Add rewrite rule replace for custom search and replace

reader/rewrite/rewrite_functions.go

@@ -221,3 +221,12 @@ func replaceTextLinks(input string) string {
 func replaceLineFeeds(input string) string {
 	return strings.Replace(input, "\n", "<br>", -1)
 }
+
+func replaceCustom(entryContent string, searchTerm string, replaceTerm string) string {
+	re, err := regexp.Compile(searchTerm)
+	if err == nil {
+		return re.ReplaceAllString(entryContent, replaceTerm)
+	}
+	return entryContent
+}
+

reader/rewrite/rewriter.go

@@ -6,11 +6,14 @@ package rewrite // import "miniflux.app/reader/rewrite"
 
 import (
 	"strings"
+	"regexp"
 
 	"miniflux.app/logger"
 	"miniflux.app/url"
 )
 
+var customReplaceRuleRegex = regexp.MustCompile(`replace\("(.*)"\|"(.*)"\)`)
+
 // Rewriter modify item contents with a set of rewriting rules.
 func Rewriter(entryURL, entryContent, customRewriteRules string) string {
 	rulesList := getPredefinedRewriteRules(entryURL)
@@ -24,7 +27,8 @@ func Rewriter(entryURL, entryContent, customRewriteRules string) string {
 	logger.Debug(`[Rewrite] Applying rules %v for %q`, rules, entryURL)
 
 	for _, rule := range rules {
-		switch strings.TrimSpace(rule) {
+		rule := strings.TrimSpace(rule)
+		switch rule {
 		case "add_image_title":
 			entryContent = addImageTitle(entryURL, entryContent)
 		case "add_mailto_subject":
@@ -47,6 +51,16 @@ func Rewriter(entryURL, entryContent, customRewriteRules string) string {
 			entryContent = fixMediumImages(entryURL, entryContent)
 		case "use_noscript_figure_images":
 			entryContent = useNoScriptImages(entryURL, entryContent)
+		default:
+			if strings.Contains(rule, "replace") {
+				// Format: replace("search-term"|"replace-term")
+				args := customReplaceRuleRegex.FindStringSubmatch(rule)
+				if len(args) >= 3 {
+					entryContent = replaceCustom(entryContent, args[1], args[2])
+				} else {
+					logger.Debug("[Rewrite] Cannot find search and replace terms for replace rule %s", rule)
+				}
+			}
 		}
 	}
 

reader/rewrite/rewriter_test.go

@@ -230,3 +230,13 @@ func TestRewriteNoScriptImageWithNoScriptTag(t *testing.T) {
 		t.Errorf(`Not expected output: %s`, output)
 	}
 }
+
+func TestRewriteReplaceCustom(t *testing.T) {
+	content := `<img src="http://example.org/logo.svg"><img src="https://example.org/article/picture.svg">`
+	expected := `<img src="http://example.org/logo.svg"><img src="https://example.org/article/picture.png">`
+	output := Rewriter("https://example.org/artcle", content, `replace("article/(.*).svg"|"article/$1.png")`)
+
+	if expected != output {
+		t.Errorf(`Not expected output: %s`, output)
+	}
+}