import { type LoaderFunctionArgs } from '@remix-run/node';
import { API_BASE_URL } from '~/config/api-config';

/**
 * GET /api/dataset/dify-files/*
 * 代理 Dify 文件下载请求
 *
 * 用于下载 Dify 知识库中的原始文件
 * 将 /api/dataset/dify-files/xxx 转发到 Dify 的 /files/xxx
 */
export async function loader({ request, params }: LoaderFunctionArgs) {
    try {
        const { getUserSession } = await import("~/api/login/auth.server");
        const { frontendJWT } = await getUserSession(request);

        if (!frontendJWT) {
            return new Response(
                JSON.stringify({ error: 'JWT认证失败，请重新登录' }),
                { status: 401, headers: { 'Content-Type': 'application/json' } }
            );
        }

        // 获取完整路径（包含查询参数）
        const url = new URL(request.url);
        const filePath = params['*'] || '';
        const queryString = url.search;

        console.log('[API] Dify File Proxy:', { filePath, queryString });

        // 构建 Dify 文件下载 URL
        // 使用专门的文件下载代理路由 /dify_file/
        // 因为 Dify 文件 API (/files/) 不需要 /v1 前缀，与其他 API 不同
        const difyFileUrl = `${API_BASE_URL}/dify_file/${filePath}${queryString}`;

        console.log('[API] Proxying to:', difyFileUrl);

        // 转发请求到 Dify
        const response = await fetch(difyFileUrl, {
            method: 'GET',
            headers: {
                'Authorization': `Bearer ${frontendJWT}`,
            },
        });

        if (!response.ok) {
            console.error('[API] Dify File Proxy - Error:', response.status, response.statusText);
            return new Response(
                JSON.stringify({ error: `文件下载失败: ${response.statusText}` }),
                { status: response.status, headers: { 'Content-Type': 'application/json' } }
            );
        }

        // 获取文件内容
        const fileBuffer = await response.arrayBuffer();

        // 返回文件，保持原始的 Content-Type
        const contentType = response.headers.get('Content-Type') || 'application/octet-stream';
        const contentDisposition = response.headers.get('Content-Disposition');

        const headers: Record<string, string> = {
            'Content-Type': contentType,
        };

        if (contentDisposition) {
            headers['Content-Disposition'] = contentDisposition;
        }

        return new Response(fileBuffer, {
            status: 200,
            headers,
        });

    } catch (error: any) {
        console.error('[API] Dify File Proxy - Error:', error.message);
        return new Response(
            JSON.stringify({ error: error.message || 'Failed to download file' }),
            { status: 500, headers: { 'Content-Type': 'application/json' } }
        );
    }
}