"""
backend/memory/oracle_sync.py — Supabase ↔ Oracle DB dual-write synchronizer.

Two public classes:

  MemorySynchronizer — Wraps a primary (Supabase) and a secondary (Oracle)
      MemoryBackend.  Writes always go to both; Oracle failures are non-fatal
      (logged but not re-raised) because Oracle is a secondary replica, not
      the source of truth.

  OracleState — Singleton lifecycle manager hooked from main.py _on_startup().
      Reads ORACLE_DB_* env vars, initialises OracleMemoryAdapter if they are
      set, and exposes oracle_adapter and memory_synchronizer as class-level
      attributes for use by other API modules.

Design decisions:
  - IDs are generated once by MemorySynchronizer (uuid4) and passed to BOTH
    backends so keys stay consistent (BUG-1 fix).
  - Secondary write is wrapped in try/except so a primary success is never
    rolled back due to an Oracle failure (BUG-4 fix).
  - sync_update / sync_delete return a dict {'primary': bool, 'secondary': bool|None}
    so callers can distinguish which backend failed (BUG-8 fix).
  - OracleState checks oracle_adapter.is_connected, not the object's truthiness,
    to avoid initialising the synchronizer against an unconnected adapter (BUG-3 fix).
"""
from __future__ import annotations

import logging
import os
import uuid
from typing import Any, Dict, List, Optional

from .memory_backend import MemoryBackend
from .oracle_adapter import OracleMemoryAdapter

_logger = logging.getLogger("memory.oracle_sync")


# ── Synchronizer ─────────────────────────────────────────────────────────────


class MemorySynchronizer:
    """
    Dual-write coordinator: primary backend is authoritative, secondary is
    best-effort.

    Args:
        primary:   Authoritative backend (Supabase).  Errors propagate.
        secondary: Replica backend (Oracle).  Errors are logged, never raised.
    """

    def __init__(self, primary: MemoryBackend, secondary: OracleMemoryAdapter) -> None:
        self.primary = primary
        self.secondary = secondary

    # ── Writes ───────────────────────────────────────────────────────────────

    async def sync_add_memory(
        self, user_id: str, memory_data: Dict[str, Any]
    ) -> str:
        """Insert into primary then Oracle.  Returns the shared memory_id."""
        shared_id = str(uuid.uuid4())          # single ID for both backends
        await self.primary.add_memory(user_id, memory_data, memory_id=shared_id)
        if self.secondary.is_connected:
            try:
                await self.secondary.add_memory(
                    user_id, memory_data, memory_id=shared_id
                )
            except Exception as exc:
                _logger.warning(
                    "OracleSync.add_memory: Oracle write failed (non-fatal) — %s", exc
                )
        return shared_id

    async def sync_update_memory(
        self, user_id: str, memory_id: str, new_data: Dict[str, Any]
    ) -> Dict[str, Optional[bool]]:
        """
        Update both backends.

        Returns:
            {'primary': bool, 'secondary': bool | None}
            None means Oracle is not connected or the call was skipped.
        """
        primary_ok = await self.primary.update_memory(user_id, memory_id, new_data)
        secondary_ok: Optional[bool] = None
        if self.secondary.is_connected:
            try:
                secondary_ok = await self.secondary.update_memory(
                    user_id, memory_id, new_data
                )
            except Exception as exc:
                _logger.warning(
                    "OracleSync.update_memory: Oracle update failed — %s", exc
                )
                secondary_ok = False
        return {"primary": primary_ok, "secondary": secondary_ok}

    async def sync_delete_memory(
        self, user_id: str, memory_id: str
    ) -> Dict[str, Optional[bool]]:
        """
        Delete from both backends.

        Returns:
            {'primary': bool, 'secondary': bool | None}
        """
        primary_ok = await self.primary.delete_memory(user_id, memory_id)
        secondary_ok: Optional[bool] = None
        if self.secondary.is_connected:
            try:
                secondary_ok = await self.secondary.delete_memory(user_id, memory_id)
            except Exception as exc:
                _logger.warning(
                    "OracleSync.delete_memory: Oracle delete failed — %s", exc
                )
                secondary_ok = False
        return {"primary": primary_ok, "secondary": secondary_ok}

    # ── Reads ────────────────────────────────────────────────────────────────

    async def get_memory_from_primary(
        self, user_id: str, memory_id: str
    ) -> Optional[Dict[str, Any]]:
        return await self.primary.get_memory(user_id, memory_id)

    async def get_memory_from_secondary(
        self, user_id: str, memory_id: str
    ) -> Optional[Dict[str, Any]]:
        if not self.secondary.is_connected:
            return None
        return await self.secondary.get_memory(user_id, memory_id)

    async def list_memories_from_primary(
        self, user_id: str, limit: int = 100, offset: int = 0
    ) -> List[Dict[str, Any]]:
        return await self.primary.list_memories(user_id, limit, offset)

    async def list_memories_from_secondary(
        self, user_id: str, limit: int = 100, offset: int = 0
    ) -> List[Dict[str, Any]]:
        if not self.secondary.is_connected:
            return []
        return await self.secondary.list_memories(user_id, limit, offset)


# ── Lifecycle singleton ───────────────────────────────────────────────────────


class OracleState:
    """
    Singleton lifecycle manager for the Oracle memory backend.

    Hooked from backend/main.py::_on_startup() — call await OracleState.initialize().
    The synchronizer is wired lazily; if ORACLE_DB_* vars are absent the class
    silently stays disabled so the rest of the API is unaffected.

    Usage after startup:
        from memory.oracle_sync import OracleState
        adapter = OracleState.oracle_adapter        # None if not configured
        sync    = OracleState.memory_synchronizer   # None if not configured
    """

    oracle_adapter: Optional[OracleMemoryAdapter] = None
    memory_synchronizer: Optional[MemorySynchronizer] = None
    _initialized: bool = False

    @classmethod
    async def initialize(cls) -> None:
        if cls._initialized:
            return

        user = os.getenv("ORACLE_DB_USER")
        password = os.getenv("ORACLE_DB_PASSWORD")
        dsn = os.getenv("ORACLE_DB_DSN")

        if not all([user, password, dsn]):
            _logger.info(
                "OracleState: ORACLE_DB_* env vars not set — Oracle backend disabled."
            )
            cls._initialized = True
            return

        adapter = OracleMemoryAdapter()
        try:
            await adapter.connect({"user": user, "password": password, "dsn": dsn})
        except Exception as exc:
            _logger.warning(
                "OracleState: connect failed (%s) — Oracle backend disabled.", exc
            )
            cls._initialized = True
            return

        cls.oracle_adapter = adapter

        # Wire up MemorySynchronizer only when a primary backend is available.
        # SupabaseMemoryBackend (backend/memory/supabase_backend.py) wraps the
        # existing state._sb client.  If that module doesn't exist yet the
        # synchronizer stays None; oracle_adapter is still available for direct use.
        try:
            from memory.supabase_backend import SupabaseMemoryBackend  # type: ignore[import]
            cls.memory_synchronizer = MemorySynchronizer(
                primary=SupabaseMemoryBackend(), secondary=cls.oracle_adapter
            )
            _logger.info(
                "OracleState: MemorySynchronizer ready (Supabase→Oracle dual-write active)."
            )
        except ImportError:
            _logger.info(
                "OracleState: supabase_backend not found — "
                "oracle_adapter available for direct use; synchronizer disabled."
            )

        cls._initialized = True

    @classmethod
    async def shutdown(cls) -> None:
        """Call from _on_shutdown() to close the Oracle pool gracefully."""
        if cls.oracle_adapter and cls.oracle_adapter.is_connected:
            await cls.oracle_adapter.disconnect()
        cls._initialized = False