# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.

"""
Data models for the Container Yard Environment.

The Container Yard environment simulates a port container yard where containers
arrive sequentially and must be placed into stacks to minimize rehandles during
retrieval operations.
"""

from typing import List, Optional
from openenv.core.env_server.types import Action, Observation
from pydantic import Field


class Container:
    """Represents a single container with ID and priority."""
    
    def __init__(self, container_id: int, priority: int):
        self.container_id = container_id
        priority_map = {1: 0, 2: 1, 3: 2}  # 1=earliest (0), 3=latest (2)
        self.retrieval_priority = priority_map.get(priority, 0)
    
    def __repr__(self):
        return f"C{self.container_id}(P{self.retrieval_priority})"


class ContainerYardAction(Action):
    """Action to place a container in a specific stack."""
    
    stack_index: int = Field(..., description="Index of the stack to place container in (0-9)")
    

class ContainerYardObservation(Observation):
    """Observation of the current container yard state."""
    
    stacks: List[List[int]] = Field(
        default_factory=list,
        description="Current state of stacks (container IDs, -1 means empty slot)"
    )
    containers_placed: int = Field(default=0, description="Number of containers placed so far")
    total_containers: int = Field(default=0, description="Total containers in this episode")
    current_container_id: int = Field(default=-1, description="ID of current container to place (-1 if done)")
    current_container_priority: int = Field(default=0, description="Priority of current container (1-3)")
    rehandles_so_far: int = Field(default=0, description="Total rehandles occurred so far")
    num_stacks: int = Field(default=10, description="Number of stacks in the yard")
    max_stack_height: int = Field(default=5, description="Maximum height of each stack")
    action_error: Optional[str] = Field(default=None, description="Error message if last action failed")