first try for calculate from stl

backend/main.py

@@ -1,16 +1,72 @@
-from fastapi import FastAPI
+import io
+import trimesh
+from fastapi import FastAPI, UploadFile, File, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
 
 app = FastAPI()
 
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=["*"],  # oppure ["http://localhost:4200"] se vuoi essere più restrittivo
+    allow_origins=["*"],
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],
 )
 
-@app.get("/api/hello")
-def hello():
-    return {"message": "Hello from Python API"}
+def calculate_volumes(total_volume_mm3: float,
+                      surface_area_mm2: float,
+                      nozzle_width_mm: float = 0.4,
+                      wall_line_count: int = 3,
+                      layer_height_mm: float = 0.2,
+                      infill_fraction: float = 0.15):
+    wall_thickness_mm = nozzle_width_mm * wall_line_count
+    wall_volume_mm3 = surface_area_mm2 * wall_thickness_mm
+    infill_volume_mm3 = max(total_volume_mm3 - wall_volume_mm3, 0) * infill_fraction
+    total_print_volume_mm3 = wall_volume_mm3 + infill_volume_mm3
+    return total_print_volume_mm3, wall_volume_mm3, infill_volume_mm3
+
+def calculate_weight(volume_mm3: float, density_g_cm3: float = 1.24):
+    density_g_mm3 = density_g_cm3 / 1000.0
+    return volume_mm3 * density_g_mm3
+
+def calculate_cost(weight_g: float, price_per_kg: float = 20.0):
+    return round((weight_g / 1000.0) * price_per_kg, 2)
+
+def estimate_time(volume_mm3: float,
+                  nozzle_width_mm: float = 0.4,
+                  layer_height_mm: float = 0.2,
+                  print_speed_mm_per_s: float = 100.0):
+    volumetric_speed_mm3_per_min = nozzle_width_mm * layer_height_mm * print_speed_mm_per_s * 60.0
+    return round(volume_mm3 / volumetric_speed_mm3_per_min, 1)
+
+@app.post("/calculate/stl")
+async def calculate_from_stl(file: UploadFile = File(...)):
+    if not file.filename.lower().endswith(".stl"):
+        raise HTTPException(status_code=400, detail="Please upload an STL file.")
+    try:
+        contents = await file.read()
+        mesh = trimesh.load(io.BytesIO(contents), file_type="stl")
+        model_volume_mm3 = mesh.volume
+        model_surface_area_mm2 = mesh.area
+
+        print_volume, wall_volume, infill_volume = calculate_volumes(
+            total_volume_mm3=model_volume_mm3,
+            surface_area_mm2=model_surface_area_mm2
+        )
+
+        weight_g = calculate_weight(print_volume)
+        cost_chf = calculate_cost(weight_g)
+        time_min = estimate_time(print_volume)
+
+        return {
+            "stl_volume_mm3": round(model_volume_mm3, 2),
+            "surface_area_mm2": round(model_surface_area_mm2, 2),
+            "wall_volume_mm3": round(wall_volume, 2),
+            "infill_volume_mm3": round(infill_volume, 2),
+            "print_volume_mm3": round(print_volume, 2),
+            "weight_g": round(weight_g, 2),
+            "cost_chf": cost_chf,
+            "time_min": time_min
+        }
+    except Exception as e:
+        raise HTTPException(status_code=500, detail=str(e))