# Service to create Stripe invoices for accounting records after successful payment
#
# This service creates post-payment invoices in Stripe for accounting purposes.
# Unlike regular Stripe invoices which are used for collection, these are
# created after payment via Checkout Sessions as accounting records.
class StripeInvoiceService
  attr_reader :order, :errors

  def initialize(order)
    @order = order
    @errors = []
  end

  # Create a post-payment invoice in Stripe
  #
  # Returns the created Stripe invoice object or nil if creation failed
  def create_post_payment_invoice
    return nil unless valid_for_invoice_creation?

    begin
      customer = find_or_create_stripe_customer
      return nil unless customer

      invoice = create_stripe_invoice(customer)
      return nil unless invoice

      add_line_items_to_invoice(customer, invoice)
      finalize_invoice(invoice)

      Rails.logger.info "Successfully created Stripe invoice #{invoice.id} for order #{@order.id}"
      invoice
    rescue Stripe::StripeError => e
      handle_stripe_error(e)
      nil
    rescue => e
      handle_generic_error(e)
      nil
    end
  end

  # Get the PDF URL for a Stripe invoice
  #
  # @param invoice_id [String] The Stripe invoice ID
  # @return [String, nil] The invoice PDF URL or nil if not available
  def self.get_invoice_pdf_url(invoice_id)
    return nil if invoice_id.blank?

    begin
      invoice = Stripe::Invoice.retrieve(invoice_id)
      invoice.invoice_pdf
    rescue Stripe::StripeError => e
      Rails.logger.error "Failed to retrieve Stripe invoice PDF URL: #{e.message}"
      nil
    end
  end

  private

  def valid_for_invoice_creation?
    unless @order.present?
      @errors << "Order is required"
      return false
    end

    unless @order.status == "paid"
      @errors << "Order must be paid to create invoice"
      return false
    end

    unless @order.user.present?
      @errors << "Order must have an associated user"
      return false
    end

    unless @order.tickets.any?
      @errors << "Order must have tickets to create invoice"
      return false
    end

    true
  end

  def find_or_create_stripe_customer
    if @order.user.stripe_customer_id.present?
      retrieve_existing_customer
    else
      create_new_customer
    end
  end

  def retrieve_existing_customer
    Stripe::Customer.retrieve(@order.user.stripe_customer_id)
  rescue Stripe::InvalidRequestError
    # Customer doesn't exist, create a new one
    Rails.logger.warn "Stripe customer #{@order.user.stripe_customer_id} not found, creating new customer"
    @order.user.update(stripe_customer_id: nil)
    create_new_customer
  end

  def create_new_customer
    customer = Stripe::Customer.create({
      email: @order.user.email,
      name: customer_name,
      metadata: {
        user_id: @order.user.id,
        created_by: "aperonight_system"
      }
    })

    @order.user.update(stripe_customer_id: customer.id)
    Rails.logger.info "Created new Stripe customer #{customer.id} for user #{@order.user.id}"
    customer
  end

  def customer_name
    parts = []
    parts << @order.user.first_name if @order.user.first_name.present?
    parts << @order.user.last_name if @order.user.last_name.present?

    if parts.empty?
      @order.user.email.split("@").first.humanize
    else
      parts.join(" ")
    end
  end

  def create_stripe_invoice(customer)
    invoice_data = {
      customer: customer.id,
      collection_method: "send_invoice", # Don't auto-charge
      auto_advance: false, # Don't automatically finalize
      metadata: {
        order_id: @order.id,
        user_id: @order.user.id,
        event_name: @order.event.name,
        created_by: "aperonight_system",
        payment_method: "checkout_session"
      },
      description: "Invoice for #{@order.event.name} - Order ##{@order.id}",
      footer: "Thank you for your purchase! This invoice is for your records as payment was already processed."
    }

    # Add due date (same day since it's already paid)
    invoice_data[:due_date] = Time.current.to_i

    Stripe::Invoice.create(invoice_data)
  end

  def add_line_items_to_invoice(customer, invoice)
    @order.tickets.group_by(&:ticket_type).each do |ticket_type, tickets|
      quantity = tickets.count

      Stripe::InvoiceItem.create({
        customer: customer.id,
        invoice: invoice.id,
        amount: ticket_type.price_cents * quantity,
        currency: "eur",
        description: build_line_item_description(ticket_type, tickets),
        metadata: {
          ticket_type_id: ticket_type.id,
          ticket_type_name: ticket_type.name,
          quantity: quantity,
          unit_price_cents: ticket_type.price_cents
        }
      })
    end
  end

  def build_line_item_description(ticket_type, tickets)
    quantity = tickets.count
    unit_price = ticket_type.price_cents / 100.0

    description_parts = [
      "#{@order.event.name}",
      "#{ticket_type.name}",
      "(#{quantity}x €#{unit_price})"
    ]

    description_parts.join(" - ")
  end

  def finalize_invoice(invoice)
    # Mark as paid since payment was already processed via checkout
    finalized_invoice = invoice.finalize_invoice

    # Mark the invoice as paid
    finalized_invoice.pay({
      paid_out_of_band: true,  # Payment was made outside of Stripe invoicing
      payment_method: nil       # No payment method needed for out-of-band payment
    })

    finalized_invoice
  end

  def handle_stripe_error(error)
    error_message = "Stripe invoice creation failed: #{error.message}"
    @errors << error_message
    Rails.logger.error "#{error_message} (Order: #{@order.id})"
  end

  def handle_generic_error(error)
    error_message = "Invoice creation failed: #{error.message}"
    @errors << error_message
    Rails.logger.error "#{error_message} (Order: #{@order.id})"
  end
end