package domain

import (
	"testing"
)

func TestNewDefaultPreferences(t *testing.T) {
	p := NewDefaultPreferences("user-123")

	if p.UserID != "user-123" {
		t.Errorf("expected UserID 'user-123', got '%s'", p.UserID)
	}
	if p.Theme != "system" {
		t.Errorf("expected theme 'system', got '%s'", p.Theme)
	}
	if p.Language != "en" {
		t.Errorf("expected language 'en', got '%s'", p.Language)
	}
	if !p.Notifications.Email {
		t.Error("expected email=true")
	}
	if !p.Notifications.Push {
		t.Error("expected push=true")
	}
	if p.Notifications.Digest != "weekly" {
		t.Errorf("expected digest 'weekly', got '%s'", p.Notifications.Digest)
	}
	if p.UpdatedAt.IsZero() {
		t.Error("expected non-zero UpdatedAt")
	}
}

func TestPreferences_Validate(t *testing.T) {
	tests := []struct {
		name    string
		modify  func(p *Preferences)
		wantErr error
	}{
		{
			name:    "valid defaults",
			modify:  func(p *Preferences) {},
			wantErr: nil,
		},
		{
			name:    "valid light theme",
			modify:  func(p *Preferences) { p.Theme = "light" },
			wantErr: nil,
		},
		{
			name:    "valid dark theme",
			modify:  func(p *Preferences) { p.Theme = "dark" },
			wantErr: nil,
		},
		{
			name:    "invalid theme",
			modify:  func(p *Preferences) { p.Theme = "blue" },
			wantErr: ErrInvalidTheme,
		},
		{
			name:    "empty theme",
			modify:  func(p *Preferences) { p.Theme = "" },
			wantErr: ErrInvalidTheme,
		},
		{
			name:    "valid language es",
			modify:  func(p *Preferences) { p.Language = "es" },
			wantErr: nil,
		},
		{
			name:    "invalid language - too long",
			modify:  func(p *Preferences) { p.Language = "eng" },
			wantErr: ErrInvalidLanguage,
		},
		{
			name:    "invalid language - uppercase",
			modify:  func(p *Preferences) { p.Language = "EN" },
			wantErr: ErrInvalidLanguage,
		},
		{
			name:    "invalid language - empty",
			modify:  func(p *Preferences) { p.Language = "" },
			wantErr: ErrInvalidLanguage,
		},
		{
			name:    "valid digest daily",
			modify:  func(p *Preferences) { p.Notifications.Digest = "daily" },
			wantErr: nil,
		},
		{
			name:    "valid digest never",
			modify:  func(p *Preferences) { p.Notifications.Digest = "never" },
			wantErr: nil,
		},
		{
			name:    "invalid digest",
			modify:  func(p *Preferences) { p.Notifications.Digest = "monthly" },
			wantErr: ErrInvalidDigest,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			p := NewDefaultPreferences("user-1")
			tt.modify(p)
			err := p.Validate()
			if err != tt.wantErr {
				t.Errorf("expected error %v, got %v", tt.wantErr, err)
			}
		})
	}
}

func TestPreferences_MergeFrom(t *testing.T) {
	strPtr := func(s string) *string { return &s }
	boolPtr := func(b bool) *bool { return &b }

	t.Run("nil update does nothing", func(t *testing.T) {
		p := NewDefaultPreferences("user-1")
		p.MergeFrom(nil)
		if p.Theme != "system" {
			t.Errorf("expected theme 'system', got '%s'", p.Theme)
		}
	})

	t.Run("partial update - theme only", func(t *testing.T) {
		p := NewDefaultPreferences("user-1")
		p.MergeFrom(&PreferencesUpdate{
			Theme: strPtr("dark"),
		})
		if p.Theme != "dark" {
			t.Errorf("expected theme 'dark', got '%s'", p.Theme)
		}
		if p.Language != "en" {
			t.Errorf("expected language 'en' unchanged, got '%s'", p.Language)
		}
	})

	t.Run("partial update - language only", func(t *testing.T) {
		p := NewDefaultPreferences("user-1")
		p.MergeFrom(&PreferencesUpdate{
			Language: strPtr("fr"),
		})
		if p.Language != "fr" {
			t.Errorf("expected language 'fr', got '%s'", p.Language)
		}
		if p.Theme != "system" {
			t.Errorf("expected theme 'system' unchanged, got '%s'", p.Theme)
		}
	})

	t.Run("notifications sub-field merge", func(t *testing.T) {
		p := NewDefaultPreferences("user-1")
		p.MergeFrom(&PreferencesUpdate{
			Notifications: &NotificationSettingsUpdate{
				Email: boolPtr(false),
			},
		})
		if p.Notifications.Email != false {
			t.Error("expected email=false")
		}
		if p.Notifications.Push != true {
			t.Error("expected push=true unchanged")
		}
		if p.Notifications.Digest != "weekly" {
			t.Errorf("expected digest 'weekly' unchanged, got '%s'", p.Notifications.Digest)
		}
	})

	t.Run("full update", func(t *testing.T) {
		p := NewDefaultPreferences("user-1")
		p.MergeFrom(&PreferencesUpdate{
			Theme:    strPtr("light"),
			Language: strPtr("es"),
			Notifications: &NotificationSettingsUpdate{
				Email:  boolPtr(false),
				Push:   boolPtr(false),
				Digest: strPtr("daily"),
			},
		})
		if p.Theme != "light" {
			t.Errorf("expected theme 'light', got '%s'", p.Theme)
		}
		if p.Language != "es" {
			t.Errorf("expected language 'es', got '%s'", p.Language)
		}
		if p.Notifications.Email != false {
			t.Error("expected email=false")
		}
		if p.Notifications.Push != false {
			t.Error("expected push=false")
		}
		if p.Notifications.Digest != "daily" {
			t.Errorf("expected digest 'daily', got '%s'", p.Notifications.Digest)
		}
	})
}

func TestUserID(t *testing.T) {
	id := UserID("test-123")
	if id.String() != "test-123" {
		t.Errorf("expected 'test-123', got '%s'", id.String())
	}
	if id.IsZero() {
		t.Error("expected non-zero")
	}

	var empty UserID
	if !empty.IsZero() {
		t.Error("expected zero")
	}
}