from sqlalchemy import Engine, select
from sqlalchemy.orm import Session
from .meta_storage_connector import MetaStorageConnector
from .models import ContactInfo, Unit, UnitInfo, FormData, FormReception
from .schema import Base, kontaktinfo, enheter, enhetsinfo, skjemadata, skjemamottak


class ParqueditStorageConnector(MetaStorageConnector):
    """(WIP) Storage connector intended for a Parquet/Delta-style backend.

    This class is currently **work-in-progress** and not usable. The design
    mirrors the `MetaStorageConnector` interface and sketches out table creation
    and insert operations targeting a file/table format that uses JSON-like
    schemas (e.g., Parquet with a schema registry). For now, certain operations
    still reference a SQLAlchemy `Engine` and issue simple selects, acting as
    placeholders until a full Parquet-backed implementation is completed.

    Attributes:

    """
    def __init__(self, engine: Engine) -> None:
        """Initializes the connector with a SQLAlchemy engine (placeholder).

        Args:
            engine (Engine): A SQLAlchemy engine used temporarily for validation
                checks and to mirror the transactional lifecycle while the class
                is developed.

        Raises:
            NotImplementedError: Always raised to indicate the connector is not
                ready for use.
        
        """
        self._engine = engine
        self._session = None
        raise NotImplementedError("WIP: Class is not usable")

    def begin_transaction(self) -> None:
        """Starts a new transactional session (placeholder).

        Notes:
            Provided to keep parity with the `MetaStorageConnector` interface.
            In a future Parquet-backed implementation, this may manage file
            writers, staging areas, or atomic rename workflows rather than a
            database transaction.

        Raises:
            Exception: Propagates any SQLAlchemy errors during session creation
                or transaction start.
        """
        self._session = Session(bind=self._engine)
        self._get_session().begin()

    def _get_session(self) -> Session:
        """Returns the active session or raises if not started.

        Returns:
            Session: The active SQLAlchemy session.

        Raises:
            RuntimeError: If a transaction/session has not been started.
        """
        if self._session is None:
            raise RuntimeError("Session is not started")
        return self._session

    def rollback(self, ref_number: str) -> None:
        """Rolls back the current transaction (placeholder).

        Args:
            ref_number (str): Reference number for diagnostic logging/context.

        Raises:
            RuntimeError: If no active session/transaction exists.
        """
        self._get_session().rollback()

    def commit(self) -> None:
        """Commits the current transaction (placeholder).

        Raises:
            RuntimeError: If no active session/transaction exists.
            Exception: Propagates SQLAlchemy commit errors.
        """
        self._get_session().commit()

    def create_tables_if_not_exists(self) -> None:
        """Creates logical tables/schemas if they do not already exist.

        Notes:
            For a Parquet/Delta backend, this would create directories and write
            schema/metadata files (or register schemas with a catalog). This WIP
            method currently only defines in-memory schema descriptors.
        """
        self._create_contact_info_table()
        self._create_control_result_table()
        self._create_controls_table()
        self._create_form_data_table()
        self._create_form_reciept_table()
        self._create_unit_info_table()
        self._create_unit_table()

    def validate_form_is_new(self, form_reference: str) -> bool:
        """Checks if a form reference is not already present.

        Args:
            form_reference (str): The reference number identifying the form.

        Returns:
            bool: ``True`` if no existing record for the reference is found,
            otherwise ``False``.

        Notes:
            This placeholder implementation uses a SQLAlchemy `SELECT` against
            ``skjemamottak``. In a Parquet/Delta backend, this would scan an
            index, metadata log, or keyed manifest to ensure idempotency.
        """
        stmt = select(skjemamottak).filter(skjemamottak.refnr == form_reference)
        conn = self._engine.connect()
        result = conn.execute(stmt).first()
        return result is None

    def _create_contact_info_table(self):
        """Defines the schema for the `kontaktinfo` table (contact info).

        Notes:
            Intended to represent a schema descriptor for Parquet/Delta creation.
            Currently unused beyond in-code documentation.
        """
        table_name = "kontaktinfo"
        schema = {
            "properties": {
                "id": {"type": "integer"},
                "aar": {"type": "integer"},
                "skjema": {"type": "string"},
                "ident": {"type": "string"},
                "refnr": {"type": "string"},
                "kontaktperson": {"type": "string"},
                "epost": {"type": "string"},
                "telefon": {"type": "string"},
                "bekreftet_kontaktinfo": {"type": "string"},
                "kommentar_kontaktinfo": {"type": "string"},
                "kommentar_krevende": {"type": "string"},
            },
            "required": ["id", "aar", "skjema", "ident", "refnr"],
        }

    def _create_form_data_table(self):
        """Defines the schema for the `skjemadata` table (field-level data).

        Notes:
            The current code assigns `table_name = "kontaktinfo"` which appears
            to be a typo. In a future implementation, ensure the table name
            matches ``skjemadata``.
        """
        table_name = "kontaktinfo"
        schema = {
            "properties": {
                "id": {"type": "integer"},
                "aar": {"type": "integer"},
                "skjema": {"type": "string"},
                "ident": {"type": "string"},
                "refnr": {"type": "string"},
                "feltsti": {"type": "string"},
                "feltnavn": {"type": "string"},
                "verdi": {"type": "string"},
                "alias": {"type": "string"},
                "dybde": {"type": "integer"},
                "indeks": {"type": "integer"},
            },
            "required": [
                "id",
                "aar",
                "skjema",
                "ident",
                "refnr",
                "feltsti",
                "feltnavn",
                "verdi",
            ],
        }

    def _create_form_reciept_table(self):
        """Defines the schema for the `skjemamottak` table (form reception).

        Notes:
            The date is represented as a string with a `date-time` format hint.
            A Parquet/Delta implementation would likely map this to a TIMESTAMP
            logical type.
        """
        table_name = "skjemamottak"
        schema = {
            "properties": {
                "id": {"type": "integer"},
                "aar": {"type": "integer"},
                "skjema": {"type": "string"},
                "ident": {"type": "string"},
                "refnr": {"type": "string"},
                "kommentar": {"type": "string"},
                "dato_mottatt": {"type": "string", "fmt": "date-time"},
                "editert": {"type": "string"},
                "aktiv": {"type": "boolean"},
            },
            "required": [
                "id",
                "aar",
                "skjema",
                "ident",
                "refnr",
                "dato_mottatt",
                "editert",
                "aktiv",
            ],
        }

    def _create_unit_table(self):
        """Defines the schema for the `enheter` table (units)."""
        table_name = "enheter"
        schema = {
            "properties": {
                "id": {"type": "integer"},
                "aar": {"type": "integer"},
                "skjema": {"type": "string"},
                "ident": {"type": "string"},
            },
            "required": [
                "id",
                "aar",
                "skjema",
                "ident",
            ],
        }

    def _create_unit_info_table(self):
        """Defines the schema for the `enhetsinfo` table (unit attributes)."""
        table_name = "enhetsinfo"
        schema = {
            "properties": {
                "id": {"type": "integer"},
                "aar": {"type": "integer"},
                "ident": {"type": "string"},
                "variabel": {"type": "string"},
                "verdi": {"type": "string"},
            },
            "required": ["id", "aar", "ident", "variabel", "verdi"],
        }

    def _create_controls_table(self):
        """Defines the schema for the `kontroller` table (control definitions)."""
        table_name = "kontroller"
        schema = {
            "properties": {
                "id": {"type": "integer"},
                "aar": {"type": "integer"},
                "kontrollid": {"type": "string"},
                "kontrolltype": {"type": "string"},
                "beskrivelse": {"type": "string"},
                "sorting_var": {"type": "string"},
                "sorting_order": {"type": "string"},
            },
            "required": [
                "id",
                "aar",
                "kontrollid",
                "kontrolltype",
                "beskrivelse",
                "sorting_var",
                "sorting_order",
            ],
        }

    def _create_control_result_table(self):
        """Defines the schema for the `kontrollutslag` table (control results)."""
        table_name = "kontrollutslag"
        schema = {
            "properties": {
                "id": {"type": "integer"},
                "aar": {"type": "integer"},
                "skjema": {"type": "string"},
                "kontrollid": {"type": "string"},
                "ident": {"type": "string"},
                "refnr": {"type": "string"},
                "utslag": {"type": "boolean"},
                "verdi": {"type": "string"},
            },
            "required": [
                "id",
                "aar",
                "kontrollid",
                "skjema",
                "ident",
                "refnr",
                "utslag",
            ],
        }

    def insert_contact_info(self, contact_info: ContactInfo) -> None:
        """Stages a contact info record for insertion (WIP).

        Args:
            contact_info (ContactInfo): Contact information to persist.

        Notes:
            In a complete implementation, this would write to a Parquet/Delta table,
            potentially via a staging area and atomic commit.
        """
        table_name = "kontaktinfo"
        model = [contact_info.model_dump()]

    def insert_form_data(self, form_data: list[FormData]) -> None:
        """Stages a batch of form data records for insertion (WIP).

        Args:
            form_data (list[FormData]): Field-level form data entries to persist.

        Notes:
            In a complete implementation, this would batch-append rows to a
            columnar file and update an index/manifest.
        """
        table_name = "skjemadata"
        models = []
        for node in form_data:
            node_data = node.model_dump()
            models.append(node_data)

    def insert_form_reception(self, form_reciept: FormReception) -> None:
        """Stages a form reception record for insertion (WIP).

        Args:
            form_reciept (FormReception): Reception metadata to persist.
        """
        table_name = "skjemamottak"
        model = [form_reciept.model_dump()]

    def insert_unit(self, unit: Unit) -> None:
        """Stages a unit record for insertion (WIP).

        Args:
            unit (Unit): Unit metadata to persist.
        
        """
        table_name = "enheter"
        model = [unit.model_dump()]

    def insert_unit_info(self, units: list[UnitInfo]) -> None:
        """Stages unit attribute records for insertion (WIP).

        Args:
            units (list[UnitInfo]): Unit key–value attributes to persist.
        """
        table_name = "enhetsinfo"
        unit_info = []
        for item in units:
            model = item.model_dump()
            unit_info.append(model)
