# cf_vision/barcode.py — barcode and QR code scanning
#
# MIT licensed. Uses pyzbar (libzbar wrapper) — no GPU required.
# Requires [barcode] extras: pip install cf-vision[barcode]
#
# Primary consumer: Kiwi (pantry item lookup by UPC/EAN barcode scan)
from __future__ import annotations

import logging
from typing import Literal

from cf_vision.models import BoundingBox, ImageElement, ImageFrame

logger = logging.getLogger(__name__)

BarcodeFormat = Literal[
    "EAN13", "EAN8", "UPCA", "UPCE", "CODE128", "CODE39",
    "QR_CODE", "PDF417", "DATAMATRIX", "ITF", "CODABAR",
]


class BarcodeScanner:
    """
    Lightweight barcode and QR code scanner using pyzbar.

    No GPU required. Works on CPU with ~5ms per image.

    Usage
    -----
        scanner = BarcodeScanner()
        frame = scanner.scan(image_bytes)
        for b in frame.barcodes():
            print(b.text, b.metadata["format"])

    Requires: pip install cf-vision[barcode]
    """

    def scan(self, image_bytes: bytes) -> ImageFrame:
        """
        Scan image_bytes for barcodes and QR codes.

        Returns an ImageFrame with element_type "barcode" or "qr_code" for
        each detected code. Elements include decoded text and bounding box.
        """
        try:
            from pyzbar.pyzbar import decode as pyzbar_decode
            from PIL import Image
            import io
        except ImportError as exc:
            raise ImportError(
                "pyzbar and Pillow are required for barcode scanning. "
                "Install with: pip install cf-vision[barcode]"
            ) from exc

        img = Image.open(io.BytesIO(image_bytes)).convert("RGB")
        w, h = img.size
        decoded = pyzbar_decode(img)

        elements: list[ImageElement] = []
        for symbol in decoded:
            fmt = symbol.type.upper()
            el_type = "qr_code" if fmt == "QRCODE" else "barcode"
            rect = symbol.rect
            bbox = BoundingBox(
                x=rect.left / w,
                y=rect.top / h,
                width=rect.width / w,
                height=rect.height / h,
            )
            elements.append(ImageElement(
                element_type=el_type,
                text=symbol.data.decode("utf-8", errors="replace"),
                confidence=1.0,   # pyzbar doesn't give confidence scores
                bbox=bbox,
                metadata={"format": fmt},
            ))

        return ImageFrame(
            source="upload",
            image_bytes=image_bytes,
            elements=elements,
            width_px=w,
            height_px=h,
            model="pyzbar",
        )