package telegram

import json "github.com/pquerna/ffjson/ffjson"

// GetFileParameters represents data for GetFile method.
type GetFileParameters struct {
	// File identifier to get info about
	FileID string `json:"file_id"`
}

// GetFile get basic info about a file and prepare it for downloading. For the
// moment, bots can download files of up to 20MB in size. On success, a File
// object is returned. The file can then be downloaded via the link
// https://api.telegram.org/file/bot<token>/<file_path>, where <file_path> is
// taken from the response. It is guaranteed that the link will be valid for at
// least 1 hour. When the link expires, a new one can be requested by calling
// getFile again.
//
// Note: This function may not preserve the original file name and MIME type. You
// should save the file's MIME type and name (if available) when the File object
// is received.
func (bot *Bot) GetFile(fileID string) (file *File, err error) {
	dst, err := json.Marshal(&GetFileParameters{FileID: fileID})
	if err != nil {
		return
	}

	resp, err := bot.request(dst, MethodGetFile)
	if err != nil {
		return
	}

	file = new(File)
	err = json.Unmarshal(*resp.Result, file)
	return
}