Update app.py

app.py

@@ -1,94 +1,117 @@
+"""
+Radar Data Downloader via Gradio
+==================================
+
+This script mimics part of Supercell Wx’s functionality by downloading the latest
+radar data file (Level 2 or Level 3) from public AWS S3 buckets. It uses boto3 in unsigned mode,
+so no AWS credentials or API keys are required. The Gradio interface lets you select the
+data type, radar station, and date (in UTC) to download a file.
+"""
+
+import datetime
+import io
+
+import boto3
+from botocore import UNSIGNED
+from botocore.client import Config
 import gradio as gr
-import folium
-
-# Dictionary of radar sites with their center coordinates (latitude, longitude)
-RADAR_SITES = {
-    "KTLX": {"name": "KTLX (Oklahoma City)", "lat": 35.333, "lon": -97.277},
-    "KFWS": {"name": "KFWS (Fort Worth)", "lat": 32.847, "lon": -97.276},
-    "KHGX": {"name": "KHGX (Houston)", "lat": 29.757, "lon": -95.389}
-}
-
-# Dictionary of radar product tile URLs (from Iowa State Mesonet)
-RADAR_PRODUCT_TILES = {
-    "Reflectivity": "https://mesonet.agron.iastate.edu/tiles/nexrad-base/{z}/{x}/{y}.png",
-    "Velocity": "https://mesonet.agron.iastate.edu/tiles/nexrad-velo/{z}/{x}/{y}.png"
-}
-
-# Function to build the base map tile URL for non-OSM providers
-def get_base_map_tiles(provider, api_key):
-    if provider == "OpenStreetMap":
-        # OpenStreetMap is the default; no API key required.
-        return None
-    elif provider == "MapTiler":
-        # MapTiler Streets style URL – uses the provided API key.
-        return f"https://api.maptiler.com/maps/streets/{{z}}/{{x}}/{{y}}.png?key={api_key}"
-    elif provider == "Mapbox":
-        # Mapbox Streets style URL – uses the provided API key.
-        return f"https://api.mapbox.com/styles/v1/mapbox/streets-v11/tiles/{{z}}/{{x}}/{{y}}?access_token={api_key}"
+
+
+def fetch_latest_radar_data(radar_type, station, date_str):
+    """
+    Downloads the latest radar data file from the appropriate S3 bucket.
+
+    Parameters:
+        radar_type (str): Either "Level 2" or "Level 3".
+        station (str): Radar station identifier (e.g. "KTLX").
+        date_str (str): Date string in the format "YYYY-MM-DD". If blank, uses current UTC date.
+
+    Returns:
+        str: A text summary including the S3 key, file size, last modified date,
+             and a hex preview of the first 64 bytes of the file.
+    """
+    # Parse the date (default to current UTC if empty)
+    if not date_str.strip():
+        date_obj = datetime.datetime.utcnow()
     else:
-        return None
-
-# Function to generate the HTML map with a radar overlay.
-def generate_map(radar_site, product, map_provider, api_key):
-    # Retrieve the selected radar site coordinates; default to center of USA if not found.
-    site = RADAR_SITES.get(radar_site, {"lat": 39.8283, "lon": -98.5795})
-    center_lat = site["lat"]
-    center_lon = site["lon"]
-
-    # Create a folium map centered on the radar site.
-    m = folium.Map(location=[center_lat, center_lon], zoom_start=6, control_scale=True)
-
-    # If a provider other than OpenStreetMap is selected, add its tile layer.
-    if map_provider != "OpenStreetMap":
-        base_tile_url = get_base_map_tiles(map_provider, api_key)
-        if base_tile_url:
-            folium.TileLayer(
-                tiles=base_tile_url,
-                attr=f"{map_provider} Map",
-                name=f"{map_provider} Map",
-                overlay=False,
-                control=True
-            ).add_to(m)
-    
-    # Add the radar overlay tile layer based on the selected product.
-    radar_tile_url = RADAR_PRODUCT_TILES.get(product)
-    if radar_tile_url:
-        folium.raster_layers.TileLayer(
-            tiles=radar_tile_url,
-            attr="NOAA NEXRAD",
-            name=f"Radar {product}",
-            overlay=True,
-            control=True,
-            opacity=0.7
-        ).add_to(m)
-    
-    # Add a layer control so users can toggle layers.
-    folium.LayerControl().add_to(m)
-    
-    # Render the map as an HTML string.
-    return m.get_root().render()
-
-# Define the choices for each input.
-site_choices = list(RADAR_SITES.keys())
-product_choices = list(RADAR_PRODUCT_TILES.keys())
-map_provider_choices = ["OpenStreetMap", "MapTiler", "Mapbox"]
-
-# Build the interface using gr.Blocks
-with gr.Blocks() as demo:
-    gr.Markdown("# Radar Viewer")
-    gr.Markdown("Select a radar site and product, choose a base map provider (enter an API key if needed), then click **Submit** to view the radar overlay.")
-    
-    with gr.Row():
-        radar_site = gr.Dropdown(choices=site_choices, label="Radar Site")
-        product = gr.Dropdown(choices=product_choices, label="Radar Product")
-    
-    with gr.Row():
-        map_provider = gr.Dropdown(choices=map_provider_choices, label="Map Provider")
-        api_key = gr.Textbox(lines=1, placeholder="Enter API key if required", label="API Key")
-    
-    submit = gr.Button("Submit")
-    output = gr.HTML(label="Radar Map")
-    
-    submit.click(generate_map, inputs=[radar_site, product, map_provider, api_key], outputs=output)
-
-demo.launch()
+        try:
+            date_obj = datetime.datetime.strptime(date_str, "%Y-%m-%d")
+        except ValueError:
+            return "Error: Date must be in YYYY-MM-DD format."
+    year = date_obj.strftime("%Y")
+    month = date_obj.strftime("%m")
+    day = date_obj.strftime("%d")
+
+    # Choose the appropriate bucket based on radar type.
+    if radar_type == "Level 2":
+        bucket_name = "noaa-nexrad-level2"
+        # For Level 2, the folder structure is: YYYY/MM/DD/STATION/
+        prefix = f"{year}/{month}/{day}/{station.upper()}/"
+    elif radar_type == "Level 3":
+        bucket_name = "unidata-nexrad-level3"
+        # For Level 3, the structure is similar.
+        prefix = f"{year}/{month}/{day}/{station.upper()}/"
+    else:
+        return "Error: Invalid radar type selected."
+
+    # Create an S3 client with unsigned requests.
+    s3 = boto3.client('s3', config=Config(signature_version=UNSIGNED))
+    try:
+        response = s3.list_objects_v2(Bucket=bucket_name, Prefix=prefix)
+    except Exception as e:
+        return f"Error accessing bucket: {e}"
+
+    if 'Contents' not in response:
+        return f"No data found for station {station.upper()} on {date_str} in {radar_type}."
+
+    # Sort objects by LastModified and choose the latest file.
+    objects = response['Contents']
+    objects_sorted = sorted(objects, key=lambda x: x['LastModified'])
+    latest_object = objects_sorted[-1]
+
+    file_key = latest_object['Key']
+    file_size = latest_object['Size']
+    last_modified = latest_object['LastModified']
+
+    # Download the file into a BytesIO buffer.
+    buffer = io.BytesIO()
+    try:
+        s3.download_fileobj(bucket_name, file_key, buffer)
+    except Exception as e:
+        return f"Error downloading file: {e}"
+    buffer.seek(0)
+
+    # Read a short preview (first 64 bytes) and convert to hex.
+    data_preview = buffer.read(64)
+    hex_preview = data_preview.hex()
+
+    # Return a summary of the downloaded file.
+    summary = (
+        f"Downloaded file: {file_key}\n"
+        f"Size: {file_size} bytes\n"
+        f"Last Modified (UTC): {last_modified}\n"
+        f"Hex preview (first 64 bytes):\n{hex_preview}"
+    )
+    return summary
+
+
+# Create the Gradio interface.
+interface = gr.Interface(
+    fn=fetch_latest_radar_data,
+    inputs=[
+        gr.inputs.Radio(choices=["Level 2", "Level 3"], label="Radar Data Type"),
+        gr.inputs.Textbox(label="Radar Station (e.g. KTLX)", default="KTLX"),
+        gr.inputs.Textbox(label="Date (YYYY-MM-DD)", default=datetime.datetime.utcnow().strftime("%Y-%m-%d"))
+    ],
+    outputs="text",
+    title="Radar Data Downloader",
+    description=(
+        "This tool downloads the latest radar data file from public AWS S3 buckets "
+        "used by Supercell Wx. Choose a radar data type (Level 2 or Level 3), enter a "
+        "radar station (e.g. KTLX), and a date (UTC). In future iterations, you can add "
+        "visualization using OpenStreetMap (which requires no API keys)."
+    )
+)
+
+if __name__ == "__main__":
+    interface.launch()