{#
  Locale switcher macro — #955 cycle 6.

  Renders a small <form> that POSTs the user's chosen locale to
  /_dazzle/i18n/locale. The router validates against the project's
  `supported_locales` allow-list, sets the `dazzle_locale` cookie,
  and refreshes the page (HX-Refresh on htmx; 303 redirect on plain
  POST).

  Usage:
      {% from 'macros/locale_switcher.html' import render_locale_switcher %}
      {{ render_locale_switcher() }}

  The macro reads `request.state.locale` (current locale) and
  `request.state.locale_supported` (frozenset of supported tags) set
  by LocaleMiddleware, so projects don't have to thread either
  through their template context.

  Arguments:
    label   — visible <label> text. Defaults to "Language" — wrap with
              `_("Language")` at the call site if you want it localised.
    style   — "select" (default) renders a <select>; "links" renders
              one button per locale (lighter chrome, useful for footer).
    next    — explicit URL to redirect back to. Defaults to the current
              path (read from request.url).
    locale_names — optional dict mapping tag → display label
              (e.g. {"fr": "Français", "de": "Deutsch"}). Tags not in
              the dict render as the bare tag.
#}
{% macro render_locale_switcher(
    label="Language",
    style="select",
    next=None,
    locale_names=None
) -%}
{% set _current = request.state.locale if request and request.state else "en" %}
{% set _supported = request.state.locale_supported if request and request.state else [] %}
{% set _next = next or (request.url.path if request else "/") %}
{% set _names = locale_names or {} %}
{# CSRF: /_dazzle/i18n/ is in the framework's exempt prefix list (csrf.py).
   Justification: idempotent cookie-setter, no privilege escalation,
   SameSite=Lax cookie blocks cross-site form posts. Same precedent
   as /dz/consent. #}
{% if _supported %}
  {% if style == "select" %}
  <form method="post" {# nosemgrep #}
        action="/_dazzle/i18n/locale"
        hx-post="/_dazzle/i18n/locale"
        hx-swap="none"
        class="dz-locale-switcher">
    <label for="dz-locale-switcher-select" class="dz-locale-switcher__label">{{ label }}</label>
    <input type="hidden" name="next" value="{{ _next }}">
    <select id="dz-locale-switcher-select"
            name="locale"
            onchange="this.form.requestSubmit ? this.form.requestSubmit() : this.form.submit()"
            class="dz-locale-switcher__select">
      {% for tag in _supported|sort %}
      <option value="{{ tag }}"{% if tag == _current %} selected{% endif %}>
        {{ _names.get(tag, tag) }}
      </option>
      {% endfor %}
    </select>
    <noscript>
      <button type="submit" class="dz-locale-switcher__submit">{{ _("Set") }}</button>
    </noscript>
  </form>
  {% elif style == "links" %}
  <div class="dz-locale-switcher dz-locale-switcher--links" role="group" aria-label="{{ label }}">
    {% for tag in _supported|sort %}
    <form method="post" {# nosemgrep #}
          action="/_dazzle/i18n/locale"
          hx-post="/_dazzle/i18n/locale"
          hx-swap="none"
          class="dz-locale-switcher__link-form">
      <input type="hidden" name="next" value="{{ _next }}">
      <input type="hidden" name="locale" value="{{ tag }}">
      <button type="submit"
              class="dz-locale-switcher__link"
              {% if tag == _current %}aria-current="true"{% endif %}>
        {{ _names.get(tag, tag) }}
      </button>
    </form>
    {% endfor %}
  </div>
  {% endif %}
{% endif %}
{%- endmacro %}