api/endpoints.py

"""
API Endpoints - Thin HTTP Layer

This module provides FastAPI endpoints with NO business logic.
All detection logic is delegated to the detection module.

Architecture:
- Validates HTTP requests
- Delegates to detection.service for business logic
- Returns standardized responses via detection.response_builder
"""

import os
os.environ['PYTORCH_ENABLE_MPS_FALLBACK'] = '1'

from fastapi import FastAPI, File, UploadFile, Form, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from PIL import Image
import io
import torch
from typing import Optional

# Import detection services
from detection.service_factory import get_detection_service
from detection import ocr_handler, response_builder

# Create FastAPI app
app = FastAPI(
    title="CU-1 UI Element Detector API",
    description="Detect and classify UI elements in screenshots using RF-DETR + CLIP + OCR + BLIP",
    version="1.0.0"
)

# Enable CORS
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.get("/")
async def root():
    """API root endpoint with documentation"""
    return {
        "name": "CU-1 UI Element Detector API",
        "version": "1.0.0",
        "architecture": "RF-DETR (Detection) + CLIP (Classification) + OCR + BLIP",
        "endpoints": {
            "/detect": "POST - Detect UI elements in an image",
            "/health": "GET - Health check",
            "/docs": "GET - Interactive API documentation"
        },
        "example": {
            "curl": """curl -X POST "http://localhost:8000/detect" \\
  -F "image=@screenshot.png" \\
  -F "confidence_threshold=0.35" \\
  -F "enable_clip=true" \\
  -F "enable_ocr=true" """
        }
    }


@app.get("/health")
async def health_check():
    """Health check endpoint"""
    return {
        "status": "healthy",
        "cuda_available": torch.cuda.is_available(),
        "device": "cuda" if torch.cuda.is_available() else "cpu"
    }


@app.post("/detect")
async def detect_ui_elements(
    image: UploadFile = File(..., description="Image file to process"),
    confidence_threshold: float = Form(0.35, description="Detection confidence threshold (0.1-0.9)"),
    line_thickness: int = Form(2, description="Bounding box thickness for annotated image (1-6)"),
    enable_clip: bool = Form(False, description="Enable CLIP classification"),
    enable_ocr: bool = Form(True, description="Enable OCR text extraction"),
    enable_blip: bool = Form(False, description="Enable BLIP visual description for icons"),
    blip_scope: str = Form("icons", description="BLIP scope: icons | all"),
    ocr_only: bool = Form(False, description="Run OCR across the full image and return OCR results only"),
    preprocess: bool = Form(False, description="Enable image preprocessing for cross-device consistency (Samsung, Pixel, Oppo, etc.)"),
    preprocess_mode: str = Form("rfdetr", description="Preprocessing mode: rfdetr (optimized for RF-DETR) | generic (for CLIP/OCR)"),
    preprocess_preset: str = Form("standard", description="Preprocessing preset (depends on mode)")
):
    """
    Detect UI elements in an uploaded image
    
    **Parameters:**
    - `image`: Image file (PNG, JPG, JPEG, WebP)
    - `confidence_threshold`: Detection sensitivity (0.1-0.9, default: 0.35)
    - `line_thickness`: Bounding box line thickness (1-6, default: 2)
    - `enable_clip`: Classify element types using CLIP (default: false)
    - `enable_ocr`: Extract text content using OCR (default: true)
    - `enable_blip`: Generate visual descriptions using BLIP (default: false)
    - `blip_scope`: BLIP scope - "icons" (image/button only) or "all" (default: icons)
    - `ocr_only`: Skip detection/classification, run OCR only (default: false)
    - `preprocess`: Enable image preprocessing for cross-device consistency (default: false)
    - `preprocess_mode`: Preprocessing mode - "rfdetr" (optimized for RF-DETR, preserves ImageNet norm) | "generic" (for CLIP/OCR) (default: rfdetr)
    - `preprocess_preset`: Preprocessing preset (depends on mode, default: standard)
    
    **Returns:**
    ```json
    {
      "success": true,
      "detections": [
        {
          "box": {"x1": 50, "y1": 100, "x2": 200, "y2": 150},
          "confidence": 0.79,
          "class_name": "button",
          "text": "Submit"
        }
      ],
      "total_detections": 1,
      "image_size": {"width": 1080, "height": 1920},
      "parameters": {...},
      "type_distribution": {"button": 5, "text": 12}
    }
    ```
    """
    try:
        # Validate confidence threshold
        if not 0.1 <= confidence_threshold <= 0.9:
            raise HTTPException(
                status_code=400,
                detail="confidence_threshold must be between 0.1 and 0.9"
            )

        if not 1 <= line_thickness <= 6:
            raise HTTPException(
                status_code=400,
                detail="line_thickness must be between 1 and 6"
            )
        
        # Read and validate image
        try:
            image_bytes = await image.read()
            pil_image = Image.open(io.BytesIO(image_bytes)).convert("RGB")
        except Exception as e:
            raise HTTPException(
                status_code=400,
                detail=f"Invalid image file: {str(e)}"
            )
        
        # Validate OCR-only mode: CLIP and BLIP are incompatible with OCR-only
        if ocr_only and (enable_clip or enable_blip):
            raise HTTPException(
                status_code=400,
                detail="When ocr_only=true, enable_clip and enable_blip must be false"
            )

        # OCR-only path: Bypass detection service
        if ocr_only:
            detections = ocr_handler.process_ocr_only(pil_image)
            annotated = ocr_handler.annotate_ocr_detections(
                pil_image,
                detections,
                thickness=line_thickness,
                return_format="numpy"
            )
            return response_builder.build_ocr_only_response(
                detections=detections,
                image_width=pil_image.width,
                image_height=pil_image.height,
                annotated_image=annotated,
                confidence_threshold=confidence_threshold,
                line_thickness=line_thickness
            )

        # Standard detection path: Use detection service
        service = get_detection_service()
        
        # Run analysis (pass parameters directly to avoid race conditions)
        analysis = service.analyze(
            pil_image,
            confidence_threshold=confidence_threshold,
            extract_text=enable_ocr,
            use_clip=enable_clip,
            use_blip=enable_blip,
            merge_global_ocr=True,
            blip_scope=(blip_scope if blip_scope in {"icons", "all"} else "icons"),
            preprocess=preprocess,
            preprocess_mode=preprocess_mode,
            preprocess_preset=preprocess_preset
        )

        # Generate annotated image
        annotated = service.get_prediction_image(
            pil_image,
            confidence_threshold=confidence_threshold,
            extract_content=True,
            thickness=line_thickness,
            return_format="numpy",
            analysis=analysis
        )

        # Build response
        return response_builder.build_detection_response(
            analysis=analysis,
            image=pil_image,
            annotated_image=annotated,
            confidence_threshold=confidence_threshold,
            line_thickness=line_thickness,
            enable_clip=enable_clip,
            enable_ocr=enable_ocr,
            enable_blip=enable_blip,
            blip_scope=blip_scope,
            ocr_only=False,
            include_annotated_image=True
        )
        
    except HTTPException:
        raise
    except Exception as e:
        import traceback
        error_msg = f"Error during detection: {str(e)}"
        print(f"{error_msg}\n{traceback.format_exc()}")
        raise HTTPException(status_code=500, detail=error_msg)