"""Reference-geometry executors (reference_plane / reference_axis).

Context features produce no solid; they register durable topology contexts
that later features resolve through owner-qualified selectors.
"""

from __future__ import annotations

import math
from typing import TYPE_CHECKING, Any

from ..registry import atomic_executor
from ..specs import AxisSpec, PlaneSpec, vector_add, vector_cross, vector_dot, vector_scale, vector_unit
from ..topology import FeaturePlanNode, FeatureResult

if TYPE_CHECKING:  # pragma: no cover - import for type checkers only
    from ..session import ExecutionSession


@atomic_executor("reference_plane")
def _reference_plane_executor(node: FeaturePlanNode, session: "ExecutionSession", sketch: dict[str, Any] | None) -> FeatureResult:
    del sketch
    # 基准面特征（reference_plane）执行入口：从参数解析平面并登记为拓扑上下文。

    # 1. 从特征参数 plane 中解析出平面定义 PlaneSpec（原点到法向）。
    plane = PlaneSpec.from_mapping(node.params.get("plane") or {})
    # 2. 将该平面注册到拓扑上下文，供后续特征（如草图基准、参考轴）引用。
    session.topology.register_context(node.feature_id, plane)
    # 3. 返回结果对象，并将该平面作为上下文一并携带。
    return session.result(node, context=plane)


@atomic_executor("reference_axis")
def _reference_axis_executor(node: FeaturePlanNode, session: "ExecutionSession", sketch: dict[str, Any] | None) -> FeatureResult:
    del sketch
    # 基准轴特征（reference_axis）执行入口：由参数直接定义轴，或由两个基准平面求交线得到轴。

    # 1. 尝试直接取参数：若同时给出原点 origin_mm 与方向 direction，则直接构造轴。
    params = node.params.get("axis") or {}
    if params.get("origin_mm") and params.get("direction"):
        axis = AxisSpec.from_mapping(params)
    else:
        # 2. 否则从特征选择器中筛选出已解析的基准平面。
        planes = [session.resolve(selector) for selector in node.selectors if selector.get("kind") == "plane"]
        resolved = [item.record.value for item in planes if item.status == "resolved" and isinstance(item.record.value, PlaneSpec)]
        # 3. 校验：轴需要两个非平行的平面，不足两个则报错。
        if len(resolved) < 2:
            raise ValueError("reference axis requires two uniquely resolved planes")
        # 4. 用两平面法线叉积求交线方向；若方向长度接近 0 说明两平面平行，无法成轴。
        first, second = resolved[0], resolved[1]
        n1, n2 = first.normal, second.normal
        direction = vector_cross(n1, n2)
        squared_length = vector_dot(direction, direction)
        if squared_length <= 1e-18:
            raise ValueError("reference planes are parallel and cannot define an axis")
        # 5. 求交线上的一点：两平面到各自原点的垂距参与线性组合，得到交线上的最近点。
        d1 = vector_dot(n1, first.origin_mm)
        d2 = vector_dot(n2, second.origin_mm)
        point = vector_scale(vector_add(vector_scale(vector_cross(n2, direction), d1), vector_scale(vector_cross(direction, n1), d2)), 1 / squared_length)
        # 6. 由该点与归一化的交线方向组合成基准轴 AxisSpec。
        axis = AxisSpec(origin_mm=point, direction=vector_unit(direction, field_name="reference axis"))
    # 7. 注册为拓扑上下文，并返回结果对象（携带该轴）。
    session.topology.register_context(node.feature_id, axis)
    return session.result(node, context=axis)


@atomic_executor("reference_point")
def _reference_point_executor(node: FeaturePlanNode, session: "ExecutionSession", sketch: dict[str, Any] | None) -> FeatureResult:
    """Execute an explicit source-datum point without changing model topology."""
    del sketch
    point = node.params.get("point_mm")
    if (
        not isinstance(point, list)
        or len(point) != 3
        or not all(isinstance(value, (int, float)) and math.isfinite(float(value)) for value in point)
    ):
        raise ValueError("reference point requires one finite three-dimensional point")
    return session.result(node, include_body=False)


@atomic_executor("assign_variable")
def _assign_variable_executor(node: FeaturePlanNode, session: "ExecutionSession", sketch: dict[str, Any] | None) -> FeatureResult:
    """Replay a source variable declaration after lowering has consumed it."""
    del sketch
    name = node.params.get("name")
    value = node.params.get("value")
    if not isinstance(name, str) or not name or not isinstance(value, (int, float)) or not math.isfinite(float(value)):
        raise ValueError("assign_variable requires one finite named value")
    return session.result(node, include_body=False)