NapCatQQ/src/onebot/action/stream/BaseDownloadStream.ts

import { OneBotAction, OneBotRequestToolkit } from '@/onebot/action/OneBotAction';
import { StreamPacket, StreamStatus } from './StreamBasic';
import fs from 'fs';
import { FileNapCatOneBotUUID } from '@/common/file-uuid';

export interface ResolvedFileInfo {
    downloadPath: string;
    fileName: string;
    fileSize: number;
}

export interface DownloadResult {
    // 文件信息
    file_name?: string;
    file_size?: number;
    chunk_size?: number;

    // 分片数据
    index?: number;
    data?: string;
    size?: number;
    progress?: number;
    base64_size?: number;

    // 完成信息
    total_chunks?: number;
    total_bytes?: number;
    message?: string;
    data_type?: 'file_info' | 'file_chunk' | 'file_complete';

    // 可选扩展字段
    width?: number;
    height?: number;
    out_format?: string;
}

export abstract class BaseDownloadStream<PayloadType, ResultType> extends OneBotAction<PayloadType, StreamPacket<ResultType>> {
    protected async resolveDownload(file?: string): Promise<ResolvedFileInfo> {
        const target = file || '';
        let downloadPath = '';
        let fileName = '';
        let fileSize = 0;

        const contextMsgFile = FileNapCatOneBotUUID.decode(target);
        if (contextMsgFile && contextMsgFile.msgId && contextMsgFile.elementId) {
            const { peer, msgId, elementId } = contextMsgFile;
            downloadPath = await this.core.apis.FileApi.downloadMedia(msgId, peer.chatType, peer.peerUid, elementId, '', '');
            const rawMessage = (await this.core.apis.MsgApi.getMsgsByMsgId(peer, [msgId]))?.msgList
                .find(msg => msg.msgId === msgId);
            const mixElement = rawMessage?.elements.find(e => e.elementId === elementId);
            const mixElementInner = mixElement?.videoElement ?? mixElement?.fileElement ?? mixElement?.pttElement ?? mixElement?.picElement;
            if (!mixElementInner) throw new Error('element not found');
            fileSize = parseInt(mixElementInner.fileSize?.toString() ?? '0');
            fileName = mixElementInner.fileName ?? '';
            return { downloadPath, fileName, fileSize };
        }

        const contextModelIdFile = FileNapCatOneBotUUID.decodeModelId(target);
        if (contextModelIdFile && contextModelIdFile.modelId) {
            const { peer, modelId } = contextModelIdFile;
            downloadPath = await this.core.apis.FileApi.downloadFileForModelId(peer, modelId, '');
            return { downloadPath, fileName, fileSize };
        }

        const searchResult = (await this.core.apis.FileApi.searchForFile([target]));
        if (searchResult) {
            downloadPath = await this.core.apis.FileApi.downloadFileById(searchResult.id, parseInt(searchResult.fileSize));
            fileSize = parseInt(searchResult.fileSize);
            fileName = searchResult.fileName;
            return { downloadPath, fileName, fileSize };
        }

        throw new Error('file not found');
    }

    protected async streamFileChunks(req: OneBotRequestToolkit, streamPath: string, chunkSize: number, chunkDataType: string): Promise<{ totalChunks: number; totalBytes: number }>
    {
        const stats = await fs.promises.stat(streamPath);
        const totalSize = stats.size;
        const readStream = fs.createReadStream(streamPath, { highWaterMark: chunkSize });
        let chunkIndex = 0;
        let bytesRead = 0;
        for await (const chunk of readStream) {
            const base64Chunk = (chunk as Buffer).toString('base64');
            bytesRead += (chunk as Buffer).length;
            await req.send({
                type: StreamStatus.Stream,
                data_type: chunkDataType,
                index: chunkIndex,
                data: base64Chunk,
                size: (chunk as Buffer).length,
                progress: Math.round((bytesRead / totalSize) * 100),
                base64_size: base64Chunk.length
            } as unknown as StreamPacket<any>);
            chunkIndex++;
        }
        return { totalChunks: chunkIndex, totalBytes: bytesRead };
    }
}