Migrate shopify line item script to shopify function

[Priyanka_]

Hi,
I am currently using shopify script to create a line item script to provide discount to employee based on customer tag and product tag.  How can I create script using shopify function. 

Here is my code :

REJECTION_MESSAGE = 'Discount codes cannot be used during this sale'
CUSTOMER_IS_EMPLOYEE = false
 
DISCOUNT_MESSAGE_30 = "Employee 30% Discount"
DISCOUNT_PERCENTAGE_30 = 30
TAG_EMP_30 = "EMP_30"
 
DISCOUNT_MESSAGE_40 = "Employee 40% Discount"
DISCOUNT_PERCENTAGE_40 = 40
TAG_EMP_40 = "EMP_40"
 
DISCOUNT_MESSAGE_50 = "Employee 50% Discount"
DISCOUNT_PERCENTAGE_50 = 50
TAG_EMP_50 = "EMP_50"
 
DISCOUNT_MESSAGE_75 = "Employee 75% Discount"
DISCOUNT_PERCENTAGE_75 = 75
TAG_EMP_75 = "EMP_75"
 
TAG_EMPLOYEE = "Employee"
 
customer = Input.cart.customer
 
######################################
CART_REJECTION_MESSAGE ="discount code can not be applied"
 
condition_is_met = false
is_discount_applied = false
##########################################
 
  
 
# employee discount
 
if customer
  if customer.tags.include?(TAG_EMPLOYEE) and customer.email.end_with?("@abc.com") || customer.email.end_with?("@xyz.com") # Check if the customer is logged in and is tagged with our target tag
    CUSTOMER_IS_EMPLOYEE = true
  end
end
 
if CUSTOMER_IS_EMPLOYEE
  Input.cart.line_items.each do |line_item| # Loop over each cart item
    product = line_item.variant.product # Access the actual product object 
    # EMP_75 tag
    if product.tags.include?(TAG_EMP_75)
      DISCOUNT = ((100 - DISCOUNT_PERCENTAGE_75) / 100)
      line_item.change_line_price(line_item.line_price * DISCOUNT, message: DISCOUNT_MESSAGE_75) #Apply the overall discount to the line-item.
      if Input.cart.discount_code != nil
      is_discount_applied = true
      end
    end
    # EMP_50 tag
    if product.tags.include?(TAG_EMP_50)
      DISCOUNT = ((100 - DISCOUNT_PERCENTAGE_50) / 100)
      line_item.change_line_price(line_item.line_price * DISCOUNT, message: DISCOUNT_MESSAGE_50) #Apply the overall discount to the line-item.
      if Input.cart.discount_code != nil
      is_discount_applied = true
      end
    end
    # EMP_40 tag
    if product.tags.include?(TAG_EMP_40)
      DISCOUNT = ((100 - DISCOUNT_PERCENTAGE_40) / 100)
      line_item.change_line_price(line_item.line_price * DISCOUNT, message: DISCOUNT_MESSAGE_40) #Apply the overall discount to the line-item.
      if Input.cart.discount_code != nil
      is_discount_applied = true
      end
    end
    

  end

end
 
if is_discount_applied
  Input.cart.discount_code.reject({
    message: CART_REJECTION_MESSAGE
  })
end
 
 
Output.cart = Input.cart

Any help is greatly appriciated.

Thanks in advance.