Implemented image links

Render.go

@@ -279,6 +279,7 @@ func (r *renderer) writeText(markdown string) {
 		searchStart   = 0
 		linkTextStart = -1
 		linkTextEnd   = -1
+		linkIsImage   = false
 		emStart       = -1
 		strongStart   = -1
 		strikeStart   = -1
@@ -286,7 +287,7 @@ func (r *renderer) writeText(markdown string) {
 
 begin:
 	for {
-		i := strings.IndexAny(markdown[searchStart:], "[]()`*_~")
+		i := strings.IndexAny(markdown[searchStart:], "[]()`*_~!")
 
 		if i == -1 {
 			r.WriteString(html.EscapeString(markdown[tokenStart:]))
@@ -332,11 +333,19 @@ begin:
 						linkText := markdown[linkTextStart+1 : linkTextEnd]
 						linkURL := markdown[i+1 : urlEnd]
 
-						r.WriteString("<a href=\"")
-						r.WriteString(sanitizeURL(linkURL))
-						r.WriteString("\">")
-						r.WriteString(html.EscapeString(linkText))
-						r.WriteString("</a>")
+						if linkIsImage {
+							r.WriteString("<img src=\"")
+							r.WriteString(sanitizeURL(linkURL))
+							r.WriteString("\" alt=\"")
+							r.WriteString(html.EscapeString(linkText))
+							r.WriteString("\">")
+						} else {
+							r.WriteString("<a href=\"")
+							r.WriteString(sanitizeURL(linkURL))
+							r.WriteString("\">")
+							r.WriteString(html.EscapeString(linkText))
+							r.WriteString("</a>")
+						}
 
 						linkTextStart = -1
 						linkTextEnd = -1
@@ -402,6 +411,17 @@ begin:
 				tokenStart = i
 				strikeStart = i + 2
 			}
+
+		case '!':
+			if i+1 >= len(markdown) || markdown[i+1] != '[' {
+				continue
+			}
+
+			r.WriteString(html.EscapeString(markdown[tokenStart:i]))
+			tokenStart = i
+			linkTextStart = i + 1
+			searchStart++
+			linkIsImage = true
 		}
 	}
 }