Sub-Store/backend/src/utils/download.js

import { FILES_KEY, MODULES_KEY, SETTINGS_KEY } from '@/constants';
import { findByName } from '@/utils/database';
import { HTTP, ENV } from '@/vendor/open-api';
import { hex_md5 } from '@/vendor/md5';
import resourceCache from '@/utils/resource-cache';
import headersResourceCache from '@/utils/headers-resource-cache';
import { getFlowField } from '@/utils/flow';
import $ from '@/core/app';

const tasks = new Map();

export default async function download(rawUrl, ua, timeout) {
    let $arguments = {};
    let url = rawUrl.replace(/#noFlow$/, '');
    const rawArgs = url.split('#');
    url = url.split('#')[0];
    if (rawArgs.length > 1) {
        try {
            // 支持 `#${encodeURIComponent(JSON.stringify({arg1: "1"}))}`
            $arguments = JSON.parse(decodeURIComponent(rawArgs[1]));
        } catch (e) {
            for (const pair of rawArgs[1].split('&')) {
                const key = pair.split('=')[0];
                const value = pair.split('=')[1];
                // 部分兼容之前的逻辑 const value = pair.split('=')[1] || true;
                $arguments[key] =
                    value == null || value === ''
                        ? true
                        : decodeURIComponent(value);
            }
        }
    }

    const downloadUrlMatch = url.match(/^\/api\/(file|module)\/(.+)/);
    if (downloadUrlMatch) {
        let type = downloadUrlMatch?.[1];
        let name = downloadUrlMatch?.[2];
        if (name == null) {
            throw new Error(`本地 ${type} URL 无效: ${url}`);
        }
        name = decodeURIComponent(name);
        const key = type === 'module' ? MODULES_KEY : FILES_KEY;
        const item = findByName($.read(key), name);
        if (!item) {
            throw new Error(`找不到本地 ${type}: ${name}`);
        }

        return item.content;
    }

    const { isNode } = ENV();
    const { defaultUserAgent, defaultTimeout } = $.read(SETTINGS_KEY);
    const userAgent = ua || defaultUserAgent || 'clash.meta';
    const requestTimeout = timeout || defaultTimeout;
    const id = hex_md5(userAgent + url);
    if (!isNode && tasks.has(id)) {
        return tasks.get(id);
    }

    const http = HTTP({
        headers: {
            'User-Agent': userAgent,
        },
        timeout: requestTimeout,
    });

    const result = new Promise((resolve, reject) => {
        // try to find in app cache
        const cached = resourceCache.get(id);
        if (!$arguments?.noCache && cached) {
            resolve(cached);
        } else {
            $.info(
                `Downloading...\nUser-Agent: ${userAgent}\nTimeout: ${requestTimeout}\nURL: ${url}`,
            );
            http.get(url)
                .then((resp) => {
                    const { body, headers } = resp;
                    if (headers) {
                        const flowInfo = getFlowField(headers);
                        if (flowInfo) {
                            headersResourceCache.set(url, flowInfo);
                        }
                    }
                    if (body.replace(/\s/g, '').length === 0)
                        reject(new Error('远程资源内容为空！'));
                    else {
                        resourceCache.set(id, body);
                        resolve(body);
                    }
                })
                .catch(() => {
                    reject(new Error(`无法下载 URL：${url}`));
                });
        }
    });

    if (!isNode) {
        tasks.set(id, result);
    }
    return result;
}