<?php
/**
 * Public guest upload endpoint used by the browser-side uploader (assets/admin.js)
 * on upload.php. Same one-multipart-POST-per-image contract as admin/api.php, but
 * authenticated by the per-gallery upload key instead of an admin session.
 *
 * Fields: slug, key, original (required), thumb (optional). Access requires the
 * gallery to have guest uploads enabled, the key to match, the gallery to be
 * unexpired, and — if the gallery has a password — the visitor to have unlocked
 * it in this session (via upload.php). Any failure returns a uniform 403.
 *
 * Uploads are image-only here, so a public link cannot store arbitrary files.
 */
require __DIR__ . '/app/bootstrap.php';

session_boot();

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    json_response(['error' => 'POST only'], 405);
}
csrf_verify();

// Take the session-held facts now, then release the session file before the slow
// S3 leg. PHP locks it exclusively for the whole request, so without this every
// parallel upload from the browser would queue behind the previous one and the
// uploader would be serial again no matter how many requests it starts.
$unlockedGalleries = (array)($_SESSION['gallery_unlocked'] ?? []);
session_write_close();

// One image per request; a single file may still be large, so lift the time cap.
@set_time_limit(0);

// When a request body exceeds post_max_size, PHP discards $_POST and $_FILES
// entirely — surface that as a clear 413 instead of a misleading "no file".
if ((int)($_SERVER['CONTENT_LENGTH'] ?? 0) > 0 && !$_POST && !$_FILES) {
    json_response(['error' => 'Upload exceeds the server post_max_size limit'], 413);
}

$gallery = gallery_load((string)($_POST['slug'] ?? ''));

// Uniform 403 for every access failure (no key, wrong key, expired, locked) so
// the endpoint reveals nothing a guest shouldn't already know from the link.
$authorized = $gallery !== null
    && !empty($gallery['upload_key'])
    && hash_equals((string)$gallery['upload_key'], (string)($_POST['key'] ?? ''))
    && !gallery_is_expired($gallery)
    && (empty($gallery['password_hash']) || !empty($unlockedGalleries[$gallery['slug']]));

if (!$authorized) {
    json_response(['error' => 'Not authorized'], 403);
}

// Image-only: a public link must not be usable to store arbitrary file types.
[$status, $payload] = gallery_store_s3_upload(
    $gallery,
    $_FILES['original'] ?? null,
    $_FILES['thumb'] ?? null,
    true
);
json_response($payload, $status);