backend/app/services/parser.py

"""Parser service for initial state and traffic strings."""

from typing import Tuple, List
from ..models.grid import Grid
from ..models.entities import Store, Destination, Tunnel
from ..models.state import SearchState


def parse_initial_state(
    initial_state: str,
) -> Tuple[int, int, List[Store], List[Destination], List[Tunnel]]:
    """
    Parse the initial state string.

    Format:
    m;n;P;S;CustomerX_1,CustomerY_1,CustomerX_2,CustomerY_2,...;
    TunnelX_1,TunnelY_1,TunnelX_1',TunnelY_1',TunnelX_2,TunnelY_2,TunnelX_2',TunnelY_2',...;
    StoreX_1,StoreY_1,StoreX_2,StoreY_2,...

    Args:
        initial_state: The initial state string

    Returns:
        Tuple of (width, height, stores, destinations, tunnels)
    """
    parts = initial_state.strip().split(";")

    # Grid dimensions
    width = int(parts[0])  # m
    height = int(parts[1])  # n

    # Number of packages/customers and stores
    num_packages = int(parts[2])  # P
    num_stores = int(parts[3])  # S

    # Parse customer locations
    destinations: List[Destination] = []
    if len(parts) > 4 and parts[4]:
        customer_coords = parts[4].split(",")
        for i in range(0, len(customer_coords), 2):
            if i + 1 < len(customer_coords):
                x = int(customer_coords[i])
                y = int(customer_coords[i + 1])
                dest_id = len(destinations) + 1
                destinations.append(Destination(id=dest_id, position=(x, y)))

    # Parse tunnel locations
    tunnels: List[Tunnel] = []
    if len(parts) > 5 and parts[5]:
        tunnel_coords = parts[5].split(",")
        for i in range(0, len(tunnel_coords), 4):
            if i + 3 < len(tunnel_coords):
                x1 = int(tunnel_coords[i])
                y1 = int(tunnel_coords[i + 1])
                x2 = int(tunnel_coords[i + 2])
                y2 = int(tunnel_coords[i + 3])
                tunnels.append(Tunnel(entrance1=(x1, y1), entrance2=(x2, y2)))

    # Parse store locations
    stores: List[Store] = []
    if len(parts) > 6 and parts[6]:
        store_coords = parts[6].split(",")
        for i in range(0, len(store_coords), 2):
            if i + 1 < len(store_coords):
                x = int(store_coords[i])
                y = int(store_coords[i + 1])
                store_id = len(stores) + 1
                stores.append(Store(id=store_id, position=(x, y)))

    return width, height, stores, destinations, tunnels


def parse_traffic(traffic_str: str, width: int, height: int) -> Grid:
    """
    Parse the traffic string and create a Grid.

    Format:
    SrcX_1,SrcY_1,DstX_1,DstY_1,Traffic_1;SrcX_2,SrcY_2,DstX_2,DstY_2,Traffic_2;...

    Args:
        traffic_str: Traffic string
        width: Grid width
        height: Grid height

    Returns:
        Grid with traffic information
    """
    grid = Grid(width=width, height=height)

    if not traffic_str:
        # Initialize all segments with default traffic level 1
        _initialize_default_traffic(grid)
        return grid

    segments = traffic_str.strip().split(";")
    for segment in segments:
        if not segment:
            continue
        parts = segment.split(",")
        if len(parts) >= 5:
            src_x = int(parts[0])
            src_y = int(parts[1])
            dst_x = int(parts[2])
            dst_y = int(parts[3])
            traffic = int(parts[4])
            grid.add_segment((src_x, src_y), (dst_x, dst_y), traffic)

    return grid


def _initialize_default_traffic(grid: Grid, default_traffic: int = 1) -> None:
    """
    Initialize all grid segments with default traffic.

    Creates horizontal and vertical segments between adjacent cells.
    """
    for x in range(grid.width):
        for y in range(grid.height):
            # Horizontal segment (right)
            if x + 1 < grid.width:
                grid.add_segment((x, y), (x + 1, y), default_traffic)
            # Vertical segment (up)
            if y + 1 < grid.height:
                grid.add_segment((x, y), (x, y + 1), default_traffic)


def parse_full_state(initial_state: str, traffic_str: str) -> SearchState:
    """
    Parse both initial state and traffic into a complete SearchState.

    Args:
        initial_state: Initial state string
        traffic_str: Traffic string

    Returns:
        Complete SearchState object
    """
    width, height, stores, destinations, tunnels = parse_initial_state(initial_state)
    grid = parse_traffic(traffic_str, width, height)

    return SearchState(
        grid=grid, stores=stores, destinations=destinations, tunnels=tunnels
    )


def format_initial_state(
    width: int,
    height: int,
    stores: List[Store],
    destinations: List[Destination],
    tunnels: List[Tunnel],
) -> str:
    """
    Format state back into initial state string.

    Args:
        width: Grid width
        height: Grid height
        stores: List of stores
        destinations: List of destinations
        tunnels: List of tunnels

    Returns:
        Formatted initial state string
    """
    parts = [
        str(width),
        str(height),
        str(len(destinations)),
        str(len(stores)),
    ]

    # Customer coordinates
    customer_coords = []
    for dest in destinations:
        customer_coords.extend([str(dest.position[0]), str(dest.position[1])])
    parts.append(",".join(customer_coords))

    # Tunnel coordinates
    tunnel_coords = []
    for tunnel in tunnels:
        tunnel_coords.extend(
            [
                str(tunnel.entrance1[0]),
                str(tunnel.entrance1[1]),
                str(tunnel.entrance2[0]),
                str(tunnel.entrance2[1]),
            ]
        )
    parts.append(",".join(tunnel_coords))

    # Store coordinates
    store_coords = []
    for store in stores:
        store_coords.extend([str(store.position[0]), str(store.position[1])])
    parts.append(",".join(store_coords))

    return ";".join(parts)


def format_traffic(grid: Grid) -> str:
    """
    Format grid traffic into traffic string.

    Args:
        grid: Grid with traffic information

    Returns:
        Formatted traffic string
    """
    segments = []
    for (src, dst), segment in grid.segments.items():
        segments.append(f"{src[0]},{src[1]},{dst[0]},{dst[1]},{segment.traffic}")
    return ";".join(segments)