from typing import Iterator
from langchain_core.documents import Document
from langchain_community.document_loaders.base import BaseBlobParser
from langchain_community.document_loaders.blob_loaders import Blob


class PptxParser(BaseBlobParser):
    """Parse Microsoft PowerPoint presentations from a blob."""

    # type: ignore[valid-type]
    def lazy_parse(self, blob: Blob) -> Iterator[Document]:
        """Parse a Microsoft PowerPoint document into the Document iterator.

        Args:
            blob: The blob to parse.

        Returns: An iterator of Documents.
        """
        try:
            from pptx import Presentation
        except ImportError as e:
            raise ImportError(
                "Could not import python-pptx, please install with `pip install python-pptx`."
            ) from e

        supported_mime_types = [
            "application/vnd.ms-powerpoint",  # .ppt
            "application/vnd.openxmlformats-officedocument.presentationml.presentation"  # .pptx
        ]

        # Debugging: Print MIME type
        print(f"Blob MIME type: {blob.mimetype}")

        # type: ignore[attr-defined]
        if blob.mimetype not in supported_mime_types:
            raise ValueError(
                f"This blob type is not supported for this parser. Supported types are: {supported_mime_types}"
            )

        with blob.as_bytes_io() as pptx_file:  # type: ignore[attr-defined]
            presentation = Presentation(pptx_file)
            text = ""
            for slide in presentation.slides:
                for shape in slide.shapes:
                    if hasattr(shape, "text"):
                        text += shape.text + "\n"
            metadata = {"source": blob.source}  # type: ignore[attr-defined]
            yield Document(page_content=text, metadata=metadata)