"""
Speech-to-text transcription for recorded calls using OpenAI Whisper.

Audio is downloaded from GCS then sent to the Whisper API. Falls back to
returning None on any failure so the intelligence pipeline can still run.
"""
import asyncio
import tempfile
import os
from typing import Optional
from app.internal.logger import logger
from app.internal import firestore as fstore

# Whisper treats `prompt` as preceding transcript text, not instructions.
# Writing it as actual radio speech primes the vocabulary toward P25 codes
# and phrasing before the model hears the audio.
_WHISPER_PROMPT = (
    "10-4. 10-23. 10-20. 10-97. 10-8. 10-7. 10-34. 10-50. 10-52. "
    "Post 4, I'm out. Post 3. En route. On scene. In route. "
    "Copy. Negative. Stand by. Be advised. Go ahead. "
    "Units responding. Dispatch. Talkgroup. "
    "Engine. Ladder. Medic. Rescue. Car. Unit. "
    "MVA. MVC. Structure fire. Working fire."
)


async def transcribe_call(
    call_id: str,
    gcs_uri: str,
    talkgroup_name: Optional[str] = None,
) -> Optional[str]:
    """
    Transcribe audio at the given GCS URI and store the result in Firestore.

    Args:
        call_id:        Firestore document ID in the 'calls' collection.
        gcs_uri:        GCS URI of the audio file, e.g. gs://bucket/calls/xyz.mp3
        talkgroup_name: Passed through to the intelligence layer; unused here.

    Returns:
        The raw Whisper transcript string, or None if transcription failed.
    """
    if not gcs_uri or not gcs_uri.startswith("gs://"):
        return None

    try:
        transcript = await asyncio.to_thread(_sync_transcribe, gcs_uri)
    except Exception as e:
        logger.warning(f"Transcription failed for call {call_id}: {e}")
        return None

    if transcript:
        try:
            await fstore.doc_set("calls", call_id, {"transcript": transcript})
            logger.info(f"Transcript saved for call {call_id} ({len(transcript)} chars)")
        except Exception as e:
            logger.warning(f"Could not save transcript for {call_id}: {e}")

    return transcript


def _sync_transcribe(gcs_uri: str) -> Optional[str]:
    """Download audio from GCS and transcribe with OpenAI Whisper."""
    from google.cloud import storage as gcs
    from google.oauth2 import service_account
    from openai import OpenAI
    from app.config import settings

    if not settings.openai_api_key:
        logger.warning("OPENAI_API_KEY not set — transcription disabled.")
        return None

    without_scheme = gcs_uri[len("gs://"):]
    bucket_name, blob_path = without_scheme.split("/", 1)

    if settings.gcp_credentials_path:
        creds = service_account.Credentials.from_service_account_file(
            settings.gcp_credentials_path,
            scopes=["https://www.googleapis.com/auth/cloud-platform"],
        )
        gcs_client = gcs.Client(credentials=creds)
    else:
        gcs_client = gcs.Client()

    bucket = gcs_client.bucket(bucket_name)
    blob = bucket.blob(blob_path)

    suffix = os.path.splitext(blob_path)[1] or ".mp3"
    with tempfile.NamedTemporaryFile(suffix=suffix, delete=False) as tmp:
        tmp_path = tmp.name

    try:
        blob.download_to_filename(tmp_path)

        openai_client = OpenAI(api_key=settings.openai_api_key)
        with open(tmp_path, "rb") as f:
            response = openai_client.audio.transcriptions.create(
                model="whisper-1",
                file=f,
                language="en",
                prompt=_WHISPER_PROMPT,
            )
        return response.text.strip() or None
    finally:
        try:
            os.unlink(tmp_path)
        except OSError:
            pass