package iot_excelize

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"

	"github.com/gogf/gf/v2/errors/gerror"
	"github.com/gogf/gf/v2/net/ghttp"
	"github.com/xuri/excelize/v2"
)

// WriteHTTP writes an Excel workbook as an attachment to the current HTTP response.
func WriteHTTP(ctx context.Context, f *excelize.File, fileName string) (err error) {
	r := ghttp.RequestFromCtx(ctx)
	if r == nil {
		return gerror.New("当前上下文不是HTTP请求")
	}
	if fileName == "" {
		fileName = "export"
	}

	writer := r.Response.Writer
	writer.Header().Set("Content-Type", "application/octet-stream")
	writer.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s.xlsx", url.QueryEscape(fileName)))
	writer.Header().Set("Content-Transfer-Encoding", "binary")
	writer.Header().Set("Access-Control-Expose-Headers", "Content-Disposition")

	if err = f.Write(writer); err != nil {
		return err
	}
	r.Response.Status = http.StatusOK
	writer.Flush()
	return nil
}

// ToReadSeeker serializes an Excel workbook into memory for secondary handling.
func ToReadSeeker(f *excelize.File) (io.ReadSeeker, error) {
	var buffer bytes.Buffer
	if err := f.Write(&buffer); err != nil {
		return nil, err
	}
	return bytes.NewReader(buffer.Bytes()), nil
}