from __future__ import annotations

from enum import Enum
from typing import TYPE_CHECKING, List, Optional

from langchain.docstore.document import Document
from langchain.document_loaders.base import BaseLoader

if TYPE_CHECKING:
    import assemblyai


class TranscriptFormat(Enum):
    """Transcript format to use for the document loader."""

    TEXT = "text"
    """One document with the transcription text"""
    SENTENCES = "sentences"
    """Multiple documents, splits the transcription by each sentence"""
    PARAGRAPHS = "paragraphs"
    """Multiple documents, splits the transcription by each paragraph"""
    SUBTITLES_SRT = "subtitles_srt"
    """One document with the transcript exported in SRT subtitles format"""
    SUBTITLES_VTT = "subtitles_vtt"
    """One document with the transcript exported in VTT subtitles format"""


class AssemblyAIAudioTranscriptLoader(BaseLoader):
    """
    Loader for AssemblyAI audio transcripts.

    It uses the AssemblyAI API to transcribe audio files
    and loads the transcribed text into one or more Documents,
    depending on the specified format.

    To use, you should have the ``assemblyai`` python package installed, and the
    environment variable ``ASSEMBLYAI_API_KEY`` set with your API key.
    Alternatively, the API key can also be passed as an argument.

    Audio files can be specified via an URL or a local file path.
    """

    def __init__(
        self,
        file_path: str,
        *,
        transcript_format: TranscriptFormat = TranscriptFormat.TEXT,
        config: Optional[assemblyai.TranscriptionConfig] = None,
        api_key: Optional[str] = None,
    ):
        """
        Initializes the AssemblyAI AudioTranscriptLoader.

        Args:
            file_path: An URL or a local file path.
            transcript_format: Transcript format to use.
                See class ``TranscriptFormat`` for more info.
            config: Transcription options and features. If ``None`` is given,
                the Transcriber's default configuration will be used.
            api_key: AssemblyAI API key.
        """
        try:
            import assemblyai
        except ImportError:
            raise ImportError(
                "Could not import assemblyai python package. "
                "Please install it with `pip install assemblyai`."
            )
        if api_key is not None:
            assemblyai.settings.api_key = api_key

        self.file_path = file_path
        self.transcript_format = transcript_format
        self.transcriber = assemblyai.Transcriber(config=config)

    def load(self) -> List[Document]:
        """Transcribes the audio file and loads the transcript into documents.

        It uses the AssemblyAI API to transcribe the audio file and blocks until
        the transcription is finished.
        """
        transcript = self.transcriber.transcribe(self.file_path)
        # This will raise a ValueError if no API key is set.

        if transcript.error:
            raise ValueError(f"Could not transcribe file: {transcript.error}")

        if self.transcript_format == TranscriptFormat.TEXT:
            return [
                Document(
                    page_content=transcript.text, metadata=transcript.json_response
                )
            ]
        elif self.transcript_format == TranscriptFormat.SENTENCES:
            sentences = transcript.get_sentences()
            return [
                Document(page_content=s.text, metadata=s.dict(exclude={"text"}))
                for s in sentences
            ]
        elif self.transcript_format == TranscriptFormat.PARAGRAPHS:
            paragraphs = transcript.get_paragraphs()
            return [
                Document(page_content=p.text, metadata=p.dict(exclude={"text"}))
                for p in paragraphs
            ]
        elif self.transcript_format == TranscriptFormat.SUBTITLES_SRT:
            return [Document(page_content=transcript.export_subtitles_srt())]
        elif self.transcript_format == TranscriptFormat.SUBTITLES_VTT:
            return [Document(page_content=transcript.export_subtitles_vtt())]
        else:
            raise ValueError("Unknown transcript format.")
