package repositories

import (
	"errors"
	"strings"
	"time"

	"gorm.io/gorm"

	"github.com/treytartt/mycrib-api/internal/models"
)

var (
	ErrUserNotFound     = errors.New("user not found")
	ErrUserExists       = errors.New("user already exists")
	ErrInvalidToken     = errors.New("invalid token")
	ErrTokenNotFound    = errors.New("token not found")
	ErrCodeNotFound     = errors.New("code not found")
	ErrCodeExpired      = errors.New("code expired")
	ErrCodeUsed         = errors.New("code already used")
	ErrTooManyAttempts  = errors.New("too many attempts")
	ErrRateLimitExceeded = errors.New("rate limit exceeded")
)

// UserRepository handles user-related database operations
type UserRepository struct {
	db *gorm.DB
}

// NewUserRepository creates a new user repository
func NewUserRepository(db *gorm.DB) *UserRepository {
	return &UserRepository{db: db}
}

// FindByID finds a user by ID
func (r *UserRepository) FindByID(id uint) (*models.User, error) {
	var user models.User
	if err := r.db.First(&user, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// FindByIDWithProfile finds a user by ID with profile preloaded
func (r *UserRepository) FindByIDWithProfile(id uint) (*models.User, error) {
	var user models.User
	if err := r.db.Preload("Profile").First(&user, id).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// FindByUsername finds a user by username (case-insensitive)
func (r *UserRepository) FindByUsername(username string) (*models.User, error) {
	var user models.User
	if err := r.db.Where("LOWER(username) = LOWER(?)", username).First(&user).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// FindByEmail finds a user by email (case-insensitive)
func (r *UserRepository) FindByEmail(email string) (*models.User, error) {
	var user models.User
	if err := r.db.Where("LOWER(email) = LOWER(?)", email).First(&user).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// FindByUsernameOrEmail finds a user by username or email
func (r *UserRepository) FindByUsernameOrEmail(identifier string) (*models.User, error) {
	var user models.User
	if err := r.db.Where("LOWER(username) = LOWER(?) OR LOWER(email) = LOWER(?)", identifier, identifier).First(&user).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// Create creates a new user
func (r *UserRepository) Create(user *models.User) error {
	return r.db.Create(user).Error
}

// Update updates a user
func (r *UserRepository) Update(user *models.User) error {
	return r.db.Save(user).Error
}

// UpdateLastLogin updates the user's last login timestamp
func (r *UserRepository) UpdateLastLogin(userID uint) error {
	now := time.Now().UTC()
	return r.db.Model(&models.User{}).Where("id = ?", userID).Update("last_login", now).Error
}

// ExistsByUsername checks if a username exists
func (r *UserRepository) ExistsByUsername(username string) (bool, error) {
	var count int64
	if err := r.db.Model(&models.User{}).Where("LOWER(username) = LOWER(?)", username).Count(&count).Error; err != nil {
		return false, err
	}
	return count > 0, nil
}

// ExistsByEmail checks if an email exists
func (r *UserRepository) ExistsByEmail(email string) (bool, error) {
	var count int64
	if err := r.db.Model(&models.User{}).Where("LOWER(email) = LOWER(?)", email).Count(&count).Error; err != nil {
		return false, err
	}
	return count > 0, nil
}

// --- Auth Token Methods ---

// GetOrCreateToken gets or creates an auth token for a user
func (r *UserRepository) GetOrCreateToken(userID uint) (*models.AuthToken, error) {
	var token models.AuthToken
	result := r.db.Where("user_id = ?", userID).First(&token)

	if errors.Is(result.Error, gorm.ErrRecordNotFound) {
		token = models.AuthToken{UserID: userID}
		if err := r.db.Create(&token).Error; err != nil {
			return nil, err
		}
	} else if result.Error != nil {
		return nil, result.Error
	}

	return &token, nil
}

// DeleteToken deletes an auth token
func (r *UserRepository) DeleteToken(token string) error {
	result := r.db.Where("key = ?", token).Delete(&models.AuthToken{})
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return ErrTokenNotFound
	}
	return nil
}

// DeleteTokenByUserID deletes an auth token by user ID
func (r *UserRepository) DeleteTokenByUserID(userID uint) error {
	return r.db.Where("user_id = ?", userID).Delete(&models.AuthToken{}).Error
}

// --- User Profile Methods ---

// GetOrCreateProfile gets or creates a user profile
func (r *UserRepository) GetOrCreateProfile(userID uint) (*models.UserProfile, error) {
	var profile models.UserProfile
	result := r.db.Where("user_id = ?", userID).First(&profile)

	if errors.Is(result.Error, gorm.ErrRecordNotFound) {
		profile = models.UserProfile{UserID: userID}
		if err := r.db.Create(&profile).Error; err != nil {
			return nil, err
		}
	} else if result.Error != nil {
		return nil, result.Error
	}

	return &profile, nil
}

// UpdateProfile updates a user profile
func (r *UserRepository) UpdateProfile(profile *models.UserProfile) error {
	return r.db.Save(profile).Error
}

// SetProfileVerified sets the profile verified status
func (r *UserRepository) SetProfileVerified(userID uint, verified bool) error {
	return r.db.Model(&models.UserProfile{}).Where("user_id = ?", userID).Update("verified", verified).Error
}

// --- Confirmation Code Methods ---

// CreateConfirmationCode creates a new confirmation code
func (r *UserRepository) CreateConfirmationCode(userID uint, code string, expiresAt time.Time) (*models.ConfirmationCode, error) {
	// Invalidate any existing unused codes for this user
	r.db.Model(&models.ConfirmationCode{}).
		Where("user_id = ? AND is_used = ?", userID, false).
		Update("is_used", true)

	confirmCode := &models.ConfirmationCode{
		UserID:    userID,
		Code:      code,
		ExpiresAt: expiresAt,
		IsUsed:    false,
	}

	if err := r.db.Create(confirmCode).Error; err != nil {
		return nil, err
	}

	return confirmCode, nil
}

// FindConfirmationCode finds a valid confirmation code for a user
func (r *UserRepository) FindConfirmationCode(userID uint, code string) (*models.ConfirmationCode, error) {
	var confirmCode models.ConfirmationCode
	if err := r.db.Where("user_id = ? AND code = ? AND is_used = ?", userID, code, false).
		First(&confirmCode).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrCodeNotFound
		}
		return nil, err
	}

	if !confirmCode.IsValid() {
		if confirmCode.IsUsed {
			return nil, ErrCodeUsed
		}
		return nil, ErrCodeExpired
	}

	return &confirmCode, nil
}

// MarkConfirmationCodeUsed marks a confirmation code as used
func (r *UserRepository) MarkConfirmationCodeUsed(codeID uint) error {
	return r.db.Model(&models.ConfirmationCode{}).Where("id = ?", codeID).Update("is_used", true).Error
}

// --- Password Reset Code Methods ---

// CreatePasswordResetCode creates a new password reset code
func (r *UserRepository) CreatePasswordResetCode(userID uint, codeHash string, resetToken string, expiresAt time.Time) (*models.PasswordResetCode, error) {
	// Invalidate any existing unused codes for this user
	r.db.Model(&models.PasswordResetCode{}).
		Where("user_id = ? AND used = ?", userID, false).
		Update("used", true)

	resetCode := &models.PasswordResetCode{
		UserID:      userID,
		CodeHash:    codeHash,
		ResetToken:  resetToken,
		ExpiresAt:   expiresAt,
		Used:        false,
		Attempts:    0,
		MaxAttempts: 5,
	}

	if err := r.db.Create(resetCode).Error; err != nil {
		return nil, err
	}

	return resetCode, nil
}

// FindPasswordResetCode finds a password reset code by email and checks validity
func (r *UserRepository) FindPasswordResetCodeByEmail(email string) (*models.PasswordResetCode, *models.User, error) {
	user, err := r.FindByEmail(email)
	if err != nil {
		return nil, nil, err
	}

	var resetCode models.PasswordResetCode
	if err := r.db.Where("user_id = ? AND used = ?", user.ID, false).
		Order("created_at DESC").
		First(&resetCode).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, nil, ErrCodeNotFound
		}
		return nil, nil, err
	}

	return &resetCode, user, nil
}

// FindPasswordResetCodeByToken finds a password reset code by reset token
func (r *UserRepository) FindPasswordResetCodeByToken(resetToken string) (*models.PasswordResetCode, error) {
	var resetCode models.PasswordResetCode
	if err := r.db.Where("reset_token = ?", resetToken).First(&resetCode).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrCodeNotFound
		}
		return nil, err
	}

	if !resetCode.IsValid() {
		if resetCode.Used {
			return nil, ErrCodeUsed
		}
		if resetCode.Attempts >= resetCode.MaxAttempts {
			return nil, ErrTooManyAttempts
		}
		return nil, ErrCodeExpired
	}

	return &resetCode, nil
}

// IncrementResetCodeAttempts increments the attempt counter
func (r *UserRepository) IncrementResetCodeAttempts(codeID uint) error {
	return r.db.Model(&models.PasswordResetCode{}).Where("id = ?", codeID).
		Update("attempts", gorm.Expr("attempts + 1")).Error
}

// MarkPasswordResetCodeUsed marks a password reset code as used
func (r *UserRepository) MarkPasswordResetCodeUsed(codeID uint) error {
	return r.db.Model(&models.PasswordResetCode{}).Where("id = ?", codeID).Update("used", true).Error
}

// CountRecentPasswordResetRequests counts reset requests in the last hour
func (r *UserRepository) CountRecentPasswordResetRequests(userID uint) (int64, error) {
	var count int64
	oneHourAgo := time.Now().UTC().Add(-1 * time.Hour)
	if err := r.db.Model(&models.PasswordResetCode{}).
		Where("user_id = ? AND created_at > ?", userID, oneHourAgo).
		Count(&count).Error; err != nil {
		return 0, err
	}
	return count, nil
}

// --- Search Methods ---

// SearchUsers searches users by username, email, first name, or last name
func (r *UserRepository) SearchUsers(query string, limit, offset int) ([]models.User, int64, error) {
	var users []models.User
	var total int64

	searchQuery := "%" + strings.ToLower(query) + "%"

	baseQuery := r.db.Model(&models.User{}).
		Where("LOWER(username) LIKE ? OR LOWER(email) LIKE ? OR LOWER(first_name) LIKE ? OR LOWER(last_name) LIKE ?",
			searchQuery, searchQuery, searchQuery, searchQuery)

	if err := baseQuery.Count(&total).Error; err != nil {
		return nil, 0, err
	}

	if err := baseQuery.Offset(offset).Limit(limit).Find(&users).Error; err != nil {
		return nil, 0, err
	}

	return users, total, nil
}

// ListUsers lists all users with pagination
func (r *UserRepository) ListUsers(limit, offset int) ([]models.User, int64, error) {
	var users []models.User
	var total int64

	if err := r.db.Model(&models.User{}).Count(&total).Error; err != nil {
		return nil, 0, err
	}

	if err := r.db.Offset(offset).Limit(limit).Find(&users).Error; err != nil {
		return nil, 0, err
	}

	return users, total, nil
}