Add price calculations in inches, minimum size on US is 1 sq ft (#76)

Co-authored-by: Anders Gustafsson <anders@photowall.se>

api/lib/prices.py

@@ -80,13 +80,23 @@ def wallpaper_price_new(
         height,
         material,
         market,
+        unit,
         inquiry=None,
 ):
     m2_prices = wallpaper_m2_price_new(product_id, material.id, market, inquiry)
 
+    if (unit == 'inch'):
+        width = width * 2.54
+        height = height * 2.54
+
     sqm = (width / 100) * (height / 100)
 
-    min_sqm = 1
+    if (market.name == 'US'):
+        # On inch markets, minimum size is 1 sq feet (12x12 inch = 30.48x30.48 cm = 0.09290304 m2)
+        min_sqm = 0.09290304
+    else:
+        # Elsewhere, minimum size is 1 sq meter
+        min_sqm = 1
 
     sqm = max(sqm, min_sqm)
 
@@ -207,6 +217,7 @@ def inquiry_price_new(
 ):
     width = kwargs.get("width", inquiry.width)
     height = kwargs.get("height", inquiry.height)
+    unit = kwargs.get("unit", None)
     material = kwargs.get("material", inquiry.material)
     external_id = kwargs.get("external_id")
 
@@ -220,9 +231,9 @@ def inquiry_price_new(
         return prices
     elif inquiry.product_group == "photo-wallpaper":
         if is_own_image:
-            prices = wallpaper_price_new(None, width, height, material, inquiry.market, inquiry)
+            prices = wallpaper_price_new(None, width, height, material, inquiry.market, unit, inquiry)
         else:
-            prices = wallpaper_price_new(product_id, width, height, material, inquiry.market, inquiry)
+            prices = wallpaper_price_new(product_id, width, height, material, inquiry.market, unit, inquiry)
     else:
         raise ValueError("Invalid product group: {}".format(inquiry.product_group))