getting closest file to date

src/file/mod.rs

@@ -1,21 +1,32 @@
-use chrono::Datelike;
-use crate::TaskGroup;
+use crate::todo::{File as TodoFile, Status as TaskStatus};
 use crate::NaiveDate;
-use crate::todo::{Status as TaskStatus,File as TodoFile};
+use crate::TaskGroup;
+use chrono::Datelike;
 use comrak::nodes::{AstNode, NodeValue};
-use comrak::{Arena, ComrakExtensionOptions, ComrakOptions, ComrakParseOptions};
-use std::str;
-use std::io::Write;
-use std::collections::HashMap;
 use comrak::parse_document;
-use std::path::{Path, PathBuf};
+use comrak::{Arena, ComrakExtensionOptions, ComrakOptions, ComrakParseOptions};
+use std::collections::HashMap;
 use std::fs::{read, read_dir, File};
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::str;
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct DatedPathBuf {
+    path: PathBuf,
+    date: NaiveDate,
+}
+
+#[derive(Debug)]
+pub enum FileNameParseError {
+    TypeConversionError(&'static str),
+    ParseError(chrono::ParseError),
+}
 
 pub fn get_filepath(data_dir: &PathBuf, date: &NaiveDate) -> PathBuf {
     let file_name = format!("{}-{:02}-{:02}.md", date.year(), date.month(), date.day());
     let mut file_path = data_dir.clone();
     file_path.push(file_name);
-
     file_path
 }
 
@@ -114,3 +125,86 @@ pub fn get_latest_file(dir: &Path) -> Result<TodoFile, String> {
         .reduce(|a, b| TodoFile::latest_file(a, b))
         .ok_or("Could not reduce items".to_string())
 }
+
+fn try_get_date(file: &PathBuf) -> Result<NaiveDate, FileNameParseError> {
+    let file_name = file
+        .file_name()
+        .ok_or(FileNameParseError::TypeConversionError(
+            "Could not get filename from path: {:?}",
+        ))?
+        .to_str()
+        .ok_or(FileNameParseError::TypeConversionError(
+            "Could not get filename from path: {:?}",
+        ))?;
+
+    NaiveDate::parse_from_str(file_name, "%Y-%m-%d.md")
+        .or_else(|e| Err(FileNameParseError::ParseError(e)))
+}
+
+impl TryFrom<PathBuf> for DatedPathBuf {
+    type Error = FileNameParseError;
+
+    fn try_from(path: PathBuf) -> Result<Self, Self::Error> {
+        Ok(Self {
+            date: try_get_date(&path)?,
+            path,
+        })
+    }
+}
+
+pub fn get_closest_files(files: &Vec<PathBuf>, target: NaiveDate, n: usize) -> Vec<DatedPathBuf> {
+    let mut dated_files = files
+        .clone()
+        .into_iter()
+        .filter_map(|file| DatedPathBuf::try_from(file).ok())
+        .collect::<Vec<_>>();
+    dated_files.sort_by_cached_key(|dated_file| (dated_file.date - target).num_days().abs());
+
+    dated_files[..n].to_vec()
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use chrono::NaiveDate;
+    use std::path::PathBuf;
+
+    #[test]
+    fn test_get_closest_date() {
+        let files = vec![
+            PathBuf::from("./2024-01-01.md"),
+            PathBuf::from("./2024-01-02.md"),
+            PathBuf::from("./2024-01-03.md"),
+            PathBuf::from("./2024-02-01.md"),
+            PathBuf::from("./2024-03-01.md"),
+            PathBuf::from("./2024-04-01.md"),
+            PathBuf::from("./2024-04-02.md"),
+            PathBuf::from("./2024-04-03.md"),
+            PathBuf::from("./2024-04-04.md"),
+        ];
+
+        let res = get_closest_files(&files, NaiveDate::from_ymd_opt(2023, 12, 30).unwrap(), 3);
+        let expected_res = vec![
+            DatedPathBuf::try_from(PathBuf::from("./2024-01-01.md")).unwrap(),
+            DatedPathBuf::try_from(PathBuf::from("./2024-01-02.md")).unwrap(),
+            DatedPathBuf::try_from(PathBuf::from("./2024-01-03.md")).unwrap(),
+        ];
+        assert_eq!(res, expected_res);
+
+        let res = get_closest_files(&files, NaiveDate::from_ymd_opt(2024, 2, 1).unwrap(), 3);
+        let expected_res = vec![
+            DatedPathBuf::try_from(PathBuf::from("./2024-02-01.md")).unwrap(),
+            DatedPathBuf::try_from(PathBuf::from("./2024-01-03.md")).unwrap(),
+            DatedPathBuf::try_from(PathBuf::from("./2024-03-01.md")).unwrap(),
+        ];
+        assert_eq!(res, expected_res);
+
+        let res = get_closest_files(&files, NaiveDate::from_ymd_opt(2024, 5, 2).unwrap(), 3);
+        let expected_res = vec![
+            DatedPathBuf::try_from(PathBuf::from("./2024-04-04.md")).unwrap(),
+            DatedPathBuf::try_from(PathBuf::from("./2024-04-03.md")).unwrap(),
+            DatedPathBuf::try_from(PathBuf::from("./2024-04-02.md")).unwrap(),
+        ];
+        assert_eq!(res, expected_res);
+    }
+}