{#
================================================================================
Track Prev/Next Navigation (Kida-Native)
================================================================================

Sequential prev/next control for a reader sitting ON a track member page
(NOT the pillar page). Finds which track owns the current page, then derives
the previous/next siblings WITHOUT `.index()` (unavailable in kida) by walking
`track.items` with a loop and recording the neighbours of the matching slug.

DOM contract: .chirp-theme-track-nav card with
  .chirp-theme-track-nav__actions  (prev/next buttons)
  .chirp-theme-track-nav__progress (progress bar)

USAGE:
  {% include 'partials/track_nav.html' %}
================================================================================
#}
{% from "chirpui/badge.html" import badge %}
{% from "chirpui/button.html" import btn %}
{% from "chirpui/card.html" import card %}
{% from "chirpui/layout.html" import cluster %}
{% from "chirpui/progress.html" import progress_bar %}

{% let _current_href = page?.href ?? '' %}
{% let all_tracks = site?.data?.tracks ?? {} %}

{% for track_id, track in all_tracks | items %}
{% let track_items = track?.items ?? [] %}

{# Walk the item list once to find the current page's position + neighbours.
   Match on resolved page identity (href), not a slug string: the Page object
   exposes no content-relative-path attribute under strict undefined, so we
   resolve each item via get_page() and compare its href to the current page.
   Avoids `.index()` (not available in kida) and capital `None`.
   Accumulate into lists (append survives loop scope). #}
{% set _positions = [] %}
{% set _prev = [] %}
{% set _next = [] %}
{% for item_slug in track_items %}
{% let _item_page = get_page(item_slug) %}
{% if _item_page and _current_href and (_item_page.href == _current_href) %}
{% set _ = _positions.append(loop.index) %}
{% if not loop.first %}{% set _ = _prev.append(track_items[loop.index0 - 1]) %}{% end %}
{% if not loop.last %}{% set _ = _next.append(track_items[loop.index0 + 1]) %}{% end %}
{% end %}
{% end %}

{% if _positions | length > 0 %}
{% let total = track_items | length %}
{% let position = _positions[0] %}
{% let prev_slug = _prev[0] if _prev | length > 0 else none %}
{% let next_slug = _next[0] if _next | length > 0 else none %}
{% let progress_value = (position / total) * 100 if total > 0 else 0 %}
{% let position_label = position ~ " of " ~ total %}

{% call card(title=track?.title ?? 'Track', subtitle=position_label, cls="chirp-theme-track-nav") %}
  {% slot header_actions %}{{ badge("Track", variant="primary") }}{% end %}
  {% call cluster(gap="sm", cls="chirp-theme-track-nav__actions") %}
    {% if prev_slug %}
    {% let prev_page = get_page(prev_slug) %}
    {% if prev_page %}
    {{ btn(prev_page.title, href=prev_page.href, variant="ghost", size="sm", icon="arrow-left") }}
    {% else %}
    <span class="chirpui-text-muted chirpui-font-sm">Previous unavailable</span>
    {% end %}
    {% else %}
    <span class="chirpui-text-muted chirpui-font-sm">Start of track</span>
    {% end %}

    {% if next_slug %}
    {% let next_page = get_page(next_slug) %}
    {% if next_page %}
    {{ btn(next_page.title, href=next_page.href, variant="primary", size="sm", icon="arrow-right") }}
    {% else %}
    <span class="chirpui-text-muted chirpui-font-sm">Next unavailable</span>
    {% end %}
    {% else %}
    {{ btn("Finish track", href=('/tracks/' | absolute_url), variant="success", size="sm", icon="check") }}
    {% end %}
  {% end %}
  {{ progress_bar(progress_value, label=position_label, variant="gold", size="sm", cls="chirp-theme-track-nav__progress") }}
{% end %}

{% end %}
{% end %}