Upload db.py

db.py

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+"""
+db.py — Database abstraction layer.
+
+- Production (HF Spaces): set DATABASE_URL env var → uses Neon PostgreSQL via psycopg2
+- Local dev: no DATABASE_URL → falls back to SQLite
+
+Usage in other modules:
+    from db import get_conn, PH, IntegrityError
+
+    conn = get_conn()
+    cursor = conn.cursor()
+    cursor.execute(f"SELECT * FROM users WHERE username = {PH}", (username,))
+    row = cursor.fetchone()
+    conn.close()
+"""
+
+import os
+import sqlite3
+import logging
+
+logger = logging.getLogger(__name__)
+
+# Connection string from environment (set as HF Space Secret)
+DATABASE_URL = os.environ.get('DATABASE_URL', '')
+
+# Are we using PostgreSQL?
+USE_POSTGRES = bool(DATABASE_URL)
+
+if USE_POSTGRES:
+    import psycopg2
+    import psycopg2.extras
+    import psycopg2.errors
+    # Placeholder style for PostgreSQL
+    PH = '%s'
+    # Exception alias
+    IntegrityError = psycopg2.errors.UniqueViolation
+    logger.info("DB: Using Neon PostgreSQL")
+else:
+    # Placeholder style for SQLite
+    PH = '?'
+    # Exception alias
+    IntegrityError = sqlite3.IntegrityError
+    logger.info("DB: Using local SQLite (dev mode)")
+
+# SQLite path (only used in local dev)
+_SQLITE_PATH = os.path.join(os.path.dirname(__file__), 'data', 'users.db')
+
+
+def get_conn():
+    """
+    Returns an open database connection.
+    Caller is responsible for calling conn.close() (use finally blocks).
+    """
+    if USE_POSTGRES:
+        if 'sslmode=' not in DATABASE_URL:
+            conn = psycopg2.connect(DATABASE_URL, sslmode='require')
+        else:
+            conn = psycopg2.connect(DATABASE_URL)
+        conn.autocommit = False
+        return conn
+    else:
+        os.makedirs(os.path.dirname(_SQLITE_PATH), exist_ok=True)
+        conn = sqlite3.connect(_SQLITE_PATH, timeout=10)
+        conn.execute('PRAGMA busy_timeout=5000')
+        return conn