import { Module, Global, DynamicModule } from '@nestjs/common'
import { ConfigModule } from '@nestjs/config'

import { EmailClientService } from './service'
import type { EmailClientModuleOptions } from './types'

export const EMAIL_CLIENT_OPTIONS = 'EMAIL_CLIENT_OPTIONS'

/**
 * Global email client module.
 * Provides EmailClientService for calling the email backend's internal API.
 *
 * @example
 * ```typescript
 * // Basic usage (defaults: service-registry URL, EMAIL_INTERNAL_API_KEY env var)
 * EmailClientModule.forRoot()
 *
 * // Custom configuration
 * EmailClientModule.forRoot({
 *   serviceUrl: 'http://custom-email:3011',
 *   apiKeyEnvVar: 'MY_CUSTOM_API_KEY',
 * })
 *
 * // Async configuration
 * EmailClientModule.forRootAsync({
 *   inject: [ConfigService],
 *   useFactory: (config: ConfigService) => ({
 *     apiKeyEnvVar: config.get('EMAIL_API_KEY_VAR'),
 *   }),
 * })
 * ```
 */
@Global()
@Module({})
export class EmailClientModule {
  static forRoot(options?: EmailClientModuleOptions): DynamicModule {
    return {
      module: EmailClientModule,
      imports: [ConfigModule],
      providers: [
        {
          provide: EMAIL_CLIENT_OPTIONS,
          useValue: options ?? {},
        },
        EmailClientService,
      ],
      exports: [EmailClientService],
    }
  }

  static forRootAsync(asyncOptions: {
    imports?: DynamicModule['imports']
    inject?: Array<new (...args: unknown[]) => unknown> | Array<string | symbol>
    useFactory: (...args: unknown[]) => EmailClientModuleOptions | Promise<EmailClientModuleOptions>
  }): DynamicModule {
    return {
      module: EmailClientModule,
      imports: [...(asyncOptions.imports ?? []), ConfigModule],
      providers: [
        {
          provide: EMAIL_CLIENT_OPTIONS,
          inject: asyncOptions.inject ?? [],
          useFactory: asyncOptions.useFactory,
        },
        EmailClientService,
      ],
      exports: [EmailClientService],
    }
  }
}