from transformers import TrOCRProcessor, VisionEncoderDecoderModel
from PIL import Image, ImageFilter
import torch
import re

# Load TrOCR model and processor
processor = TrOCRProcessor.from_pretrained("microsoft/trocr-base-handwritten")
model = VisionEncoderDecoderModel.from_pretrained("microsoft/trocr-base-handwritten")

def clean_ocr_text(text):
    # Fix common OCR misreads
    text = text.replace(",", ".").replace("s", "5").replace("o", "0").replace("O", "0")
    return re.sub(r"[^\d.kg]", "", text.lower())

def restore_decimal(text):
    if re.fullmatch(r"\d{5}", text):
        return f"{text[:2]}.{text[2:]}"
    elif re.fullmatch(r"\d{4}", text):
        return f"{text[:2]}.{text[2:]}"
    return text

def extract_unit_from_text(raw_text):
    raw_text = raw_text.lower()
    if "kg" in raw_text:
        return "kg"
    elif "g" in raw_text:
        return "g"
    return "g"  # fallback if no unit

def extract_weight(image):
    try:
        # Resize & sharpen image
        image = image.resize((image.width * 2, image.height * 2), Image.BICUBIC)
        image = image.filter(ImageFilter.SHARPEN)

        # OCR inference
        pixel_values = processor(images=image, return_tensors="pt").pixel_values
        generated_ids = model.generate(pixel_values)
        raw_text = processor.batch_decode(generated_ids, skip_special_tokens=True)[0].strip()

        cleaned = clean_ocr_text(raw_text)

        # Case 1: Match decimal with unit
        match = re.search(r"(\d{1,3}\.\d{1,3})\s*(kg|g)?", cleaned)
        if match:
            return f"{match.group(1)} {match.group(2) or ''}".strip(), raw_text

        # Case 2: Large number fallback like 53255 → 52.255
        match = re.search(r"\d{4,5}", cleaned)
        if match:
            decimal_fixed = restore_decimal(match.group())
            unit = extract_unit_from_text(raw_text)
            return f"{decimal_fixed} {unit}", raw_text

        # Final fallback: plain number
        match = re.search(r"\d+", cleaned)
        if match:
            return f"{match.group()} g", raw_text

        return "Error: No valid weight found", raw_text

    except Exception as e:
        return f"Error: {str(e)}", ""