strat-gameplay-webapp/backend/app/core/state_manager.py

"""
State Manager - In-memory game state management.

Manages active game states in memory for fast gameplay (<500ms response time).
Provides CRUD operations, lineup management, and state recovery from database.

This is the single source of truth for active game states during gameplay.

Author: Claude
Date: 2025-10-22
"""

import logging
from typing import Dict, Optional
from uuid import UUID
import pendulum

from app.models.game_models import GameState, TeamLineupState
from app.database.operations import DatabaseOperations

logger = logging.getLogger(f'{__name__}.StateManager')


class StateManager:
    """
    Manages in-memory game states for active games.

    Responsibilities:
    - Store game states in memory for fast access
    - Manage team lineups per game
    - Track last access times for eviction
    - Recover game states from database on demand

    This class uses dictionaries for O(1) lookups of game state by game_id.
    """

    def __init__(self):
        """Initialize the state manager with empty storage"""
        self._states: Dict[UUID, GameState] = {}
        self._lineups: Dict[UUID, Dict[int, TeamLineupState]] = {}  # game_id -> {team_id: lineup}
        self._last_access: Dict[UUID, pendulum.DateTime] = {}
        self.db_ops = DatabaseOperations()

        logger.info("StateManager initialized")

    async def create_game(
        self,
        game_id: UUID,
        league_id: str,
        home_team_id: int,
        away_team_id: int,
        home_team_is_ai: bool = False,
        away_team_is_ai: bool = False
    ) -> GameState:
        """
        Create a new game state in memory.

        Args:
            game_id: Unique game identifier
            league_id: League identifier ('sba' or 'pd')
            home_team_id: Home team ID
            away_team_id: Away team ID
            home_team_is_ai: Whether home team is AI-controlled
            away_team_is_ai: Whether away team is AI-controlled

        Returns:
            Newly created GameState

        Raises:
            ValueError: If game_id already exists
        """
        if game_id in self._states:
            raise ValueError(f"Game {game_id} already exists in state manager")

        logger.info(f"Creating game state for {game_id} ({league_id} league)")

        state = GameState(
            game_id=game_id,
            league_id=league_id,
            home_team_id=home_team_id,
            away_team_id=away_team_id,
            home_team_is_ai=home_team_is_ai,
            away_team_is_ai=away_team_is_ai
        )

        self._states[game_id] = state
        self._lineups[game_id] = {}
        self._last_access[game_id] = pendulum.now('UTC')

        logger.debug(f"Game {game_id} created in memory")
        return state

    def get_state(self, game_id: UUID) -> Optional[GameState]:
        """
        Get game state by ID.

        Updates last access time when accessed.

        Args:
            game_id: Game identifier

        Returns:
            GameState if found, None otherwise
        """
        if game_id in self._states:
            self._last_access[game_id] = pendulum.now('UTC')
            return self._states[game_id]
        return None

    def update_state(self, game_id: UUID, state: GameState) -> None:
        """
        Update game state.

        Args:
            game_id: Game identifier
            state: Updated GameState

        Raises:
            ValueError: If game_id doesn't exist
        """
        if game_id not in self._states:
            raise ValueError(f"Game {game_id} not found in state manager")

        self._states[game_id] = state
        self._last_access[game_id] = pendulum.now('UTC')
        logger.debug(f"Updated state for game {game_id} (inning {state.inning}, {state.half})")

    def set_lineup(self, game_id: UUID, team_id: int, lineup: TeamLineupState) -> None:
        """
        Set team lineup for a game.

        Args:
            game_id: Game identifier
            team_id: Team identifier
            lineup: Team lineup state

        Raises:
            ValueError: If game_id doesn't exist
        """
        if game_id not in self._states:
            raise ValueError(f"Game {game_id} not found in state manager")

        if game_id not in self._lineups:
            self._lineups[game_id] = {}

        self._lineups[game_id][team_id] = lineup
        logger.info(f"Set lineup for team {team_id} in game {game_id} ({len(lineup.players)} players)")

    def get_lineup(self, game_id: UUID, team_id: int) -> Optional[TeamLineupState]:
        """
        Get team lineup for a game.

        Args:
            game_id: Game identifier
            team_id: Team identifier

        Returns:
            TeamLineupState if found, None otherwise
        """
        return self._lineups.get(game_id, {}).get(team_id)

    def remove_game(self, game_id: UUID) -> None:
        """
        Remove game from memory.

        Call this when a game is completed or being archived.

        Args:
            game_id: Game identifier
        """
        removed_parts = []

        if game_id in self._states:
            self._states.pop(game_id)
            removed_parts.append("state")

        if game_id in self._lineups:
            self._lineups.pop(game_id)
            removed_parts.append("lineups")

        if game_id in self._last_access:
            self._last_access.pop(game_id)
            removed_parts.append("access")

        if removed_parts:
            logger.info(f"Removed game {game_id} from memory ({', '.join(removed_parts)})")
        else:
            logger.warning(f"Attempted to remove game {game_id} but it was not in memory")

    async def recover_game(self, game_id: UUID) -> Optional[GameState]:
        """
        Recover game state from database.

        This is called when a game needs to be loaded (e.g., after server restart,
        or when a game is accessed that's not currently in memory).

        Loads game data from database and rebuilds the in-memory state.

        Args:
            game_id: Game identifier

        Returns:
            Recovered GameState if found in database, None otherwise
        """
        logger.info(f"Recovering game {game_id} from database")

        # Load from database
        game_data = await self.db_ops.load_game_state(game_id)
        if not game_data:
            logger.warning(f"Game {game_id} not found in database")
            return None

        # Rebuild state from loaded data
        state = await self._rebuild_state_from_data(game_data)

        # Cache in memory
        self._states[game_id] = state
        self._last_access[game_id] = pendulum.now('UTC')

        logger.info(f"Recovered game {game_id} - inning {state.inning}, {state.half}")
        return state

    async def _rebuild_state_from_data(self, game_data: dict) -> GameState:
        """
        Rebuild game state from database data using the last completed play.

        This method recovers the complete game state without replaying all plays.
        It uses the final positions from the last play to reconstruct runners and
        batter indices.

        Args:
            game_data: Dictionary with 'game', 'lineups', and 'plays' keys

        Returns:
            Reconstructed GameState
        """
        game = game_data['game']

        state = GameState(
            game_id=game['id'],
            league_id=game['league_id'],
            home_team_id=game['home_team_id'],
            away_team_id=game['away_team_id'],
            home_team_is_ai=game.get('home_team_is_ai', False),
            away_team_is_ai=game.get('away_team_is_ai', False),
            status=game['status'],
            inning=game.get('current_inning', 1),
            half=game.get('current_half', 'top'),
            home_score=game.get('home_score', 0),
            away_score=game.get('away_score', 0),
            play_count=len(game_data.get('plays', []))
        )

        # Get last completed play to recover runner state and batter indices
        plays = game_data.get('plays', [])
        if plays:
            # Sort by play_number desc and get last completed play
            completed_plays = [p for p in plays if p.get('complete', False)]
            if completed_plays:
                last_play = max(completed_plays, key=lambda p: p['play_number'])

                # Recover runner state from final positions
                from app.models.game_models import RunnerState

                runners = []
                # Check each base for a runner (using *_final fields)
                for base_num, final_field in [(1, 'on_first_final'), (2, 'on_second_final'), (3, 'on_third_final')]:
                    final_base = last_play.get(final_field)
                    if final_base == base_num:  # Runner ended on this base
                        # Get lineup_id from corresponding on_X_id field
                        lineup_id = last_play.get(f'on_{["", "first", "second", "third"][base_num]}_id')
                        if lineup_id:
                            runners.append(RunnerState(
                                lineup_id=lineup_id,
                                card_id=0,  # Will be populated when needed
                                on_base=base_num
                            ))

                # Check if batter reached base
                batter_final = last_play.get('batter_final')
                if batter_final and 1 <= batter_final <= 3:
                    batter_id = last_play.get('batter_id')
                    if batter_id:
                        runners.append(RunnerState(
                            lineup_id=batter_id,
                            card_id=0,
                            on_base=batter_final
                        ))

                state.runners = runners

                # Recover batter indices from lineups
                # We need to find where each team is in their batting order
                home_lineup = [l for l in game_data.get('lineups', []) if l['team_id'] == state.home_team_id]
                away_lineup = [l for l in game_data.get('lineups', []) if l['team_id'] == state.away_team_id]

                # For now, we'll need to be called with _prepare_next_play() after recovery
                # to set the proper batter indices and snapshot
                # Initialize to 0 - will be corrected by _prepare_next_play()
                state.away_team_batter_idx = 0
                state.home_team_batter_idx = 0

                logger.debug(
                    f"Recovered state from play {last_play['play_number']}: "
                    f"{len(runners)} runners on base"
                )
            else:
                logger.debug("No completed plays found - initializing fresh state")
        else:
            logger.debug("No plays found - initializing fresh state")

        logger.info(f"Rebuilt state for game {state.game_id}: {state.play_count} plays, {len(state.runners)} runners")
        return state

    def evict_idle_games(self, idle_minutes: int = 60) -> int:
        """
        Remove games that haven't been accessed recently.

        This helps manage memory by removing inactive games. Evicted games
        can be recovered from database if needed later.

        Args:
            idle_minutes: Minutes of inactivity before eviction (default 60)

        Returns:
            Number of games evicted
        """
        cutoff = pendulum.now('UTC').subtract(minutes=idle_minutes)
        to_evict = [
            game_id for game_id, last_access in self._last_access.items()
            if last_access < cutoff
        ]

        for game_id in to_evict:
            self.remove_game(game_id)

        if to_evict:
            logger.info(f"Evicted {len(to_evict)} idle games (idle > {idle_minutes}m)")

        return len(to_evict)

    def get_stats(self) -> dict:
        """
        Get state manager statistics.

        Returns:
            Dictionary with current state statistics:
            - active_games: Number of games in memory
            - total_lineups: Total lineups across all games
            - games_by_league: Count of games per league
            - games_by_status: Count of games by status
        """
        stats = {
            "active_games": len(self._states),
            "total_lineups": sum(len(lineups) for lineups in self._lineups.values()),
            "games_by_league": {},
            "games_by_status": {},
        }

        # Count by league
        for state in self._states.values():
            league = state.league_id
            stats["games_by_league"][league] = stats["games_by_league"].get(league, 0) + 1

        # Count by status
        for state in self._states.values():
            status = state.status
            stats["games_by_status"][status] = stats["games_by_status"].get(status, 0) + 1

        return stats

    def exists(self, game_id: UUID) -> bool:
        """
        Check if game exists in memory.

        Args:
            game_id: Game identifier

        Returns:
            True if game is in memory, False otherwise
        """
        return game_id in self._states

    def get_all_game_ids(self) -> list[UUID]:
        """
        Get list of all game IDs currently in memory.

        Returns:
            List of game UUIDs
        """
        return list(self._states.keys())


# Singleton instance for global access
state_manager = StateManager()