package util

import (
	"io"
	"mime/multipart"
	"net/http"
	"os"
)

/**
http-server 响应file流
*/
func ResponseFile(writer http.ResponseWriter, fileName string, body io.Reader) error {
	writer.Header().Set("Content-Type", "application/octet-stream")
	writer.Header().Set("Content-Disposition", "attachment; filename="+fileName)
	writer.Header().Set("Content-Transfer-Encoding", "binary")
	_, err := io.Copy(writer, body)
	return err
}

func ResponseFileV2(writer http.ResponseWriter, fileName string) {
	writer.Header().Set("Content-Type", "application/octet-stream")
	writer.Header().Set("Content-Disposition", "attachment; filename="+fileName)
	writer.Header().Set("Content-Transfer-Encoding", "binary")
}

/**
http-client 请求文件流
*/
type FileForm struct {
	filedName string
	fileName  string

	// form file
	filePath string

	// form stream
	reader io.Reader
}

func NewFileFormFromFile(fieldName, fileName, filePath string) FileForm {
	return FileForm{
		filedName: fieldName,
		fileName:  fileName,
		filePath:  filePath,
	}
}

func NewFileFormFromStream(fieldName, fileName string, reader io.Reader) FileForm {
	return FileForm{
		filedName: fieldName,
		fileName:  fileName,
		reader:    reader,
	}
}

/**
创建 Content-Type: multipart/form-data 的请求
返回参数1是 请求体
返回参数2是 Content-Type的value ，记得设置请求header Content-Type:参数2
返回参数3是 异常
*/
func NewMultiFormRequest(params map[string]string, fileTypeParams []FileForm) (_ io.Reader, _ string, err error) {
	requestBody := newRequestBody()
	bodyWriter := multipart.NewWriter(requestBody)
	defer func() {
		err = bodyWriter.Close()
	}()
	writeFile := func(file FileForm) (err error) {
		fileWriter, err := bodyWriter.CreateFormFile(file.filedName, file.fileName)
		if err != nil {
			return err
		}
		if file.reader == nil {
			fileReader, err := os.Open(file.filePath)
			if err != nil {
				return err
			}
			defer func() {
				err = fileReader.Close()
			}()
			file.reader = fileReader
		}
		_, err = io.Copy(fileWriter, file.reader)
		if err != nil {
			return err
		}
		return nil
	}
	writeParams := func(key, value string) error {
		return bodyWriter.WriteField(key, value)
	}
	for key, value := range params {
		if err := writeParams(key, value); err != nil {
			return nil, "", err
		}
	}
	for _, file := range fileTypeParams {
		if err := writeFile(file); err != nil {
			return nil, "", err
		}
	}
	contentType := bodyWriter.FormDataContentType()
	return requestBody, contentType, nil
}