implement initial backend structure with authentication, user management, and database integration

backend/app/services/auth.py

@@ -0,0 +1,132 @@
+"""Authentication service: password hashing, JWT creation/verification, token management."""
+import os
+from datetime import datetime, timedelta, timezone
+from typing import Any
+
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+
+from backend.app.db import get_conn, get_write_lock
+
+_pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+
+ACCESS_TOKEN_EXPIRE_MINUTES = 15
+REFRESH_TOKEN_EXPIRE_DAYS = 7
+ALGORITHM = "HS256"
+
+
+def _secret() -> str:
+    secret = os.getenv("JWT_SECRET")
+    if not secret:
+        raise RuntimeError("JWT_SECRET environment variable is not set.")
+    return secret
+
+
+# --- Password ---
+
+def hash_password(plain: str) -> str:
+    return _pwd_context.hash(plain)
+
+
+def verify_password(plain: str, hashed: str) -> bool:
+    return _pwd_context.verify(plain, hashed)
+
+
+# --- Tokens ---
+
+def create_access_token(user_id: str, email: str, role: str) -> str:
+    expire = datetime.now(timezone.utc) + timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    payload = {
+        "sub": user_id,
+        "email": email,
+        "role": role,
+        "exp": expire,
+        "type": "access",
+    }
+    return jwt.encode(payload, _secret(), algorithm=ALGORITHM)
+
+
+def create_refresh_token(user_id: str, jti: str) -> str:
+    expire = datetime.now(timezone.utc) + timedelta(days=REFRESH_TOKEN_EXPIRE_DAYS)
+    payload = {
+        "sub": user_id,
+        "jti": jti,
+        "exp": expire,
+        "type": "refresh",
+    }
+    return jwt.encode(payload, _secret(), algorithm=ALGORITHM)
+
+
+def decode_token(token: str) -> dict[str, Any]:
+    """Decode and validate a JWT. Raises JWTError on failure."""
+    return jwt.decode(token, _secret(), algorithms=[ALGORITHM])
+
+
+# --- Database operations ---
+
+async def register_user(email: str, password: str) -> dict[str, Any]:
+    """Insert a new user. Returns the created user row."""
+    conn = get_conn()
+    lock = get_write_lock()
+    async with lock:
+        existing = conn.execute(
+            "SELECT id FROM users WHERE email = ?", [email]
+        ).fetchone()
+        if existing:
+            raise ValueError("Email already registered.")
+        conn.execute(
+            "INSERT INTO users (email, password_hash) VALUES (?, ?)",
+            [email, hash_password(password)],
+        )
+        row = conn.execute(
+            "SELECT id, email, role FROM users WHERE email = ?", [email]
+        ).fetchone()
+    return {"id": str(row[0]), "email": row[1], "role": row[2]}
+
+
+async def authenticate_user(email: str, password: str) -> dict[str, Any] | None:
+    """Return user dict if credentials are valid, else None."""
+    conn = get_conn()
+    row = conn.execute(
+        "SELECT id, email, password_hash, role FROM users WHERE email = ?", [email]
+    ).fetchone()
+    if row is None or not verify_password(password, row[2]):
+        return None
+    return {"id": str(row[0]), "email": row[1], "role": row[3]}
+
+
+async def store_refresh_token(user_id: str, jti: str) -> None:
+    """Persist a refresh token JTI in the database."""
+    conn = get_conn()
+    lock = get_write_lock()
+    from datetime import timedelta
+    expires_at = datetime.now(timezone.utc) + timedelta(days=REFRESH_TOKEN_EXPIRE_DAYS)
+    async with lock:
+        conn.execute(
+            "INSERT INTO refresh_tokens (jti, user_id, expires_at) VALUES (?, ?, ?)",
+            [jti, user_id, expires_at],
+        )
+
+
+async def revoke_refresh_token(jti: str) -> None:
+    """Mark a refresh token as revoked."""
+    conn = get_conn()
+    lock = get_write_lock()
+    async with lock:
+        conn.execute(
+            "UPDATE refresh_tokens SET revoked = true WHERE jti = ?", [jti]
+        )
+
+
+async def validate_refresh_token_jti(jti: str, user_id: str) -> bool:
+    """Return True if the JTI exists, is not revoked, and belongs to user_id."""
+    conn = get_conn()
+    now = datetime.now(timezone.utc)
+    row = conn.execute(
+        """
+        SELECT 1 FROM refresh_tokens
+        WHERE jti = ? AND user_id = ? AND revoked = false AND expires_at > ?
+        """,
+        [jti, user_id, now],
+    ).fetchone()
+    return row is not None