melib: create address.rs from email.rs

2 files changed, 833 insertions, 0 deletions

diff --git a/melib/src/email.rs b/melib/src/email/address.rs
index 1775cb5e..1775cb5e 100644
--- a/melib/src/email.rs
+++ b/melib/src/email/address.rs
diff --git a/melib/src/email/mod.rs b/melib/src/email/mod.rs
new file mode 100644
index 00000000..1775cb5e
--- /dev/null
+++ b/melib/src/email/mod.rs
@@ -0,0 +1,833 @@
+/*
+ * meli - email module
+ *
+ * Copyright 2017 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/>.
+ */
+
+/*!
+ * Email parsing, handling, sending etc.
+ */
+use fnv::FnvHashMap;
+mod compose;
+pub use self::compose::*;
+
+mod mailto;
+pub use mailto::*;
+mod attachment_types;
+pub mod attachments;
+pub use crate::attachments::*;
+pub mod parser;
+use crate::parser::BytesExt;
+
+use crate::backends::BackendOp;
+use crate::error::{MeliError, Result};
+use crate::thread::ThreadHash;
+
+use std::borrow::Cow;
+use std::cmp::Ordering;
+use std::collections::hash_map::DefaultHasher;
+use std::fmt;
+use std::hash::Hasher;
+use std::option::Option;
+use std::str;
+use std::string::String;
+
+use chrono;
+use chrono::TimeZone;
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct GroupAddress {
+    pub raw: Vec<u8>,
+    pub display_name: StrBuilder,
+    pub mailbox_list: Vec<Address>,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct MailboxAddress {
+    pub raw: Vec<u8>,
+    pub display_name: StrBuilder,
+    pub address_spec: StrBuilder,
+}
+
+#[derive(Clone, Serialize, Deserialize)]
+pub enum Address {
+    Mailbox(MailboxAddress),
+    Group(GroupAddress),
+}
+
+impl Address {
+    pub fn get_display_name(&self) -> String {
+        match self {
+            Address::Mailbox(m) => m.display_name.display(&m.raw),
+            Address::Group(g) => g.display_name.display(&g.raw),
+        }
+    }
+
+    pub fn get_email(&self) -> String {
+        match self {
+            Address::Mailbox(m) => m.address_spec.display(&m.raw),
+            Address::Group(_) => String::new(),
+        }
+    }
+    pub fn get_fqdn(&self) -> Option<String> {
+        match self {
+            Address::Mailbox(m) => {
+                let raw_address = m.address_spec.display_bytes(&m.raw);
+                let fqdn_pos = raw_address.iter().position(|&b| b == b'@')? + 1;
+                Some(String::from_utf8_lossy(&raw_address[fqdn_pos..]).into())
+            }
+            Address::Group(_) => None,
+        }
+    }
+}
+
+impl Eq for Address {}
+impl PartialEq for Address {
+    fn eq(&self, other: &Address) -> bool {
+        match (self, other) {
+            (Address::Mailbox(_), Address::Group(_)) | (Address::Group(_), Address::Mailbox(_)) => {
+                false
+            }
+            (Address::Mailbox(s), Address::Mailbox(o)) => {
+                s.address_spec.display_bytes(&s.raw) == o.address_spec.display_bytes(&o.raw)
+            }
+            (Address::Group(s), Address::Group(o)) => {
+                s.display_name.display_bytes(&s.raw) == o.display_name.display_bytes(&o.raw)
+                    && s.mailbox_list
+                        .iter()
+                        .zip(o.mailbox_list.iter())
+                        .fold(true, |b, (s, o)| b && (s == o))
+            }
+        }
+    }
+}
+
+impl fmt::Display for Address {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Address::Mailbox(m) if m.display_name.length > 0 => write!(
+                f,
+                "{} <{}>",
+                m.display_name.display(&m.raw),
+                m.address_spec.display(&m.raw)
+            ),
+            Address::Group(g) => {
+                let attachment_strings: Vec<String> =
+                    g.mailbox_list.iter().map(|a| format!("{}", a)).collect();
+                write!(
+                    f,
+                    "{}: {}",
+                    g.display_name.display(&g.raw),
+                    attachment_strings.join(", ")
+                )
+            }
+            Address::Mailbox(m) => write!(f, "{}", m.address_spec.display(&m.raw)),
+        }
+    }
+}
+
+impl fmt::Debug for Address {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(self, f)
+    }
+}
+
+/// Helper struct to return slices from a struct field on demand.
+#[derive(Clone, Debug, Serialize, Deserialize, Default)]
+pub struct StrBuilder {
+    pub offset: usize,
+    pub length: usize,
+}
+
+/// Structs implementing this trait must contain a `StrBuilder` field.
+pub trait StrBuild {
+    /// Create a new `Self` out of a string and a slice
+    fn new(string: &[u8], slice: &[u8]) -> Self;
+    /// Get the slice part of the string
+    fn raw(&self) -> &[u8];
+    /// Get the entire string as a slice
+    fn val(&self) -> &[u8];
+}
+
+impl StrBuilder {
+    fn display<'a>(&self, s: &'a [u8]) -> String {
+        let offset = self.offset;
+        let length = self.length;
+        String::from_utf8(s[offset..offset + length].to_vec()).unwrap()
+    }
+    fn display_bytes<'a>(&self, b: &'a [u8]) -> &'a [u8] {
+        &b[self.offset..(self.offset + self.length)]
+    }
+}
+
+/// `MessageID` is accessed through the `StrBuild` trait.
+#[derive(Clone, Serialize, Deserialize, Default)]
+pub struct MessageID(pub Vec<u8>, pub StrBuilder);
+
+impl StrBuild for MessageID {
+    fn new(string: &[u8], slice: &[u8]) -> Self {
+        let offset = string.find(slice).unwrap();
+        MessageID(
+            string.to_owned(),
+            StrBuilder {
+                offset,
+                length: slice.len() + 1,
+            },
+        )
+    }
+    fn raw(&self) -> &[u8] {
+        let offset = self.1.offset;
+        let length = self.1.length;
+        &self.0[offset..offset + length.saturating_sub(1)]
+    }
+    fn val(&self) -> &[u8] {
+        &self.0
+    }
+}
+
+#[test]
+fn test_strbuilder() {
+    let m_id = b"<20170825132332.6734-1@el13635@mail.ntua.gr>";
+    let (_, slice) = parser::message_id(m_id).unwrap();
+    assert_eq!(
+        MessageID::new(m_id, slice),
+        MessageID(
+            m_id.to_vec(),
+            StrBuilder {
+                offset: 1,
+                length: 43,
+            }
+        )
+    );
+}
+
+impl fmt::Display for MessageID {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.val().is_ascii() {
+            write!(f, "{}", unsafe { str::from_utf8_unchecked(self.val()) })
+        } else {
+            write!(f, "{}", String::from_utf8_lossy(self.val()))
+        }
+    }
+}
+
+impl PartialEq for MessageID {
+    fn eq(&self, other: &MessageID) -> bool {
+        self.raw() == other.raw()
+    }
+}
+impl fmt::Debug for MessageID {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", String::from_utf8(self.raw().to_vec()).unwrap())
+    }
+}
+
+#[derive(Clone, Serialize, Deserialize)]
+struct References {
+    raw: Vec<u8>,
+    refs: Vec<MessageID>,
+}
+
+impl fmt::Debug for References {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:#?}", self.refs)
+    }
+}
+
+bitflags! {
+    #[derive(Default, Serialize, Deserialize)]
+    pub struct Flag: u8 {
+        const PASSED  =  0b0000_0001;
+        const REPLIED =  0b0000_0010;
+        const SEEN    =  0b0000_0100;
+        const TRASHED =  0b0000_1000;
+        const DRAFT   =  0b0001_0000;
+        const FLAGGED =  0b0010_0000;
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct EnvelopeWrapper {
+    envelope: Envelope,
+    buffer: Vec<u8>,
+}
+
+use std::ops::Deref;
+
+impl Deref for EnvelopeWrapper {
+    type Target = Envelope;
+
+    fn deref(&self) -> &Envelope {
+        &self.envelope
+    }
+}
+
+impl EnvelopeWrapper {
+    pub fn new(buffer: Vec<u8>) -> Result<Self> {
+        Ok(EnvelopeWrapper {
+            envelope: Envelope::from_bytes(&buffer, None)?,
+            buffer,
+        })
+    }
+
+    pub fn update(&mut self, new_buffer: Vec<u8>) {
+        // TODO: Propagate error.
+        if let Ok(e) = EnvelopeWrapper::new(new_buffer) {
+            *self = e;
+        }
+    }
+
+    pub fn envelope(&self) -> &Envelope {
+        &self.envelope
+    }
+    pub fn buffer(&self) -> &[u8] {
+        &self.buffer
+    }
+}
+
+pub type UnixTimestamp = u64;
+pub type EnvelopeHash = u64;
+
+/// `Envelope` represents all the data of an email we need to know.
+///
+///  Attachments (the email's body) is parsed on demand with `body`.
+///
+///  Access to the underlying email object in the account's backend (for example the file or the
+///  entry in an IMAP server) is given through `operation_token`. For more information see
+///  `BackendOp`.
+#[derive(Clone, Default, Serialize, Deserialize)]
+pub struct Envelope {
+    date: String,
+    from: Vec<Address>,
+    to: Vec<Address>,
+    cc: Vec<Address>,
+    bcc: Vec<Address>,
+    subject: Option<Vec<u8>>,
+    message_id: MessageID,
+    in_reply_to: Option<MessageID>,
+    references: Option<References>,
+    other_headers: FnvHashMap<String, String>,
+
+    timestamp: UnixTimestamp,
+    thread: ThreadHash,
+
+    hash: EnvelopeHash,
+
+    flags: Flag,
+    has_attachments: bool,
+}
+
+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)
+    }
+}
+
+impl Envelope {
+    pub fn new(hash: EnvelopeHash) -> Self {
+        Envelope {
+            date: String::new(),
+            from: Vec::new(),
+            to: Vec::new(),
+            cc: Vec::new(),
+            bcc: Vec::new(),
+            subject: None,
+            message_id: MessageID::default(),
+            in_reply_to: None,
+            references: None,
+            other_headers: FnvHashMap::default(),
+
+            timestamp: 0,
+
+            thread: ThreadHash::null(),
+
+            hash,
+            has_attachments: false,
+            flags: Flag::default(),
+        }
+    }
+
+    pub fn set_hash(&mut self, new_hash: EnvelopeHash) {
+        self.hash = new_hash;
+    }
+
+    pub fn from_bytes(bytes: &[u8], flags: Option<Flag>) -> Result<Envelope> {
+        let mut h = DefaultHasher::new();
+        h.write(bytes);
+        let mut e = Envelope::new(h.finish());
+        let res = e.populate_headers(bytes).ok();
+        if res.is_some() {
+            if let Some(f) = flags {
+                e.flags = f;
+            }
+            return Ok(e);
+        }
+        Err(MeliError::new("Couldn't parse mail."))
+    }
+    pub fn from_token(mut operation: Box<dyn BackendOp>, hash: EnvelopeHash) -> Option<Envelope> {
+        let mut e = Envelope::new(hash);
+        e.flags = operation.fetch_flags();
+        if let Ok(bytes) = operation.as_bytes() {
+            let res = e.populate_headers(bytes).ok();
+            if res.is_some() {
+                return Some(e);
+            }
+        }
+        None
+    }
+    pub fn hash(&self) -> EnvelopeHash {
+        self.hash
+    }
+    pub fn populate_headers(&mut self, bytes: &[u8]) -> Result<()> {
+        let (headers, body) = match parser::mail(bytes).to_full_result() {
+            Ok(v) => v,
+            Err(e) => {
+                debug!("error in parsing mail\n{:?}\n", e);
+                let error_msg = String::from("Mail cannot be shown because of errors.");
+                return Err(MeliError::new(error_msg));
+            }
+        };
+        let mut in_reply_to = None;
+
+        for (name, value) in headers {
+            if value.len() == 1 && value.is_empty() {
+                continue;
+            }
+            if name.eq_ignore_ascii_case(b"to") {
+                let parse_result = parser::rfc2822address_list(value);
+                if parse_result.is_done() {
+                    let value = parse_result.to_full_result().unwrap();
+                    self.set_to(value);
+                };
+            } else if name.eq_ignore_ascii_case(b"cc") {
+                let parse_result = parser::rfc2822address_list(value);
+                if parse_result.is_done() {
+                    let value = parse_result.to_full_result().unwrap();
+                    self.set_cc(value);
+                };
+            } else if name.eq_ignore_ascii_case(b"bcc") {
+                let parse_result = parser::rfc2822address_list(value);
+                if parse_result.is_done() {
+                    let value = parse_result.to_full_result().unwrap();
+                    self.set_bcc(value);
+                };
+            } else if name.eq_ignore_ascii_case(b"from") {
+                let parse_result = parser::rfc2822address_list(value);
+                if parse_result.is_done() {
+                    let value = parse_result.to_full_result().unwrap();
+                    self.set_from(value);
+                }
+            } else if name.eq_ignore_ascii_case(b"subject") {
+                let parse_result = parser::phrase(value.trim());
+                if parse_result.is_done() {
+                    let value = parse_result.to_full_result().unwrap();
+                    self.set_subject(value);
+                };
+            } else if name.eq_ignore_ascii_case(b"message-id") {
+                self.set_message_id(value);
+            } else if name.eq_ignore_ascii_case(b"references") {
+                {
+                    let parse_result = parser::references(value);
+                    if parse_result.is_done() {
+                        for v in parse_result.to_full_result().unwrap() {
+                            self.push_references(v);
+                        }
+                    }
+                }
+                self.set_references(value);
+            } else if name.eq_ignore_ascii_case(b"in-reply-to") {
+                self.set_in_reply_to(value);
+                in_reply_to = Some(value);
+            } else if name.eq_ignore_ascii_case(b"date") {
+                let parse_result = parser::phrase(value);
+                if parse_result.is_done() {
+                    let value = parse_result.to_full_result().unwrap();
+                    self.set_date(value.as_slice());
+                } else {
+                    self.set_date(value);
+                }
+            } else if name.eq_ignore_ascii_case(b"content-type") {
+                match parser::content_type(value).to_full_result() {
+                    Ok((ct, cst, _))
+                        if ct.eq_ignore_ascii_case(b"multipart")
+                            && cst.eq_ignore_ascii_case(b"mixed") =>
+                    {
+                        let mut builder = AttachmentBuilder::new(body);
+                        builder.set_content_type_from_bytes(value);
+                        let b = builder.build();
+                        let subs = b.attachments();
+
+                        self.has_attachments = subs.iter().any(|sub| !sub.is_text());
+                    }
+                    _ => {}
+                }
+            } else {
+                self.other_headers.insert(
+                    String::from_utf8_lossy(name).into(),
+                    String::from_utf8_lossy(value).into(),
+                );
+            }
+        }
+        /*
+         * https://tools.ietf.org/html/rfc5322#section-3.6.4
+         *
+         * if self.message_id.is_none()  ...
+         */
+        if let Some(ref mut x) = in_reply_to {
+            self.push_references(x);
+        }
+        if let Some(d) = parser::date(&self.date.as_bytes()) {
+            self.set_datetime(d);
+        }
+        if self.message_id.raw().is_empty() {
+            let hash = self.hash;
+            self.set_message_id(format!("<{:x}>", hash).as_bytes());
+        }
+        if self.references.is_some() {
+            if let Some(pos) = self
+                .references
+                .as_ref()
+                .map(|r| &r.refs)
+                .unwrap()
+                .iter()
+                .position(|r| r == &self.message_id)
+            {
+                self.references.as_mut().unwrap().refs.remove(pos);
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn populate_headers_from_token(&mut self, mut operation: Box<dyn BackendOp>) -> Result<()> {
+        let headers = operation.fetch_headers()?;
+        self.populate_headers(headers)
+    }
+    pub fn date(&self) -> UnixTimestamp {
+        self.timestamp
+    }
+
+    pub fn datetime(&self) -> chrono::DateTime<chrono::FixedOffset> {
+        if let Some(d) = parser::date(&self.date.as_bytes()) {
+            return d;
+        }
+        chrono::FixedOffset::west(0)
+            .ymd(1970, 1, 1)
+            .and_hms(0, 0, 0)
+    }
+    pub fn date_as_str(&self) -> &str {
+        &self.date
+    }
+    pub fn from(&self) -> &Vec<Address> {
+        &self.from
+    }
+    pub fn field_bcc_to_string(&self) -> String {
+        let _strings: Vec<String> = self.bcc.iter().map(|a| format!("{}", a)).collect();
+        _strings.join(", ")
+    }
+    pub fn field_cc_to_string(&self) -> String {
+        let _strings: Vec<String> = self.cc.iter().map(|a| format!("{}", a)).collect();
+        _strings.join(", ")
+    }
+    pub fn field_from_to_string(&self) -> String {
+        let _strings: Vec<String> = self.from().iter().map(|a| format!("{}", a)).collect();
+        _strings.join(", ")
+    }
+    pub fn to(&self) -> &Vec<Address> {
+        &self.to
+    }
+    pub fn field_to_to_string(&self) -> String {
+        let _strings: Vec<String> = self.to.iter().map(|a| format!("{}", a)).collect();
+        _strings.join(", ")
+    }
+    pub fn bytes(&self, mut operation: Box<dyn BackendOp>) -> Vec<u8> {
+        operation
+            .as_bytes()
+            .map(|v| v.into())
+            .unwrap_or_else(|_| Vec::new())
+    }
+    pub fn body_bytes(&self, bytes: &[u8]) -> Attachment {
+        if bytes.is_empty() {
+            let builder = AttachmentBuilder::new(bytes);
+            return builder.build();
+        }
+
+        let (headers, body) = match parser::mail(bytes).to_full_result() {
+            Ok(v) => v,
+            Err(_) => {
+                debug!("error in parsing mail\n");
+                let error_msg = b"Mail cannot be shown because of errors.";
+                let builder = AttachmentBuilder::new(error_msg);
+                return builder.build();
+            }
+        };
+        let mut builder = AttachmentBuilder::new(body);
+        for (name, value) in headers {
+            if value.len() == 1 && value.is_empty() {
+                continue;
+            }
+            if name.eq_ignore_ascii_case(b"content-transfer-encoding") {
+                builder.set_content_transfer_encoding(ContentTransferEncoding::from(value));
+            } else if name.eq_ignore_ascii_case(b"content-type") {
+                builder.set_content_type_from_bytes(value);
+            }
+        }
+        builder.build()
+    }
+    pub fn headers<'a>(&self, bytes: &'a [u8]) -> Result<Vec<(&'a str, &'a str)>> {
+        let ret = parser::headers(bytes).to_full_result()?;
+        let len = ret.len();
+        ret.into_iter()
+            .try_fold(Vec::with_capacity(len), |mut acc, (a, b)| {
+                Ok({
+                    acc.push((std::str::from_utf8(a)?, std::str::from_utf8(b)?));
+                    acc
+                })
+            })
+    }
+    pub fn body(&self, mut operation: Box<dyn BackendOp>) -> Attachment {
+        debug!("searching body for {:?}", self.message_id_display());
+        let file = operation.as_bytes();
+        self.body_bytes(file.unwrap())
+        /*
+        let (headers, body) = match parser::mail(file.unwrap()).to_full_result() {
+            Ok(v) => v,
+            Err(_) => {
+            debug!("2error in parsing mail\n");
+                let error_msg = b"Mail cannot be shown because of errors.";
+                let mut builder = AttachmentBuilder::new(error_msg);
+                return builder.build();
+            }
+        };
+        let mut builder = AttachmentBuilder::new(body);
+        for (name, value) in headers {
+            if value.len() == 1 && value.is_empty() {
+                continue;
+            }
+            if name.eq_ignore_ascii_case(b"content-transfer-encoding") {
+                builder.content_transfer_encoding(value);
+            } else if name.eq_ignore_ascii_case(b"content-type") {
+                builder.content_type(value);
+            }
+        }
+        builder.build()
+        */
+    }
+    pub fn subject(&self) -> Cow<str> {
+        match self.subject {
+            Some(ref s) => String::from_utf8_lossy(s),
+            _ => Cow::from(String::new()),
+        }
+    }
+    pub fn in_reply_to(&self) -> Option<&MessageID> {
+        self.in_reply_to.as_ref()
+    }
+    pub fn in_reply_to_display(&self) -> Option<Cow<str>> {
+        if let Some(ref m) = self.in_reply_to {
+            Some(String::from_utf8_lossy(m.val()))
+        } else {
+            None
+        }
+    }
+    pub fn in_reply_to_raw(&self) -> Option<Cow<str>> {
+        if let Some(ref m) = self.in_reply_to {
+            Some(String::from_utf8_lossy(m.raw()))
+        } else {
+            None
+        }
+    }
+    pub fn message_id(&self) -> &MessageID {
+        &self.message_id
+    }
+    pub fn message_id_display(&self) -> Cow<str> {
+        String::from_utf8_lossy(self.message_id.val())
+    }
+    pub fn message_id_raw(&self) -> Cow<str> {
+        String::from_utf8_lossy(self.message_id.raw())
+    }
+    pub fn set_date(&mut self, new_val: &[u8]) {
+        self.date = String::from_utf8_lossy(new_val).into_owned();
+    }
+    pub fn set_bcc(&mut self, new_val: Vec<Address>) {
+        self.bcc = new_val;
+    }
+    pub fn set_cc(&mut self, new_val: Vec<Address>) {
+        self.cc = new_val;
+    }
+    pub fn set_from(&mut self, new_val: Vec<Address>) {
+        self.from = new_val;
+    }
+    pub fn set_to(&mut self, new_val: Vec<Address>) {
+        self.to = new_val;
+    }
+    pub fn set_in_reply_to(&mut self, new_val: &[u8]) {
+        let slice = match parser::message_id(new_val).to_full_result() {
+            Ok(v) => v,
+            Err(_) => {
+                self.in_reply_to = None;
+                return;
+            }
+        };
+        self.in_reply_to = Some(MessageID::new(new_val, slice));
+    }
+    pub fn set_subject(&mut self, new_val: Vec<u8>) {
+        self.subject = Some(new_val);
+    }
+    pub fn set_message_id(&mut self, new_val: &[u8]) {
+        let slice = match parser::message_id(new_val).to_full_result() {
+            Ok(v) => v,
+            Err(e) => {
+                debug!(e);
+                return;
+            }
+        };
+        self.message_id = MessageID::new(new_val, slice);
+    }
+    pub fn push_references(&mut self, new_val: &[u8]) {
+        let slice = match parser::message_id(new_val).to_full_result() {
+            Ok(v) => v,
+            Err(e) => {
+                debug!(e);
+                return;
+            }
+        };
+        let new_ref = MessageID::new(new_val, slice);
+        match self.references {
+            Some(ref mut s) => {
+                if s.refs.contains(&new_ref) {
+                    if s.refs[s.refs.len() - 1] != new_ref {
+                        if let Some(index) = s.refs.iter().position(|x| *x == new_ref) {
+                            s.refs.remove(index);
+                        } else {
+                            panic!();
+                        }
+                    } else {
+                        return;
+                    }
+                }
+                s.refs.push(new_ref);
+            }
+            None => {
+                let v = vec![new_ref];
+                self.references = Some(References {
+                    raw: "".into(),
+                    refs: v,
+                });
+            }
+        }
+    }
+    pub fn set_references(&mut self, new_val: &[u8]) {
+        match self.references {
+            Some(ref mut s) => {
+                s.raw = new_val.into();
+            }
+            None => {
+                self.references = Some(References {
+                    raw: new_val.into(),
+                    refs: Vec::new(),
+                });
+            }
+        }
+    }
+    pub fn references(&self) -> Vec<&MessageID> {
+        match self.references {
+            Some(ref s) => s
+                .refs
+                .iter()
+                .fold(Vec::with_capacity(s.refs.len()), |mut acc, x| {
+                    acc.push(x);
+                    acc
+                }),
+            None => Vec::new(),
+        }
+    }
+    pub fn other_headers(&self) -> &FnvHashMap<String, String> {
+        &self.other_headers
+    }
+
+    pub fn other_headers_mut(&mut self) -> &mut FnvHashMap<String, String> {
+        &mut self.other_headers
+    }
+
+    pub fn thread(&self) -> ThreadHash {
+        self.thread
+    }
+    pub fn set_thread(&mut self, new_val: ThreadHash) {
+        self.thread = new_val;
+    }
+    pub fn set_datetime(&mut self, new_val: chrono::DateTime<chrono::FixedOffset>) {
+        self.timestamp = new_val.timestamp() as UnixTimestamp;
+    }
+    pub fn set_flag(&mut self, f: Flag, mut operation: Box<dyn BackendOp>) -> Result<()> {
+        self.flags.toggle(f);
+        operation.set_flag(self, f)?;
+        Ok(())
+    }
+    pub fn set_flags(&mut self, f: Flag) {
+        self.flags = f;
+    }
+    pub fn flags(&self) -> Flag {
+        self.flags
+    }
+    pub fn set_seen(&mut self, operation: Box<dyn BackendOp>) -> Result<()> {
+        if !self.flags.contains(Flag::SEEN) {
+            self.set_flag(Flag::SEEN, operation)
+        } else {
+            Ok(())
+        }
+    }
+    pub fn set_unseen(&mut self, operation: Box<dyn BackendOp>) -> Result<()> {
+        if self.flags.contains(Flag::SEEN) {
+            self.set_flag(Flag::SEEN, operation)
+        } else {
+            Ok(())
+        }
+    }
+    pub fn is_seen(&self) -> bool {
+        self.flags.contains(Flag::SEEN)
+    }
+    pub fn has_attachments(&self) -> bool {
+        self.has_attachments
+    }
+}
+
+impl Eq for Envelope {}
+impl Ord for Envelope {
+    fn cmp(&self, other: &Envelope) -> Ordering {
+        self.datetime().cmp(&other.datetime())
+    }
+}
+impl PartialOrd for Envelope {
+    fn partial_cmp(&self, other: &Envelope) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl PartialEq for Envelope {
+    fn eq(&self, other: &Envelope) -> bool {
+        self.hash == other.hash
+    }
+}