from __future__ import annotations

from math import hypot
from typing import Sequence

from .models import GridCellModel, GridDescriptor


class GridPlanner:
    """Helper that picks a grid cell using simple heuristics."""

    def select_cell(
        self, descriptor: GridDescriptor, preferred_label: str | None = None
    ) -> GridCellModel | None:
        if not descriptor.cells:
            return None

        if preferred_label:
            match = self._match_label(descriptor.cells, preferred_label)
            if match:
                return match

        center_point = self._grid_center(descriptor)
        return min(descriptor.cells, key=lambda cell: self._distance(self._cell_center(cell), center_point))

    def describe(self, descriptor: GridDescriptor) -> str:
        cell_count = len(descriptor.cells)
        return (
            f"Grid {descriptor.grid_id} is {descriptor.rows}x{descriptor.columns} with {cell_count} cells."
        )

    def _grid_center(self, descriptor: GridDescriptor) -> tuple[float, float]:
        width = descriptor.metadata.get("width", 0)
        height = descriptor.metadata.get("height", 0)
        return (width / 2, height / 2)

    def _cell_center(self, cell: GridCellModel) -> tuple[float, float]:
        left, top, right, bottom = cell.bounds
        return ((left + right) / 2, (top + bottom) / 2)

    def _distance(
        self, first: tuple[float, float], second: tuple[float, float]
    ) -> float:
        return hypot(first[0] - second[0], first[1] - second[1])

    def _match_label(
        self, cells: Sequence[GridCellModel], label: str
    ) -> GridCellModel | None:
        lowered = label.lower()
        for cell in cells:
            if cell.label and lowered in cell.label.lower():
                return cell
        return None