melib/email: add case-insensitive Header struct

- HeaderName is either 32 or less inlined bytes or heap-allocated vec for more than that.
- Equality and hashing is case-insensitive
- A HeaderMap is a hashmap from HeaderName to Strings that can be
indexed with &str, case insensitive. Insertion order is also preserved

8 files changed, 409 insertions, 159 deletions

diff --git a/melib/src/email.rs b/melib/src/email.rs
index 092603c1..9f26575a 100644
--- a/melib/src/email.rs
+++ b/melib/src/email.rs
@@ -22,7 +22,7 @@
 /*!
  * Email parsing, handling, sending etc.
  */
-use std::collections::HashMap;
+use std::convert::TryInto;
 mod compose;
 pub use self::compose::*;
 
@@ -37,7 +37,9 @@ mod address;
 pub mod parser;
 use crate::parser::BytesExt;
 pub use address::*;
+mod headers;
 pub mod signatures;
+pub use headers::*;
 
 use crate::backends::BackendOp;
 use crate::datetime::UnixTimestamp;
@@ -139,7 +141,7 @@ pub struct Envelope {
     message_id: MessageID,
     in_reply_to: Option<MessageID>,
     pub references: Option<References>,
-    other_headers: HashMap<String, String>,
+    other_headers: HeaderMap,
 
     timestamp: UnixTimestamp,
     thread: ThreadNodeHash,
@@ -153,15 +155,16 @@ pub struct Envelope {
 
 impl fmt::Debug for Envelope {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "Envelope {{\n\tsubject: {}\n\tdate: {},\n\tfrom:{:#?},\n\tto {:#?},\n\tmessage_id: {},\n\tin_reply_to: {:?}\n\treferences: {:#?},\n\thash: {}\n}}",
-               self.subject(),
-               self.date,
-               self.from,
-               self.to,
-               self.message_id_display(),
-               self.in_reply_to_display(),
-               self.references,
-               self.hash)
+        f.debug_struct("Envelope")
+            .field("Subject", &self.subject())
+            .field("Date", &self.date)
+            .field("From", &self.from)
+            .field("To", &self.to)
+            .field("Message-ID", &self.message_id_display())
+            .field("In-Reply-To", &self.in_reply_to_display())
+            .field("References", &self.references)
+            .field("Hash", &self.hash)
+            .finish()
     }
 }
 
@@ -183,17 +186,7 @@ impl Envelope {
             message_id: MessageID::default(),
             in_reply_to: None,
             references: None,
-            other_headers: [
-                ("From".to_string(), String::new()),
-                ("To".to_string(), String::new()),
-                ("Subject".to_string(), String::new()),
-                ("Date".to_string(), String::new()),
-                ("Cc".to_string(), String::new()),
-                ("Bcc".to_string(), String::new()),
-            ]
-            .iter()
-            .cloned()
-            .collect(),
+            other_headers: Default::default(),
 
             timestamp: 0,
 
@@ -253,49 +246,40 @@ impl Envelope {
         let mut in_reply_to = None;
 
         for (name, value) in headers {
-            self.other_headers.insert(
-                String::from_utf8(name.to_vec())
-                    .unwrap_or_else(|err| String::from_utf8_lossy(&err.into_bytes()).into()),
-                parser::encodings::phrase(value, false)
-                    .map(|(_, value)| {
-                        String::from_utf8(value)
-                            .unwrap_or_else(|err| String::from_utf8_lossy(&err.into_bytes()).into())
-                    })
-                    .unwrap_or_else(|_| String::from_utf8_lossy(value).into()),
-            );
-            if name.eq_ignore_ascii_case(b"to") {
+            let name: HeaderName = name.try_into()?;
+            if name == "to" {
                 let parse_result = parser::address::rfc2822address_list(value);
                 if parse_result.is_ok() {
                     let value = parse_result.unwrap().1;
                     self.set_to(value);
                 };
-            } else if name.eq_ignore_ascii_case(b"cc") {
+            } else if name == "cc" {
                 let parse_result = parser::address::rfc2822address_list(value);
                 if parse_result.is_ok() {
                     let value = parse_result.unwrap().1;
                     self.set_cc(value);
                 };
-            } else if name.eq_ignore_ascii_case(b"bcc") {
+            } else if name == "bcc" {
                 let parse_result = parser::address::rfc2822address_list(value);
                 if parse_result.is_ok() {
                     let value = parse_result.unwrap().1;
                     self.set_bcc(value.to_vec());
                 };
-            } else if name.eq_ignore_ascii_case(b"from") {
+            } else if name == "from" {
                 let parse_result = parser::address::rfc2822address_list(value);
                 if parse_result.is_ok() {
                     let value = parse_result.unwrap().1;
                     self.set_from(value);
                 }
-            } else if name.eq_ignore_ascii_case(b"subject") {
+            } else if name == "subject" {
                 let parse_result = parser::encodings::phrase(value.trim(), false);
                 if parse_result.is_ok() {
                     let value = parse_result.unwrap().1;
                     self.set_subject(value);
                 };
-            } else if name.eq_ignore_ascii_case(b"message-id") {
+            } else if name == "message-id" {
                 self.set_message_id(value);
-            } else if name.eq_ignore_ascii_case(b"references") {
+            } else if name == "references" {
                 {
                     let parse_result = parser::address::references(value);
                     if parse_result.is_ok() {
@@ -305,10 +289,10 @@ impl Envelope {
                     }
                 }
                 self.set_references(value);
-            } else if name.eq_ignore_ascii_case(b"in-reply-to") {
+            } else if name == "in-reply-to" {
                 self.set_in_reply_to(value);
                 in_reply_to = Some(value);
-            } else if name.eq_ignore_ascii_case(b"date") {
+            } else if name == "date" {
                 let parse_result = parser::encodings::phrase(value, false);
                 if parse_result.is_ok() {
                     let value = parse_result.unwrap().1;
@@ -316,7 +300,7 @@ impl Envelope {
                 } else {
                     self.set_date(value);
                 }
-            } else if name.eq_ignore_ascii_case(b"content-type") {
+            } else if name == "content-type" {
                 match parser::attachments::content_type(value) {
                     Ok((_, (ct, cst, ref params)))
                         if ct.eq_ignore_ascii_case(b"multipart")
@@ -341,6 +325,15 @@ impl Envelope {
                     _ => {}
                 }
             }
+            self.other_headers.insert(
+                name,
+                parser::encodings::phrase(value, false)
+                    .map(|(_, value)| {
+                        String::from_utf8(value)
+                            .unwrap_or_else(|err| String::from_utf8_lossy(&err.into_bytes()).into())
+                    })
+                    .unwrap_or_else(|_| String::from_utf8_lossy(value).into()),
+            );
         }
         /*
          * https://tools.ietf.org/html/rfc5322#section-3.6.4
@@ -644,11 +637,11 @@ impl Envelope {
         }
     }
 
-    pub fn other_headers(&self) -> &HashMap<String, String> {
+    pub fn other_headers(&self) -> &HeaderMap {
         &self.other_headers
     }
 
-    pub fn other_headers_mut(&mut self) -> &mut HashMap<String, String> {
+    pub fn other_headers_mut(&mut self) -> &mut HeaderMap {
         &mut self.other_headers
     }
 
diff --git a/melib/src/email/compose.rs b/melib/src/email/compose.rs
index 9984499e..0d0ca99e 100644
--- a/melib/src/email/compose.rs
+++ b/melib/src/email/compose.rs
@@ -20,11 +20,9 @@
  */
 
 use super::*;
-use crate::backends::BackendOp;
 use crate::email::attachments::AttachmentBuilder;
 use crate::shellexpand::ShellExpandTrait;
 use data_encoding::BASE64_MIME;
-use indexmap::IndexMap;
 use std::ffi::OsStr;
 use std::io::Read;
 use std::path::{Path, PathBuf};
@@ -39,7 +37,7 @@ use super::parser;
 
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub struct Draft {
-    pub headers: IndexMap<String, String>,
+    pub headers: HeaderMap,
     pub body: String,
 
     pub attachments: Vec<AttachmentBuilder>,
@@ -47,17 +45,17 @@ pub struct Draft {
 
 impl Default for Draft {
     fn default() -> Self {
-        let mut headers = IndexMap::with_capacity_and_hasher(8, Default::default());
+        let mut headers = HeaderMap::default();
         headers.insert(
-            "Date".into(),
+            HeaderName::new_unchecked("Date"),
             crate::datetime::timestamp_to_string(crate::datetime::now(), None),
         );
-        headers.insert("From".into(), "".into());
-        headers.insert("To".into(), "".into());
-        headers.insert("Cc".into(), "".into());
-        headers.insert("Bcc".into(), "".into());
+        headers.insert(HeaderName::new_unchecked("From"), "".into());
+        headers.insert(HeaderName::new_unchecked("To"), "".into());
+        headers.insert(HeaderName::new_unchecked("Cc"), "".into());
+        headers.insert(HeaderName::new_unchecked("Bcc"), "".into());
+        headers.insert(HeaderName::new_unchecked("Subject"), "".into());
 
-        headers.insert("Subject".into(), "".into());
         Draft {
             headers,
             body: String::new(),
@@ -78,20 +76,9 @@ impl str::FromStr for Draft {
         let mut ret = Draft::default();
 
         for (k, v) in headers {
-            ret.headers.insert(
-                String::from_utf8(k.to_vec())?,
-                String::from_utf8(v.to_vec())?,
-            );
-        }
-        if ret.headers.contains_key("From") && !ret.headers.contains_key("Message-ID") {
-            if let Ok((_, addr)) = super::parser::address::mailbox(ret.headers["From"].as_bytes()) {
-                if let Some(fqdn) = addr.get_fqdn() {
-                    ret.headers
-                        .insert("Message-ID".into(), random::gen_message_id(&fqdn));
-                }
-            }
+            ret.headers
+                .insert(k.try_into()?, String::from_utf8(v.to_vec())?);
         }
-
         let body = Envelope::new(0).body_bytes(s.as_bytes());
 
         ret.body = String::from_utf8(decode(&body, None))?;
@@ -101,30 +88,28 @@ impl str::FromStr for Draft {
 }
 
 impl Draft {
-    pub fn edit(envelope: &Envelope, mut op: Box<dyn BackendOp>) -> Result<Self> {
+    pub fn edit(envelope: &Envelope, bytes: &[u8]) -> Result<Self> {
         let mut ret = Draft::default();
         //TODO: Inform user if error
-        {
-            let bytes = futures::executor::block_on(op.as_bytes()?)?;
-            for (k, v) in envelope.headers(&bytes).unwrap_or_else(|_| Vec::new()) {
-                ret.headers.insert(k.into(), v.into());
-            }
+        for (k, v) in envelope.headers(&bytes).unwrap_or_else(|_| Vec::new()) {
+            ret.headers.insert(k.try_into()?, v.into());
         }
 
-        ret.body = envelope.body(op)?.text();
+        ret.body = envelope.body_bytes(bytes).text();
 
         Ok(ret)
     }
 
     pub fn set_header(&mut self, header: &str, value: String) -> &mut Self {
-        self.headers.insert(header.to_string(), value);
+        self.headers
+            .insert(HeaderName::new_unchecked(header), value);
         self
     }
 
     pub fn new_reply(envelope: &Envelope, bytes: &[u8], reply_to_all: bool) -> Self {
         let mut ret = Draft::default();
         ret.headers_mut().insert(
-            "References".into(),
+            HeaderName::new_unchecked("References"),
             format!(
                 "{} {}",
                 envelope
@@ -140,35 +125,47 @@ impl Draft {
                 envelope.message_id_display()
             ),
         );
-        ret.headers_mut()
-            .insert("In-Reply-To".into(), envelope.message_id_display().into());
+        ret.headers_mut().insert(
+            HeaderName::new_unchecked("In-Reply-To"),
+            envelope.message_id_display().into(),
+        );
         // "Mail-Followup-To/(To+Cc+(Mail-Reply-To/Reply-To/From)) for follow-up,
         // Mail-Reply-To/Reply-To/From for reply-to-author."
         // source: https://cr.yp.to/proto/replyto.html
         if reply_to_all {
             if let Some(reply_to) = envelope.other_headers().get("Mail-Followup-To") {
-                ret.headers_mut().insert("To".into(), reply_to.to_string());
+                ret.headers_mut()
+                    .insert(HeaderName::new_unchecked("To"), reply_to.to_string());
             } else {
                 if let Some(reply_to) = envelope.other_headers().get("Reply-To") {
-                    ret.headers_mut().insert("To".into(), reply_to.to_string());
-                } else {
                     ret.headers_mut()
-                        .insert("To".into(), envelope.field_from_to_string());
+                        .insert(HeaderName::new_unchecked("To"), reply_to.to_string());
+                } else {
+                    ret.headers_mut().insert(
+                        HeaderName::new_unchecked("To"),
+                        envelope.field_from_to_string(),
+                    );
                 }
                 // FIXME: add To/Cc
             }
         } else {
             if let Some(reply_to) = envelope.other_headers().get("Mail-Reply-To") {
-                ret.headers_mut().insert("To".into(), reply_to.to_string());
+                ret.headers_mut()
+                    .insert(HeaderName::new_unchecked("To"), reply_to.to_string());
             } else if let Some(reply_to) = envelope.other_headers().get("Reply-To") {
-                ret.headers_mut().insert("To".into(), reply_to.to_string());
-            } else {
                 ret.headers_mut()
-                    .insert("To".into(), envelope.field_from_to_string());
+                    .insert(HeaderName::new_unchecked("To"), reply_to.to_string());
+            } else {
+                ret.headers_mut().insert(
+                    HeaderName::new_unchecked("To"),
+                    envelope.field_from_to_string(),
+                );
             }
         }
-        ret.headers_mut()
-            .insert("Cc".into(), envelope.field_cc_to_string());
+        ret.headers_mut().insert(
+            HeaderName::new_unchecked("Cc"),
+            envelope.field_cc_to_string(),
+        );
         let body = envelope.body_bytes(bytes);
         ret.body = {
             let reply_body_bytes = decode_rec(&body, None);
@@ -177,7 +174,7 @@ impl Draft {
             let mut ret = format!(
                 "On {} {} wrote:\n",
                 envelope.date_as_str(),
-                ret.headers()["To"]
+                &ret.headers()["To"]
             );
             for l in lines {
                 ret.push('>');
@@ -191,11 +188,11 @@ impl Draft {
         ret
     }
 
-    pub fn headers_mut(&mut self) -> &mut IndexMap<String, String> {
+    pub fn headers_mut(&mut self) -> &mut HeaderMap {
         &mut self.headers
     }
 
-    pub fn headers(&self) -> &IndexMap<String, String> {
+    pub fn headers(&self) -> &HeaderMap {
         &self.headers
     }
 
@@ -219,7 +216,7 @@ impl Draft {
     pub fn to_string(&self) -> Result<String> {
         let mut ret = String::new();
 
-        for (k, v) in &self.headers {
+        for (k, v) in self.headers.deref() {
             ret.extend(format!("{}: {}\n", k, v).chars());
         }
 
@@ -236,12 +233,14 @@ impl Draft {
             if let Ok((_, addr)) = super::parser::address::mailbox(self.headers["From"].as_bytes())
             {
                 if let Some(fqdn) = addr.get_fqdn() {
-                    self.headers
-                        .insert("Message-ID".into(), random::gen_message_id(&fqdn));
+                    self.headers.insert(
+                        HeaderName::new_unchecked("Message-ID"),
+                        random::gen_message_id(&fqdn),
+                    );
                 }
             }
         }
-        for (k, v) in &self.headers {
+        for (k, v) in self.headers.deref() {
             if v.is_ascii() {
                 ret.extend(format!("{}: {}\n", k, v).chars());
             } else {
diff --git a/melib/src/email/headers.rs b/melib/src/email/headers.rs
new file mode 100644
index 00000000..4dbe9899
--- /dev/null
+++ b/melib/src/email/headers.rs
@@ -0,0 +1,288 @@
+/*
+ * meli - headers
+ *
+ * Copyright 2020 Manos Pitsidianakis
+ *
+ * This file is part of meli.
+ *
+ * meli is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * meli is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with meli. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+use crate::error::MeliError;
+use indexmap::IndexMap;
+use smallvec::SmallVec;
+use std::borrow::Borrow;
+use std::cmp::{Eq, PartialEq};
+use std::convert::TryFrom;
+use std::fmt;
+use std::hash::{Hash, Hasher};
+use std::ops::{Deref, DerefMut};
+
+#[derive(Clone, Copy, Serialize, Deserialize)]
+pub struct HeaderNameType<S>(S);
+
+///Case insensitive wrapper for a header name. As of `RFC5322` it's guaranteened to be ASCII.
+pub type HeaderName = HeaderNameType<SmallVec<[u8; 32]>>;
+
+impl HeaderName {
+    pub fn new_unchecked(from: &str) -> Self {
+        HeaderNameType(from.as_bytes().into())
+    }
+}
+
+impl<S: AsRef<[u8]>> fmt::Display for HeaderNameType<S> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.normalize())
+    }
+}
+
+impl<S: AsRef<[u8]>> fmt::Debug for HeaderNameType<S> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.as_str())
+    }
+}
+
+impl<S: AsRef<[u8]>> PartialEq<[u8]> for HeaderNameType<S> {
+    fn eq(&self, other: &[u8]) -> bool {
+        self.0.as_ref().eq_ignore_ascii_case(other)
+    }
+}
+
+impl<S: AsRef<[u8]>> PartialEq<&str> for HeaderNameType<S> {
+    fn eq(&self, other: &&str) -> bool {
+        self.0.as_ref().eq_ignore_ascii_case(other.as_bytes())
+    }
+}
+
+impl<S1: AsRef<[u8]>, S2: AsRef<[u8]>> PartialEq<HeaderNameType<S2>> for HeaderNameType<S1> {
+    fn eq(&self, other: &HeaderNameType<S2>) -> bool {
+        self.0.as_ref().eq_ignore_ascii_case(other.0.as_ref())
+    }
+}
+
+impl<S: AsRef<[u8]>> Eq for HeaderNameType<S> {}
+
+impl<S: AsRef<[u8]>> Hash for HeaderNameType<S> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        for b in self.0.as_ref().iter() {
+            b.to_ascii_lowercase().hash(state);
+        }
+    }
+}
+
+impl TryFrom<&[u8]> for HeaderName {
+    type Error = MeliError;
+
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
+        if value.is_ascii() {
+            Ok(HeaderNameType(value.into()))
+        } else {
+            Err(MeliError::new(format!(
+                "Header value is not ascii: {:?}",
+                value
+            )))
+        }
+    }
+}
+
+impl TryFrom<&str> for HeaderName {
+    type Error = MeliError;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        if value.is_ascii() {
+            Ok(HeaderNameType(value.as_bytes().into()))
+        } else {
+            Err(MeliError::new(format!(
+                "Header value is not ascii: {:?}",
+                value
+            )))
+        }
+    }
+}
+
+trait HeaderKey {
+    fn to_key(&self) -> &[u8];
+}
+
+impl Hash for dyn HeaderKey + '_ {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        for b in self.to_key().iter() {
+            b.to_ascii_lowercase().hash(state);
+        }
+    }
+}
+
+impl PartialEq for dyn HeaderKey + '_ {
+    fn eq(&self, other: &Self) -> bool {
+        self.to_key().eq_ignore_ascii_case(other.to_key())
+    }
+}
+
+impl Eq for dyn HeaderKey + '_ {}
+
+impl<S: AsRef<[u8]>> HeaderKey for HeaderNameType<S> {
+    fn to_key(&self) -> &[u8] {
+        self.0.as_ref()
+    }
+}
+
+//Implement Borrow for all the lookup types as returning our trait object:
+
+impl<'a> Borrow<dyn HeaderKey + 'a> for HeaderName {
+    fn borrow(&self) -> &(dyn HeaderKey + 'a) {
+        self
+    }
+}
+
+impl<S: AsRef<[u8]>> HeaderNameType<S> {
+    pub fn as_str(&self) -> &str {
+        //HeadersType are ascii so valid utf8
+        unsafe { std::str::from_utf8_unchecked(self.0.as_ref()) }
+    }
+
+    pub fn normalize(&self) -> &str {
+        if self == &b"subject"[..] {
+            "Subject"
+        } else if self == &b"from"[..] {
+            "From"
+        } else if self == &b"to"[..] {
+            "To"
+        } else if self == &b"cc"[..] {
+            "Cc"
+        } else if self == &b"bcc"[..] {
+            "Bcc"
+        } else if self == &b"reply-to"[..] {
+            "Reply-To"
+        } else if self == &b"in-reply-to"[..] {
+            "In-Reply-To"
+        } else if self == &b"references"[..] {
+            "References"
+        } else if self == &b"sender"[..] {
+            "Sender"
+        } else if self == &b"mail-reply-to"[..] {
+            "Mail-Reply-To"
+        } else if self == &b"mail-followup-to"[..] {
+            "Mail-Followup-To"
+        } else if self == &b"mime-version"[..] {
+            "MIME-Version"
+        } else if self == &b"content-disposition"[..] {
+            "Content-Disposition"
+        } else if self == &b"content-transfer-encoding"[..] {
+            "Content-Transfer-Encoding"
+        } else if self == &b"content-type"[..] {
+            "Content-Type"
+        } else if self == &b"content-id"[..] {
+            "Content-ID"
+        } else if self == &b"content-description"[..] {
+            "Content-Description"
+        } else if self == &b"authentication-results"[..] {
+            "Authentication-Results"
+        } else if self == &b"dkim-signature"[..] {
+            "DKIM-Signature"
+        } else if self == &b"delivered-to"[..] {
+            "Delivered-To"
+        } else if self == &b"message-id"[..] {
+            "Message-ID"
+        } else if self == &b"comments"[..] {
+            "Comments"
+        } else if self == &b"keywords"[..] {
+            "Keywords"
+        } else if self == &b"resent-from"[..] {
+            "Resent-From"
+        } else if self == &b"resent-sender"[..] {
+            "Resent-Sender"
+        } else if self == &b"resent-to"[..] {
+            "Resent-To"
+        } else if self == &b"resent-cc"[..] {
+            "Resent-Cc"
+        } else if self == &b"resent-bcc"[..] {
+            "Resent-Bcc"
+        } else if self == &b"resent-date"[..] {
+            "Resent-Date"
+        } else if self == &b"resent-message-id"[..] {
+            "Resent-Message-ID"
+        } else if self == &b"resent-reply-to"[..] {
+            "Resent-Reply-To"
+        } else if self == &b"return-path"[..] {
+            "Return-Path"
+        } else if self == &b"received"[..] {
+            "Received"
+        } else {
+            self.as_str()
+        }
+    }
+}
+
+#[derive(Debug, Default, PartialEq, Eq, Clone, Serialize, Deserialize)]
+pub struct HeaderMap(indexmap::IndexMap<HeaderName, String>);
+
+impl std::ops::Index<&[u8]> for HeaderMap {
+    type Output = str;
+    fn index(&self, k: &[u8]) -> &Self::Output {
+        (self.0)[HeaderNameType(k).borrow() as &dyn HeaderKey].as_str()
+    }
+}
+
+impl std::ops::Index<&str> for HeaderMap {
+    type Output = str;
+    fn index(&self, k: &str) -> &Self::Output {
+        (self.0)[HeaderNameType(k).borrow() as &dyn HeaderKey].as_str()
+    }
+}
+
+impl HeaderMap {
+    pub fn get_mut(&mut self, key: &str) -> Option<&mut String> {
+        (self.0).get_mut(HeaderNameType(key).borrow() as &dyn HeaderKey)
+    }
+
+    pub fn get(&self, key: &str) -> Option<&String> {
+        (self.0).get(HeaderNameType(key).borrow() as &dyn HeaderKey)
+    }
+
+    pub fn contains_key(&self, key: &str) -> bool {
+        (self.0).contains_key(HeaderNameType(key).borrow() as &dyn HeaderKey)
+    }
+
+    pub fn remove(&mut self, key: &str) -> Option<String> {
+        (self.0).remove(HeaderNameType(key).borrow() as &dyn HeaderKey)
+    }
+}
+
+impl Deref for HeaderMap {
+    type Target = IndexMap<HeaderName, String>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for HeaderMap {
+    fn deref_mut(&mut self) -> &mut IndexMap<HeaderName, String> {
+        &mut self.0
+    }
+}
+
+#[test]
+fn test_headers_case_sensitivity() {
+    use std::convert::TryInto;
+    let mut headers = HeaderMap::default();
+    headers.insert("from".try_into().unwrap(), "Myself <a@b.c>".into());
+    assert_eq!(&headers["From"], "Myself <a@b.c>");
+    assert_eq!(&headers["From"], &headers["from"]);
+    assert_eq!(&headers["fROm"], &headers["from"]);
+    headers.get_mut("from").unwrap().pop();
+    assert_eq!(&headers["From"], "Myself <a@b.c");
+    headers.insert("frOM".try_into().unwrap(), "nada".into());
+    assert_eq!(&headers["fROm"], "nada");
+}
diff --git a/src/components/mail/compose.rs b/src/components/mail/compose.rs
index 78f3dfa1..eed9afba 100644
--- a/src/components/mail/compose.rs
+++ b/src/components/mail/compose.rs
@@ -137,7 +137,7 @@ impl fmt::Display for Composer {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         // TODO display subject/info
         if self.reply_context.is_some() {
-            write!(f, "reply: {:8}", self.draft.headers()["Subject"])
+            write!(f, "reply: {:8}", &self.draft.headers()["Subject"])
         } else {
             write!(f, "composing")
         }
@@ -158,21 +158,11 @@ impl Composer {
             if v.is_empty() {
                 continue;
             }
-            if let Some(k) = ret
-                .draft
-                .headers()
-                .keys()
-                .find(|k| k.eq_ignore_ascii_case(h))
-            {
-                let _k = k.clone();
-                ret.draft.headers_mut().insert(_k, v.into());
-            } else {
-                ret.draft.set_header(h, v.into());
-            }
+            ret.draft.set_header(h, v.into());
         }
         if *mailbox_acc_settings!(context[account_hash].composing.insert_user_agent) {
             ret.draft.set_header(
-                "User-Agent".into(),
+                "User-Agent",
                 format!("meli {}", option_env!("CARGO_PKG_VERSION").unwrap_or("0.0")),
             );
         }
@@ -181,14 +171,18 @@ impl Composer {
         ret
     }
 
-    pub fn edit(new_account_hash: AccountHash, h: EnvelopeHash, context: &Context) -> Result<Self> {
+    pub fn edit(
+        account_hash: AccountHash,
+        env_hash: EnvelopeHash,
+        bytes: &[u8],
+        context: &Context,
+    ) -> Result<Self> {
         let mut ret = Composer::default();
-        let op = context.accounts[&new_account_hash].operation(h)?;
-        let envelope: EnvelopeRef = context.accounts[&new_account_hash].collection.get_env(h);
+        let envelope: EnvelopeRef = context.accounts[&account_hash].collection.get_env(env_hash);
 
-        ret.draft = Draft::edit(&envelope, op)?;
+        ret.draft = Draft::edit(&envelope, bytes)?;
 
-        ret.account_hash = new_account_hash;
+        ret.account_hash = account_hash;
         Ok(ret)
     }
 
@@ -202,16 +196,16 @@ impl Composer {
         let account = &context.accounts[&coordinates.0];
         let envelope = account.collection.get_env(coordinates.2);
         let subject = envelope.subject();
-        ret.draft.headers_mut().insert(
-            "Subject".into(),
+        ret.draft.set_header(
+            "Subject",
             if !subject.starts_with("Re: ") {
                 format!("Re: {}", subject)
             } else {
                 subject.into()
             },
         );
-        ret.draft.headers_mut().insert(
-            "References".into(),
+        ret.draft.set_header(
+            "References",
             format!(
                 "{} {}",
                 envelope
@@ -228,8 +222,7 @@ impl Composer {
             ),
         );
         ret.draft
-            .headers_mut()
-            .insert("In-Reply-To".into(), envelope.message_id_display().into());
+            .set_header("In-Reply-To", envelope.message_id_display().into());
 
         // "Mail-Followup-To/(To+Cc+(Mail-Reply-To/Reply-To/From)) for follow-up,
         // Mail-Reply-To/Reply-To/From for reply-to-author."
@@ -274,7 +267,7 @@ impl Composer {
             {
                 to.remove(&ours);
             }
-            ret.draft.headers_mut().insert("To".into(), {
+            ret.draft.set_header("To", {
                 let mut ret: String =
                     to.into_iter()
                         .fold(String::new(), |mut s: String, n: Address| {
@@ -286,22 +279,14 @@ impl Composer {
                 ret.pop();
                 ret
             });
-            ret.draft
-                .headers_mut()
-                .insert("Cc".into(), envelope.field_cc_to_string());
+            ret.draft.set_header("Cc", envelope.field_cc_to_string());
         } else {
             if let Some(reply_to) = envelope.other_headers().get("Mail-Reply-To") {
-                ret.draft
-                    .headers_mut()
-                    .insert("To".into(), reply_to.to_string());
+                ret.draft.set_header("To", reply_to.to_string());
             } else if let Some(reply_to) = envelope.other_headers().get("Reply-To") {
-                ret.draft
-                    .headers_mut()
-                    .insert("To".into(), reply_to.to_string());
+                ret.draft.set_header("To", reply_to.to_string());
             } else {
-                ret.draft
-                    .headers_mut()
-                    .insert("To".into(), envelope.field_from_to_string());
+                ret.draft.set_header("To", envelope.field_from_to_string());
             }
         }
         let body = envelope.body_bytes(bytes);
@@ -399,7 +384,7 @@ impl Composer {
         let header_values = self.form.values_mut();
         let draft_header_map = self.draft.headers_mut();
         for (k, v) in draft_header_map.iter_mut() {
-            if let Some(ref vn) = header_values.get(k) {
+            if let Some(ref vn) = header_values.get(k.as_str()) {
                 *v = vn.as_str().to_string();
             }
         }
@@ -537,8 +522,8 @@ impl Component for Composer {
             }
             if !self.draft.headers().contains_key("From") || self.draft.headers()["From"].is_empty()
             {
-                self.draft.headers_mut().insert(
-                    "From".into(),
+                self.draft.set_header(
+                    "From",
                     crate::components::mail::get_display_name(context, self.account_hash),
                 );
             }
@@ -798,8 +783,7 @@ impl Component for Composer {
             ) if selector.id() == *id => {
                 if let Some(to_val) = result.downcast_mut::<String>() {
                     self.draft
-                        .headers_mut()
-                        .insert("To".to_string(), std::mem::replace(to_val, String::new()));
+                        .set_header("To", std::mem::replace(to_val, String::new()));
                     self.update_form();
                 }
                 self.mode = ViewMode::Edit;
diff --git a/src/components/mail/view.rs b/src/components/mail/view.rs
index ca61fa6d..f39301a3 100644
--- a/src/components/mail/view.rs
+++ b/src/components/mail/view.rs
@@ -1563,8 +1563,8 @@ impl Component for MailView {
                                     list_management::ListAction::Email(email) => {
                                         if let Ok(mailto) = Mailto::try_from(*email) {
                                             let mut draft: Draft = mailto.into();
-                                            draft.headers_mut().insert(
-                                                "From".into(),
+                                            draft.set_header(
+                                                "From",
                                                 crate::components::mail::get_display_name(
                                                     context,
                                                     self.coordinates.0,
diff --git a/src/components/utilities.rs b/src/components/utilities.rs
index f7f03e99..be1b8a52 100644
--- a/src/components/utilities.rs
+++ b/src/components/utilities.rs
@@ -1675,7 +1675,8 @@ impl Component for Tabbed {
                 self.help_curr_views = children_maps;
                 return true;
             }
-            UIEvent::Action(Tab(Edit(account_hash, msg))) => {
+            UIEvent::Action(Tab(Edit(_, _))) => {
+                /* FIXME
                 let composer = match Composer::edit(*account_hash, *msg, context) {
                     Ok(c) => c,
                     Err(e) => {
@@ -1704,6 +1705,7 @@ impl Component for Tabbed {
                 let mut children_maps = self.children[self.cursor_pos].get_shortcuts(context);
                 children_maps.extend(self.get_shortcuts(context));
                 self.help_curr_views = children_maps;
+                */
                 return true;
             }
             UIEvent::Action(Tab(New(ref mut e))) if e.is_some() => {
diff --git a/tests/generated.mail b/tests/generated.mail
index 267c23a0..20f23ff0 100644
--- a/tests/generated.mail
+++ b/tests/generated.mail
@@ -1,8 +1,8 @@
+Subject: 
 From: 
 To: 
 Cc: 
 Bcc: 
-Subject: 
 MIME-Version: 1.0
 Content-Type: multipart/mixed; charset="utf-8"; boundary="bzz_bzz__bzz__"
 
diff --git a/tests/generating_email.rs b/tests/generating_email.rs
index c0acd498..04b94a9d 100644
--- a/tests/generating_email.rs
+++ b/tests/generating_email.rs
@@ -15,24 +15,8 @@ fn build_draft() {
             _ => {}
         }
     }