eml-codec 0.1.2

/// Parse and represent IMF (Internet Message Format) headers (RFC822, RFC5322)
pub mod address;
pub mod datetime;
pub mod field;
pub mod identification;
pub mod mailbox;
pub mod mime;
pub mod trace;

use nom::{combinator::map, IResult};

use crate::header;
use crate::imf::address::AddressRef;
use crate::imf::field::Field;
use crate::imf::identification::MessageID;
use crate::imf::mailbox::{AddrSpec, MailboxRef};
use crate::imf::mime::Version;
use crate::imf::trace::ReceivedLog;
use crate::text::misc_token::{PhraseList, Unstructured};
use chrono::{DateTime, FixedOffset};

#[derive(Debug, PartialEq, Default)]
pub struct Imf<'a> {
    // 3.6.1.  The Origination Date Field
    pub date: Option<DateTime<FixedOffset>>,

    // 3.6.2.  Originator Fields
    pub from: Vec<MailboxRef<'a>>,
    pub sender: Option<MailboxRef<'a>>,
    pub reply_to: Vec<AddressRef<'a>>,

    // 3.6.3.  Destination Address Fields
    pub to: Vec<AddressRef<'a>>,
    pub cc: Vec<AddressRef<'a>>,
    pub bcc: Vec<AddressRef<'a>>,

    // 3.6.4.  Identification Fields
    pub msg_id: Option<MessageID<'a>>,
    pub in_reply_to: Vec<MessageID<'a>>,
    pub references: Vec<MessageID<'a>>,

    // 3.6.5.  Informational Fields
    pub subject: Option<Unstructured<'a>>,
    pub comments: Vec<Unstructured<'a>>,
    pub keywords: Vec<PhraseList<'a>>,

    // 3.6.6 Not implemented
    // 3.6.7 Trace Fields
    pub return_path: Vec<AddrSpec<'a>>,
    pub received: Vec<ReceivedLog<'a>>,

    // MIME
    pub mime_version: Option<Version>,
}

//@FIXME min and max limits are not enforced,
// it may result in missing data or silently overriden data.
impl<'a> FromIterator<Field<'a>> for Imf<'a> {
    fn from_iter<I: IntoIterator<Item = Field<'a>>>(iter: I) -> Self {
        iter.into_iter().fold(Imf::default(), |mut section, field| {
            match field {
                Field::Date(v) => section.date = v,
                Field::From(v) => section.from.extend(v),
                Field::Sender(v) => section.sender = Some(v),
                Field::ReplyTo(v) => section.reply_to.extend(v),
                Field::To(v) => section.to.extend(v),
                Field::Cc(v) => section.cc.extend(v),
                Field::Bcc(v) => section.bcc.extend(v),
                Field::MessageID(v) => section.msg_id = Some(v),
                Field::InReplyTo(v) => section.in_reply_to.extend(v),
                Field::References(v) => section.references.extend(v),
                Field::Subject(v) => section.subject = Some(v),
                Field::Comments(v) => section.comments.push(v),
                Field::Keywords(v) => section.keywords.push(v),
                Field::ReturnPath(v) => v.map(|x| section.return_path.push(x)).unwrap_or(()),
                Field::Received(v) => section.received.push(v),
                Field::MIMEVersion(v) => section.mime_version = Some(v),
            };
            section
        })
    }
}

pub fn imf(input: &[u8]) -> IResult<&[u8], Imf> {
    map(header::header_kv, |fields| {
        fields
            .iter()
            .flat_map(Field::try_from)
            .into_iter()
            .collect::<Imf>()
    })(input)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::imf::address::*;
    use crate::imf::mailbox::*;
    use crate::text::misc_token::*;
    use chrono::{FixedOffset, TimeZone};

    #[test]
    fn test_header() {
        let fullmail = b"Date: 7 Mar 2023 08:00:00 +0200
From: someone@example.com
To: someone_else@example.com
Subject: An RFC 822 formatted message

This is the plain text body of the message. Note the blank line
between the header information and the body of the message.";

        assert_eq!(
            imf(fullmail),
            Ok((
                &b"This is the plain text body of the message. Note the blank line\nbetween the header information and the body of the message."[..],
                Imf {
                    date: Some(FixedOffset::east_opt(2 * 3600).unwrap().with_ymd_and_hms(2023, 3, 7, 8, 0, 0).unwrap()),
                    from: vec![MailboxRef {
                        name: None,
                        addrspec: AddrSpec {
                            local_part: LocalPart(vec![LocalPartToken::Word(Word::Atom(&b"someone"[..]))]),
                            domain: Domain::Atoms(vec![&b"example"[..], &b"com"[..]]),
                        }
                    }],
                    to: vec![AddressRef::Single(MailboxRef {
                        name: None,
                        addrspec: AddrSpec {
                            local_part: LocalPart(vec![LocalPartToken::Word(Word::Atom(&b"someone_else"[..]))]),
                            domain: Domain::Atoms(vec![&b"example"[..], &b"com"[..]]),
                        }
                    })],
                    subject: Some(Unstructured(vec![
                        UnstrToken::Plain(&b"An"[..]),
                        UnstrToken::Plain(&b"RFC"[..]),
                        UnstrToken::Plain(&b"822"[..]), 
                        UnstrToken::Plain(&b"formatted"[..]), 
                        UnstrToken::Plain(&b"message"[..]),
                    ])),
                    ..Imf::default()
                }
            )),
        )
    }
}