package starnet

import (
	"context"
	"io"
	"mime/multipart"
	"os"
)

// applyMultipartBody 应用 multipart 请求体
func (r *Request) applyMultipartBody(execCtx context.Context) error {
	pr, pw := io.Pipe()
	writer := multipart.NewWriter(pw)

	r.httpReq.Header.Set("Content-Type", writer.FormDataContentType())
	r.httpReq.Body = pr

	go func() {
		defer pw.Close()
		defer writer.Close()

		for key, values := range r.config.Body.FormData {
			for _, value := range values {
				if err := writer.WriteField(key, value); err != nil {
					pw.CloseWithError(wrapError(err, "write form field"))
					return
				}
			}
		}

		for _, file := range r.config.Body.Files {
			if err := r.writeFile(execCtx, writer, file); err != nil {
				pw.CloseWithError(err)
				return
			}
		}
	}()

	return nil
}

// writeFile 写入文件到 multipart writer
func (r *Request) writeFile(execCtx context.Context, writer *multipart.Writer, file RequestFile) error {
	part, err := writer.CreateFormFile(file.FormName, file.FileName)
	if err != nil {
		return wrapError(err, "create form file")
	}

	var reader io.Reader
	if file.FileData != nil {
		reader = file.FileData
	} else if file.FilePath != "" {
		f, err := os.Open(file.FilePath)
		if err != nil {
			return wrapError(err, "open file")
		}
		defer f.Close()
		reader = f
	} else {
		return ErrNilReader
	}

	_, err = copyWithProgress(execCtx, part, reader, file.FileName, file.FileSize, r.config.UploadProgress)
	if err != nil {
		return wrapError(err, "copy file data")
	}

	return nil
}