<?php
// 保存图片到本地，不做清理；保存目录按照远程URL的路径结构组织
header('Content-Type: application/json; charset=utf-8');

function respond($ok, $message = '', $path = '') {
    echo json_encode(['success' => $ok, 'message' => $message, 'path' => $path], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

// 读取JSON输入
$raw = file_get_contents('php://input');
$data = json_decode($raw, true);
$url = $data['url'] ?? '';
if (!$url || !filter_var($url, FILTER_VALIDATE_URL)) {
    respond(false, 'URL无效');
}

// 只允许 http/https
$scheme = parse_url($url, PHP_URL_SCHEME);
if (!in_array(strtolower($scheme), ['http','https'])) {
    respond(false, '仅支持http/https图片地址');
}

$root = __DIR__ . '/../pictures';
if (!is_dir($root)) { @mkdir($root, 0777, true); }

// 解析远程路径：按照域名后的路径作为保存文件夹结构
$path = parse_url($url, PHP_URL_PATH) ?: '';
if (!$path) { respond(false, '无法解析远程路径'); }

// 将路径拆分并进行安全过滤，避免非法字符与上级目录
$segments = array_values(array_filter(explode('/', $path), function($s){ return $s !== ''; }));
if (!count($segments)) { respond(false, '路径为空'); }

$filename = array_pop($segments);
$safeSegs = array_map(function($seg){
    $seg = preg_replace('/[^A-Za-z0-9._-]+/u', '_', $seg);
    return trim($seg, '._-') ?: 'unk';
}, $segments);
$safeName = preg_replace('/[^A-Za-z0-9._-]+/u', '_', $filename);
if (!$safeName) { $safeName = 'image_' . time() . '.jpg'; }

$targetDir = $root;
foreach ($safeSegs as $seg) { $targetDir .= DIRECTORY_SEPARATOR . $seg; if (!is_dir($targetDir)) { @mkdir($targetDir, 0777, true); } }
$targetPath = $targetDir . DIRECTORY_SEPARATOR . $safeName;

// 如果文件已存在则跳过下载
if (file_exists($targetPath)) {
    respond(true, '文件已存在，跳过下载', str_replace($_SERVER['DOCUMENT_ROOT'], '', $targetPath));
}

// 下载保存
try {
    $read = @fopen($url, 'rb');
    if (!$read) { respond(false, '无法读取远程图片'); }
    $write = @fopen($targetPath, 'wb');
    if (!$write) { respond(false, '无法写入文件'); }
    stream_copy_to_stream($read, $write);
    fclose($read);
    fclose($write);
} catch (Throwable $e) {
    respond(false, '保存失败: ' . $e->getMessage());
}

respond(true, '保存成功', str_replace($_SERVER['DOCUMENT_ROOT'], '', $targetPath));