==================================================
Infrastructure  (transects, streets, inlets, LIDs)
==================================================

.. note::

   **Engine:** OpenSWMM 6 — refactored.

.. currentmodule:: openswmm.engine

``solver.infrastructure`` groups four hydraulic-infrastructure families
under one top-level namespace:

* :attr:`Infrastructure.transects` — irregular cross-sections.
* :attr:`Infrastructure.streets` — street cross-section templates.
* :attr:`Infrastructure.inlets` — inlet usage on conduits.
* :attr:`Infrastructure.lids` — LID control definitions + per-subcatchment usage.

Reference: ``openswmm_infrastructure.h``.

----

Quickstart
==========

.. code-block:: python

    from openswmm.engine import Solver, LidType

    with Solver("model.inp") as s:
        infra = s.infrastructure

        # Transects.
        idx = infra.transects.add("T1")
        infra.transects.set_roughness(idx, n_left=0.05, n_right=0.05, n_channel=0.03)
        infra.transects.add_station(idx, station=0.0, elevation=100.0)

        # Streets.
        sidx = infra.streets.add("ST1")
        infra.streets.set_params(
            sidx,
            t_crown=10.0, h_curb=0.5, sx=0.02, n_road=0.016,
            sides=2,
        )

        # Inlets.
        iidx = infra.inlets.add("IN1", "GRATE")
        infra.inlets.set_params(
            iidx, length=2.0, width=1.0, grate_type="P_BAR-50",
        )

        # LIDs.
        lidx = infra.lids.add("BC1", LidType.BIO_CELL)
        infra.lids.set_surface(lidx, storage=0.0, roughness=0.0, slope=0.5)
        infra.lids.set_soil(
            lidx, thick=12.0, porosity=0.45, fc=0.2, wp=0.1,
            ksat=0.5, kslope=10.0)
        infra.lids.set_storage(lidx, thick=12.0, void_frac=0.75, ksat=0.5)
        infra.lids.set_drain(lidx, coeff=0.0, expon=0.5, offset=6.0)

        # Place a LID control on a subcatchment.
        infra.lids.usage_add(
            "S1", lidx, number=1, area=100.0, width=10.0,
            init_sat=0.0, from_imperv=25.0)

----

Surface
=======

Each sub-view exposes ``__len__`` plus ``add`` and the relevant
parameter setters. The C API has no generic id→index lookup for these
families, so the views are intentionally flat — no ``__getitem__``
collection protocol.

Transects
---------

``transects.add(id) → int``
   Returns the integer index of the new transect.

``transects.set_roughness(idx, n_left, n_right, n_channel)``
   Set Manning's roughness for the three transect zones.

``transects.add_station(idx, station, elevation)``
   Append a profile station to a transect.

Streets
-------

``streets.add(id) → int`` — returns the integer index.

``streets.set_params(idx, *, t_crown, h_curb, sx, n_road, ...)``
   Configure the street cross-section. All parameters are keyword-only
   for clarity.

Inlets
------

``inlets.add(id, inlet_type) → int``

``inlets.set_params(idx, *, length, width, grate_type, open_area, splash_veloc)``

LIDs
----

``lids.add(id, lid_type) → int`` — ``lid_type`` is a
:class:`LidType` enum.

``lids.set_surface(idx, *, storage, roughness, slope)``
``lids.set_soil(idx, *, thick, porosity, fc, wp, ksat, kslope)``
``lids.set_storage(idx, *, thick, void_frac, ksat)``
``lids.set_drain(idx, *, coeff, expon, offset)``

``lids.usage_add(subcatchment, lid, *, number, area, width, init_sat, from_imperv)``
   Place a LID control on a subcatchment. ``subcatchment`` accepts
   ``int | str``; ``lid`` is currently an integer index because the C
   API has no id→index lookup for LID controls (passing a string
   raises :exc:`TypeError`).

----

See also
========

* :doc:`subcatchments` — LID-bearing subcatchments and their
  ``coverage`` mapping.
* :doc:`links` — irregular cross-sections via :attr:`Link.xsect`
  (``XSectShape.IRREGULAR`` references a transect id).
* :doc:`error_handling`.