package service

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

	"git.threesix.ai/jordan/slack5-1770606136/pkg/logging"
	"git.threesix.ai/jordan/slack5-1770606136/services/preferences-api/internal/domain"
	"git.threesix.ai/jordan/slack5-1770606136/services/preferences-api/internal/port"
)

// mockPreferenceRepository implements port.PreferenceRepository for testing.
type mockPreferenceRepository struct {
	mu    sync.RWMutex
	prefs map[string]*domain.UserPreferences
}

var _ port.PreferenceRepository = (*mockPreferenceRepository)(nil)

func newMockPreferenceRepository() *mockPreferenceRepository {
	return &mockPreferenceRepository{
		prefs: make(map[string]*domain.UserPreferences),
	}
}

func (m *mockPreferenceRepository) Get(ctx context.Context, userID string) (*domain.UserPreferences, error) {
	m.mu.RLock()
	defer m.mu.RUnlock()

	p, ok := m.prefs[userID]
	if !ok {
		return nil, nil
	}
	// Return a copy
	cp := *p
	cpPrefs := make(map[string]any)
	for k, v := range p.Preferences {
		cpPrefs[k] = v
	}
	cp.Preferences = cpPrefs
	return &cp, nil
}

func (m *mockPreferenceRepository) Upsert(ctx context.Context, prefs *domain.UserPreferences) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	cp := *prefs
	cpPrefs := make(map[string]any)
	for k, v := range prefs.Preferences {
		cpPrefs[k] = v
	}
	cp.Preferences = cpPrefs
	m.prefs[prefs.UserID] = &cp
	return nil
}

func TestPreferenceService_Get(t *testing.T) {
	repo := newMockPreferenceRepository()
	svc := NewPreferenceService(repo, logging.Nop())

	t.Run("returns nil for non-existent user", func(t *testing.T) {
		result, err := svc.Get(context.Background(), "user-1")
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		if result != nil {
			t.Error("expected nil result for non-existent user")
		}
	})

	t.Run("returns existing preferences", func(t *testing.T) {
		_, _ = svc.Upsert(context.Background(), UpsertInput{
			UserID:      "user-2",
			Preferences: map[string]any{"theme": "dark"},
		})

		result, err := svc.Get(context.Background(), "user-2")
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		if result == nil {
			t.Fatal("expected non-nil result")
		}
		if result.Preferences["theme"] != "dark" {
			t.Errorf("expected theme 'dark', got '%v'", result.Preferences["theme"])
		}
	})
}

func TestPreferenceService_Upsert(t *testing.T) {
	repo := newMockPreferenceRepository()
	svc := NewPreferenceService(repo, logging.Nop())

	t.Run("creates preferences for new user", func(t *testing.T) {
		result, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-1",
			Preferences: map[string]any{
				"theme":    "dark",
				"language": "en",
			},
		})
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		if result.Preferences["theme"] != "dark" {
			t.Errorf("expected theme 'dark', got '%v'", result.Preferences["theme"])
		}
		if result.Preferences["language"] != "en" {
			t.Errorf("expected language 'en', got '%v'", result.Preferences["language"])
		}
	})

	t.Run("merges preferences with existing", func(t *testing.T) {
		result, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-1",
			Preferences: map[string]any{
				"notifications_enabled": true,
			},
		})
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		// Existing keys should be preserved
		if result.Preferences["theme"] != "dark" {
			t.Errorf("expected theme 'dark' preserved, got '%v'", result.Preferences["theme"])
		}
		if result.Preferences["language"] != "en" {
			t.Errorf("expected language 'en' preserved, got '%v'", result.Preferences["language"])
		}
		// New key should be added
		if result.Preferences["notifications_enabled"] != true {
			t.Errorf("expected notifications_enabled true, got '%v'", result.Preferences["notifications_enabled"])
		}
	})

	t.Run("overwrites existing key", func(t *testing.T) {
		result, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-1",
			Preferences: map[string]any{
				"theme": "light",
			},
		})
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		if result.Preferences["theme"] != "light" {
			t.Errorf("expected theme 'light', got '%v'", result.Preferences["theme"])
		}
		// Other keys preserved
		if result.Preferences["language"] != "en" {
			t.Errorf("expected language 'en' preserved, got '%v'", result.Preferences["language"])
		}
	})

	t.Run("accepts unknown keys without validation", func(t *testing.T) {
		result, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-2",
			Preferences: map[string]any{
				"custom_setting": "anything",
				"sidebar_width":  42.0,
			},
		})
		if err != nil {
			t.Fatalf("unexpected error: %v", err)
		}
		if result.Preferences["custom_setting"] != "anything" {
			t.Errorf("expected custom_setting 'anything', got '%v'", result.Preferences["custom_setting"])
		}
	})

	t.Run("rejects invalid theme", func(t *testing.T) {
		_, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-3",
			Preferences: map[string]any{
				"theme": "neon",
			},
		})
		if err == nil {
			t.Fatal("expected error for invalid theme")
		}
		if !errors.Is(err, domain.ErrInvalidPreferenceValue) {
			t.Errorf("expected ErrInvalidPreferenceValue, got %v", err)
		}
		var valErr *ValidationError
		if !errors.As(err, &valErr) {
			t.Fatal("expected ValidationError type")
		}
		if valErr.Details["theme"] == "" {
			t.Error("expected details for theme key")
		}
	})

	t.Run("rejects invalid language", func(t *testing.T) {
		_, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-3",
			Preferences: map[string]any{
				"language": "not-a-language-!!!",
			},
		})
		if err == nil {
			t.Fatal("expected error for invalid language")
		}
		var valErr *ValidationError
		if !errors.As(err, &valErr) {
			t.Fatal("expected ValidationError type")
		}
		if valErr.Details["language"] == "" {
			t.Error("expected details for language key")
		}
	})

	t.Run("rejects non-boolean notifications_enabled", func(t *testing.T) {
		_, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-3",
			Preferences: map[string]any{
				"notifications_enabled": "yes",
			},
		})
		if err == nil {
			t.Fatal("expected error for non-boolean notifications_enabled")
		}
		var valErr *ValidationError
		if !errors.As(err, &valErr) {
			t.Fatal("expected ValidationError type")
		}
		if valErr.Details["notifications_enabled"] == "" {
			t.Error("expected details for notifications_enabled key")
		}
	})

	t.Run("collects multiple validation errors", func(t *testing.T) {
		_, err := svc.Upsert(context.Background(), UpsertInput{
			UserID: "user-3",
			Preferences: map[string]any{
				"theme":                 "invalid",
				"notifications_enabled": "not-bool",
			},
		})
		if err == nil {
			t.Fatal("expected error for multiple invalid values")
		}
		var valErr *ValidationError
		if !errors.As(err, &valErr) {
			t.Fatal("expected ValidationError type")
		}
		if len(valErr.Details) != 2 {
			t.Errorf("expected 2 validation errors, got %d", len(valErr.Details))
		}
	})

	t.Run("accepts valid BCP-47 tags", func(t *testing.T) {
		validTags := []string{"en", "fr", "es", "de", "ja", "zh-Hans", "pt-BR"}
		for _, tag := range validTags {
			_, err := svc.Upsert(context.Background(), UpsertInput{
				UserID: "user-lang-" + tag,
				Preferences: map[string]any{
					"language": tag,
				},
			})
			if err != nil {
				t.Errorf("expected no error for valid BCP-47 tag '%s', got %v", tag, err)
			}
		}
	})
}