Changed from_preset file downloading to use GFile when able (#1665)

* Changed from_preset file downloading to use GFile when able

* Formatted

* Addressed Comments

* Conditional TF import

* More comment addressing

* Renamed arg and changed import

* Better handling of scheme detection

Author: VarunS1997

keras_nlp/src/utils/preset_utils.py

@@ -23,8 +23,18 @@
 from packaging.version import parse
 
 from keras_nlp.src.api_export import keras_nlp_export
+from keras_nlp.src.backend import config
 from keras_nlp.src.backend import config as backend_config
 from keras_nlp.src.backend import keras
+from keras_nlp.src.utils.keras_utils import print_msg
+
+try:
+    import tensorflow as tf
+except ImportError:
+    raise ImportError(
+        "To use `keras_nlp`, please install Tensorflow: `pip install tensorflow`. "
+        "The TensorFlow package is required for data preprocessing with any backend."
+    )
 
 try:
     import kagglehub
@@ -43,6 +53,10 @@
 GS_PREFIX = "gs://"
 HF_PREFIX = "hf://"
 
+KAGGLE_SCHEME = "kaggle"
+GS_SCHEME = "gs"
+HF_SCHEME = "hf"
+
 TOKENIZER_ASSET_DIR = "assets/tokenizer"
 
 # Config file names.
@@ -99,13 +113,18 @@ def get_file(preset, path):
         )
     if preset in BUILTIN_PRESETS:
         preset = BUILTIN_PRESETS[preset]["kaggle_handle"]
-    if preset.startswith(KAGGLE_PREFIX):
+
+    scheme = None
+    if "://" in preset:
+        scheme = preset.split("://")[0].lower()
+
+    if scheme == KAGGLE_SCHEME:
         if kagglehub is None:
             raise ImportError(
                 "`from_preset()` requires the `kagglehub` package. "
                 "Please install with `pip install kagglehub`."
             )
-        kaggle_handle = preset.removeprefix(KAGGLE_PREFIX)
+        kaggle_handle = preset.removeprefix(KAGGLE_SCHEME + "://")
         num_segments = len(kaggle_handle.split("/"))
         if num_segments not in (4, 5):
             raise ValueError(
@@ -134,25 +153,23 @@ def get_file(preset, path):
             else:
                 raise ValueError(message)
 
-    elif preset.startswith(GS_PREFIX):
+    elif scheme in tf.io.gfile.get_registered_schemes():
         url = os.path.join(preset, path)
-        url = url.replace(GS_PREFIX, "https://storage.googleapis.com/")
-        subdir = preset.replace(GS_PREFIX, "gs_")
-        subdir = subdir.replace("/", "_").replace("-", "_")
+        subdir = preset.replace("://", "_").replace("-", "_")
         filename = os.path.basename(path)
         subdir = os.path.join(subdir, os.path.dirname(path))
-        return keras.utils.get_file(
+        return copy_gfile_to_cache(
             filename,
             url,
             cache_subdir=os.path.join("models", subdir),
         )
-    elif preset.startswith(HF_PREFIX):
+    elif scheme == HF_SCHEME:
         if huggingface_hub is None:
             raise ImportError(
                 f"`from_preset()` requires the `huggingface_hub` package to load from '{preset}'. "
                 "Please install with `pip install huggingface_hub`."
             )
-        hf_handle = preset.removeprefix(HF_PREFIX)
+        hf_handle = preset.removeprefix(HF_SCHEME + "://")
         try:
             return huggingface_hub.hf_hub_download(
                 repo_id=hf_handle, filename=path
@@ -192,6 +209,25 @@ def get_file(preset, path):
         )
 
 
+def copy_gfile_to_cache(filename, url, cache_subdir):
+    """Much of this is adapted from get_file of keras core."""
+    if cache_subdir is None:
+        cache_dir = config.keras_home()
+
+    datadir_base = os.path.expanduser(cache_dir)
+    if not os.access(datadir_base, os.W_OK):
+        datadir_base = os.path.join("/tmp", ".keras")
+    datadir = os.path.join(datadir_base, cache_subdir)
+    os.makedirs(datadir, exist_ok=True)
+
+    fpath = os.path.join(datadir, filename)
+    if not os.path.exists(fpath):
+        print_msg(f"Downloading data from {url}")
+        tf.io.gfile.copy(url, fpath)
+
+    return fpath
+
+
 def check_file_exists(preset, path):
     try:
         get_file(preset, path)