import base64
import io
import logging
import struct

_logger = logging.getLogger(__name__)


class ImageProcessor:
    """Process product images: EXIF geo-tagging, metadata, optimization."""

    @staticmethod
    def geo_tag_image(image_b64, company_name, address, phone, lat, lng):
        """Write EXIF metadata with company info and GPS coordinates.

        Args:
            image_b64: base64-encoded image data
            company_name: company name for Copyright/Artist tags
            address: company address for ImageDescription
            phone: company phone
            lat: GPS latitude (float)
            lng: GPS longitude (float)

        Returns:
            base64-encoded image with EXIF data
        """
        try:
            import piexif
        except ImportError:
            _logger.warning("piexif not installed — skipping geo-tagging. Run: pip install piexif")
            return image_b64

        try:
            image_data = base64.b64decode(image_b64)

            # Check if it's a JPEG (piexif only works with JPEG)
            if not image_data[:2] == b'\xff\xd8':
                _logger.info("Image is not JPEG — skipping EXIF geo-tagging")
                return image_b64

            # Try to load existing EXIF
            try:
                exif_dict = piexif.load(image_data)
            except Exception:
                exif_dict = {"0th": {}, "Exif": {}, "GPS": {}, "1st": {}}

            # Set 0th IFD tags
            exif_dict["0th"][piexif.ImageIFD.ImageDescription] = address.encode('utf-8') if address else b''
            exif_dict["0th"][piexif.ImageIFD.Copyright] = (
                f"Copyright {company_name}".encode('utf-8') if company_name else b''
            )
            exif_dict["0th"][piexif.ImageIFD.Artist] = company_name.encode('utf-8') if company_name else b''

            # Set GPS tags if coordinates provided
            if lat and lng:
                lat_deg = ImageProcessor._decimal_to_dms(abs(lat))
                lng_deg = ImageProcessor._decimal_to_dms(abs(lng))

                exif_dict["GPS"] = {
                    piexif.GPSIFD.GPSLatitudeRef: b'N' if lat >= 0 else b'S',
                    piexif.GPSIFD.GPSLatitude: lat_deg,
                    piexif.GPSIFD.GPSLongitudeRef: b'E' if lng >= 0 else b'W',
                    piexif.GPSIFD.GPSLongitude: lng_deg,
                }

            exif_bytes = piexif.dump(exif_dict)
            output = io.BytesIO()
            piexif.insert(exif_bytes, image_data, output)
            return base64.b64encode(output.getvalue()).decode('utf-8')

        except Exception as e:
            _logger.error("Failed to geo-tag image: %s", str(e))
            return image_b64

    @staticmethod
    def _decimal_to_dms(decimal):
        """Convert decimal degrees to EXIF DMS format (degrees, minutes, seconds as rationals)."""
        degrees = int(decimal)
        minutes_float = (decimal - degrees) * 60
        minutes = int(minutes_float)
        seconds = int((minutes_float - minutes) * 60 * 10000)
        return (
            (degrees, 1),
            (minutes, 1),
            (seconds, 10000),
        )

    @staticmethod
    def prepare_wc_image(image_b64, filename, alt_text='', caption='', title='', description=''):
        """Prepare image data for WooCommerce upload.

        Returns dict ready for WC product images array, using src as base64 data URL.
        Note: WC REST API v3 accepts image URLs in 'src'. For base64, we need to upload
        via WordPress media endpoint first, then reference by URL.
        """
        return {
            'name': title or filename,
            'alt': alt_text or '',
            'caption': caption or '',
            'description': description or '',
            # The actual upload will be handled by the wizard
            '_base64': image_b64,
            '_filename': filename,
        }