package repository

import (
	"context"
	"errors"

	"github.com/Tencent/WeKnora/internal/types"
	"github.com/Tencent/WeKnora/internal/types/interfaces"
	"gorm.io/gorm"
)

var (
	ErrUserNotFound      = errors.New("user not found")
	ErrUserAlreadyExists = errors.New("user already exists")
	ErrTokenNotFound     = errors.New("token not found")
)

// userRepository implements user repository interface
type userRepository struct {
	db *gorm.DB
}

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

// CreateUser creates a user
func (r *userRepository) CreateUser(ctx context.Context, user *types.User) error {
	return r.db.WithContext(ctx).Create(user).Error
}

// GetUserByID gets a user by ID
func (r *userRepository) GetUserByID(ctx context.Context, id string) (*types.User, error) {
	var user types.User
	if err := r.db.WithContext(ctx).Where("id = ?", id).First(&user).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// GetUserByEmail gets a user by email
func (r *userRepository) GetUserByEmail(ctx context.Context, email string) (*types.User, error) {
	var user types.User
	if err := r.db.WithContext(ctx).Where("email = ?", email).First(&user).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// GetUserByUsername gets a user by username
func (r *userRepository) GetUserByUsername(ctx context.Context, username string) (*types.User, error) {
	var user types.User
	if err := r.db.WithContext(ctx).Where("username = ?", username).First(&user).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrUserNotFound
		}
		return nil, err
	}
	return &user, nil
}

// UpdateUser updates a user
func (r *userRepository) UpdateUser(ctx context.Context, user *types.User) error {
	return r.db.WithContext(ctx).Save(user).Error
}

// DeleteUser deletes a user
func (r *userRepository) DeleteUser(ctx context.Context, id string) error {
	return r.db.WithContext(ctx).Where("id = ?", id).Delete(&types.User{}).Error
}

// ListUsers lists users with pagination
func (r *userRepository) ListUsers(ctx context.Context, offset, limit int) ([]*types.User, error) {
	var users []*types.User
	query := r.db.WithContext(ctx).Order("created_at DESC")

	if limit > 0 {
		query = query.Limit(limit)
	}

	if offset > 0 {
		query = query.Offset(offset)
	}

	if err := query.Find(&users).Error; err != nil {
		return nil, err
	}
	return users, nil
}

// authTokenRepository implements auth token repository interface
type authTokenRepository struct {
	db *gorm.DB
}

// NewAuthTokenRepository creates a new auth token repository
func NewAuthTokenRepository(db *gorm.DB) interfaces.AuthTokenRepository {
	return &authTokenRepository{db: db}
}

// CreateToken creates an auth token
func (r *authTokenRepository) CreateToken(ctx context.Context, token *types.AuthToken) error {
	return r.db.WithContext(ctx).Create(token).Error
}

// GetTokenByValue gets a token by its value
func (r *authTokenRepository) GetTokenByValue(ctx context.Context, tokenValue string) (*types.AuthToken, error) {
	var token types.AuthToken
	if err := r.db.WithContext(ctx).Where("token = ?", tokenValue).First(&token).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTokenNotFound
		}
		return nil, err
	}
	return &token, nil
}

// GetTokensByUserID gets all tokens for a user
func (r *authTokenRepository) GetTokensByUserID(ctx context.Context, userID string) ([]*types.AuthToken, error) {
	var tokens []*types.AuthToken
	if err := r.db.WithContext(ctx).Where("user_id = ?", userID).Find(&tokens).Error; err != nil {
		return nil, err
	}
	return tokens, nil
}

// UpdateToken updates a token
func (r *authTokenRepository) UpdateToken(ctx context.Context, token *types.AuthToken) error {
	return r.db.WithContext(ctx).Save(token).Error
}

// DeleteToken deletes a token
func (r *authTokenRepository) DeleteToken(ctx context.Context, id string) error {
	return r.db.WithContext(ctx).Where("id = ?", id).Delete(&types.AuthToken{}).Error
}

// DeleteExpiredTokens deletes all expired tokens
func (r *authTokenRepository) DeleteExpiredTokens(ctx context.Context) error {
	return r.db.WithContext(ctx).Where("expires_at < NOW()").Delete(&types.AuthToken{}).Error
}

// RevokeTokensByUserID revokes all tokens for a user
func (r *authTokenRepository) RevokeTokensByUserID(ctx context.Context, userID string) error {
	return r.db.WithContext(ctx).Model(&types.AuthToken{}).Where("user_id = ?", userID).Update("is_revoked", true).Error
}