import { z } from 'zod';
import { createTRPCRouter, permissionRequiredProcedure } from '@/server/trpc';
import {
  generatePresignedPostPolicy,
  generatePresignedGetObject,
  type PresignedPostPolicyOptions,
  type PresignedGetObjectOptions
} from '@/server/minio';
import { TRPCError, inferProcedureInput, inferProcedureOutput } from '@trpc/server';
import { randomBytes } from 'crypto';
import { Permissions } from '@/constants/permissions';


interface UploadConfig {
  /** 业务类型（category） public/开头是可以公开GetObject的 */
  category: string;
  /** 最大文件大小（字节），默认 100MB */
  maxSize?: number;
  /** 允许的文件类型（MIME类型，支持精确匹配和通配符如 'image/*'），默认允许所有类型 */
  allowedContentType?: string;
  /** 过期时间（秒），默认 1 小时 */
  expirySeconds?: number;
  /** 所需权限，默认为空字符串（需要登录但无特定权限要求） */
  permission?: string;
}

// eslint-disable-next-line @typescript-eslint/no-empty-object-type
interface SingleUploadConfig extends UploadConfig {}

// eslint-disable-next-line @typescript-eslint/no-empty-object-type
interface BatchUploadConfig extends UploadConfig {}

interface DownloadConfig {
  /** 过期时间（秒），默认 1 小时 */
  expirySeconds?: number;
  /** 所需权限，默认为空字符串（需要登录但无特定权限要求） */
  permission?: string;
}

/**
 * 生成随机哈希字符串
 */
function generateHash(length: number = 7): string {
  return randomBytes(Math.ceil(length / 2))
    .toString('hex')
    .slice(0, length);
}

/**
 * 创建单文件上传接口的工厂函数
 *
 * 生成的对象路径格式：${category}/${userId}/${hash}_${fileName}
 *
 * @param config 单文件上传配置
 * @returns tRPC mutation procedure
 */
export function createSingleUploadProcedure(config: SingleUploadConfig) {
  const {
    category,
    maxSize = 100 * 1024 * 1024, // 默认 100MB
    allowedContentType,
    expirySeconds = 3600,
    permission = '',
  } = config;

  return permissionRequiredProcedure(permission)
    .input(
      z.object({
        fileName: z.string().min(1, '文件名不能为空'),
      })
    )
    .mutation(async ({ input, ctx }) => {
      const { fileName } = input;
      const userId = ctx.session!.user.id;
      const hash = generateHash();
      
      // 单文件上传指定完整的文件路径
      const prefix = `${category}/${userId}`;
      const fullFileName = `${hash}_${fileName}`;

      try {
        const policyOptions: PresignedPostPolicyOptions = {
          prefix,
          fileName: fullFileName,
          expirySeconds: expirySeconds,
          maxSize,
          allowedContentType,
        };

        const result = await generatePresignedPostPolicy(policyOptions);

        return {
          postURL: result.postURL,
          formData: result.formData,
          objectName: result.objectName,
          expiresIn: expirySeconds,
          maxSize,
          allowedContentType,
        };
      } catch (error) {
        console.error('生成单文件上传策略失败:', error);
        throw new TRPCError({
          code: 'INTERNAL_SERVER_ERROR',
          message: '生成上传策略失败',
        });
      }
    });
}

/**
 * 创建批量上传接口的工厂函数
 *
 * 生成的对象路径格式：${category}/${userId}/${hash}/（前缀，客户端上传时需要在此前缀下）
 *
 * @param config 批量上传配置
 * @returns tRPC mutation procedure
 */
export function createBatchUploadProcedure(config: BatchUploadConfig) {
  const {
    category,
    maxSize = 100 * 1024 * 1024, // 默认 100MB
    allowedContentType,
    expirySeconds = 3600,
    permission = '',
  } = config;

  return permissionRequiredProcedure(permission)
    .mutation(async ({ ctx }) => {
      const userId = ctx.session!.user.id;
      const hash = generateHash();
      
      // 批量上传只校验前缀，不指定具体文件名
      const prefix = `${category}/${userId}/${hash}`;

      try {
        const policyOptions: PresignedPostPolicyOptions = {
          prefix,
          expirySeconds: expirySeconds,
          maxSize,
          allowedContentType,
        };

        const result = await generatePresignedPostPolicy(policyOptions);

        return {
          postURL: result.postURL,
          formData: result.formData,
          prefix: result.objectName,
          expiresIn: expirySeconds,
          maxSize,
          allowedContentType,
        };
      } catch (error) {
        console.error('生成批量上传策略失败:', error);
        throw new TRPCError({
          code: 'INTERNAL_SERVER_ERROR',
          message: '生成上传策略失败',
        });
      }
    });
}

/**
 * 创建下载接口的工厂函数
 *
 * 生成预签名的 GET URL，用于下载对象
 * 文件名默认使用对象的 x-amz-meta-original-filename 元信息
 *
 * @param config 下载配置
 * @returns tRPC mutation procedure
 */
export function createDownloadProcedure(config: DownloadConfig) {
  const {
    expirySeconds = 3600,
    permission = '',
  } = config;

  return permissionRequiredProcedure(permission)
    .input(
      z.object({
        objectName: z.string().min(1, '对象名称不能为空'),
        fileName: z.string().optional(),
        contentType: z.string().optional(),
      })
    )
    .mutation(async ({ input }) => {
      const { objectName, fileName, contentType } = input;

      try {
        const options: PresignedGetObjectOptions = {
          objectName,
          expirySeconds,
          responseHeaders: {},
        };

        // 如果指定了自定义文件名，覆盖默认行为
        if (fileName) {
          options.responseHeaders!['response-content-disposition'] =
            `attachment; filename*=UTF-8''${encodeURIComponent(fileName)}`;
        }

        // 如果指定了自定义 Content-Type，覆盖默认行为
        if (contentType) {
          options.responseHeaders!['response-content-type'] = contentType;
        }

        const result = await generatePresignedGetObject(options);

        return {
          url: result.url,
          expiresIn: result.expiresIn,
        };
      } catch (error) {
        console.error('生成下载链接失败:', error);
        throw new TRPCError({
          code: 'INTERNAL_SERVER_ERROR',
          message: '生成下载链接失败',
        });
      }
    });
}

/**
 * 上传路由
 * 提供文件上传相关的接口，使用工厂函数创建特定业务的上传接口
 */
export const uploadRouter = createTRPCRouter({

});

export type SingleUploadProcedureInput = inferProcedureInput<ReturnType<typeof createSingleUploadProcedure>>; // createSingleUploadProcedure 创建的接口调用参数
export type SingleUploadProcedureOutput = inferProcedureOutput<ReturnType<typeof createSingleUploadProcedure>>; // createSingleUploadProcedure 创建的接口返回值
export type BatchUploadProcedureInput = inferProcedureInput<ReturnType<typeof createBatchUploadProcedure>>; // createBatchUploadProcedure 创建的接口调用参数
export type BatchUploadProcedureOutput = inferProcedureOutput<ReturnType<typeof createBatchUploadProcedure>>; // createBatchUploadProcedure 创建的接口返回值
export type DownloadProcedureInput = inferProcedureInput<ReturnType<typeof createDownloadProcedure>>; // createDownloadProcedure 创建的接口调用参数
export type DownloadProcedureOutput = inferProcedureOutput<ReturnType<typeof createDownloadProcedure>>; // createDownloadProcedure 创建的接口返回值