app.py

import gradio as gr
import numpy as np
import cv2
from paddleocr import PaddleOCR

ocr = None  # lazy init

def get_ocr():
    global ocr
    if ocr is None:
        ocr = PaddleOCR(use_angle_cls=True, lang="en")
    return ocr

def preprocess_for_ocr(pil_img):
    rgb = np.array(pil_img)
    if rgb.dtype != np.uint8:
        rgb = rgb.astype(np.uint8)

    bgr = cv2.cvtColor(rgb, cv2.COLOR_RGB2BGR)

    # upscale helps thin kid-book text
    h, w = bgr.shape[:2]
    scale = 1.8
    bgr = cv2.resize(bgr, (int(w * scale), int(h * scale)), interpolation=cv2.INTER_CUBIC)

    # contrast boost
    lab = cv2.cvtColor(bgr, cv2.COLOR_BGR2LAB)
    l, a, b = cv2.split(lab)
    clahe = cv2.createCLAHE(clipLimit=2.0, tileGridSize=(8, 8))
    l2 = clahe.apply(l)
    lab2 = cv2.merge([l2, a, b])
    bgr = cv2.cvtColor(lab2, cv2.COLOR_LAB2BGR)

    return bgr

def crop_bottom_text_region(bgr):
    """Kids books often place text at the bottom. Crop bottom ~35%."""
    h, w = bgr.shape[:2]
    return bgr[int(h * 0.65):h, 0:w]

def cloud_ocr_stub(_pil_img):
    """
    Placeholder for GPU/VLM OCR (olmOCR-2 / Nanonets OCR2).
    Later this will call an API endpoint.
    """
    return "[Cloud OCR placeholder] PaddleOCR confidence was low. Next: call olmOCR-2 / OCR2 via API."

def run_ocr(img):
    if img is None:
        return "(No image)", 0.0, "No"

    bgr = preprocess_for_ocr(img)
    bgr_crop = crop_bottom_text_region(bgr)

    ocr_engine = get_ocr()
    result = ocr_engine.ocr(bgr_crop)

    lines = []
    confs = []

    blocks = result[0] if isinstance(result, list) and result and isinstance(result[0], list) else result
    for item in blocks:
        try:
            text, conf = item[1]
            lines.append(str(text))
            confs.append(float(conf))
        except Exception:
            continue

    extracted = "\n".join(lines).strip()
    avg_conf = float(sum(confs) / len(confs)) if confs else 0.0

    # ---- fallback decision (simple + effective) ----
    needs_cloud = (avg_conf < 0.45) or (len(extracted) < 15)

    if needs_cloud:
        extracted = extracted if extracted else "(PaddleOCR found no text)\n\n" + cloud_ocr_stub(img)
        return extracted, avg_conf, "Yes"

    return extracted, avg_conf, "No"


demo = gr.Interface(
    fn=run_ocr,
    inputs=gr.Image(type="pil", label="Upload a page photo"),
    outputs=[
        gr.Textbox(label="Extracted text", lines=12),
        gr.Number(label="Average confidence (0–1)"),
        gr.Textbox(label="Cloud fallback needed?", interactive=False),
    ],
    title="BookReader × Reachy Mini",
    description="CPU PaddleOCR + smart fallback (VLM OCR stub). Crops bottom text region for kid books.",
)

demo.launch(ssr_mode=False)