from pathlib import Path
from sqlalchemy.orm import sessionmaker, scoped_session
from sqlalchemy import MetaData, Table
from sqlalchemy.exc import (
    IllegalStateChangeError,
    NoInspectionAvailable,
    NoSuchTableError,
)
from nxc.logger import nxc_logger
import sys


class database:
    def __init__(self, db_engine):
        self.CredentialsTable = None
        self.HostsTable = None

        self.db_engine = db_engine
        self.db_path = self.db_engine.url.database
        self.protocol = Path(self.db_path).stem.upper()
        self.metadata = MetaData()
        self.reflect_tables()
        session_factory = sessionmaker(bind=self.db_engine, expire_on_commit=True)

        Session = scoped_session(session_factory)
        # this is still named "conn" when it is the session object; TODO: rename
        self.conn = Session()

    @staticmethod
    def db_schema(db_conn):
        db_conn.execute(
            """CREATE TABLE "credentials" (
            "id" integer PRIMARY KEY,
            "username" text,
            "password" text
            )"""
        )

        db_conn.execute(
            """CREATE TABLE "hosts" (
            "id" integer PRIMARY KEY,
            "ip" text,
            "hostname" text,
            "port" integer
            )"""
        )

    def reflect_tables(self):
        with self.db_engine.connect():
            try:
                self.CredentialsTable = Table("credentials", self.metadata, autoload_with=self.db_engine)
                self.HostsTable = Table("hosts", self.metadata, autoload_with=self.db_engine)
            except (NoInspectionAvailable, NoSuchTableError):
                print(
                    f"""
                    [-] Error reflecting tables for the {self.protocol} protocol - this means there is a DB schema mismatch
                    [-] This is probably because a newer version of nxc is being ran on an old DB schema
                    [-] Optionally save the old DB data (`cp {self.db_path} ~/nxc_{self.protocol.lower()}.bak`)
                    [-] Then remove the nxc {self.protocol} DB (`rm -f {self.db_path}`) and run nxc to initialize the new DB"""
                )
                sys.exit()

    def shutdown_db(self):
        try:
            self.conn.close()
        # due to the async nature of nxc, sometimes session state is a bit messy and this will throw:
        # Method 'close()' can't be called here; method '_connection_for_bind()' is already in progress and
        # this would cause an unexpected state change to <SessionTransactionState.CLOSED: 5>
        except IllegalStateChangeError as e:
            nxc_logger.debug(f"Error while closing session db object: {e}")

    def clear_database(self):
        for table in self.metadata.sorted_tables:
            self.conn.execute(table.delete())