<?php
/**
 * Admin upload endpoint used by the browser-side uploader (assets/admin.js).
 *
 * One multipart POST per image (X-CSRF-Token header, fields below); the webhost
 * streams the file straight to S3 and appends it to the gallery's JSON file.
 * Keeping it to a single file per request means each PHP process only ever
 * handles one image, so a multi-gigabyte gallery upload never trips
 * post_max_size / max_execution_time — only the largest single image does.
 *
 * Fields:
 *   slug      gallery slug
 *   original  the full-resolution file (required, stored unmodified)
 *   thumb     browser-generated JPEG thumbnail (optional; absent for RAW/video)
 *
 * The browser never receives an S3 URL or any credential for writing.
 */
require dirname(__DIR__) . '/app/bootstrap.php';

if (!auth_check()) {
    json_response(['error' => 'Not authenticated'], 401);
}
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    json_response(['error' => 'POST only'], 405);
}
csrf_verify();

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

/** Human-readable reason for a PHP upload error code. */
function upload_error_message(int $code): string
{
    return match ($code) {
        UPLOAD_ERR_INI_SIZE, UPLOAD_ERR_FORM_SIZE => 'file exceeds the server upload size limit',
        UPLOAD_ERR_PARTIAL                        => 'upload was interrupted',
        UPLOAD_ERR_NO_FILE                        => 'no file received',
        UPLOAD_ERR_NO_TMP_DIR, UPLOAD_ERR_CANT_WRITE => 'server cannot store the upload',
        default                                   => 'upload error ' . $code,
    };
}

// 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'] ?? ''));
if ($gallery === null) {
    json_response(['error' => 'Unknown gallery'], 404);
}
$slug = $gallery['slug'];

$original = $_FILES['original'] ?? null;
if (!is_array($original) || ($original['error'] ?? UPLOAD_ERR_NO_FILE) !== UPLOAD_ERR_OK) {
    json_response(['error' => upload_error_message((int)($original['error'] ?? UPLOAD_ERR_NO_FILE))], 400);
}
if (!is_uploaded_file((string)$original['tmp_name'])) {
    json_response(['error' => 'Invalid upload'], 400);
}

$name  = substr(safe_filename((string)($original['name'] ?? '')), 0, 120);
$token = random_token(6);
$base  = s3_gallery_prefix($slug);
$key   = "$base/originals/$token-$name";

// Stream the original to S3 byte-for-byte from the PHP upload temp file.
$type = (string)($original['type'] ?? '') ?: 'application/octet-stream';
[$status, $resp] = s3_put_file($key, (string)$original['tmp_name'], $type);
if ($status < 200 || $status >= 300) {
    json_response(['error' => "S3 rejected the original (HTTP $status)"], 502);
}

// Optional browser-generated thumbnail. A thumb failure is non-fatal: the
// original stays, and the grid falls back to the original key.
$thumbKey = null;
$thumb = $_FILES['thumb'] ?? null;
if (is_array($thumb)
    && ($thumb['error'] ?? UPLOAD_ERR_NO_FILE) === UPLOAD_ERR_OK
    && is_uploaded_file((string)$thumb['tmp_name'])
) {
    $candidate = "$base/thumbs/$token-$name.jpg";
    [$tstatus] = s3_put_file($candidate, (string)$thumb['tmp_name'], 'image/jpeg');
    if ($tstatus >= 200 && $tstatus < 300) {
        $thumbKey = $candidate;
    } else {
        s3_delete($candidate);
    }
}

// Append under a fresh load to reduce lost updates between concurrent uploads.
$gallery = gallery_load($slug);
$gallery['images'][] = [
    'key'   => $key,
    'thumb' => $thumbKey,
    'name'  => substr((string)($original['name'] ?? basename($key)), 0, 200),
    'size'  => (int)($original['size'] ?? 0),
];
gallery_save($gallery);

json_response(['ok' => true, 'key' => $key, 'thumb' => $thumbKey, 'count' => count($gallery['images'])]);