package user

import (
	"fmt"
	"strings"
	"time"

	"knowfoolery/backend/shared/types"
	"knowfoolery/backend/shared/errors"
	"knowfoolery/backend/services/user-service/internal/domain/valueobjects"
)

// User represents a user aggregate
type User struct {
	// Identity
	id           types.UserID
	email        string
	
	// Profile information
	profile      *valueobjects.UserProfile
	playerName   *valueobjects.PlayerName
	preferences  *valueobjects.UserPreferences
	
	// Authentication data
	authProvider string         // "zitadel", "google", "facebook", etc.
	externalID   string         // ID from external auth provider
	emailVerified bool
	
	// Account status
	status       types.UserStatus
	isActive     bool
	isBanned     bool
	banReason    *string
	bannedUntil  *types.Timestamp
	
	// Statistics
	statistics   *valueobjects.UserStatistics
	
	// Lifecycle
	createdAt    types.Timestamp
	updatedAt    types.Timestamp
	lastLoginAt  *types.Timestamp
	
	// Security
	roles        []types.UserRole
	permissions  []string
	
	// Privacy settings
	privacySettings *valueobjects.PrivacySettings
	
	// Version control
	version      int
}

// NewUser creates a new user
func NewUser(
	email string,
	authProvider string,
	externalID string,
) (*User, error) {
	// Validate inputs
	if err := validateEmail(email); err != nil {
		return nil, fmt.Errorf("invalid email: %w", err)
	}
	
	if authProvider == "" {
		return nil, errors.ErrValidationFailed("auth_provider", "auth provider cannot be empty")
	}
	
	if externalID == "" {
		return nil, errors.ErrValidationFailed("external_id", "external ID cannot be empty")
	}

	now := types.NewTimestamp()

	// Create default profile
	profile, err := valueobjects.NewUserProfile("", "", nil, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to create default profile: %w", err)
	}

	// Create default preferences
	preferences := valueobjects.NewDefaultUserPreferences()
	
	// Create default privacy settings
	privacySettings := valueobjects.NewDefaultPrivacySettings()
	
	// Create default statistics
	statistics := valueobjects.NewUserStatistics()

	user := &User{
		id:              types.NewUserID(),
		email:           strings.ToLower(strings.TrimSpace(email)),
		profile:         profile,
		playerName:      nil, // Will be set later
		preferences:     preferences,
		authProvider:    authProvider,
		externalID:      externalID,
		emailVerified:   false,
		status:          types.UserStatusActive,
		isActive:        true,
		isBanned:        false,
		banReason:       nil,
		bannedUntil:     nil,
		statistics:      statistics,
		createdAt:       now,
		updatedAt:       now,
		lastLoginAt:     nil,
		roles:           []types.UserRole{types.UserRolePlayer}, // Default role
		permissions:     []string{},
		privacySettings: privacySettings,
		version:         1,
	}

	return user, nil
}

// NewUserWithID creates a user with a specific ID (for loading from persistence)
func NewUserWithID(
	id types.UserID,
	email string,
	authProvider string,
	externalID string,
	createdAt types.Timestamp,
) (*User, error) {
	if id.IsEmpty() {
		return nil, errors.ErrValidationFailed("id", "user ID cannot be empty")
	}

	user, err := NewUser(email, authProvider, externalID)
	if err != nil {
		return nil, err
	}

	user.id = id
	user.createdAt = createdAt
	user.updatedAt = createdAt

	return user, nil
}

// Getters

// ID returns the user's unique identifier
func (u *User) ID() types.UserID {
	return u.id
}

// Email returns the user's email address
func (u *User) Email() string {
	return u.email
}

// Profile returns the user's profile
func (u *User) Profile() *valueobjects.UserProfile {
	return u.profile
}

// PlayerName returns the user's player name
func (u *User) PlayerName() *valueobjects.PlayerName {
	return u.playerName
}

// Preferences returns the user's preferences
func (u *User) Preferences() *valueobjects.UserPreferences {
	return u.preferences
}

// AuthProvider returns the authentication provider
func (u *User) AuthProvider() string {
	return u.authProvider
}

// ExternalID returns the external ID from auth provider
func (u *User) ExternalID() string {
	return u.externalID
}

// IsEmailVerified returns true if email is verified
func (u *User) IsEmailVerified() bool {
	return u.emailVerified
}

// Status returns the user status
func (u *User) Status() types.UserStatus {
	return u.status
}

// IsActive returns true if the user is active
func (u *User) IsActive() bool {
	return u.isActive && u.status == types.UserStatusActive && !u.isBanned
}

// IsBanned returns true if the user is banned
func (u *User) IsBanned() bool {
	return u.isBanned
}

// BanReason returns the ban reason if banned
func (u *User) BanReason() *string {
	return u.banReason
}

// BannedUntil returns when the ban expires
func (u *User) BannedUntil() *types.Timestamp {
	return u.bannedUntil
}

// Statistics returns the user's statistics
func (u *User) Statistics() *valueobjects.UserStatistics {
	return u.statistics
}

// CreatedAt returns the creation timestamp
func (u *User) CreatedAt() types.Timestamp {
	return u.createdAt
}

// UpdatedAt returns the last update timestamp
func (u *User) UpdatedAt() types.Timestamp {
	return u.updatedAt
}

// LastLoginAt returns the last login timestamp
func (u *User) LastLoginAt() *types.Timestamp {
	return u.lastLoginAt
}

// Roles returns the user's roles
func (u *User) Roles() []types.UserRole {
	return append([]types.UserRole(nil), u.roles...) // Return copy
}

// Permissions returns the user's permissions
func (u *User) Permissions() []string {
	return append([]string(nil), u.permissions...) // Return copy
}

// PrivacySettings returns the user's privacy settings
func (u *User) PrivacySettings() *valueobjects.PrivacySettings {
	return u.privacySettings
}

// Version returns the current version
func (u *User) Version() int {
	return u.version
}

// Business methods

// UpdateProfile updates the user's profile
func (u *User) UpdateProfile(
	firstName string,
	lastName string,
	dateOfBirth *types.Date,
	avatar *string,
) error {
	newProfile, err := valueobjects.NewUserProfile(firstName, lastName, dateOfBirth, avatar)
	if err != nil {
		return fmt.Errorf("failed to update profile: %w", err)
	}

	u.profile = newProfile
	u.markUpdated()

	return nil
}

// SetPlayerName sets the user's player name
func (u *User) SetPlayerName(playerName string) error {
	if playerName == "" {
		u.playerName = nil
		u.markUpdated()
		return nil
	}

	newPlayerName, err := valueobjects.NewPlayerName(playerName)
	if err != nil {
		return fmt.Errorf("failed to set player name: %w", err)
	}

	u.playerName = newPlayerName
	u.markUpdated()

	return nil
}

// UpdateEmail updates the user's email address
func (u *User) UpdateEmail(newEmail string) error {
	if err := validateEmail(newEmail); err != nil {
		return fmt.Errorf("invalid email: %w", err)
	}

	normalizedEmail := strings.ToLower(strings.TrimSpace(newEmail))
	if normalizedEmail == u.email {
		return nil // No change
	}

	u.email = normalizedEmail
	u.emailVerified = false // Reset verification when email changes
	u.markUpdated()

	return nil
}

// VerifyEmail marks the email as verified
func (u *User) VerifyEmail() {
	if !u.emailVerified {
		u.emailVerified = true
		u.markUpdated()
	}
}

// UpdatePreferences updates the user's preferences
func (u *User) UpdatePreferences(preferences *valueobjects.UserPreferences) error {
	if preferences == nil {
		return errors.ErrValidationFailed("preferences", "preferences cannot be nil")
	}

	if err := preferences.Validate(); err != nil {
		return fmt.Errorf("invalid preferences: %w", err)
	}

	u.preferences = preferences
	u.markUpdated()

	return nil
}

// UpdatePrivacySettings updates the user's privacy settings
func (u *User) UpdatePrivacySettings(settings *valueobjects.PrivacySettings) error {
	if settings == nil {
		return errors.ErrValidationFailed("privacy_settings", "privacy settings cannot be nil")
	}

	if err := settings.Validate(); err != nil {
		return fmt.Errorf("invalid privacy settings: %w", err)
	}

	u.privacySettings = settings
	u.markUpdated()

	return nil
}

// RecordLogin records a successful login
func (u *User) RecordLogin() error {
	if !u.IsActive() {
		return errors.ErrOperationNotAllowed("record login", "user is not active")
	}

	now := types.NewTimestamp()
	u.lastLoginAt = &now
	
	// Update statistics
	u.statistics.RecordLogin()
	
	u.markUpdated()

	return nil
}

// Ban bans the user
func (u *User) Ban(reason string, bannedBy types.UserID, duration *types.Duration) error {
	if u.isBanned {
		return errors.ErrOperationNotAllowed("ban user", "user is already banned")
	}

	if reason == "" {
		return errors.ErrValidationFailed("reason", "ban reason cannot be empty")
	}

	if bannedBy.IsEmpty() {
		return errors.ErrValidationFailed("banned_by", "banned by user ID cannot be empty")
	}

	u.isBanned = true
	u.banReason = &reason

	// Set ban expiration if duration provided
	if duration != nil {
		bannedUntil := types.NewTimestamp().Add(*duration)
		u.bannedUntil = &bannedUntil
	}

	u.status = types.UserStatusBanned
	u.markUpdated()

	return nil
}

// Unban removes the ban from the user
func (u *User) Unban() error {
	if !u.isBanned {
		return errors.ErrOperationNotAllowed("unban user", "user is not banned")
	}

	u.isBanned = false
	u.banReason = nil
	u.bannedUntil = nil
	u.status = types.UserStatusActive
	u.markUpdated()

	return nil
}

// CheckBanExpiration checks if a temporary ban has expired
func (u *User) CheckBanExpiration() bool {
	if !u.isBanned || u.bannedUntil == nil {
		return false
	}

	now := types.NewTimestamp()
	if now.After(*u.bannedUntil) {
		// Ban has expired, unban the user
		u.Unban()
		return true
	}

	return false
}

// Deactivate deactivates the user account
func (u *User) Deactivate() error {
	if !u.isActive {
		return errors.ErrOperationNotAllowed("deactivate user", "user is already inactive")
	}

	u.isActive = false
	u.status = types.UserStatusInactive
	u.markUpdated()

	return nil
}

// Reactivate reactivates the user account
func (u *User) Reactivate() error {
	if u.isActive {
		return errors.ErrOperationNotAllowed("reactivate user", "user is already active")
	}

	if u.isBanned {
		return errors.ErrOperationNotAllowed("reactivate user", "cannot reactivate banned user")
	}

	u.isActive = true
	u.status = types.UserStatusActive
	u.markUpdated()

	return nil
}

// AddRole adds a role to the user
func (u *User) AddRole(role types.UserRole) error {
	// Check if role already exists
	for _, existingRole := range u.roles {
		if existingRole == role {
			return nil // Already has role
		}
	}

	u.roles = append(u.roles, role)
	u.markUpdated()

	return nil
}

// RemoveRole removes a role from the user
func (u *User) RemoveRole(role types.UserRole) error {
	// Don't allow removal of Player role (everyone must have it)
	if role == types.UserRolePlayer {
		return errors.ErrOperationNotAllowed("remove role", "cannot remove Player role")
	}

	for i, existingRole := range u.roles {
		if existingRole == role {
			u.roles = append(u.roles[:i], u.roles[i+1:]...)
			u.markUpdated()
			return nil
		}
	}

	return errors.ErrNotFound("role", string(role))
}

// AddPermission adds a permission to the user
func (u *User) AddPermission(permission string) error {
	permission = strings.TrimSpace(permission)
	if permission == "" {
		return errors.ErrValidationFailed("permission", "permission cannot be empty")
	}

	// Check if permission already exists
	for _, existingPermission := range u.permissions {
		if existingPermission == permission {
			return nil // Already has permission
		}
	}

	u.permissions = append(u.permissions, permission)
	u.markUpdated()

	return nil
}

// RemovePermission removes a permission from the user
func (u *User) RemovePermission(permission string) error {
	for i, existingPermission := range u.permissions {
		if existingPermission == permission {
			u.permissions = append(u.permissions[:i], u.permissions[i+1:]...)
			u.markUpdated()
			return nil
		}
	}

	return errors.ErrNotFound("permission", permission)
}

// UpdateStatistics updates user statistics
func (u *User) UpdateStatistics(stats *valueobjects.UserStatistics) error {
	if stats == nil {
		return errors.ErrValidationFailed("statistics", "statistics cannot be nil")
	}

	if err := stats.Validate(); err != nil {
		return fmt.Errorf("invalid statistics: %w", err)
	}

	u.statistics = stats
	u.markUpdated()

	return nil
}

// Query methods

// HasRole checks if the user has a specific role
func (u *User) HasRole(role types.UserRole) bool {
	for _, userRole := range u.roles {
		if userRole == role {
			return true
		}
	}
	return false
}

// HasPermission checks if the user has a specific permission
func (u *User) HasPermission(permission string) bool {
	for _, userPermission := range u.permissions {
		if userPermission == permission {
			return true
		}
	}
	return false
}

// IsAdmin returns true if the user is an admin
func (u *User) IsAdmin() bool {
	return u.HasRole(types.UserRoleAdmin)
}

// IsModerator returns true if the user is a moderator
func (u *User) IsModerator() bool {
	return u.HasRole(types.UserRoleModerator)
}

// CanPlay returns true if the user can play games
func (u *User) CanPlay() bool {
	return u.IsActive() && !u.isBanned
}

// GetDisplayName returns the best display name for the user
func (u *User) GetDisplayName() string {
	// Prefer player name
	if u.playerName != nil && u.playerName.Value() != "" {
		return u.playerName.Value()
	}

	// Fall back to profile name
	if u.profile != nil {
		fullName := strings.TrimSpace(u.profile.FirstName() + " " + u.profile.LastName())
		if fullName != "" {
			return fullName
		}
		
		if u.profile.FirstName() != "" {
			return u.profile.FirstName()
		}
	}

	// Fall back to email prefix
	parts := strings.Split(u.email, "@")
	if len(parts) > 0 && parts[0] != "" {
		return parts[0]
	}

	// Last resort
	return "User"
}

// GetAge returns the user's age if date of birth is available
func (u *User) GetAge() *int {
	if u.profile == nil || u.profile.DateOfBirth() == nil {
		return nil
	}

	now := time.Now()
	birthDate := time.Time(*u.profile.DateOfBirth())
	
	age := now.Year() - birthDate.Year()
	if now.YearDay() < birthDate.YearDay() {
		age--
	}

	return &age
}

// GetAccountAge returns how long the user has been registered
func (u *User) GetAccountAge() time.Duration {
	now := types.NewTimestamp()
	return now.Sub(u.createdAt)
}

// IsNewUser returns true if the user registered recently
func (u *User) IsNewUser() bool {
	age := u.GetAccountAge()
	return age < 7*24*time.Hour // Less than 7 days old
}

// Validation

// Validate performs comprehensive validation
func (u *User) Validate() *types.ValidationResult {
	result := types.NewValidationResult()

	// Validate ID
	if u.id.IsEmpty() {
		result.AddError("user ID cannot be empty")
	}

	// Validate email
	if err := validateEmail(u.email); err != nil {
		result.AddErrorf("invalid email: %v", err)
	}

	// Validate auth provider
	if u.authProvider == "" {
		result.AddError("auth provider cannot be empty")
	}

	// Validate external ID
	if u.externalID == "" {
		result.AddError("external ID cannot be empty")
	}

	// Validate profile
	if u.profile != nil {
		if profileResult := u.profile.Validate(); !profileResult.IsValid() {
			for _, error := range profileResult.Errors() {
				result.AddErrorf("profile validation failed: %s", error)
			}
		}
	}

	// Validate player name
	if u.playerName != nil {
		if playerNameResult := u.playerName.Validate(); !playerNameResult.IsValid() {
			for _, error := range playerNameResult.Errors() {
				result.AddErrorf("player name validation failed: %s", error)
			}
		}
	}

	// Validate preferences
	if u.preferences != nil {
		if prefResult := u.preferences.Validate(); !prefResult.IsValid() {
			for _, error := range prefResult.Errors() {
				result.AddErrorf("preferences validation failed: %s", error)
			}
		}
	}

	// Validate privacy settings
	if u.privacySettings != nil {
		if privacyResult := u.privacySettings.Validate(); !privacyResult.IsValid() {
			for _, error := range privacyResult.Errors() {
				result.AddErrorf("privacy settings validation failed: %s", error)
			}
		}
	}

	// Validate statistics
	if u.statistics != nil {
		if statsResult := u.statistics.Validate(); !statsResult.IsValid() {
			for _, error := range statsResult.Errors() {
				result.AddErrorf("statistics validation failed: %s", error)
			}
		}
	}

	// Validate roles
	if len(u.roles) == 0 {
		result.AddError("user must have at least one role")
	}

	// Check for Player role
	hasPlayerRole := false
	for _, role := range u.roles {
		if role == types.UserRolePlayer {
			hasPlayerRole = true
			break
		}
	}
	if !hasPlayerRole {
		result.AddError("user must have Player role")
	}

	// Validate ban logic
	if u.isBanned && u.banReason == nil {
		result.AddError("banned user must have ban reason")
	}

	if u.banReason != nil && !u.isBanned {
		result.AddError("user has ban reason but is not marked as banned")
	}

	return result
}

// Helper methods

// markUpdated updates the timestamp and version
func (u *User) markUpdated() {
	u.updatedAt = types.NewTimestamp()
	u.version++
}

// ToSnapshot creates a read-only snapshot of the user
func (u *User) ToSnapshot() *UserSnapshot {
	var playerName *string
	if u.playerName != nil {
		name := u.playerName.Value()
		playerName = &name
	}

	return &UserSnapshot{
		ID:              u.id,
		Email:           u.email,
		Profile:         u.profile.ToSnapshot(),
		PlayerName:      playerName,
		Preferences:     u.preferences.ToSnapshot(),
		AuthProvider:    u.authProvider,
		ExternalID:      u.externalID,
		EmailVerified:   u.emailVerified,
		Status:          u.status,
		IsActive:        u.isActive,
		IsBanned:        u.isBanned,
		BanReason:       u.banReason,
		BannedUntil:     u.bannedUntil,
		Statistics:      u.statistics.ToSnapshot(),
		CreatedAt:       u.createdAt,
		UpdatedAt:       u.updatedAt,
		LastLoginAt:     u.lastLoginAt,
		Roles:           append([]types.UserRole(nil), u.roles...),
		Permissions:     append([]string(nil), u.permissions...),
		PrivacySettings: u.privacySettings.ToSnapshot(),
		Version:         u.version,
	}
}

// UserSnapshot represents a read-only view of a user
type UserSnapshot struct {
	ID              types.UserID                            `json:"id"`
	Email           string                                  `json:"email"`
	Profile         *valueobjects.UserProfileSnapshot       `json:"profile"`
	PlayerName      *string                                 `json:"player_name,omitempty"`
	Preferences     *valueobjects.UserPreferencesSnapshot   `json:"preferences"`
	AuthProvider    string                                  `json:"auth_provider"`
	ExternalID      string                                  `json:"external_id"`
	EmailVerified   bool                                    `json:"email_verified"`
	Status          types.UserStatus                        `json:"status"`
	IsActive        bool                                    `json:"is_active"`
	IsBanned        bool                                    `json:"is_banned"`
	BanReason       *string                                 `json:"ban_reason,omitempty"`
	BannedUntil     *types.Timestamp                        `json:"banned_until,omitempty"`
	Statistics      *valueobjects.UserStatisticsSnapshot    `json:"statistics"`
	CreatedAt       types.Timestamp                         `json:"created_at"`
	UpdatedAt       types.Timestamp                         `json:"updated_at"`
	LastLoginAt     *types.Timestamp                        `json:"last_login_at,omitempty"`
	Roles           []types.UserRole                        `json:"roles"`
	Permissions     []string                                `json:"permissions"`
	PrivacySettings *valueobjects.PrivacySettingsSnapshot   `json:"privacy_settings"`
	Version         int                                     `json:"version"`
}

// GetDisplayName returns the display name for the snapshot
func (us *UserSnapshot) GetDisplayName() string {
	if us.PlayerName != nil && *us.PlayerName != "" {
		return *us.PlayerName
	}
	
	if us.Profile != nil {
		fullName := strings.TrimSpace(us.Profile.FirstName + " " + us.Profile.LastName)
		if fullName != "" {
			return fullName
		}
		if us.Profile.FirstName != "" {
			return us.Profile.FirstName
		}
	}

	parts := strings.Split(us.Email, "@")
	if len(parts) > 0 && parts[0] != "" {
		return parts[0]
	}

	return "User"
}

// Validation helper functions

func validateEmail(email string) error {
	email = strings.TrimSpace(email)
	if email == "" {
		return errors.ErrValidationFailed("email", "email cannot be empty")
	}

	if len(email) > types.MaxEmailLength {
		return errors.ErrValidationFailed("email", fmt.Sprintf("email too long (max %d characters)", types.MaxEmailLength))
	}

	// Basic email format validation
	if !strings.Contains(email, "@") {
		return errors.ErrValidationFailed("email", "email must contain @ symbol")
	}

	parts := strings.Split(email, "@")
	if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
		return errors.ErrValidationFailed("email", "invalid email format")
	}

	// More comprehensive email validation would go here
	// For production, use a proper email validation library

	return nil
}