feat: add dataset acquisition script and set up dependencies (#2)

- Rename fetch script to download_sbb_gtfs.py for clearer intent.
- Enhance download script with standard English comments and error handling.
- Update requirements.txt to include requests for fetching data.
- Ignore data/raw_data/ directory in .gitignore to avoid tracking large files.

Author: BruceKZ

.gitignore

@@ -42,3 +42,6 @@ coverage/
 # Misc
 .vercel
 .netlify
+
+# Data
+data/raw_data/

data/scripts/download_sbb_gtfs.py

@@ -0,0 +1,54 @@
+import requests
+import zipfile
+import os
+
+# Define absolute paths based on this script's location
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+# DATA_DIR represents the 'data' folder
+DATA_DIR = os.path.dirname(SCRIPT_DIR)
+DEFAULT_EXTRACT_DIR = os.path.join(DATA_DIR, "raw_data")
+
+def download_sbb_gtfs(extract_dir=DEFAULT_EXTRACT_DIR):
+    # Official SBB 2026 GTFS static data permalink
+    # No API Key required, directly downloads the latest version
+    permalink_url = "https://data.opentransportdata.swiss/dataset/timetable-2026-gtfs2020/permalink"
+
+    print("Connecting to official SBB permalink to fetch the latest GTFS data...")
+
+    try:
+        # Save temp zip in the data directory
+        zip_filename = os.path.join(DATA_DIR, "sbb_gtfs_temp.zip")
+        print("Starting dataset download...")
+
+        # Use allow_redirects=True to follow redirects to the actual zip file URL
+        with requests.get(permalink_url, stream=True, allow_redirects=True) as r:
+            r.raise_for_status()
+            with open(zip_filename, 'wb') as f:
+                for chunk in r.iter_content(chunk_size=8192):
+                    if chunk:
+                        f.write(chunk)
+
+        print(f"Download completed. Extracting to directory: ./{extract_dir}/")
+
+        # Extract the contents of the zip file
+        os.makedirs(extract_dir, exist_ok=True)
+        with zipfile.ZipFile(zip_filename, 'r') as zip_ref:
+            zip_ref.extractall(extract_dir)
+
+        # Clean up the temporary zip file
+        os.remove(zip_filename)
+        print("Done. The dataset is ready for use.")
+
+        # List core files to verify extraction
+        extracted_files = os.listdir(extract_dir)
+        print(f"Total files extracted: {len(extracted_files)}. Examples: {', '.join(extracted_files[:5])}...")
+
+    except requests.exceptions.RequestException as e:
+        print(f"Network request failed: {e}")
+    except zipfile.BadZipFile:
+        print("Error: The downloaded ZIP file is corrupted.")
+    except Exception as e:
+        print(f"An unknown error occurred: {e}")
+
+if __name__ == "__main__":
+    download_sbb_gtfs()

requirements.txt

@@ -0,0 +1 @@
+requests