Refactor prompt generation logic in app.py to enhance validation and user experience

- Introduced a helper function to validate input values, ensuring that 'None' and 'Keep Existing' selections are excluded from the prompt generation.
- Improved the construction of prompt parts for room, floor, wall, and accessories by checking for valid values before appending to the prompt.
- Streamlined the logic for adding accessories and custom text, ensuring only valid entries are included in the final prompt.
- Enhanced overall clarity and maintainability of the code by reducing redundancy and improving the structure of the prompt generation process.

app.py

@@ -383,6 +383,10 @@ def create_ui(model: DesignModel):
         with gr.Row(elem_classes="button-row"):
             submit = gr.Button("✨ Create My Design", variant="primary", size="lg")
 
+        def is_valid_value(*values):
+            """Helper function to check if values are valid (not None or Keep Existing)"""
+            return all(v not in ["None", "Keep Existing"] for v in values)
+
         def update_prompt(room, style, colors, floor_t, floor_c, floor_p,
                          wall_t, wall_c, wall_f, custom_text,
                          art_en, art_col, art_size,
@@ -390,59 +394,72 @@ def create_ui(model: DesignModel):
                          sconce_en, sconce_col, sconce_style,
                          shelf_en, shelf_col, shelf_size,
                          plants_en, plants_type, plants_size):
-            # Start with basic room, style, and color scheme (these should always be included as they have valid defaults)
-            prompt_parts = [f"Design a {style} {room.lower()} with a {colors} color scheme"]
+            """Generate a prompt for the design, skipping any None or Keep Existing values."""
+            
+            invalid_values = {"None", "Keep Existing", None, ""}
+            prompt_parts = []
+            
+            # Basic room settings - each part separate for maximum flexibility
+            if all(x not in invalid_values for x in [style, room, colors]):
+                base_parts = []
+                if style not in invalid_values:
+                    base_parts.append(style)
+                if room not in invalid_values:
+                    base_parts.append(room.lower())
+                if colors not in invalid_values:
+                    base_parts.append(f"with a {colors} color scheme")
+                if base_parts:
+                    prompt_parts.append("Design a " + " ".join(base_parts))
             
-            # Add floor details only if not "Keep Existing" or "None"
-            if floor_t not in ["Keep Existing", "None"]:
-                floor_desc = floor_t
-                if floor_c not in ["Keep Existing", "None"]:
-                    floor_desc += f" in {floor_c}"
-                if floor_p not in ["Keep Existing", "None"]:
-                    floor_desc += f" with {floor_p} pattern"
-                prompt_parts.append(f"featuring {floor_desc} flooring")
+            # Floor details - build up piece by piece
+            if floor_t not in invalid_values:
+                floor_parts = [floor_t]
+                if floor_c not in invalid_values:
+                    floor_parts.append(f"in {floor_c}")
+                if floor_p not in invalid_values:
+                    floor_parts.append(f"with {floor_p} pattern")
+                prompt_parts.append(f"featuring {' '.join(floor_parts)} flooring")
             
-            # Add wall details only if not "Keep Existing" or "None"
-            if wall_t not in ["Keep Existing", "None"]:
-                wall_desc = wall_t
-                if wall_c not in ["Keep Existing", "None"]:
-                    wall_desc += f" in {wall_c}"
-                if wall_f not in ["Keep Existing", "None"]:
-                    wall_desc += f" with {wall_f} finish"
-                prompt_parts.append(f"with {wall_desc} walls")
+            # Wall details - build up piece by piece
+            if wall_t not in invalid_values:
+                wall_parts = [wall_t]
+                if wall_c not in invalid_values:
+                    wall_parts.append(f"in {wall_c}")
+                if wall_f not in invalid_values:
+                    wall_parts.append(f"with {wall_f} finish")
+                prompt_parts.append(f"with {' '.join(wall_parts)} walls")
             
-            # Add accessories only if enabled AND properties are not "Keep Existing" or "None"
+            # Accessories - only add valid combinations
             accessories = []
             
             # Art Print
-            if art_en and art_col not in ["Keep Existing", "None"] and art_size not in ["Keep Existing", "None"]:
+            if art_en and art_col not in invalid_values and art_size not in invalid_values:
                 accessories.append(f"{art_size} {art_col} Art Print")
             
             # Mirror
-            if mirror_en and mirror_fr not in ["Keep Existing", "None"] and mirror_size not in ["Keep Existing", "None"]:
+            if mirror_en and mirror_fr not in invalid_values and mirror_size not in invalid_values:
                 accessories.append(f"{mirror_size} Mirror with {mirror_fr} frame")
             
             # Wall Sconce
-            if sconce_en and sconce_col not in ["Keep Existing", "None"] and sconce_style not in ["Keep Existing", "None"]:
+            if sconce_en and sconce_col not in invalid_values and sconce_style not in invalid_values:
                 accessories.append(f"{sconce_style} {sconce_col} Wall Sconce")
             
             # Floating Shelves
-            if shelf_en and shelf_col not in ["Keep Existing", "None"] and shelf_size not in ["Keep Existing", "None"]:
+            if shelf_en and shelf_col not in invalid_values and shelf_size not in invalid_values:
                 accessories.append(f"{shelf_size} {shelf_col} Floating Shelves")
             
             # Wall Plants
-            if plants_en and plants_type not in ["Keep Existing", "None"] and plants_size not in ["Keep Existing", "None"]:
+            if plants_en and plants_type not in invalid_values and plants_size not in invalid_values:
                 accessories.append(f"{plants_size} {plants_type}")
             
-            # Only add accessories section if there are any accessories
             if accessories:
                 prompt_parts.append("decorated with " + ", ".join(accessories))
             
-            # Add custom text only if provided and non-empty
-            if custom_text and custom_text.strip():
+            # Add custom text if present
+            if custom_text and custom_text.strip() and custom_text not in invalid_values:
                 prompt_parts.append(custom_text.strip())
             
-            return ", ".join(prompt_parts)
+            return ", ".join(prompt_parts) if prompt_parts else "Please select room type, style, and color scheme"
 
         def on_submit(image, room, style, colors, floor_t, floor_c, floor_p,
                      wall_t, wall_c, wall_f, custom_text,