Per-vendor fee (charge once per distinct vendor in cart)

{% liquid
  # Add $3 per distinct vendor present (useful for split-ship approximations).
  # Example: 2 vendors in cart -> $6 fee. Optionally cap at a max.

  # --- editable settings ---
  assign service_name = "Per-Vendor Shipping"
  assign service_code = "PER_VENDOR"
  assign currency = "USD"
  assign description = "Adds a fee per distinct vendor"
  assign base_price = 0                         # cents base
  assign per_vendor_fee = 300                   # cents
  assign max_vendor_fee = 1500                  # cents cap (set to a big number to effectively disable)

  # --- logic ---
  assign seen = ""                              # we'll store tokens like |VENDOR|
  assign vendor_count = 0

  for item in shopify_rate_check.items
    assign token = "|" | append: item.vendor | append: "|"
    unless seen contains token
      assign seen = seen | append: token
      assign vendor_count = vendor_count | plus: 1
    endunless
  endfor

  assign calc_fee = per_vendor_fee | times: vendor_count
  assign calc_fee = calc_fee | at_most: max_vendor_fee
  assign shipping_price = base_price | plus: calc_fee

  assign rate = rate | merge: "currency", currency
  assign rate = rate | merge: "service_name", service_name
  assign rate = rate | merge: "service_code", service_code
  assign rate = rate | merge: "total_price", shipping_price
  assign rate = rate | merge: "description", description

  assign rates = rates | array_append: rate
%}
{
  "rates": {{ rates | array_wrap | json }}
}