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//! Message summaries and body extraction.
use mailparse::{MailHeaderMap, ParsedMail};
use serde::Serialize;
#[derive(Debug, Serialize)]
pub struct MsgSummary {
pub uid: u32,
pub flags: Vec<String>,
pub size: Option<u32>,
pub date: Option<String>,
pub from: Option<String>,
pub to: Option<String>,
pub subject: Option<String>,
}
/// The header fields shown in listings, decoded (RFC 2047) by mailparse.
#[derive(Debug, Default, PartialEq)]
pub struct HeaderSummary {
pub date: Option<String>,
pub from: Option<String>,
pub to: Option<String>,
pub subject: Option<String>,
}
pub fn parse_header_summary(raw: &[u8]) -> HeaderSummary {
match mailparse::parse_headers(raw) {
Ok((headers, _)) => HeaderSummary {
date: headers.get_first_value("Date"),
from: headers.get_first_value("From"),
to: headers.get_first_value("To"),
subject: headers.get_first_value("Subject"),
},
Err(_) => HeaderSummary::default(),
}
}
pub fn flag_to_string(f: &imap::types::Flag) -> String {
use imap::types::Flag::*;
match f {
Seen => "\\Seen".into(),
Answered => "\\Answered".into(),
Flagged => "\\Flagged".into(),
Deleted => "\\Deleted".into(),
Draft => "\\Draft".into(),
Recent => "\\Recent".into(),
Custom(c) => c.to_string(),
other => format!("{other:?}"),
}
}
pub fn summarize(f: &imap::types::Fetch) -> Option<MsgSummary> {
let uid = f.uid?;
let h = f.header().map(parse_header_summary).unwrap_or_default();
Some(MsgSummary {
uid,
flags: f.flags().iter().map(flag_to_string).collect(),
size: f.size,
date: h.date,
from: h.from,
to: h.to,
subject: h.subject,
})
}
fn find_part(mail: &ParsedMail, mimetype: &str) -> Option<String> {
if mail.ctype.mimetype.eq_ignore_ascii_case(mimetype) {
return mail.get_body().ok();
}
mail.subparts.iter().find_map(|sp| find_part(sp, mimetype))
}
/// Picks the best displayable body: text/plain by default, text/html on request,
/// falling back to the other one when the preferred part is missing.
pub fn extract_body(mail: &ParsedMail, prefer_html: bool) -> Option<String> {
let order: [&str; 2] = if prefer_html {
["text/html", "text/plain"]
} else {
["text/plain", "text/html"]
};
order.iter().find_map(|mt| find_part(mail, mt))
}
#[cfg(test)]
mod tests {
use super::*;
const PLAIN: &[u8] = b"From: Alice <alice@example.com>\r\n\
To: bob@example.com\r\n\
Date: Fri, 17 Jul 2026 10:00:00 -0300\r\n\
Subject: Hello\r\n\
Content-Type: text/plain; charset=utf-8\r\n\
\r\n\
Just checking in.\r\n";
// Subject uses RFC 2047 encoded words; body parts use quoted-printable/base64.
const MULTIPART: &[u8] = b"From: =?utf-8?Q?Mar=C3=ADa?= <maria@example.com>\r\n\
To: bob@example.com\r\n\
Subject: =?utf-8?B?SG9sYSDwn5qA?=\r\n\
MIME-Version: 1.0\r\n\
Content-Type: multipart/alternative; boundary=XYZ\r\n\
\r\n\
--XYZ\r\n\
Content-Type: text/plain; charset=utf-8\r\n\
Content-Transfer-Encoding: quoted-printable\r\n\
\r\n\
Hola, =C2=BFtodo bien?\r\n\
--XYZ\r\n\
Content-Type: text/html; charset=utf-8\r\n\
Content-Transfer-Encoding: base64\r\n\
\r\n\
PGI+SG9sYTwvYj4=\r\n\
--XYZ--\r\n";
#[test]
fn header_summary_reads_basic_fields() {
let h = parse_header_summary(PLAIN);
assert_eq!(h.from.as_deref(), Some("Alice <alice@example.com>"));
assert_eq!(h.subject.as_deref(), Some("Hello"));
assert_eq!(h.date.as_deref(), Some("Fri, 17 Jul 2026 10:00:00 -0300"));
}
#[test]
fn header_summary_decodes_rfc2047() {
let h = parse_header_summary(MULTIPART);
assert_eq!(h.from.as_deref(), Some("María <maria@example.com>"));
assert_eq!(h.subject.as_deref(), Some("Hola 🚀"));
}
#[test]
fn garbage_headers_yield_empty_summary() {
assert_eq!(
parse_header_summary(b"\xff\xfe\x00"),
HeaderSummary::default()
);
}
#[test]
fn plain_body_is_extracted() {
let mail = mailparse::parse_mail(PLAIN).unwrap();
assert_eq!(
extract_body(&mail, false).unwrap().trim(),
"Just checking in."
);
}
#[test]
fn multipart_prefers_plain_and_decodes_qp() {
let mail = mailparse::parse_mail(MULTIPART).unwrap();
assert_eq!(
extract_body(&mail, false).unwrap().trim(),
"Hola, ¿todo bien?"
);
}
#[test]
fn html_flag_prefers_html_and_decodes_base64() {
let mail = mailparse::parse_mail(MULTIPART).unwrap();
assert_eq!(extract_body(&mail, true).unwrap().trim(), "<b>Hola</b>");
}
#[test]
fn html_only_message_falls_back_when_plain_requested() {
let raw = b"Content-Type: text/html\r\n\r\n<p>hi</p>\r\n";
let mail = mailparse::parse_mail(raw).unwrap();
assert_eq!(extract_body(&mail, false).unwrap().trim(), "<p>hi</p>");
}
}
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