max / goingson

6.0 KB · 175 lines History Blame Raw

1	//! Reply/forward compose-prefill construction.
2	//!
3	//! Building a reply or forward is domain logic — recipient assembly with
4	//! own-address exclusion, `Re:`/`Fwd:` subject prefixing, and body quoting.
5	//! It lives here in `core` (not the JS frontend) so the rules are uniform,
6	//! unit-tested, and driven by the authoritative account list rather than a
7	//! browser-side cache.
8
9	/// The text parts of a compose prefill. Threading/account IDs are plumbed by
10	/// the command that calls these functions.
11	#[derive(Debug, Clone, PartialEq, Eq)]
12	pub struct ComposePrefill {
13	pub to: String,
14	pub subject: String,
15	pub body: String,
16	}
17
18	/// Extract the bare address from `Name <addr@host>`, or return the trimmed input
19	/// when there is no angle-bracket form.
20	pub fn extract_email_address(addr: &str) -> &str {
21	let trimmed = addr.trim();
22	if let Some(open) = trimmed.find('<')
23	&& let Some(rel_close) = trimmed[open + 1..].find('>')
24	{
25	return trimmed[open + 1..open + 1 + rel_close].trim();
26	}
27	trimmed
28	}
29
30	/// Prefix `Re:` unless the subject already begins with it (case-insensitive),
31	/// matching the old JS `/^Re:/i` guard.
32	pub fn reply_subject(subject: &str) -> String {
33	prefix_once(subject, "Re:")
34	}
35
36	/// Prefix `Fwd:` unless the subject already begins with it (case-insensitive).
37	pub fn forward_subject(subject: &str) -> String {
38	prefix_once(subject, "Fwd:")
39	}
40
41	fn prefix_once(subject: &str, prefix: &str) -> String {
42	let already = subject.len() >= prefix.len()
43	&& subject.is_char_boundary(prefix.len())
44	&& subject[..prefix.len()].eq_ignore_ascii_case(prefix);
45	if already {
46	subject.to_string()
47	} else {
48	format!("{} {}", prefix, subject)
49	}
50	}
51
52	/// Build the `To` line for a reply.
53	///
54	/// - Plain reply: the original sender's address.
55	/// - Reply-all: sender + every original `To` recipient, in order, de-duplicated,
56	/// with the user's own addresses removed. `own_addresses` may be in any case.
57	pub fn reply_recipients(from: &str, to: &str, own_addresses: &[String], reply_all: bool) -> String {
58	if !reply_all {
59	let sender = extract_email_address(from);
60	return if sender.is_empty() {
61	from.trim().to_string()
62	} else {
63	sender.to_string()
64	};
65	}
66
67	let own: std::collections::HashSet<String> =
68	own_addresses.iter().map(\|a\| a.to_lowercase()).collect();
69	let mut result: Vec<String> = Vec::new();
70
71	let push_unique = \|addr: &str, result: &mut Vec<String>\| {
72	if addr.is_empty() \|\| own.contains(&addr.to_lowercase()) {
73	return;
74	}
75	if !result.iter().any(\|r\| r == addr) {
76	result.push(addr.to_string());
77	}
78	};
79
80	push_unique(extract_email_address(from), &mut result);
81	for part in to.split(',') {
82	push_unique(extract_email_address(part.trim()), &mut result);
83	}
84	result.join(", ")
85	}
86
87	/// Build the quoted body for a reply: an attribution line followed by the
88	/// original body with each line prefixed by `> `.
89	pub fn quoted_reply_body(from: &str, date: &str, body: &str) -> String {
90	let quoted: String = body
91	.split('\n')
92	.map(\|l\| format!("> {}", l))
93	.collect::<Vec<_>>()
94	.join("\n");
95	format!("\n\nOn {}, {} wrote:\n>\n{}", date, from, quoted)
96	}
97
98	/// Build the body for a forwarded message: a header block followed by the
99	/// original body verbatim.
100	pub fn forward_body(from: &str, date: &str, subject: &str, to: &str, body: &str) -> String {
101	format!(
102	"\n\n---------- Forwarded message ----------\n\
103	From: {}\n\
104	Date: {}\n\
105	Subject: {}\n\
106	To: {}\n\n\
107	{}",
108	from, date, subject, to, body
109	)
110	}
111
112	#[cfg(test)]
113	mod tests {
114	use super::*;
115
116	#[test]
117	fn extract_handles_angle_brackets_and_plain() {
118	assert_eq!(extract_email_address("Max <max@example.com>"), "max@example.com");
119	assert_eq!(extract_email_address(" plain@example.com "), "plain@example.com");
120	assert_eq!(extract_email_address("Name < spaced@example.com >"), "spaced@example.com");
121	assert_eq!(extract_email_address(""), "");
122	}
123
124	#[test]
125	fn subject_prefix_is_idempotent_and_case_insensitive() {
126	assert_eq!(reply_subject("Hello"), "Re: Hello");
127	assert_eq!(reply_subject("Re: Hello"), "Re: Hello");
128	assert_eq!(reply_subject("re: hello"), "re: hello");
129	assert_eq!(forward_subject("Hello"), "Fwd: Hello");
130	assert_eq!(forward_subject("Fwd: Hello"), "Fwd: Hello");
131	assert_eq!(forward_subject(""), "Fwd: ");
132	}
133
134	#[test]
135	fn plain_reply_targets_sender_only() {
136	let to = reply_recipients("Alice <alice@x.com>", "me@x.com, bob@x.com", &[], false);
137	assert_eq!(to, "alice@x.com");
138	}
139
140	#[test]
141	fn reply_all_includes_recipients_minus_self_deduped() {
142	let own = vec!["me@x.com".to_string()];
143	let to = reply_recipients(
144	"Alice <alice@x.com>",
145	"me@x.com, Bob <bob@x.com>, alice@x.com",
146	&own,
147	true,
148	);
149	// sender first, then To recipients; own address dropped; alice not duplicated.
150	assert_eq!(to, "alice@x.com, bob@x.com");
151	}
152
153	#[test]
154	fn reply_all_excludes_self_case_insensitively() {
155	let own = vec!["Me@X.com".to_string()];
156	let to = reply_recipients("boss@x.com", "ME@x.com, peer@x.com", &own, true);
157	assert_eq!(to, "boss@x.com, peer@x.com");
158	}
159
160	#[test]
161	fn quoted_reply_body_prefixes_each_line() {
162	let body = quoted_reply_body("Alice <a@x.com>", "Mar 1", "line1\nline2");
163	assert_eq!(body, "\n\nOn Mar 1, Alice <a@x.com> wrote:\n>\n> line1\n> line2");
164	}
165
166	#[test]
167	fn forward_body_has_header_block() {
168	let body = forward_body("a@x.com", "Mar 1", "Hi", "b@x.com", "original");
169	assert!(body.contains("---------- Forwarded message ----------"));
170	assert!(body.contains("From: a@x.com"));
171	assert!(body.contains("Subject: Hi"));
172	assert!(body.ends_with("original"));
173	}
174	}
175