<?php
declare(strict_types=1);
header('Content-Type: application/json; charset=utf-8');
header('Cache-Control: no-store');

$source = 'https://spireason.neocities.org/';

// Human-curated suppressions: links intentionally excluded from LandScaper even if they remain in source.
// Keep exact normalized URLs here when a source link is deliberately removed from the clone.
$deliberatelyRemoved = [
    // Example format: 'https://spireason.neocities.org/removed-example.html',
];

$context = stream_context_create([
    'http' => [
        'timeout' => 12,
        'header' => "User-Agent: Laegna-LandScaper-VisibleLinkScanner/1.1\r\n",
    ],
]);
$html = @file_get_contents($source, false, $context);
if ($html === false || $html === '') {
    http_response_code(502);
    echo json_encode(['success' => false, 'error' => 'Could not fetch source page.']);
    exit;
}

$links = [];
$seen = [];
$ignoredCount = 0;
$suppressedCount = 0;

if (preg_match_all('~<a\b([^>]*)>(.*?)</a>~is', $html, $matches, PREG_SET_ORDER)) {
    foreach ($matches as $match) {
        $attrs = $match[1] ?? '';
        $inner = $match[2] ?? '';

        if (is_hidden_anchor($attrs)) {
            $ignoredCount++;
            continue;
        }
        if (!preg_match('~\bhref\s*=\s*(["\'])(.*?)\1~is', $attrs, $hrefMatch)) {
            $ignoredCount++;
            continue;
        }

        $href = html_entity_decode(trim($hrefMatch[2]), ENT_QUOTES | ENT_HTML5, 'UTF-8');
        $label = visible_label($attrs, $inner);
        if ($label === '') {
            $ignoredCount++;
            continue;
        }

        $absolute = absolutize_url($href, $source);
        $normalized = normalize_for_compare($absolute);
        $skipReason = skip_reason($href, $absolute, $normalized, $deliberatelyRemoved);
        if ($skipReason === 'suppressed') {
            $suppressedCount++;
            continue;
        }
        if ($skipReason !== '') {
            $ignoredCount++;
            continue;
        }

        if (isset($seen[$normalized])) {
            continue;
        }
        $seen[$normalized] = true;

        $category = categorize_link($absolute, $label);
        $host = strtolower((string)(parse_url($absolute, PHP_URL_HOST) ?: ''));
        $links[] = [
            'text' => unicode_limit($label, 160),
            'href' => $absolute,
            'host' => $host,
            'category' => $category,
            'category_label' => category_label($category),
            'safety' => safety_class($host),
        ];
    }
}

echo json_encode([
    'success' => true,
    'source' => $source,
    'count' => count($links),
    'ignored_count' => $ignoredCount,
    'suppressed_count' => $suppressedCount,
    'scanned_at' => gmdate('Y-m-d H:i:s') . ' UTC',
    'filters' => [
        'visible_anchor_text_required' => true,
        'skips_schemes' => ['javascript', 'mailto', 'tel', 'data', 'blob'],
        'skips_asset_extensions' => ['js', 'mjs', 'css', 'map', 'png', 'jpg', 'jpeg', 'gif', 'svg', 'webp', 'ico', 'woff', 'woff2', 'ttf', 'eot'],
        'unknown_external_hosts' => 'included but marked review',
    ],
    'links' => $links,
], JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);

function is_hidden_anchor(string $attrs): bool
{
    if (preg_match('~(?:^|\s)hidden(?:\s|=|$)~i', $attrs)) {
        return true;
    }
    if (preg_match('~\baria-hidden\s*=\s*(["\'])true\1~i', $attrs)) {
        return true;
    }
    if (preg_match('~\bstyle\s*=\s*(["\'])(.*?)\1~is', $attrs, $m)) {
        $style = strtolower($m[2]);
        return str_contains($style, 'display:none')
            || str_contains($style, 'display: none')
            || str_contains($style, 'visibility:hidden')
            || str_contains($style, 'visibility: hidden')
            || str_contains($style, 'opacity:0')
            || str_contains($style, 'opacity: 0');
    }
    return false;
}

function visible_label(string $attrs, string $inner): string
{
    $cleanInner = preg_replace('~<(script|style)\b[^>]*>.*?</\1>~is', ' ', $inner) ?? $inner;
    $text = html_entity_decode(strip_tags($cleanInner), ENT_QUOTES | ENT_HTML5, 'UTF-8');
    $text = trim(preg_replace('/\s+/u', ' ', $text) ?? '');
    if ($text !== '') {
        return $text;
    }

    foreach ([$attrs, $inner] as $source) {
        if (preg_match_all('~\b(?:aria-label|title|alt)\s*=\s*(["\'])(.*?)\1~is', $source, $matches, PREG_SET_ORDER)) {
            foreach ($matches as $match) {
                $candidate = trim(preg_replace('/\s+/u', ' ', html_entity_decode($match[2], ENT_QUOTES | ENT_HTML5, 'UTF-8')) ?? '');
                if ($candidate !== '') {
                    return $candidate;
                }
            }
        }
    }
    return '';
}

function skip_reason(string $href, string $absolute, string $normalized, array $deliberatelyRemoved): string
{
    $hrefLower = strtolower(trim($href));
    if ($hrefLower === '' || $hrefLower[0] === '#') {
        return 'fragment';
    }
    foreach (['javascript:', 'mailto:', 'tel:', 'data:', 'blob:'] as $scheme) {
        if (str_starts_with($hrefLower, $scheme)) {
            return 'scheme';
        }
    }
    if (!preg_match('~^https?://~i', $absolute)) {
        return 'scheme';
    }

    $path = (string)(parse_url($absolute, PHP_URL_PATH) ?: '');
    if (preg_match('~\.(?:js|mjs|css|map|png|jpe?g|gif|svg|webp|ico|woff2?|ttf|eot)(?:$|[?#])~i', $path)) {
        return 'asset';
    }

    foreach ($deliberatelyRemoved as $removed) {
        if ($normalized === normalize_for_compare((string)$removed)) {
            return 'suppressed';
        }
    }
    return '';
}

function categorize_link(string $url, string $label): string
{
    $host = strtolower((string)(parse_url($url, PHP_URL_HOST) ?: ''));
    $path = strtolower((string)(parse_url($url, PHP_URL_PATH) ?: ''));
    $haystack = strtolower($url . ' ' . $label);
    if (str_ends_with($path, '.pdf')) return 'pdf';
    if (str_ends_with($path, '.zip')) return 'archive';
    if (str_ends_with($path, ".json") || str_contains($path, "numberdatabase")) return "dataset";
    if (str_ends_with($path, ".py") || str_contains($haystack, "script")) return "source";
    if (str_contains($haystack, 'frequency') || str_contains($haystack, 'frequential') || str_contains($haystack, 'octave') || str_contains($haystack, 'calculator') || str_contains($haystack, 'counter')) return 'tool';
    if (str_contains($haystack, 'bot') || str_contains($host, 'perplexity.ai')) return 'bot';
    if (str_contains($host, 'github')) return 'github';
    if (str_contains($path, 'apples') || str_contains($haystack, 'app')) return 'applet';
    if (str_contains($host, 'prezi')) return 'presentation';
    if (str_contains($host, 'youtube') || str_contains($host, 'notion')) return 'media';
    if ($host !== 'spireason.neocities.org') return 'external';
    return 'onsite';
}

function category_label(string $category): string
{
    return [
        'pdf' => 'PDF text',
        'archive' => 'Archive',
        "dataset" => "Dataset",
        "source" => "Source file",
        'tool' => 'Tool',
        'bot' => 'External bot/system',
        'github' => 'Repository',
        'applet' => 'Applet',
        'presentation' => 'Presentation',
        'media' => 'Media',
        'external' => 'External system',
        'onsite' => 'On-site branch',
    ][$category] ?? ucfirst(str_replace('-', ' ', $category));
}

function safety_class(string $host): string
{
    if ($host === 'spireason.neocities.org') {
        return 'source';
    }
    $knownHosts = [
        'laegna.notaku.site',
        'prezi.com',
        'www.perplexity.ai',
        'huggingface.co',
        'assorted-canopy-961.notion.site',
        'www.youtube.com',
        'youtube.com',
        'github.com',
        'tambetvali.github.io',
    ];
    foreach ($knownHosts as $knownHost) {
        if ($host === $knownHost || str_ends_with($host, '.' . $knownHost)) {
            return 'known-external';
        }
    }
    return 'review';
}

function unicode_limit(string $text, int $limit): string
{
    if (preg_match_all('/./us', $text, $chars) && count($chars[0]) > $limit) {
        return implode('', array_slice($chars[0], 0, $limit - 1)) . '…';
    }
    return $text;
}

function normalize_for_compare(string $url): string
{
    $url = trim($url);
    $url = preg_replace('/#$/', '', $url) ?? $url;
    return $url;
}

function absolutize_url(string $href, string $base): string
{
    $href = trim($href);
    if (preg_match('~^https?://~i', $href)) {
        return encode_spaces($href);
    }
    $parts = parse_url($base);
    $scheme = $parts['scheme'] ?? 'https';
    $host = $parts['host'] ?? 'spireason.neocities.org';
    if (str_starts_with($href, '//')) {
        return encode_spaces($scheme . ':' . $href);
    }
    if (str_starts_with($href, '/')) {
        return encode_spaces($scheme . '://' . $host . $href);
    }
    $path = $parts['path'] ?? '/';
    $dir = preg_replace('~/[^/]*$~', '/', $path) ?: '/';
    return encode_spaces($scheme . '://' . $host . $dir . $href);
}

function encode_spaces(string $url): string
{
    return str_replace(' ', '%20', $url);
}