max / makenotwork

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1	//! Shared pagination helpers for the public page handlers.
2
3	use crate::constants;
4
5	/// Build a sliding window of page numbers for pagination controls.
6	///
7	/// One definition for every public list page (feed, discover, landing), they
8	/// previously each carried a byte-identical copy, so a tweak to the window
9	/// behavior had to be made in lockstep or silently drift.
10	///
11	/// `pub(crate)` rather than `pub(super)` because the feed is described now and
12	/// `crate::quasi::feeds::load` windows the same way the Askama handlers did.
13	/// Widening it was the alternative to a fourth copy; do not narrow it back
14	/// without moving the function.
15	pub(crate) fn build_pagination_range(current_page: u32, total_pages: u32) -> Vec<u32> {
16	if total_pages <= constants::PAGINATION_WINDOW_SIZE {
17	(1..=total_pages).collect()
18	} else {
19	let start = current_page.saturating_sub(2).max(1);
20	let end = (start + 4).min(total_pages);
21	let start = end.saturating_sub(4).max(1);
22	(start..=end).collect()
23	}
24	}
25
26	#[cfg(test)]
27	mod tests {
28	use super::*;
29
30	#[test]
31	fn pagination_small_total() {
32	assert_eq!(build_pagination_range(1, 3), vec![1, 2, 3]);
33	assert_eq!(build_pagination_range(2, 5), vec![1, 2, 3, 4, 5]);
34	}
35
36	#[test]
37	fn pagination_large_at_start() {
38	assert_eq!(build_pagination_range(1, 20), vec![1, 2, 3, 4, 5]);
39	assert_eq!(build_pagination_range(2, 20), vec![1, 2, 3, 4, 5]);
40	}
41
42	#[test]
43	fn pagination_large_at_middle() {
44	assert_eq!(build_pagination_range(10, 20), vec![8, 9, 10, 11, 12]);
45	}
46
47	#[test]
48	fn pagination_large_at_end() {
49	assert_eq!(build_pagination_range(20, 20), vec![16, 17, 18, 19, 20]);
50	assert_eq!(build_pagination_range(19, 20), vec![16, 17, 18, 19, 20]);
51	}
52
53	#[test]
54	fn pagination_zero_pages() {
55	assert_eq!(build_pagination_range(1, 0), Vec::<u32>::new());
56	}
57
58	#[test]
59	fn pagination_single_page() {
60	assert_eq!(build_pagination_range(1, 1), vec![1]);
61	}
62	}
63