<?php
/**
 * api/_bootstrap.php
 * ------------------
 * Shared setup for every endpoint under /api: loads config, applies error
 * settings, and provides small HTTP / JSON helpers.
 */

require_once __DIR__ . '/../config.php';

if (cfg('runtime.show_errors')) {
    ini_set('display_errors', '1');
    ini_set('display_startup_errors', '1');
    error_reporting(E_ALL);
} else {
    error_reporting(0);
}

/** Send a JSON response and stop. */
function json_out($data, $status = 200) {
    http_response_code($status);
    header('Content-Type: application/json; charset=utf-8');
    header('Access-Control-Allow-Origin: *');
    header('Cache-Control: no-cache, must-revalidate, max-age=0');
    echo json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
    exit;
}

/** Plain-text response and stop (used by the lyrics endpoint). */
function text_out($text, $status = 200) {
    http_response_code($status);
    header('Content-Type: text/plain; charset=utf-8');
    header('Access-Control-Allow-Origin: *');
    header('Cache-Control: no-cache, must-revalidate, max-age=0');
    echo $text;
    exit;
}

/**
 * Perform an HTTP GET and return the body (or null on failure).
 * Falls back to file_get_contents when cURL is unavailable.
 */
function http_get($url, $timeout = 5, $headers = []) {
    if ($url === '') return null;

    if (function_exists('curl_init')) {
        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_CONNECTTIMEOUT => (int) $timeout,
            CURLOPT_TIMEOUT        => (int) $timeout,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_MAXREDIRS      => 3,
            CURLOPT_USERAGENT      => cfg('runtime.user_agent'),
        ]);
        if (!empty($headers)) {
            curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        }
        $body = curl_exec($ch);
        $code = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
        curl_close($ch);
        if ($body === false || $code >= 400) return null;
        return $body;
    }

    // Fallback without cURL.
    $ctx = stream_context_create([
        'http' => [
            'timeout' => (int) $timeout,
            'header'  => implode("\r\n", array_merge(['User-Agent: ' . cfg('runtime.user_agent')], $headers)),
            'ignore_errors' => true,
        ],
        'ssl' => ['verify_peer' => true, 'verify_peer_name' => true],
    ]);
    $body = @file_get_contents($url, false, $ctx);
    return ($body === false) ? null : $body;
}

/**
 * Read a value out of a decoded-JSON structure using dot notation.
 * Supports array indexes: "a.b.0.c".
 */
function dot_get($data, $path, $default = null) {
    if ($path === '' || $path === null) return $default;
    $node = $data;
    foreach (explode('.', $path) as $key) {
        if (is_array($node) && array_key_exists($key, $node)) {
            $node = $node[$key];
        } elseif (is_object($node) && isset($node->$key)) {
            $node = $node->$key;
        } else {
            return $default;
        }
    }
    return $node;
}

/** Read the artist/title the browser sends to artwork/lyrics endpoints. */
function request_track() {
    $artist = $_POST['artist'] ?? $_GET['artist'] ?? '';
    $title  = $_POST['title']  ?? $_GET['title']  ?? '';
    return [trim((string) $artist), trim((string) $title)];
}

/**
 * Strip a featuring-artist credit ("(feat. X)", "(ft. X)", "(featuring X)",
 * "(with X)", bracket variants, or an unparenthesized trailing "feat. X")
 * before it goes into a Genius/dumb search query.
 *
 * Genius's canonical song title never includes the featuring credit (it's
 * separate metadata), but translation/cover pages often spell it out
 * verbatim in their title — e.g. searching "Havana (feat. Young Thug)"
 * surfaces only German/French translation pages (titled "... ft. Young
 * Thug ... (Deutsche Übersetzung)" etc.), while "Havana" alone correctly
 * finds the original as the first hit. Leaves other qualifiers like
 * "(Remix)"/"(Live)" alone — those genuinely change which page you want.
 */
function strip_feature_credit($title) {
    $title = preg_replace('/[\(\[]\s*(?:feat\.?|ft\.?|featuring|with)\b[^\)\]]*[\)\]]/i', '', $title);
    $title = preg_replace('/\s+(?:feat\.?|ft\.?|featuring)\b.+$/i', '', $title);
    return trim(preg_replace('/\s{2,}/', ' ', $title));
}

/**
 * Loose "is this search hit actually by the artist we want" check —
 * case-insensitive, ignores punctuation/spacing and anything in brackets
 * (so "Camila Cabello (Ft. Young Thug)" still matches "Camila Cabello").
 * An empty side always matches (nothing to compare against). Used to skip
 * past hits attributed to someone else entirely — most notably Genius's
 * "Genius Deutsche Übersetzungen" / "Genius traductions françaises" / etc.
 * pseudo-artist accounts that translation pages get filed under.
 */
function artist_loosely_matches($hitArtist, $wantArtist) {
    $norm = function ($s) {
        $s = preg_replace('/[\(\[][^\)\]]*[\)\]]/', '', (string) $s);
        $s = preg_replace('/[^\p{L}\p{N}]+/u', '', $s);
        return strtolower($s);
    };
    $a = $norm($hitArtist);
    $b = $norm($wantArtist);
    if ($a === '' || $b === '') return true;
    return strpos($a, $b) !== false || strpos($b, $a) !== false;
}

/**
 * Return the inner HTML of a balanced <div> whose opening tag starts at $lt.
 * Correctly handles nested <div> elements. Shared by the Genius and dumb
 * lyrics scrapers (both extract a lyrics container out of a raw HTML page).
 */
function inner_balanced_div($html, $lt) {
    $open = strpos($html, '>', $lt);
    if ($open === false) return '';
    $i = $open + 1;
    $start = $i;
    $len = strlen($html);
    $depth = 1;
    while ($i < $len && $depth > 0) {
        $next = strpos($html, '<', $i);
        if ($next === false) break;
        if (strncasecmp(substr($html, $next, 5), '</div', 5) === 0) {
            $depth--;
            if ($depth === 0) return substr($html, $start, $next - $start);
            $i = $next + 5;
        } elseif (strncasecmp(substr($html, $next, 4), '<div', 4) === 0) {
            $depth++;
            $i = $next + 4;
        } else {
            $i = $next + 1;
        }
    }
    return substr($html, $start, max(0, $i - $start));
}

/** Turn one container's HTML into plain text with newlines. */
function container_to_text($fragment) {
    // Line breaks -> newlines before stripping tags.
    $fragment = preg_replace('#<br\s*/?>#i', "\n", $fragment);
    // Drop any stray script/style.
    $fragment = preg_replace('#<(script|style)\b[^>]*>.*?</\1>#is', '', $fragment);
    // Block-level tags imply a line break.
    $fragment = preg_replace('#</(p|div)>#i', "\n", $fragment);
    $text = strip_tags($fragment);
    $text = html_entity_decode($text, ENT_QUOTES | ENT_HTML5, 'UTF-8');
    return $text;
}

/**
 * dumb (https://github.com/rramiachraf/dumb): a self-hosted/public Genius
 * frontend that server-renders search + song pages. When USE_DUMB is on,
 * these replace the official Genius API as the lyrics/artwork source (no
 * GENIUS_TOKEN needed) — same idea as the Genius HTML scrape elsewhere in
 * this codebase, just against dumb's own pages instead of genius.com.
 * Fragile by nature (scrapes another project's HTML): if dumb changes its
 * templates, these regexes may need updating.
 */

/**
 * Search dumb for a track; returns a song result's page path (e.g.
 * "/Artist-title-lyrics"), or '' if none. Scans the first 5 song hits for
 * one actually attributed to $artist (see artist_loosely_matches) and
 * returns that; falls back to the top hit if none match rather than
 * returning nothing, so an unusual artist-name spelling can't regress
 * availability entirely.
 */
function dumb_search($artist, $title, $timeout) {
    $base = cfg('dumb.url');
    if ($base === '') return '';
    $query = rawurlencode(trim($artist . ' - ' . strip_feature_credit($title), ' -'));
    $html = http_get($base . '/search?q=' . $query, $timeout);
    if ($html === null) return '';

    if (!preg_match('/<h2>\s*Songs\s*<\/h2>(.*?)(?=<h2>|$)/is', $html, $section)) return '';
    if (!preg_match_all('/<a[^>]+id="search-item"[^>]+href="([^"]+)"[^>]*>.*?<span>([^<]*)<\/span>/is', $section[1], $hits, PREG_SET_ORDER)) {
        return '';
    }

    $fallback = '';
    $checked = 0;
    foreach ($hits as $h) {
        $href = html_entity_decode($h[1], ENT_QUOTES | ENT_HTML5, 'UTF-8');
        if ($fallback === '') $fallback = $href;
        if ($checked++ >= 5) break;
        $hitArtist = html_entity_decode($h[2], ENT_QUOTES | ENT_HTML5, 'UTF-8');
        if (artist_loosely_matches($hitArtist, $artist)) return $href;
    }
    return $fallback;
}

/**
 * Extract Genius annotation ("referent") links out of a raw lyrics HTML
 * fragment. Returns an ordered list of ['text' => plain annotated lyric
 * text, 'path' => dumb path to fetch the annotation JSON from]. Matched
 * structurally — href = "/{id}/{song-slug}/{verse-slug}" — rather than by
 * CSS class, since Genius's class names are build-hashed (styled-components)
 * and change on their end without notice.
 */
function dumb_extract_annotations($fragment) {
    $out = [];
    if (!preg_match_all('#<a\s+href="(/\d+/[^"/]+/[^"/]+)"[^>]*>(.*?)</a>#is', $fragment, $matches, PREG_SET_ORDER)) {
        return $out;
    }
    foreach ($matches as $m) {
        $text = trim(container_to_text($m[2]));
        if ($text === '') continue;
        $out[] = ['text' => $text, 'path' => $m[1] . '/annotations'];
    }
    return $out;
}

/**
 * Fetch + parse a dumb song page ($path from dumb_search()). Returns
 * ['lyrics' => plain text, 'annotations' => [{text, path}, …] (see
 * dumb_extract_annotations), 'album' => name, 'art' => absolute album art
 * url, 'song_art' => absolute song thumbnail url] (any field may be ''/[]),
 * or null if the page couldn't be fetched.
 */
function dumb_song($path, $timeout) {
    $base = cfg('dumb.url');
    if ($base === '' || $path === '') return null;
    $html = http_get($base . $path, $timeout);
    if ($html === null) return null;

    $out = ['lyrics' => '', 'annotations' => [], 'album' => '', 'art' => '', 'song_art' => ''];

    // <div id="lyrics"> wraps the raw Genius lyrics HTML that dumb already
    // extracted server-side (no data-lyrics-container markers left in it).
    $idPos = strpos($html, 'id="lyrics"');
    if ($idPos !== false) {
        $lt = strrpos(substr($html, 0, $idPos), '<div');
        if ($lt !== false) {
            $fragment = inner_balanced_div($html, $lt);
            $out['annotations'] = dumb_extract_annotations($fragment);
            $out['lyrics'] = trim(container_to_text($fragment));
        }
    }

    // Two <img id="album-artwork"> tags can appear: the song thumbnail
    // (#metadata, always present) and the album cover (#lyrics-album-
    // container, only when the song belongs to an album — marked with a
    // title="Album: …" attribute so the two are distinguishable).
    if (preg_match_all('/<img\b[^>]*>/i', $html, $imgs)) {
        foreach ($imgs[0] as $img) {
            if (strpos($img, 'id="album-artwork"') === false) continue;
            if (!preg_match('/\bsrc="([^"]+)"/i', $img, $src)) continue;
            $url = $base . html_entity_decode($src[1], ENT_QUOTES | ENT_HTML5, 'UTF-8');
            if (preg_match('/\btitle="Album:\s*([^"]*)"/i', $img, $t)) {
                $out['album'] = html_entity_decode($t[1], ENT_QUOTES | ENT_HTML5, 'UTF-8');
                $out['art'] = $url;
            } elseif ($out['song_art'] === '') {
                $out['song_art'] = $url;
            }
        }
    }

    return $out;
}