package settings_test

import (
	"context"
	"errors"
	"sync"
	"testing"

	"github.com/dariuszjaniak/warp/server/internal/settings"
)

// memStore is an in-memory storage.SettingsStore.
type memStore struct {
	mu      sync.Mutex
	values  map[string]string
	failSet error
}

func newMemStore(initial map[string]string) *memStore {
	values := map[string]string{}
	for k, v := range initial {
		values[k] = v
	}
	return &memStore{values: values}
}

func (m *memStore) Get(_ context.Context, key string) (string, bool, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	v, ok := m.values[key]
	return v, ok, nil
}

func (m *memStore) GetAll(context.Context) (map[string]string, error) {
	m.mu.Lock()
	defer m.mu.Unlock()
	out := map[string]string{}
	for k, v := range m.values {
		out[k] = v
	}
	return out, nil
}

func (m *memStore) Set(_ context.Context, key, value string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	if m.failSet != nil {
		return m.failSet
	}
	m.values[key] = value
	return nil
}

func (m *memStore) Delete(_ context.Context, key string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	delete(m.values, key)
	return nil
}

func togglableDefaults() settings.Defaults {
	return settings.Defaults{
		FederationEnabled:              false,
		FederationAllowRuntimeToggle:   true,
		RegistrationEnabled:            false,
		RegistrationAllowRuntimeToggle: true,
	}
}

func TestStoredValueOverridesConfig(t *testing.T) {
	store := newMemStore(map[string]string{settings.KeyFederationEnabled: "true"})

	svc, err := settings.New(t.Context(), store, togglableDefaults(), nil)
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	if !svc.FederationEnabled() {
		t.Error("the persisted value should win over the config default")
	}
}

func TestPinnedSettingIgnoresStoredValue(t *testing.T) {
	store := newMemStore(map[string]string{settings.KeyFederationEnabled: "true"})
	defaults := togglableDefaults()
	defaults.FederationAllowRuntimeToggle = false

	svc, err := settings.New(t.Context(), store, defaults, nil)
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	if svc.FederationEnabled() {
		t.Error("with allow_runtime_toggle false the config file is authoritative")
	}
	if err := svc.SetFederationEnabled(t.Context(), true); !errors.Is(err, settings.ErrNotToggleable) {
		t.Errorf("SetFederationEnabled = %v, want ErrNotToggleable", err)
	}
	if _, found, _ := store.Get(t.Context(), settings.KeyFederationEnabled); !found {
		t.Error("the stored value should be kept for when the toggle is re-enabled")
	}
}

func TestUnparseableStoredValueFallsBackToConfig(t *testing.T) {
	store := newMemStore(map[string]string{settings.KeyRegistrationEnabled: "maybe"})
	defaults := togglableDefaults()
	defaults.RegistrationEnabled = true

	svc, err := settings.New(t.Context(), store, defaults, nil)
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	if !svc.RegistrationEnabled() {
		t.Error("a corrupt stored value must fall back to the config value, not to false")
	}
}

func TestSetPersistsAndNotifies(t *testing.T) {
	store := newMemStore(nil)
	svc, err := settings.New(t.Context(), store, togglableDefaults(), nil)
	if err != nil {
		t.Fatal(err)
	}

	var got []settings.Snapshot
	svc.Subscribe(func(s settings.Snapshot) { got = append(got, s) })

	if err := svc.SetFederationEnabled(t.Context(), true); err != nil {
		t.Fatalf("SetFederationEnabled: %v", err)
	}
	if !svc.FederationEnabled() {
		t.Error("the cached value was not updated")
	}
	if v, _, _ := store.Get(t.Context(), settings.KeyFederationEnabled); v != "true" {
		t.Errorf("stored value = %q, want \"true\"", v)
	}
	if len(got) != 1 || !got[0].FederationEnabled {
		t.Fatalf("subscriber saw %v, want one snapshot with federation on", got)
	}

	// Setting the same value again changes nothing and must not notify.
	if err := svc.SetFederationEnabled(t.Context(), true); err != nil {
		t.Fatal(err)
	}
	if len(got) != 1 {
		t.Errorf("a no-op change notified subscribers: %v", got)
	}
}

func TestSetKeepsCacheOnStoreFailure(t *testing.T) {
	store := newMemStore(nil)
	store.failSet = errors.New("disk on fire")

	svc, err := settings.New(t.Context(), store, togglableDefaults(), nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := svc.SetFederationEnabled(t.Context(), true); err == nil {
		t.Fatal("expected the store failure to surface")
	}
	if svc.FederationEnabled() {
		t.Error("the cached value must not change when persistence fails")
	}
}

func TestSnapshotIsConsistent(t *testing.T) {
	store := newMemStore(map[string]string{
		settings.KeyFederationEnabled:   "true",
		settings.KeyRegistrationEnabled: "true",
	})
	svc, err := settings.New(t.Context(), store, togglableDefaults(), nil)
	if err != nil {
		t.Fatal(err)
	}
	snap := svc.Snapshot()
	if !snap.FederationEnabled || !snap.RegistrationEnabled {
		t.Errorf("Snapshot() = %+v, want both enabled", snap)
	}
}

func TestConcurrentReadsAndWrites(t *testing.T) {
	store := newMemStore(nil)
	svc, err := settings.New(t.Context(), store, togglableDefaults(), nil)
	if err != nil {
		t.Fatal(err)
	}

	var wg sync.WaitGroup
	for i := range 8 {
		wg.Add(1)
		go func() {
			defer wg.Done()
			if i%2 == 0 {
				_ = svc.SetFederationEnabled(t.Context(), i%4 == 0)
				return
			}
			_ = svc.FederationEnabled()
			_ = svc.Snapshot()
		}()
	}
	wg.Wait()
}