export class Upload {
    private controllers: Map<string, AbortController> = new Map();

    constructor() {
        this.uploadFile = this.uploadFile.bind(this);
        this.abortUpload = this.abortUpload.bind(this);
        this.abortAllUploads = this.abortAllUploads.bind(this);
        this.getUploadStatus = this.getUploadStatus.bind(this);
        this.getActiveUploads = this.getActiveUploads.bind(this);
    }

    async uploadFile(
        file: File | string,
        name: string,
        uploadUrl: string,
        formData: Record<string, any>,
        autoInform?: boolean,
        getPercent?: Function,
        uploadId?: string, // 新增：上传任务ID，用于中断特定上传
        method: "POST" | "PUT" | "PATCH" = "POST",
    ): Promise<any> {
        const isPut = method === "PUT";
        const id = uploadId || this.generateUploadId(file, uploadUrl);

        // 如果已有相同ID的上传在进行，先中断它
        if (this.controllers.has(id)) {
            this.abortUpload(id);
        }

        // 创建新的 AbortController
        const controller = new AbortController();
        this.controllers.set(id, controller);

        // 进度监听模式
        if (getPercent) {
            return new Promise((resolve, reject) => {
                const xhr = new XMLHttpRequest();
                let percent = 0;

                // 监听中止信号
                controller.signal.addEventListener('abort', () => {
                    xhr.abort();
                    reject(new DOMException('Upload aborted', 'AbortError'));
                });

                xhr.upload.addEventListener("progress", (event) => {
                    if (event.lengthComputable) {
                        percent = Math.round((event.loaded / event.total) * 100);
                        getPercent(percent);
                    }
                });

                xhr.onload = () => {
                    this.controllers.delete(id); // 清理控制器
                    if (xhr.status >= 200 && xhr.status < 300) {
                        if (xhr.status === 204) {
                            resolve({ status: 204 });
                        } else {
                            try {
                                const data = JSON.parse(xhr.responseText);
                                resolve(data);
                            } catch {
                                resolve({ status: xhr.status, raw: xhr.responseText });
                            }
                        }
                    } else {
                        reject(new Error(`HTTP Error: ${xhr.status}`));
                    }
                };

                xhr.onerror = () => {
                    this.controllers.delete(id);
                    // 如果不是因为中止导致的错误
                    if (!controller.signal.aborted) {
                        reject(new Error("Network Error"));
                    }
                };

                xhr.onabort = () => {
                    this.controllers.delete(id);
                    if (controller.signal.aborted) {
                        reject(new DOMException('Upload aborted', 'AbortError'));
                    }
                };

                xhr.open(method, uploadUrl);

                if (isPut) {
                    // PUT 模式：直接上传文件
                    if (file instanceof File) {
                        xhr.setRequestHeader("Content-Type", file.type || "application/octet-stream");
                    }
                    xhr.send(file as any);
                } else {
                    // POST / PATCH 模式：构建表单
                    const formData2 = new FormData();
                    Object.entries(formData).forEach(([key, value]) => {
                        formData2.append(key, value);
                    });
                    formData2.append(name || "file", file as File);
                    xhr.send(formData2);
                }
            });
        }

        // 无进度监听模式（直接 fetch）
        try {
            let result: Response;
            
            if (isPut) {
                // S3 预签名上传
                const headers: Record<string, string> = {};
                if (file instanceof File) {
                    headers["Content-Type"] = file.type || "application/octet-stream";
                }

                result = await fetch(uploadUrl, {
                    method: "PUT",
                    headers,
                    body: file as any,
                    signal: controller.signal, // 添加中止信号
                });
            } else {
                // 表单上传
                const formData2 = new FormData();
                for (const key of Object.keys(formData)) {
                    formData2.append(key, formData[key]);
                }
                formData2.append(name || "file", file as File);

                result = await fetch(uploadUrl, {
                    method,
                    body: formData2,
                    signal: controller.signal, // 添加中止信号
                });
            }

            this.controllers.delete(id); // 成功后清理控制器
            return result;

        } catch (error) {
            this.controllers.delete(id); // 失败后清理控制器
            
            // 人为中断返回204 使general-business处理成功
            if (error instanceof DOMException && error.name === 'AbortError') {
                return {
                    status: 204,
                };
            }
            throw error;
        }
    }

    // 中断特定上传
    abortUpload(uploadId: string): boolean {
        const controller = this.controllers.get(uploadId);
        if (controller) {
            controller.abort();
            this.controllers.delete(uploadId);
            return true;
        }
        return false;
    }

    // 中断所有上传
    abortAllUploads(): void {
        this.controllers.forEach((controller, id) => {
            controller.abort();
        });
        this.controllers.clear();
    }

    // 获取上传状态
    getUploadStatus(uploadId: string): 'uploading' | 'completed' | 'aborted' | 'not-found' {
        const controller = this.controllers.get(uploadId);
        if (!controller) return 'not-found';
        if (controller.signal.aborted) return 'aborted';
        return 'uploading';
    }

    // 生成唯一的上传ID
    private generateUploadId(file: File | string, uploadUrl: string): string {
        const timestamp = Date.now();
        const random = Math.random().toString(36).substring(2, 9);
        const fileInfo = file instanceof File ? `${file.name}-${file.size}` : String(file);
        return `${uploadUrl}-${fileInfo}-${timestamp}-${random}`;
    }

    // 获取所有进行中的上传任务
    getActiveUploads(): string[] {
        return Array.from(this.controllers.keys());
    }
}