{{--
  Server-rendered line/area chart (inline SVG, no JS).
  @include('partials.charts.line', ['data' => [['label'=>'Jan','value'=>10], …], 'height' => 180, 'format' => 'money'|'int'|'pct', 'title' => 'Enrollments'])
  Optional: 'area' => false to drop the soft fill, 'empty' => 'text'.
--}}
@php
    $rows = collect($data ?? [])->values();
    $height = (int) ($height ?? 180);
    $format = $format ?? 'int';
    $title = $title ?? 'Line chart';
    $area = $area ?? true;
    $n = max(1, $rows->count());
    $max = (float) $rows->max(fn ($r) => (float) ($r['value'] ?? 0));
    // four even intervals: pick a "nice" step so the axis reads 0 · s · 2s · 3s · 4s
    $steps = $format === 'int' ? [1, 2, 3, 4, 5, 6, 8, 10] : [1, 2, 2.5, 3, 4, 5, 6, 8, 10];
    if ($max <= 0) { $niceMax = 1; }
    elseif ($format === 'int' && $max <= 4) { $niceMax = 4; }
    else {
        $k = 10 ** floor(log10($max / 4));
        $niceMax = 4 * $k * (collect($steps)->first(fn ($st) => 4 * $st * $k >= $max - 1e-9) ?? 10);
    }
    $compact = function ($v) use ($format) {
        $v = (float) $v;
        if ($format === 'pct') { return round($v).'%'; }
        $a = abs($v);
        if ($a >= 1e6) { return rtrim(rtrim(number_format($v / 1e6, 1), '0'), '.').'M'; }
        if ($a >= 1e3) { return rtrim(rtrim(number_format($v / 1e3, 1), '0'), '.').'K'; }
        return (string) round($v, 1);
    };
    $full = fn ($v) => match ($format) { 'money' => money($v), 'pct' => round((float) $v, 1).'%', default => number_format((float) $v) };
    $pts = $rows->map(fn ($r, $i) => [round(($i + .5) / $n * 100, 3), round(100 - ((float) ($r['value'] ?? 0)) / $niceMax * 100, 3)]);
    $line = $pts->map(fn ($p, $i) => ($i ? 'L' : 'M').$p[0].' '.$p[1])->implode(' ');
    $fill = $pts->isNotEmpty() ? $line.' L'.$pts->last()[0].' 100 L'.$pts->first()[0].' 100 Z' : '';
@endphp
@if($rows->isEmpty() || $max <= 0)
    <div class="viz-empty" style="min-height:{{ $height }}px">{{ $empty ?? 'No data for this period yet.' }}</div>
@else
<figure class="viz viz-line{{ ' viz-every-'.($rows->count() > 16 ? 3 : ($rows->count() > 8 ? 2 : 1)) }}{{ $rows->count() <= 12 ? ' viz-dots' : '' }}" style="--viz-h:{{ $height }}px;--viz-n:{{ $n }}" aria-label="{{ $title }}">
    <div class="viz-y" aria-hidden="true">
        @foreach([1, .75, .5, .25, 0] as $t)<span>{{ $compact($niceMax * $t) }}</span>@endforeach
    </div>
    <div class="viz-plot">
        <div class="viz-grid" aria-hidden="true"><i></i><i></i><i></i><i></i><i></i></div>
        <svg viewBox="0 0 100 100" preserveAspectRatio="none" aria-hidden="true" focusable="false">
            @if($area)<path class="viz-area" d="{{ $fill }}"/>@endif
            <path class="viz-stroke" d="{{ $line }}" vector-effect="non-scaling-stroke"/>
        </svg>
        <div class="viz-cols">
            @foreach($rows as $i => $r)
                @php $v = (float) ($r['value'] ?? 0); @endphp
                <div class="viz-col" title="{{ ($r['label'] ?? '') }}: {{ $full($v) }}"><b class="viz-dot" style="bottom:{{ round($v / $niceMax * 100, 2) }}%"></b></div>
            @endforeach
        </div>
    </div>
    <div class="viz-x" aria-hidden="true">@foreach($rows as $r)<span>{{ $r['label'] ?? '' }}</span>@endforeach</div>
    <table class="sr-only"><caption>{{ $title }}</caption><tbody>@foreach($rows as $r)<tr><th scope="row">{{ $r['label'] ?? '' }}</th><td>{{ $full($r['value'] ?? 0) }}</td></tr>@endforeach</tbody></table>
</figure>
@endif