request.go

package telegram

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"

	"github.com/technoweenie/multipartstreamer"
)

const requestAddress = "https://api.telegram.org"

type RequestHandler func(methodName string, req interface{}) (json.RawMessage, error)

type Response struct {
	Ok          bool                `json:"ok"`
	Result      json.RawMessage     `json:"result"`
	ErrorCode   int                 `json:"error_code"`
	Description string              `json:"description"`
	Parameters  *ResponseParameters `json:"parameters"`
}

type ErrorResponse Response

func (e ErrorResponse) Error() string {
	return fmt.Sprintf("resp not ok, descr=%v, code=%v", e.Description, e.ErrorCode)
}

func (b *Bot) executeRequest(methodName string, req interface{}) (json.RawMessage, error) {
	url := fmt.Sprintf("%s/bot%s/%s", requestAddress, b.token, methodName)

	var httpReq *http.Request

	if upload, ok := isFileUpload(req); ok {
		if upload.err != nil {
			return nil, upload.err
		}

		ms := multipartstreamer.New()
		ms.WriteFields(upload.params)

		r, err := upload.file.Reader()
		if err != nil {
			return nil, err
		}

		ms.WriteReader(upload.fieldname, upload.file.Name(), upload.file.Size(), r)
		if rc, ok := r.(io.ReadCloser); ok {
			defer rc.Close()
		}

		httpReq, err = http.NewRequest("POST", url, nil)
		if err != nil {
			return nil, err
		}
		ms.SetupRequest(httpReq)
	} else {
		body, err := json.Marshal(req)
		if err != nil {
			return nil, err
		}

		httpReq, err = http.NewRequest("POST", url, bytes.NewReader(body))
		if err != nil {
			return nil, err
		}
		httpReq.Header.Set("Content-Type", "application/json")
	}

	resp, err := b.client.Do(httpReq)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	var respObj Response
	err = json.NewDecoder(resp.Body).Decode(&respObj)
	if err != nil {
		return nil, err
	}

	if !respObj.Ok {
		return nil, ErrorResponse(respObj)
	}

	return respObj.Result, nil
}