git.giacomolli.uk - onechat/blob - telegram_image.go

   1 package main
   2
   3 import (
   4         "context"
   5         "errors"
   6         "fmt"
   7         "strings"
   8 )
   9
  10 var (
  11         errTelegramOtherMedia = errors.New("only text messages are supported")
  12         errTelegramPhotoSize  = errors.New("no photo size fits 1568 pixels")
  13 )
  14
  15 // telegramImageText selects a supplied photo size, or an image document, and
  16 // stores it before returning marker text with the unchanged caption.
  17 func telegramImageText(ctx context.Context, api *TelegramAPI, store *ImageStore, message *TelegramMessage) (string, error) {
  18         var (
  19                 id   string
  20                 size int64
  21         )
  22
  23         if len(message.Photo) > 0 {
  24                 var area int
  25
  26                 for _, photo := range message.Photo {
  27                         if photo.Width <= 0 || photo.Height <= 0 || max(photo.Width, photo.Height) > 1568 {
  28                                 continue
  29                         }
  30
  31                         if photo.Width*photo.Height > area {
  32                                 id = photo.FileID
  33                                 size = photo.FileSize
  34                                 area = photo.Width * photo.Height
  35                         }
  36                 }
  37
  38                 if id == "" {
  39                         return "", errTelegramPhotoSize
  40                 }
  41         } else if message.Document != nil {
  42                 document := message.Document
  43                 switch document.MimeType {
  44                 case "image/jpeg", "image/png", "image/webp":
  45                         id = document.FileID
  46                         size = document.FileSize
  47                 default:
  48                         if strings.HasPrefix(document.MimeType, "image/") {
  49                                 return "", errImageFormat
  50                         }
  51
  52                         return "", errTelegramOtherMedia
  53                 }
  54         }
  55
  56         if size > imageMaxBytes {
  57                 return "", errImageSize
  58         }
  59
  60         data, err := api.GetImage(ctx, id)
  61         if err != nil {
  62                 return "", fmt.Errorf("download image: %w", err)
  63         }
  64
  65         name, err := store.Save(data)
  66         if err != nil {
  67                 return "", fmt.Errorf("store image: %w", err)
  68         }
  69
  70         return imageText([]string{name}, message.Caption), nil
  71 }