logo
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168

//! Utilities for paths and sets of paths.

use std::{
	collections::{HashMap, HashSet},
	ffi::OsString,
	path::{Path, PathBuf},
};

use crate::event::{Event, FileType, Tag};

/// The separator for paths used in environment variables.
#[cfg(unix)]
pub const PATH_SEPARATOR: &str = ":";
/// The separator for paths used in environment variables.
#[cfg(not(unix))]
pub const PATH_SEPARATOR: &str = ";";

/// Returns the longest common prefix of all given paths.
///
/// This is a utility function which is useful for finding the common root of a set of origins.
///
/// Returns `None` if zero paths are given or paths share no common prefix.
pub fn common_prefix<I, P>(paths: I) -> Option<PathBuf>
where
	I: IntoIterator<Item = P>,
	P: AsRef<Path>,
{
	let mut paths = paths.into_iter();
	let first_path = paths.next().map(|p| p.as_ref().to_owned());
	let mut longest_path = if let Some(ref p) = first_path {
		p.components().collect::<Vec<_>>()
	} else {
		return None;
	};

	for path in paths {
		let mut greatest_distance = 0;
		for component_pair in path.as_ref().components().zip(longest_path.iter()) {
			if component_pair.0 != *component_pair.1 {
				break;
			}

			greatest_distance += 1;
		}

		if greatest_distance != longest_path.len() {
			longest_path.truncate(greatest_distance);
		}
	}

	if longest_path.is_empty() {
		None
	} else {
		let mut result = PathBuf::new();
		for component in longest_path {
			result.push(component.as_os_str());
		}
		Some(result)
	}
}

/// Summarise [`Event`]s as a set of environment variables by category.
///
/// - `CREATED` -> `Create(_)`
/// - `META_CHANGED` -> `Modify(Metadata(_))`
/// - `REMOVED` -> `Remove(_)`
/// - `RENAMED` -> `Modify(Name(_))`
/// - `WRITTEN` -> `Modify(Data(_))`, `Access(Close(Write))`
/// - `OTHERWISE_CHANGED` -> anything else
/// - plus `COMMON` with the common prefix of all paths (even if there's only one path).
///
/// It ignores non-path events and pathed events without event kind. Multiple events are sorted in
/// byte order and joined with the platform-specific path separator (`:` for unix, `;` for Windows).
pub fn summarise_events_to_env<'events>(
	events: impl IntoIterator<Item = &'events Event>,
) -> HashMap<&'static str, OsString> {
	let mut all_trunks = Vec::new();
	let mut kind_buckets = HashMap::new();
	for event in events {
		let (paths, trunks): (Vec<_>, Vec<_>) = event
			.paths()
			.map(|(p, ft)| {
				(
					p.to_owned(),
					match ft {
						Some(FileType::Dir) => None,
						_ => p.parent(),
					}
					.unwrap_or(p)
					.to_owned(),
				)
			})
			.unzip();
		tracing::trace!(?paths, ?trunks, "event paths");

		if paths.is_empty() {
			continue;
		}

		all_trunks.extend(trunks.clone());

		// usually there's only one but just in case
		for kind in event.tags.iter().filter_map(|t| {
			if let Tag::FileEventKind(kind) = t {
				Some(kind.clone())
			} else {
				None
			}
		}) {
			kind_buckets
				.entry(kind)
				.or_insert_with(HashSet::new)
				.extend(paths.clone());
		}
	}

	let common_path = common_prefix(all_trunks);

	let mut grouped_buckets = HashMap::new();
	for (kind, paths) in kind_buckets {
		use notify::event::{AccessKind::*, AccessMode::*, EventKind::*, ModifyKind::*};
		grouped_buckets
			.entry(match kind {
				Modify(Data(_)) | Access(Close(Write)) => "WRITTEN",
				Modify(Metadata(_)) => "META_CHANGED",
				Remove(_) => "REMOVED",
				Create(_) => "CREATED",
				Modify(Name(_)) => "RENAMED",
				_ => "OTHERWISE_CHANGED",
			})
			.or_insert_with(HashSet::new)
			.extend(paths.into_iter().map(|p| {
				if let Some(suffix) = common_path
					.as_ref()
					.and_then(|prefix| p.strip_prefix(prefix).ok())
				{
					suffix.as_os_str().to_owned()
				} else {
					p.into_os_string()
				}
			}));
	}

	let mut res: HashMap<&'static str, OsString> = grouped_buckets
		.into_iter()
		.map(|(kind, paths)| {
			let mut joined =
				OsString::with_capacity(paths.iter().map(|p| p.len()).sum::<usize>() + paths.len());

			let mut paths = paths.into_iter().collect::<Vec<_>>();
			paths.sort();
			paths.into_iter().enumerate().for_each(|(i, path)| {
				if i > 0 {
					joined.push(PATH_SEPARATOR);
				}
				joined.push(path);
			});

			(kind, joined)
		})
		.collect();

	if let Some(common_path) = common_path {
		res.insert("COMMON", common_path.into_os_string());
	}

	res
}