1 files changed, 60 insertions, 0 deletions
diff --git a/src/dates.rs b/src/dates.rs
new file mode 100644
index 0000000..fc3863c
--- /dev/null
+++ b/src/dates.rs
@@ -0,0 +1,60 @@
+use std::path::Path;
+// use std::str::FromStr;
+// use chrono::{Datelike, NaiveDate, NaiveTime, Weekday, Duration, Timelike};
+use chrono::{Datelike, NaiveDate, Duration};
+
+pub struct WTDPath<'a> {
+    pub path: &'a Path,
+    pub week_start: Option<NaiveDate>,
+    pub is_weekly_file: bool,
+}
+
+// both start, end are inclusive.
+pub fn relevant_files<'a>(start: &'a NaiveDate, end: &'a NaiveDate) -> Vec<WTDPath<'a>> {
+    let mut paths: Vec<WTDPath> = vec![];
+    if let Some(path) = maybe_path("wtd.md".to_string()) {
+        paths.push(WTDPath {
+            path: &path,
+            week_start: None,
+            is_weekly_file: false,
+        });
+    }
+
+    let weekly = maybe_path("weekly.md".to_string());
+
+    let start_week = week_start_of(start);
+    let end_week = week_start_of(end); // inclusive
+
+    let mut curr_week = start_week;
+    while curr_week <= end_week {
+        let maybe_week_path = week_file(curr_week);
+        let path = match [maybe_week_path, weekly] {
+            [Some(path), _] => path,
+            [_, Some(path)] => path,
+            [None, None] => continue,
+        };
+        paths.push(WTDPath {
+            path: path,
+            week_start: Some(curr_week),
+            is_weekly_file: maybe_week_path.is_none(),
+        });
+        curr_week = curr_week + Duration::weeks(1);
+    }
+
+    return paths;
+}
+
+fn week_file(week_start: NaiveDate) -> Option<&'static Path> {
+    let filename = week_start.format("%b_%d_%Y.md").to_string().to_lowercase();
+    return maybe_path(filename);
+}
+
+fn maybe_path(name: String) -> Option<&'static Path> {
+    let path = Path::new("wtd.md");
+    return if path.exists() { Some(&path) } else { None };
+}
+
+fn week_start_of(date: &NaiveDate) -> NaiveDate {
+    let days_from_monday = date.weekday().number_from_monday();
+    return *date - Duration::days(days_from_monday.into());
+}