hermes-agent/gateway/platforms/media_cache.py

202 lines
7.7 KiB
Python

"""Shared mime↔extension dispatch for inbound (downloaded) platform media.
Historically every gateway adapter hand-rolled its own mime→extension map
before handing downloaded bytes to the cache primitives in
``gateway.platforms.base`` (``cache_image_from_bytes``,
``cache_audio_from_bytes``, ``cache_document_from_bytes``). Those maps
*disagree* with each other on purpose — e.g. BlueBubbles coerces
``image/heic`` to ``.jpg`` because downstream vision tools can't read HEIC,
while WhatsApp Cloud pins ``audio/ogg`` to ``.ogg`` (not the RFC-correct
``.oga`` Python's ``mimetypes`` returns) because the STT pipeline whitelists
extensions.
This module owns:
* ``DEFAULT_MIME_TO_EXT`` — the union table of entries the adapters already
agree on (plus a few uncontroversial document types).
* ``DEFAULT_EXT_TO_MIME`` — the canonical inverse (used by Signal to map a
sniffed extension back to a content type).
* ``ext_for_mime`` / ``mime_for_ext`` — lookup helpers that accept
per-adapter ``overrides`` so each adapter's historical (divergent)
behavior is preserved byte-for-byte.
* ``cache_media_bytes`` — one-call dispatch: classify the mime, resolve the
extension, and write to the right cache (image / audio / document).
Behavior-preservation contract: adapters that had divergent maps pass them
as ``overrides`` (and, where their historical code never consulted
``mimetypes`` or a shared table, disable those fallbacks via
``use_defaults`` / ``use_mimetypes``). The parity tests in
``tests/gateway/test_media_cache.py`` hardcode the historical outputs as
the contract.
NOTE: ``gateway/platforms/weixin.py`` also has a private mime map
(``_mime_from_filename``) but is intentionally NOT migrated here — another
in-flight branch edits that file. Follow-up: fold it in once that lands.
"""
from __future__ import annotations
import mimetypes
import uuid
from typing import Mapping, Optional
# ---------------------------------------------------------------------------
# Shared tables
# ---------------------------------------------------------------------------
# Union of the per-adapter maps where the adapters already agree (or where
# only one adapter pinned the type and no other adapter contradicts it).
# Entries deliberately favor the common-in-the-wild extension over the
# RFC-correct one (``audio/ogg`` → ``.ogg``, not ``.oga``) because the
# downstream STT/vision pipelines whitelist real-world extensions.
DEFAULT_MIME_TO_EXT: dict[str, str] = {
# --- images (bluebubbles + whatsapp_cloud agree; matches mimetypes) ---
"image/jpeg": ".jpg",
"image/png": ".png",
"image/gif": ".gif",
"image/webp": ".webp",
# --- audio ---
"audio/ogg": ".ogg", # bluebubbles + whatsapp_cloud agree
"audio/x-opus+ogg": ".ogg", # whatsapp voice notes (opus-in-ogg)
"audio/opus": ".ogg", # whatsapp voice notes (opus-in-ogg)
"audio/mpeg": ".mp3",
"audio/mp3": ".mp3", # non-standard but seen in the wild
"audio/wav": ".wav",
"audio/mp4": ".m4a", # bluebubbles + whatsapp_cloud agree
"audio/x-m4a": ".m4a",
"audio/aac": ".aac",
# --- video / documents (from signal's inverse table) ---
"video/mp4": ".mp4",
"application/pdf": ".pdf",
"application/zip": ".zip",
}
# Canonical inverse. Kept explicit (rather than mechanically inverted)
# because the forward table is many-to-one — e.g. both ``audio/mpeg`` and
# ``audio/mp3`` map to ``.mp3`` and the inverse must pick the canonical
# mime. This is byte-identical to Signal's historical ``_EXT_TO_MIME``.
DEFAULT_EXT_TO_MIME: dict[str, str] = {
".jpg": "image/jpeg", ".jpeg": "image/jpeg", ".png": "image/png",
".gif": "image/gif", ".webp": "image/webp",
".ogg": "audio/ogg", ".mp3": "audio/mpeg", ".wav": "audio/wav",
".m4a": "audio/mp4", ".aac": "audio/aac",
".mp4": "video/mp4", ".pdf": "application/pdf",
".zip": "application/zip",
}
def _normalize_mime(mime: str) -> str:
"""Lowercase and strip any ``; charset=...`` style parameters."""
return (mime or "").split(";")[0].strip().lower()
# ---------------------------------------------------------------------------
# Lookups
# ---------------------------------------------------------------------------
def ext_for_mime(
mime: str,
*,
overrides: Optional[Mapping[str, str]] = None,
use_defaults: bool = True,
use_mimetypes: bool = True,
fallback: Optional[str] = None,
) -> Optional[str]:
"""Resolve a mime type to a file extension (including the dot).
Resolution order: ``overrides`` → ``DEFAULT_MIME_TO_EXT`` (if
``use_defaults``) → ``mimetypes.guess_extension`` (if
``use_mimetypes``) → ``fallback``.
Adapters with historical divergent maps pass them via ``overrides``
and disable the stages their old code never consulted, keeping their
outputs byte-identical to the pre-refactor behavior.
"""
primary = _normalize_mime(mime)
if not primary:
return fallback
if overrides:
ext = overrides.get(primary)
if ext:
return ext
if use_defaults:
ext = DEFAULT_MIME_TO_EXT.get(primary)
if ext:
return ext
if use_mimetypes:
ext = mimetypes.guess_extension(primary)
if ext:
return ext
return fallback
def mime_for_ext(
ext: str,
*,
overrides: Optional[Mapping[str, str]] = None,
fallback: str = "application/octet-stream",
) -> str:
"""Inverse lookup: file extension → canonical mime type.
Resolution order: ``overrides`` → ``DEFAULT_EXT_TO_MIME`` → ``fallback``.
"""
key = (ext or "").strip().lower()
if overrides:
mime = overrides.get(key)
if mime:
return mime
return DEFAULT_EXT_TO_MIME.get(key, fallback)
# ---------------------------------------------------------------------------
# One-call cache dispatch
# ---------------------------------------------------------------------------
def cache_media_bytes(
data: bytes,
mime: str,
*,
filename_hint: str = "",
kind_hint: Optional[str] = None,
ext_overrides: Optional[Mapping[str, str]] = None,
) -> str:
"""Cache downloaded media bytes and return the local file path.
Picks the image / audio / document cache primitive from
``gateway.platforms.base`` based on the mime class (or an explicit
``kind_hint`` of ``"image"``, ``"audio"`` or ``"document"``).
``filename_hint`` is used for document caching (falls back to a
generated name with the resolved extension). ``ext_overrides`` is
threaded through to :func:`ext_for_mime` for adapters that need their
historical mappings.
"""
# Local import: base is a large module and some adapters import this
# module very early; keep import-time coupling minimal.
from gateway.platforms.base import (
cache_audio_from_bytes,
cache_document_from_bytes,
cache_image_from_bytes,
)
primary = _normalize_mime(mime)
kind = kind_hint
if kind is None:
if primary.startswith("image/"):
kind = "image"
elif primary.startswith("audio/"):
kind = "audio"
else:
kind = "document"
if kind == "image":
ext = ext_for_mime(primary, overrides=ext_overrides, fallback=".jpg") or ".jpg"
return cache_image_from_bytes(data, ext)
if kind == "audio":
ext = ext_for_mime(primary, overrides=ext_overrides, fallback=".ogg") or ".ogg"
return cache_audio_from_bytes(data, ext)
filename = filename_hint
if not filename:
ext = ext_for_mime(primary, overrides=ext_overrides, fallback=".bin")
filename = f"file_{uuid.uuid4().hex[:8]}{ext}"
return cache_document_from_bytes(data, filename)