import { type DynamicModule, Module, type Type } from "@nestjs/common";
import { DiskFileStorage } from "./disk-file-storage";
import { FILE_STORAGE } from "./file-storage.interface";
import { R2FileStorage, type R2FileStorageConfig } from "./r2-file-storage";

type DiskConfig = { driver: "disk"; baseDir: string };
type R2Config = { driver: "r2" } & R2FileStorageConfig;
export type FileStorageModuleConfig = DiskConfig | R2Config;

/**
 * Implement this interface to provide FileStorage configuration
 * via NestJS DI. Register it with `FileStorageModule.forRootAsync()`.
 */
export interface FileStorageConfigProvider {
  createFileStorageConfig(): FileStorageModuleConfig;
}

export const FILE_STORAGE_CONFIG_PROVIDER = Symbol("FILE_STORAGE_CONFIG_PROVIDER");

@Module({})
export class FileStorageModule {
  /**
   * Static configuration — pass the config directly.
   */
  static forRoot(config: FileStorageModuleConfig): DynamicModule {
    return {
      module: FileStorageModule,
      providers: [
        {
          provide: FILE_STORAGE,
          useFactory: () => createStorage(config),
        },
      ],
      exports: [FILE_STORAGE],
      global: true,
    };
  }

  /**
   * Async configuration — provide a class that implements
   * `FileStorageConfigProvider`. The class can inject ConfigService
   * or any other NestJS provider.
   */
  static forRootAsync(options: {
    imports?: Type[];
    useClass: Type<FileStorageConfigProvider>;
  }): DynamicModule {
    return {
      module: FileStorageModule,
      imports: options.imports ?? [],
      providers: [
        {
          provide: FILE_STORAGE_CONFIG_PROVIDER,
          useClass: options.useClass,
        },
        {
          provide: FILE_STORAGE,
          useFactory: (provider: FileStorageConfigProvider) =>
            createStorage(provider.createFileStorageConfig()),
          inject: [FILE_STORAGE_CONFIG_PROVIDER],
        },
      ],
      exports: [FILE_STORAGE],
      global: true,
    };
  }
}

const createStorage = (config: FileStorageModuleConfig) =>
  config.driver === "r2"
    ? new R2FileStorage(config)
    : new DiskFileStorage(config.baseDir);