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https://github.com/esimov/caire.git
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95 lines
2.2 KiB
Go
95 lines
2.2 KiB
Go
package utils
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import (
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"bytes"
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"fmt"
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"io"
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"log"
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"net/http"
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"net/url"
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"os"
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"strings"
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)
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// DownloadImage downloads the image from the internet and saves it into a temporary file.
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func DownloadImage(url string) (*os.File, error) {
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// Retrieve the url and decode the response body.
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res, err := http.Get(url)
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if err != nil {
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return nil, fmt.Errorf("unable to download image file from URI: %s, status %v", url, res.Status)
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}
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defer res.Body.Close()
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data, err := io.ReadAll(res.Body)
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if err != nil {
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return nil, fmt.Errorf("unable to read response body: %w", err)
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}
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tmpfile, err := os.CreateTemp("/tmp", "image")
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if err != nil {
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return nil, fmt.Errorf("unable to create temporary file: %w", err)
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}
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// Copy the image binary data into the temporary file.
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_, err = io.Copy(tmpfile, bytes.NewBuffer(data))
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if err != nil {
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return nil, fmt.Errorf("unable to copy the source URI into the destination file")
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}
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ctype, err := DetectContentType(tmpfile.Name())
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if err != nil {
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return nil, err
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}
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if !strings.Contains(ctype.(string), "image") {
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return nil, fmt.Errorf("the downloaded file is not a valid image type")
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}
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return tmpfile, nil
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}
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// IsValidUrl tests a string to determine if it is a well-structured url or not.
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func IsValidUrl(uri string) bool {
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_, err := url.ParseRequestURI(uri)
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if err != nil {
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return false
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}
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u, err := url.Parse(uri)
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if err != nil || u.Scheme == "" || u.Host == "" {
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return false
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}
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return true
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}
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// DetectContentType detects the file type by reading MIME type information of the file content.
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func DetectContentType(fname string) (any, error) {
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file, err := os.Open(fname)
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if err != nil {
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return nil, err
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}
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defer func() {
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if err := file.Close(); err != nil {
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log.Printf("could not close the opened file: %v", err)
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}
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}()
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// Only the first 512 bytes are used to sniff the content type.
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buffer := make([]byte, 512)
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_, err = file.Read(buffer)
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if err != nil {
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return nil, err
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}
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// Reset the read pointer if necessary.
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if _, err := file.Seek(0, 0); err != nil {
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return nil, err
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}
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// Always returns a valid content-type and "application/octet-stream" if no others seemed to match.
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contentType := http.DetectContentType(buffer)
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return string(contentType), nil
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}
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