Image attachments: use full-resolution file if available (#87)

* Image attachments: use full-resolution file if available

Images embedded in posts/pages may sometimes use downscaled image thumbnails or thumbnails sizes that don't exist anymore, patterned like `some-file-1920x1080.jpg`. We try to find the full-resolution image if any, like `some-file.jpg`, then fall-back to whatever URL was given in content if this failed.

This assumes Hugo image partials will handle resizing to theme width and responsive image sizes internally (see https://discourse.gohugo.io/t/hugo-image-processing-and-responsive-images/43110/4).

* Update output file path too if full-res image was found

* Add log lines, refine media retrieving logic

* Fix Go formatting

src/wp2hugo/internal/hugogenerator/hugo_gen_setup.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/exec"
 	"path"
+	"regexp"
 	"runtime"
 	"strings"
 	"time"
@@ -37,6 +38,9 @@ placeholder: "placeholder text in search input box"
 ---
 `
 
+// Find image media thumbnails resized by WP, like `some-file-1920x1080.jpg`
+var _resizedMedia = regexp.MustCompile(`(.*)-\d+x\d+\.(jpg|jpeg|png|webp|gif)`)
+
 type Generator struct {
 	fontName         string
 	imageURLProvider hugopage.ImageURLProvider
@@ -478,7 +482,31 @@ func (g Generator) downloadPageMedia(outputMediaDirPath string, p *hugopage.Page
 		if !strings.HasPrefix(link, "http") {
 			link = g.wpInfo.Link() + link
 		}
-		media, err := g.mediaProvider.GetReader(link)
+
+		// Try full-res images first.
+		// It is assumed here that Hugo will handle responsive sizes and such internally.
+		// see https://discourse.gohugo.io/t/hugo-image-processing-and-responsive-images/43110/4
+		fullResLink := _resizedMedia.ReplaceAllString(link, "$1.$2")
+		media, err := g.mediaProvider.GetReader(fullResLink)
+
+		if err != nil {
+			// If full-res image not found, try again with resized one.
+			if strings.Compare(fullResLink, link) != 0 {
+				log.Info().
+					Str("fullResLink", fullResLink).
+					Str("link", link).
+					Msg("full-resolution image file not found, falling back to resized thumbnail")
+				media, err = g.mediaProvider.GetReader(link)
+			} // else fullResLink == link, so no need to retry
+		} else {
+			// If full-res image found, update target file path too
+			outputFilePath = _resizedMedia.ReplaceAllString(outputFilePath, "$1.$2")
+			log.Info().
+				Str("fullResLink", fullResLink).
+				Str("link", link).
+				Msg("resized thumbnail was replaced by full-resolution image")
+		}
+
 		if err != nil {
 			if g.continueOnMediaDownloadFailure {
 				log.Error().