"""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 ..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