Make tag-checking error message more explicit about what is wrong

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

1 files changed, 12 insertions, 6 deletions

diff --git a/lib/entry/libimagentrytag/src/tag.rs b/lib/entry/libimagentrytag/src/tag.rs
index 3cba2016..a2d68e73 100644
--- a/lib/entry/libimagentrytag/src/tag.rs
+++ b/lib/entry/libimagentrytag/src/tag.rs
@@ -26,21 +26,27 @@ pub type TagSlice<'a> = &'a str;
 
 /// validator which can be used by clap to validate that a string is a valid tag
 pub fn is_tag(s: String) -> Result<(), String> {
-    is_tag_str(&s).map_err(|_| format!("The string '{}' is not a valid tag", s))
+    check_tag_string(&s)
 }
 
 pub fn is_tag_str(s: &str) -> Result<(), Error> {
-    use filters::filter::Filter;
+    check_tag_string(s).map_err(|s| format_err!("{}", s))
+}
+
+fn check_tag_string(s: &str) -> Result<(), String> {
     trace!("Checking whether '{}' is a valid tag", s);
 
     let is_lower      = |s: &&str| s.chars().all(|c| c.is_lowercase());
     let no_whitespace = |s: &&str| s.chars().all(|c| !c.is_whitespace());
     let is_alphanum   = |s: &&str| s.chars().all(|c| c.is_alphanumeric());
 
-    if is_lower.and(no_whitespace).and(is_alphanum).filter(&s) {
-        Ok(())
-    } else {
-        Err(format_err!("The string '{}' is not a valid tag", s))
+    match (is_lower(&s), no_whitespace(&s), is_alphanum(&s)) {
+        (true, true, true) => Ok(()),
+        (false, false, false) => Err(format!("The string '{}' is not valid, because it is not all-lowercase, has whitespace and is not alphanumeric", s)),
+        (false, false, _ )    => Err(format!("The string '{}' is not valid, because it is not all-lowercase and has whitespace", s)),
+        (false, _, _ )        => Err(format!("The string '{}' is not valid, because it is not all-lowercase", s)),
+        (_, false, _ )        => Err(format!("The string '{}' is not valid, because it has whitespace", s)),
+        (_, _, false)         => Err(format!("The string '{}' is not valid, because it is not alphanumeric", s)),
     }
 }