melib/email: Improve Debug impl for ContentType etc

Improve Debug impl for ContentType, Text, ContentTransferEncoding which
all include bytes in some of their variants. The derived Debug
implementation did not show them as readable ascii strings, so a custom
impl was necessary to make it readable.

Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is>

melib/src/email/attachment_types.rs

@@ -243,7 +243,7 @@ impl<B: AsRef<[u8]>> From<B> for MultipartType {
     }
 }
 
-#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+#[derive(Clone, Deserialize, Eq, Hash, PartialEq, Serialize)]
 pub enum ContentType {
     Text {
         kind: Text,
@@ -270,6 +270,66 @@ pub enum ContentType {
     },
 }
 
+impl std::fmt::Debug for ContentType {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
+        macro_rules! fmt_params {
+            ($p:expr) => {
+                &$p.iter()
+                    .map(|(b1, b2)| (String::from_utf8_lossy(b1), String::from_utf8_lossy(b2)))
+                    .collect::<Vec<(_, _)>>()
+            };
+        }
+        match self {
+            Self::Text {
+                kind,
+                parameters,
+                charset,
+            } => fmt
+                .debug_struct(stringify!(ContentType::Text))
+                .field("kind", &kind)
+                .field("parameters", fmt_params! { parameters })
+                .field("charset", &charset)
+                .finish(),
+            Self::Multipart {
+                boundary,
+                parameters,
+                kind,
+                parts,
+            } => fmt
+                .debug_struct(stringify!(ContentType::Multipart))
+                .field("kind", &kind)
+                .field("boundary", &String::from_utf8_lossy(boundary))
+                .field("parameters", fmt_params! { parameters })
+                .field("parts", &parts)
+                .finish(),
+            Self::MessageRfc822 => fmt
+                .debug_struct(stringify!(ContentType::MessageRfc822))
+                .finish(),
+            Self::PGPSignature => fmt
+                .debug_struct(stringify!(ContentType::PGPSignature))
+                .finish(),
+            Self::CMSSignature => fmt
+                .debug_struct(stringify!(ContentType::CMSSignature))
+                .finish(),
+            Self::Other {
+                tag,
+                name,
+                parameters,
+            } => fmt
+                .debug_struct(stringify!(ContentType::Other))
+                .field("tag", &String::from_utf8_lossy(tag))
+                .field("name", name)
+                .field("parameters", fmt_params! { parameters })
+                .finish(),
+            Self::OctetStream { name, parameters } => fmt
+                .debug_struct(stringify!(ContentType::OctetStream))
+                .field("name", name)
+                .field("parameters", fmt_params! { parameters })
+                .finish(),
+        }
+    }
+}
+
 impl Default for ContentType {
     fn default() -> Self {
         Self::Text {
@@ -439,7 +499,7 @@ impl ContentType {
     }
 }
 
-#[derive(Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
+#[derive(Clone, Deserialize, Eq, Hash, PartialEq, Serialize)]
 pub enum Text {
     Plain,
     Html,
@@ -464,7 +524,18 @@ impl std::fmt::Display for Text {
     }
 }
 
-#[derive(Clone, Debug, Default, Deserialize, Eq, Hash, PartialEq, Serialize)]
+impl std::fmt::Debug for Text {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            Self::Plain => write!(fmt, "plain"),
+            Self::Html => write!(fmt, "html"),
+            Self::Rfc822 => write!(fmt, "rfc822"),
+            Self::Other { tag } => write!(fmt, "{}", String::from_utf8_lossy(tag)),
+        }
+    }
+}
+
+#[derive(Clone, Default, Deserialize, Eq, Hash, PartialEq, Serialize)]
 pub enum ContentTransferEncoding {
     #[default]
     _8Bit,
@@ -476,6 +547,29 @@ pub enum ContentTransferEncoding {
     },
 }
 
+impl std::fmt::Debug for ContentTransferEncoding {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            Self::_7Bit => fmt
+                .debug_struct(stringify!(ContentTransferEncoding::_7Bit))
+                .finish(),
+            Self::_8Bit => fmt
+                .debug_struct(stringify!(ContentTransferEncoding::_8Bit))
+                .finish(),
+            Self::Base64 => fmt
+                .debug_struct(stringify!(ContentTransferEncoding::Base64))
+                .finish(),
+            Self::QuotedPrintable => fmt
+                .debug_struct(stringify!(ContentTransferEncoding::QuotedPrintable))
+                .finish(),
+            Self::Other { tag } => fmt
+                .debug_struct(stringify!(ContentTransferEncoding::Other))
+                .field("tag", &String::from_utf8_lossy(tag))
+                .finish(),
+        }
+    }
+}
+
 impl std::fmt::Display for ContentTransferEncoding {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         match *self {