149 lines
5.0 KiB
Python
149 lines
5.0 KiB
Python
"""
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/export/pdf - MusicXML to PDF via music21 + LilyPond (or Audiveris)
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/export/mp3 - WAV buffer to MP3 via FFmpeg
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"""
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import base64
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import binascii
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import logging
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import os
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import subprocess
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import tempfile
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from fastapi import APIRouter, BackgroundTasks, HTTPException
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from fastapi.responses import FileResponse
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from pydantic import BaseModel
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logger = logging.getLogger(__name__)
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router = APIRouter()
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# C2 - size caps
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MAX_B64_BYTES = 300 * 1024 * 1024 # 300 MB base64 string (≈ 200 MB decoded)
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MAX_WAV_BYTES = 200 * 1024 * 1024 # 200 MB decoded WAV
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MAX_MUSICXML_BYTES = 10 * 1024 * 1024 # 10 MB
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# M5 - WAV magic bytes: "RIFF....WAVE"
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_WAV_RIFF = b"RIFF"
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_WAV_WAVE = b"WAVE"
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class ExportPdfRequest(BaseModel):
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musicxml: str
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class ExportMp3Request(BaseModel):
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wav_base64: str # base64-encoded WAV
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def _rm(path: str) -> None:
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try:
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os.unlink(path)
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except OSError:
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pass
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@router.post("/pdf")
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async def export_pdf(req: ExportPdfRequest, background_tasks: BackgroundTasks):
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"""Convert MusicXML to PDF sheet music."""
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if len(req.musicxml.encode()) > MAX_MUSICXML_BYTES:
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raise HTTPException(status_code=413, detail="MusicXML payload too large (max 10 MB)")
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try:
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from services.music21_svc import musicxml_to_pdf
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pdf_path = await musicxml_to_pdf(req.musicxml)
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background_tasks.add_task(_rm, pdf_path) # H5
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return FileResponse(
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pdf_path,
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media_type="application/pdf",
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filename="sheet.pdf",
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headers={
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"Cache-Control": "no-store",
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"Content-Disposition": 'attachment; filename="sheet.pdf"',
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},
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)
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except HTTPException:
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raise
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except Exception as e:
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# Surface actionable runtime errors (e.g. missing LilyPond) to the client
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# so the user knows what to install instead of seeing a generic message.
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# NOTE: musicxml_to_pdf runs in a ProcessPoolExecutor; exceptions get
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# round-tripped through pickle, so we match by message substring rather
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# than exception type (which can be wrapped / mutated on the way back).
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logger.exception("export_pdf failed")
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msg = str(e)
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if "lilypond" in msg.lower():
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raise HTTPException(
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status_code=503,
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detail=(
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"PDF export needs LilyPond on the backend (not bundled by default).\n\n"
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"Quick install: brew install lilypond (macOS) or apt install lilypond "
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"(Linux). For Docker, see the README section 'Optional: PDF export via "
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"LilyPond'. MIDI and MusicXML export work without it."
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),
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)
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raise HTTPException(status_code=500, detail=f"PDF export failed: {msg or 'Unknown error'}")
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@router.post("/mp3")
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async def export_mp3(req: ExportMp3Request, background_tasks: BackgroundTasks):
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"""Convert base64 WAV to MP3 using FFmpeg."""
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# L6 - size-check before decoding; catch malformed base64 explicitly
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if len(req.wav_base64) > MAX_B64_BYTES:
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raise HTTPException(status_code=413, detail="WAV payload too large (max 200 MB)")
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try:
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wav_bytes = base64.b64decode(req.wav_base64, validate=True)
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except binascii.Error:
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raise HTTPException(status_code=422, detail="Invalid base64 encoding")
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# C2 - check decoded size too
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if len(wav_bytes) > MAX_WAV_BYTES:
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raise HTTPException(status_code=413, detail="WAV data too large (max 200 MB)")
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# M5 - validate WAV magic bytes: "RIFF....WAVE"
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if len(wav_bytes) < 12 or wav_bytes[:4] != _WAV_RIFF or wav_bytes[8:12] != _WAV_WAVE:
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raise HTTPException(status_code=422, detail="Not a valid WAV file")
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try:
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wav_tmp = tempfile.NamedTemporaryFile(suffix=".wav", delete=False)
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wav_tmp.write(wav_bytes)
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wav_tmp.close()
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mp3_tmp = tempfile.NamedTemporaryFile(suffix=".mp3", delete=False)
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mp3_tmp.close()
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# H5 - register cleanup regardless of success/failure
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background_tasks.add_task(_rm, wav_tmp.name)
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background_tasks.add_task(_rm, mp3_tmp.name)
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result = subprocess.run(
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[
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"ffmpeg", "-y",
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"-i", wav_tmp.name,
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"-codec:a", "libmp3lame",
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"-q:a", "2",
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mp3_tmp.name,
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],
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capture_output=True,
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timeout=60,
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)
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if result.returncode != 0:
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logger.error("ffmpeg failed: %s", result.stderr.decode(errors="replace")[:500])
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raise RuntimeError("ffmpeg conversion failed")
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return FileResponse(
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mp3_tmp.name,
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media_type="audio/mpeg",
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filename="export.mp3",
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headers={
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"Cache-Control": "no-store",
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"Content-Disposition": 'attachment; filename="export.mp3"',
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},
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)
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except HTTPException:
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raise
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except Exception:
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logger.exception("export_mp3 failed")
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raise HTTPException(status_code=500, detail="MP3 export failed. Please try again.")
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