max / goingson

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1	//! Deterministic email ID generation using UUID v5.
2	//!
3	//! Emails synced from IMAP/JMAP get a UUID derived from their Message-ID header,
4	//! so the same email produces the same ID on every device. Manually created emails
5	//! (no Message-ID) fall back to random UUIDs.
6
7	use crate::id_types::EmailId;
8	use uuid::Uuid;
9
10	/// Fixed namespace UUID for GoingsOn email IDs (generated once, never changes).
11	pub const GOINGSON_EMAIL_NS: Uuid = Uuid::from_bytes([
12	0x7a, 0x3b, 0x8c, 0x2d, 0x4e, 0x5f, 0x6a, 0x1b,
13	0x9c, 0x0d, 0x8e, 0x7f, 0xa2, 0xb3, 0xc4, 0xd5,
14	]);
15
16	/// Generate a deterministic email ID from a Message-ID header.
17	///
18	/// - `Some(message_id)` → UUID v5 from namespace + message_id bytes
19	/// - `None` → random UUID v4 (for manually created emails without Message-ID)
20	pub fn deterministic_email_id(message_id: Option<&str>) -> EmailId {
21	match message_id {
22	Some(mid) => EmailId::from(Uuid::new_v5(&GOINGSON_EMAIL_NS, mid.as_bytes())),
23	None => EmailId::new(),
24	}
25	}
26
27	#[cfg(test)]
28	mod tests {
29	use super::*;
30
31	#[test]
32	fn same_message_id_same_uuid() {
33	let a = deterministic_email_id(Some("<abc@example.com>"));
34	let b = deterministic_email_id(Some("<abc@example.com>"));
35	assert_eq!(a, b);
36	}
37
38	#[test]
39	fn different_message_ids_different_uuids() {
40	let a = deterministic_email_id(Some("<abc@example.com>"));
41	let b = deterministic_email_id(Some("<def@example.com>"));
42	assert_ne!(a, b);
43	}
44
45	#[test]
46	fn none_gives_random_uuid() {
47	let a = deterministic_email_id(None);
48	let b = deterministic_email_id(None);
49	assert_ne!(a, b);
50	}
51
52	#[test]
53	fn v5_uuid_version() {
54	let id = deterministic_email_id(Some("<test@example.com>"));
55	assert_eq!(id.get_version_num(), 5);
56	}
57	}
58