"""Shared UI helper utilities used by both Streamlit frontends.

This module intentionally contains pure helpers so unit tests can run
without a live Streamlit server or network dependencies.
"""
from typing import Dict, Any


def detect_audio_media_type(data: bytes) -> str:
    """Lightweight magic-byte detection for common audio formats."""
    if not data:
        return "application/octet-stream"
    # WAV: RIFF....WAVE
    if data[:4] == b"RIFF" and b"WAVE" in data[:12]:
        return "audio/wav"
    # OGG: OggS
    if data[:4] == b"OggS":
        return "audio/ogg"
    # MP3: ID3 tag or 0xFF 0xFB frame header
    if data[:3] == b"ID3" or data[:2] == bytes([0xFF, 0xFB]):
        return "audio/mpeg"
    return "application/octet-stream"


def ext_for_media_type(media_type: str) -> str:
    mapping = {
        "audio/wav": ".wav",
        "audio/ogg": ".ogg",
        "audio/mpeg": ".mp3",
        "audio/mp4": ".m4a",
    }
    return mapping.get(media_type, "")


def infer_download_filename(request_id: str, media_type: str) -> str:
    """Return a sensible download filename for an audio artifact."""
    ext = ext_for_media_type(media_type) or ""
    return f"{request_id}{ext}"


def format_result_for_display(result: Dict[str, Any]) -> Dict[str, Any]:
    """Normalize a pipeline result dict for the UI renderer.

    This function is purposely conservative: it doesn't change content,
    only ensures expected keys exist so the UI can render reliably.
    """
    out = {}
    out["summary"] = result.get("summary") or ""
    out["translated_summary"] = result.get("translated_summary") or ""
    out["transcript"] = result.get("transcript") or ""
    out["word_count"] = result.get("word_count") or 0
    out["reading_time_seconds"] = result.get("reading_time_seconds") or 0
    out["target_language"] = result.get("target_language") or ""
    out["request_id"] = result.get("request_id")
    out["audio_b64"] = result.get("audio_b64")
    return out


__all__ = [
    "detect_audio_media_type",
    "ext_for_media_type",
    "infer_download_filename",
    "format_result_for_display",
]