# myapp/repositories/service_availability.py
# ------------------------------------------------------------
# Persistence layer for the ServiceAvailability table.
# ------------------------------------------------------------

from __future__ import annotations

from typing import List, Optional, Sequence, Any

from ..db import BaseRepository
from ..models import ServiceAvailability as ServiceAvailabilityModel


class ServiceAvailabilityRepository(BaseRepository[ServiceAvailabilityModel]):
    """
    CRUD + query helpers for the ``ServiceAvailability`` table.

    The table records which members are allowed to receive which
    service‑type slots (e.g. “9 AM”, “11 AM”, “6 PM”).  All SQL is
    parameterised to stay safe from injection attacks.
    """

    # ------------------------------------------------------------------
    # Table‑level constants – change them in one place if the schema evolves.
    # ------------------------------------------------------------------
    _TABLE = "ServiceAvailability"
    _PK = "ServiceAvailabilityId"

    # ------------------------------------------------------------------
    # Basic CRUD helpers
    # ------------------------------------------------------------------
    def create(
        self,
        member_id: int,
        service_type_id: int,
    ) -> ServiceAvailabilityModel:
        """
        Insert a new availability row.

        The ``UNIQUE (MemberId, ServiceTypeId)`` constraint guarantees
        idempotency – if the pair already exists SQLite will raise an
        ``IntegrityError``.  To make the operation truly idempotent we
        first check for an existing row and return it unchanged.
        """
        existing = self.get(member_id, service_type_id)
        if existing:
            return existing

        avail = ServiceAvailabilityModel(
            ServiceAvailabilityId=-1,   # placeholder – will be overwritten
            MemberId=member_id,
            ServiceTypeId=service_type_id,
        )
        return self._insert(self._TABLE, avail, self._PK)

    def get(
        self,
        member_id: int,
        service_type_id: int,
    ) -> Optional[ServiceAvailabilityModel]:
        """
        Retrieve a single availability record for the given member /
        service‑type pair, or ``None`` if it does not exist.
        """
        sql = f"""
            SELECT *
            FROM {self._TABLE}
            WHERE MemberId = ?
              AND ServiceTypeId = ?
        """
        row = self.db.fetchone(sql, (member_id, service_type_id))
        return ServiceAvailabilityModel.from_row(row) if row else None

    def delete(self, availability_id: int) -> None:
        """
        Hard‑delete an availability row by its primary key.
        Use with care – most callers will prefer ``revoke`` (by member &
        service type) which is a bit more expressive.
        """
        sql = f"DELETE FROM {self._TABLE} WHERE {self._PK} = ?"
        self.db.execute(sql, (availability_id,))

    # ------------------------------------------------------------------
    # Convenience “grant / revoke” helpers (the most common ops)
    # ------------------------------------------------------------------
    def grant(self, member_id: int, service_type_id: int) -> ServiceAvailabilityModel:
        """
        Public API to give a member permission for a particular service slot.
        Internally delegates to ``create`` which already handles the
        idempotent‑check.
        """
        return self.create(member_id, service_type_id)

    def revoke(self, member_id: int, service_type_id: int) -> None:
        """
        Remove a member’s permission for a particular service slot.
        """
        sql = f"""
            DELETE FROM {self._TABLE}
            WHERE MemberId = ?
              AND ServiceTypeId = ?
        """
        self.db.execute(sql, (member_id, service_type_id))

    # ------------------------------------------------------------------
    # Query helpers used by the scheduling service
    # ------------------------------------------------------------------
    def list_by_member(self, member_id: int) -> List[ServiceAvailabilityModel]:
        """
        Return every ``ServiceAvailability`` row that belongs to the given
        member.  Handy for building a member’s personal “available slots”
        view.
        """
        sql = f"""
            SELECT *
            FROM {self._TABLE}
            WHERE MemberId = ?
        """
        rows = self.db.fetchall(sql, (member_id,))
        return [ServiceAvailabilityModel.from_row(r) for r in rows]

    def list_by_service_type(self, service_type_id: int) -> List[ServiceAvailabilityModel]:
        """
        Return all members that are allowed to receive the given service type.
        """
        sql = f"""
            SELECT *
            FROM {self._TABLE}
            WHERE ServiceTypeId = ?
        """
        rows = self.db.fetchall(sql, (service_type_id,))
        return [ServiceAvailabilityModel.from_row(r) for r in rows]

    def list_all(self) -> List[ServiceAvailabilityModel]:
        """
        Return every row in the table – useful for admin dashboards or
        bulk‑export scripts.
        """
        return self._select_all(self._TABLE, ServiceAvailabilityModel)

    # ------------------------------------------------------------------
    # Helper for the round‑robin scheduler
    # ------------------------------------------------------------------
    def members_for_type(self, service_type_id: int) -> List[int]:
        """
        Return a flat list of ``MemberId`` values that are eligible for the
        supplied ``service_type_id``.  The scheduling service can then
        intersect this list with the pool of members that have the correct
        classification, activity flag, etc.
        """
        sql = f"""
            SELECT MemberId
            FROM {self._TABLE}
            WHERE ServiceTypeId = ?
        """
        rows = self.db.fetchall(sql, (service_type_id,))
        # ``rows`` is a sequence of sqlite3.Row objects; each row acts like a dict.
        return [row["MemberId"] for row in rows]