export type ApiCoreHeaderValue = [string, ...string[]] | undefined
export interface ApiCoreHeaders {
  [key: string]: ApiCoreHeaderValue
}
export interface ApiCoreRequestFormDataEntry {
  name: string
  value: string | File
}
export type ApiCoreRequestFormData = ApiCoreRequestFormDataEntry[]
export interface ApiCoreRequestFile {
  name: string
  value: File
}
export type ApiCoreRequestFiles = ApiCoreRequestFile[]
export interface ApiCoreStream {
  write(chunk: Buffer | string, encoding: BufferEncoding): Promise<void>
  end(): Promise<void>
}

/**
 * @description 参考 WHATWG 语义的稳定内部抽象类，适配不同环境的 HTTP 请求和响应。
 */
export abstract class ApiCore {
  /**
   * @description Header names are in lowercase for consistency.
   */
  abstract getRequestHeaders(): Promise<ApiCoreHeaders>
  async getRequestHeader(name: string): Promise<ApiCoreHeaderValue> {
    const headers = await this.getRequestHeaders()
    const headerValue = headers[name.toLowerCase()]
    return headerValue
  }

  /**
   * @description Method names are in uppercase for consistency with the standard HTTP method names.
   */
  abstract getRequestMethod(): Promise<string>

  abstract getRequestUrl(): string
  async getRequestPath(): Promise<string> {
    const urlInString = this.getRequestUrl()
    const url = new URL(urlInString)
    const path = url.pathname
    return await Promise.resolve(path)
  }
  async getRequestSearch(): Promise<string> {
    const urlInString = this.getRequestUrl()
    const url = new URL(urlInString)
    const search = url.search
    return await Promise.resolve(search)
  }

  abstract getRequestBodyText(): Promise<string>
  async getRequestBodyJson(): Promise<unknown> {
    const bodyText = await this.getRequestBodyText()

    if (bodyText.trim().length === 0) {
      return {}
    }

    return JSON.parse(bodyText) as unknown
  }
  abstract getRequestBodyFormData(): Promise<ApiCoreRequestFormData>
  async getRequestFiles(): Promise<ApiCoreRequestFiles> {
    const formData = await this.getRequestBodyFormData()
    const files: ApiCoreRequestFiles = []

    for (const entry of formData) {
      if (entry.value instanceof File) {
        files.push({
          name: entry.name,
          value: entry.value,
        })
      }
    }

    return files
  }

  abstract text(data: unknown): Promise<void>
  abstract json(data: unknown): Promise<void>
  abstract stream(): Promise<ApiCoreStream>
  abstract error(): Promise<void>
}