, &registry.Component{
		Name: "api", Service: "metacrypt", Image: "img:v1",
		Restart: "unless-stopped", DesiredState: "running", ObservedState: "running",
	}); err != nil {
		t.Fatalf("create component: %v", err)
	}

	// First call should fire.
	al.Evaluate("metacrypt", "api", "running", "exited", "running")
	key := "metacrypt/api"
	first, ok := al.lastAlert[key]
	if !ok {
		t.Fatal("expected first alert to fire")
	}

	// Second call should be suppressed (within cooldown).
	al.Evaluate("metacrypt", "api", "running", "exited", "exited")
	second := al.lastAlert[key]
	if !second.Equal(first) {
		t.Fatal("expected second alert to be suppressed by cooldown")
	}
}

func TestAlerterFlapDetection(t *testing.T) {
	db := openTestDB(t)
	logger := testLogger()
	cfg := testMonitorConfig()
	cfg.FlapThreshold = 2
	cfg.FlapWindow.Duration = 10 * time.Minute
	cfg.Cooldown.Duration = 0 // disable cooldown for this test

	al := NewAlerter(cfg, "test-node", db, logger)

	if err := registry.CreateService(db, "metacrypt", true); err != nil {
		t.Fatalf("create service: %v", err)
	}
	if err := registry.CreateComponent(db, &registry.Component{
		Name: "api", Service: "metacrypt", Image: "img:v1",
		Restart: "unless-stopped", DesiredState: "running", ObservedState: "unknown",
	}); err != nil {
		t.Fatalf("create component: %v", err)
	}

	// Insert enough events to exceed the flap threshold.
	for i := 0; i < 3; i++ {
		if err := registry.InsertEvent(db, "metacrypt", "api", "running", "exited"); err != nil {
			t.Fatalf("insert event %d: %v", i, err)
		}
	}

	// Evaluate with a state transition -- should detect flapping.
	al.Evaluate("metacrypt", "api", "running", "exited", "running")

	key := "metacrypt/api"
	if _, ok := al.lastAlert[key]; !ok {
		t.Fatal("expected flap alert to fire")
	}
}

func TestMonitorTickStateChange(t *testing.T) {
	db := openTestDB(t)
	logger := testLogger()
	cfg := testMonitorConfig()

	if err := registry.CreateService(db, "metacrypt", true); err != nil {
		t.Fatalf("create service: %v", err)
	}
	if err := registry.CreateComponent(db, &registry.Component{
		Name: "api", Service: "metacrypt", Image: "img:v1",
		Restart: "unless-stopped", DesiredState: "running", ObservedState: "unknown",
	}); err != nil {
		t.Fatalf("create component: %v", err)
	}

	rt := &fakeRuntime{
		containers: []runtime.ContainerInfo{
			{Name: "metacrypt-api", State: "running"},
		},
	}

	m := New(db, rt, cfg, "test-node", logger)

	// Run a single tick.
	m.tick()

	// Verify observed state was updated in the registry.
	comp, err := registry.GetComponent(db, "metacrypt", "api")
	if err != nil {
		t.Fatalf("get component: %v", err)
	}
	if comp.ObservedState != "running" {
		t.Fatalf("observed state: got %q, want %q", comp.ObservedState, "running")
	}

	// Verify an event was recorded (unknown -> running).
	events, err := registry.QueryEvents(db, "metacrypt", "api", time.Now().Add(-1*time.Hour), 0)
	if err != nil {
		t.Fatalf("query events: %v", err)
	}
	if len(events) != 1 {
		t.Fatalf("events: got %d, want 1", len(events))
	}
	if events[0].PrevState != "unknown" || events[0].NewState != "running" {
		t.Fatalf("event: got %q->%q, want unknown->running", events[0].PrevState, events[0].NewState)
	}

	// Verify prevState map was updated.
	if m.prevState["metacrypt/api"] != "running" {
		t.Fatalf("prevState: got %q, want %q", m.prevState["metacrypt/api"], "running")
	}
}

func TestMonitorStartStop(t *testing.T) {
	db := openTestDB(t)
	logger := testLogger()
	cfg := testMonitorConfig()
	cfg.Interval.Duration = 50 * time.Millisecond

	rt := &fakeRuntime{}
	m := New(db, rt, cfg, "test-node", logger)

	m.Start()

	// Give it a moment to tick at least once.
	time.Sleep(150 * time.Millisecond)

	m.Stop()

	// If Stop returns, the goroutine exited cleanly.
}

func TestMonitorNoChangeNoEvent(t *testing.T) {
	db := openTestDB(t)
	logger := testLogger()
	cfg := testMonitorConfig()

	if err := registry.CreateService(db, "metacrypt", true); err != nil {
		t.Fatalf("create service: %v", err)
	}
	if err := registry.CreateComponent(db, &registry.Component{
		Name: "api", Service: "metacrypt", Image: "img:v1",
		Restart: "unless-stopped", DesiredState: "running", ObservedState: "running",
	}); err != nil {
		t.Fatalf("create component: %v", err)
	}

	rt := &fakeRuntime{
		containers: []runtime.ContainerInfo{
			{Name: "metacrypt-api", State: "running"},
		},
	}

	m := New(db, rt, cfg, "test-node", logger)
	// Seed prevState so that observed == prev (no change).
	m.prevState["metacrypt/api"] = "running"

	m.tick()

	// No events should be recorded when state is unchanged.
	events, err := registry.QueryEvents(db, "metacrypt", "api", time.Now().Add(-1*time.Hour), 0)
	if err != nil {
		t.Fatalf("query events: %v", err)
	}
	if len(events) != 0 {
		t.Fatalf("events: got %d, want 0 (no state change)", len(events))
	}
}