import { HttpStatus, Inject, Injectable } from '@nestjs/common';
import { randomUUID } from 'node:crypto';

import {
  API_ERROR_CODES,
  type ConfirmUploadResponse,
  type CreateUploadIntentResponse,
  type CreateMediaUploadIntentRequest,
  type ServiceRecordAttachment,
} from '@lehuo/contracts';

import { ApplicationError } from '../common/application-error';
import type { AuthContext, RequestContext } from '../common/request-context';
import { FilesRepository } from '../files/files.repository';
import { OBJECT_STORAGE_ADAPTER, type ObjectStorageAdapter } from '../files/object-storage.adapter';
import type { File, FileBusinessType } from '../generated/prisma/client';
import { SensitiveDataService } from '../security/sensitive-data.service';

const EXTENSIONS: Record<string, string> = {
  'image/jpeg': 'jpg',
  'image/png': 'png',
  'image/webp': 'webp',
};

@Injectable()
export class MediaService {
  constructor(
    @Inject(FilesRepository) private readonly files: FilesRepository,
    @Inject(OBJECT_STORAGE_ADAPTER) private readonly storage: ObjectStorageAdapter,
    @Inject(SensitiveDataService) private readonly sensitive: SensitiveDataService,
  ) {}

  async createIntent(
    input: CreateMediaUploadIntentRequest,
    actor: AuthContext,
    request: RequestContext,
  ): Promise<CreateUploadIntentResponse> {
    this.assertConfigured();
    const filename = this.safeFilename(input.filename);
    const extension = EXTENSIONS[input.mimeType];
    if (!extension || !this.extensionMatches(filename, extension)) {
      throw this.validation('文件扩展名与图片类型不一致');
    }
    const fingerprint = this.sensitive.lookupHash(
      'cover-upload-intent',
      JSON.stringify({ ...input, filename }),
    );
    const previous = await this.files.findByIdempotency(actor.userId, input.clientRequestId);
    if (previous) {
      if (
        previous.requestFingerprint !== fingerprint ||
        previous.businessType !== input.businessType
      ) {
        throw this.duplicate();
      }
      return this.uploadResponse(previous, true);
    }
    const now = new Date();
    const prefix =
      input.businessType === 'OLD_ITEM_DONATION_IMAGE' ? 'private-old-items' : 'public-covers';
    const objectKey = `${prefix}/${now.getUTCFullYear()}/${String(now.getUTCMonth() + 1).padStart(2, '0')}/${randomUUID()}.${extension}`;
    const file = await this.files.createPending(
      {
        publicId: randomUUID(),
        businessType: input.businessType,
        clientRequestId: input.clientRequestId,
        requestFingerprint: fingerprint,
        provider: this.storage.providerName,
        bucket: this.storage.bucket ?? '',
        objectKey,
        filenameEncrypted: this.sensitive.encrypt(filename),
        mimeType: input.mimeType,
        size: BigInt(input.size),
        sha256: input.sha256,
      },
      actor,
      request,
    );
    return this.uploadResponse(file, false);
  }

  async confirm(
    publicId: string,
    actor: AuthContext,
    request: RequestContext,
  ): Promise<ConfirmUploadResponse> {
    this.assertConfigured();
    const file = await this.files.findByPublicId(publicId);
    if (!file || file.caseId !== null || file.uploaderUserId !== actor.userId)
      throw this.notFound();
    if (
      file.businessType !== 'PROJECT_COVER' &&
      file.businessType !== 'ACTIVITY_COVER' &&
      file.businessType !== 'OLD_ITEM_DONATION_IMAGE'
    ) {
      throw this.notFound();
    }
    if (file.status === 'AVAILABLE') return { file: this.attachment(file) };
    if (file.status !== 'UPLOAD_PENDING') throw this.notReady();
    let metadata;
    try {
      metadata = await this.storage.headObject(file.objectKey);
    } catch {
      throw this.storageUnavailable();
    }
    if (!metadata) throw this.notReady();
    if (
      metadata.contentLength !== Number(file.size) ||
      metadata.contentType !== file.mimeType ||
      (file.sha256 !== null && metadata.sha256 !== file.sha256)
    ) {
      await this.files.quarantine(publicId, actor, request, 'OBJECT_METADATA_MISMATCH');
      throw this.validation('图片校验未通过，请重新选择文件');
    }
    return { file: this.attachment(await this.files.markAvailable(publicId, actor, request)) };
  }

  async requireCover(
    publicId: string | undefined,
    businessType: FileBusinessType,
    actor: AuthContext,
  ): Promise<File | null> {
    if (!publicId) return null;
    const file = await this.files.findByPublicId(publicId);
    if (
      !file ||
      file.status !== 'AVAILABLE' ||
      file.businessType !== businessType ||
      file.uploaderUserId !== actor.userId ||
      file.caseId !== null
    ) {
      throw this.validation('封面图片无效或尚未确认上传');
    }
    return file;
  }

  async publicUrl(file: Pick<File, 'objectKey' | 'status'> | null): Promise<string | null> {
    if (!file || file.status !== 'AVAILABLE' || !this.storage.configured) return null;
    try {
      return await this.storage.createDownloadUrl(file.objectKey, 600);
    } catch {
      return null;
    }
  }

  private async uploadResponse(
    file: File,
    idempotentReplay: boolean,
  ): Promise<CreateUploadIntentResponse> {
    // 缩短上传 URL 有效期至 120 秒，降低截获后滥用的风险窗口。
    const expiresIn = 120;
    let uploadUrl: string;
    try {
      uploadUrl = await this.storage.createUploadUrl(
        file.objectKey,
        file.mimeType,
        file.sha256 ?? undefined,
        expiresIn,
      );
    } catch {
      throw this.storageUnavailable();
    }
    return {
      file: this.attachment(file),
      uploadUrl,
      uploadHeaders: {
        'Content-Type': file.mimeType,
        ...(file.sha256 ? { 'x-amz-meta-sha256': file.sha256 } : {}),
      },
      expiresAt: new Date(Date.now() + expiresIn * 1000).toISOString(),
      idempotentReplay,
    };
  }

  private attachment(file: File): ServiceRecordAttachment {
    return {
      publicId: file.publicId,
      filename: this.sensitive.decrypt(file.originalFilenameEncrypted),
      mimeType: file.mimeType,
      size: Number(file.size),
    };
  }

  private safeFilename(value: string): string {
    const filename = value.trim();
    if (
      !filename ||
      filename.includes('/') ||
      filename.includes('\\') ||
      Array.from(filename).some((character) => character.charCodeAt(0) <= 31)
    ) {
      throw this.validation('文件名不合法');
    }
    return filename;
  }

  private extensionMatches(filename: string, extension: string): boolean {
    const lower = filename.toLowerCase();
    return lower.endsWith(`.${extension}`) || (extension === 'jpg' && lower.endsWith('.jpeg'));
  }

  private assertConfigured(): void {
    if (!this.storage.configured || !this.storage.bucket) throw this.storageUnavailable();
  }

  private validation(message: string): ApplicationError {
    return new ApplicationError(API_ERROR_CODES.VALIDATION_ERROR, message, HttpStatus.BAD_REQUEST);
  }

  private duplicate(): ApplicationError {
    return new ApplicationError(
      API_ERROR_CODES.DUPLICATE_REQUEST,
      '请求标识已用于其他文件',
      HttpStatus.CONFLICT,
    );
  }

  private notFound(): ApplicationError {
    return new ApplicationError(
      API_ERROR_CODES.FILE_NOT_FOUND,
      '未找到该图片',
      HttpStatus.NOT_FOUND,
    );
  }

  private notReady(): ApplicationError {
    return new ApplicationError(
      API_ERROR_CODES.UPLOAD_NOT_READY,
      '尚未收到上传文件，请完成上传后重试',
      HttpStatus.CONFLICT,
    );
  }

  private storageUnavailable(): ApplicationError {
    return new ApplicationError(
      API_ERROR_CODES.STORAGE_UNAVAILABLE,
      '图片服务尚未配置或暂时不可用',
      HttpStatus.SERVICE_UNAVAILABLE,
    );
  }
}