import { ElMessage } from "element-plus";
import { uploadImage, uploadDocument, uploadFile } from "@/api/upload";

/**
 * 文件大小格式化
 * @param bytes 字节数
 * @returns 格式化后的字符串
 */
export function formatFileSize(bytes: number): string {
  if (bytes === 0) return "0 B";
  const k = 1024;
  const sizes = ["B", "KB", "MB", "GB", "TB"];
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  return Math.round((bytes / Math.pow(k, i)) * 100) / 100 + " " + sizes[i];
}

/**
 * 获取文件扩展名
 * @param filename 文件名
 * @returns 扩展名（小写）
 */
export function getFileExtension(filename: string): string {
  return filename
    .slice(((filename.lastIndexOf(".") - 1) >>> 0) + 2)
    .toLowerCase();
}

/**
 * 验证文件类型
 * @param file 文件对象
 * @param allowedTypes 允许的类型数组
 * @returns 是否通过验证
 */
export function validateFileType(file: File, allowedTypes: string[]): boolean {
  return allowedTypes.includes(file.type);
}

/**
 * 验证文件大小
 * @param file 文件对象
 * @param maxSizeMB 最大大小（MB）
 * @returns 是否通过验证
 */
export function validateFileSize(file: File, maxSizeMB: number): boolean {
  return file.size <= maxSizeMB * 1024 * 1024;
}

/**
 * 通用上传处理函数
 * @param file 文件对象
 * @param options 配置选项
 * @returns Promise<string> 返回文件 URL
 */
export interface UploadOptions {
  type?: "image" | "document" | "file";
  maxSize?: number;
  allowedTypes?: string[];
  onProgress?: (progress: number) => void;
  onSuccess?: (url: string) => void;
  onError?: (error: Error) => void;
}

export async function handleUpload(
  file: File,
  options: UploadOptions = {}
): Promise<string> {
  const {
    type = "file",
    maxSize,
    allowedTypes,
    onProgress,
    onSuccess,
    onError,
  } = options;

  try {
    // 进度回调包装
    const progressCallback = onProgress
      ? (progressEvent: any) => {
          const progress = Math.round(
            (progressEvent.loaded * 100) / progressEvent.total
          );
          onProgress(progress);
        }
      : undefined;

    let res;

    // 根据类型选择上传方法
    switch (type) {
      case "image":
        res = await uploadImage(file, {
          maxSize,
          allowedTypes,
          onProgress: progressCallback,
        });
        break;
      case "document":
        res = await uploadDocument(file, {
          maxSize,
          allowedTypes,
          onProgress: progressCallback,
        });
        break;
      default:
        res = await uploadFile(file, progressCallback);
    }

    const url = res.data.url;

    if (onSuccess) {
      onSuccess(url);
    }

    return url;
  } catch (error: any) {
    if (onError) {
      onError(error);
    } else {
      ElMessage.error(error.message || "上传失败");
    }
    throw error;
  }
}

/**
 * 图片压缩
 * @param file 图片文件
 * @param maxWidth 最大宽度
 * @param quality 压缩质量 0-1
 * @returns Promise<File> 压缩后的文件
 */
export function compressImage(
  file: File,
  maxWidth = 1920,
  quality = 0.8
): Promise<File> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.readAsDataURL(file);

    reader.onload = (e) => {
      const img = new Image();
      img.src = e.target?.result as string;

      img.onload = () => {
        const canvas = document.createElement("canvas");
        let width = img.width;
        let height = img.height;

        // 计算缩放比例
        if (width > maxWidth) {
          height = (height * maxWidth) / width;
          width = maxWidth;
        }

        canvas.width = width;
        canvas.height = height;

        const ctx = canvas.getContext("2d");
        ctx?.drawImage(img, 0, 0, width, height);

        canvas.toBlob(
          (blob) => {
            if (blob) {
              const compressedFile = new File([blob], file.name, {
                type: file.type,
                lastModified: Date.now(),
              });
              resolve(compressedFile);
            } else {
              reject(new Error("图片压缩失败"));
            }
          },
          file.type,
          quality
        );
      };

      img.onerror = () => {
        reject(new Error("图片加载失败"));
      };
    };

    reader.onerror = () => {
      reject(new Error("文件读取失败"));
    };
  });
}

/**
 * Base64 转 File
 * @param base64 base64 字符串
 * @param filename 文件名
 * @returns File 对象
 */
export function base64ToFile(base64: string, filename: string): File {
  const arr = base64.split(",");
  const mime = arr[0].match(/:(.*?);/)?.[1] || "image/png";
  const bstr = atob(arr[1]);
  let n = bstr.length;
  const u8arr = new Uint8Array(n);

  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }

  return new File([u8arr], filename, { type: mime });
}

/**
 * File 转 Base64
 * @param file 文件对象
 * @returns Promise<string> base64 字符串
 */
export function fileToBase64(file: File): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.readAsDataURL(file);
    reader.onload = () => resolve(reader.result as string);
    reader.onerror = (error) => reject(error);
  });
}