add a new from_str_at_date(date, string) function (#2)

Co-authored-by: Daniel Hofstetter <daniel.hofstetter@42dh.com>

README.md

@@ -11,6 +11,7 @@ A Rust crate for parsing human-readable relative time strings and converting the
 - Parses a variety of human-readable time formats.
 - Supports positive and negative durations.
 - Allows for chaining time units (e.g., "1 hour 2 minutes" or "2 days and 2 hours").
+- Calculate durations relative to a specified date.
 
 ## Usage
 
@@ -21,18 +22,25 @@ Add this to your `Cargo.toml`:
 humantime_to_duration = "0.1.1"
 ```
 
-Then, import the crate and use the from_str function:
+Then, import the crate and use the `from_str` and `from_str_at_date` functions:
 ```
-use humantime_to_duration::from_str;
+use humantime_to_duration::{from_str, from_str_at_date};
 use time::Duration;
 
 let duration = from_str("+3 days");
 assert_eq!(duration.unwrap(), Duration::days(3));
+
+let today = OffsetDateTime::now_utc().date();
+let yesterday = today - Duration::days(1);
+assert_eq!(
+    from_str_at_date(yesterday, "2 days").unwrap(),
+    Duration::days(1)
+);
 ```
 
 ### Supported Formats
 
-The `from_str` function supports the following formats for relative time:
+The `from_str` and `from_str_at_date` functions support the following formats for relative time:
 
 - `num` `unit` (e.g., "-1 hour", "+3 days")
 - `unit` (e.g., "hour", "day")
@@ -47,7 +55,7 @@ The `from_str` function supports the following formats for relative time:
 
 ## Return Values
 
-The `from_str` function returns:
+The `from_str` and `from_str_at_date` functions return:
 
 - `Ok(Duration)` - If the input string can be parsed as a relative time
 - `Err(ParseDurationError)` - If the input string cannot be parsed as a relative time

src/lib.rs

@@ -4,7 +4,7 @@
 use regex::{Error as RegexError, Regex};
 use std::error::Error;
 use std::fmt::{self, Display};
-use time::Duration;
+use time::{Date, Duration, OffsetDateTime};
 
 #[derive(Debug)]
 pub enum ParseDurationError {
@@ -77,6 +77,17 @@ impl From<RegexError> for ParseDurationError {
 ///
 /// This function will return `Err(ParseDurationError::InvalidInput)` if the input string
 /// cannot be parsed as a relative time.
+///
+/// # Examples
+///
+/// ```
+/// use time::Duration;
+/// use humantime_to_duration::{from_str, ParseDurationError};
+///
+/// assert_eq!(from_str("1 hour, 30 minutes").unwrap(), Duration::minutes(90));
+/// assert_eq!(from_str("tomorrow").unwrap(), Duration::days(1));
+/// assert!(matches!(from_str("invalid"), Err(ParseDurationError::InvalidInput)));
+/// ```
 pub fn from_str(s: &str) -> Result<Duration, ParseDurationError> {
     let time_pattern: Regex = Regex::new(
         r"(?x)
@@ -153,12 +164,39 @@ pub fn from_str(s: &str) -> Result<Duration, ParseDurationError> {
     }
 }
 
+/// Parses a duration string and returns a `Duration` instance, with the duration
+/// calculated from the specified date.
+///
+/// # Arguments
+///
+/// * `date` - A `Date` instance representing the base date for the calculation
+/// * `s` - A string slice representing the relative time.
+///
+/// # Examples
+///
+/// ```
+/// use time::{Date, Duration, OffsetDateTime};
+/// use humantime_to_duration::{from_str_at_date, ParseDurationError};
+/// let today = OffsetDateTime::now_utc().date();
+/// let yesterday = today - Duration::days(1);
+/// assert_eq!(
+///     from_str_at_date(yesterday, "2 days").unwrap(),
+///     Duration::days(1) // 1 day from the specified date + 1 day from the input string
+/// );
+/// ```
+pub fn from_str_at_date(date: Date, s: &str) -> Result<Duration, ParseDurationError> {
+    let time_now = OffsetDateTime::now_utc().date();
+    let date_duration = date - time_now;
+
+    Ok(from_str(s)? + date_duration)
+}
+
 #[cfg(test)]
 mod tests {
 
-    use super::from_str;
     use super::ParseDurationError;
-    use time::Duration;
+    use super::{from_str, from_str_at_date};
+    use time::{Date, Duration, Month, OffsetDateTime};
 
     #[test]
     fn test_years() {
@@ -300,4 +338,30 @@ mod tests {
             _ => assert!(false),
         }*/
     }
+
+    #[test]
+    fn test_from_str_at_date() {
+        let date = Date::from_calendar_date(2014, Month::September, 5).unwrap();
+        let now = OffsetDateTime::now_utc().date();
+        let days_diff = (date - now).whole_days();
+
+        assert_eq!(
+            from_str_at_date(date, "1 day").unwrap(),
+            Duration::days(days_diff + 1)
+        );
+
+        assert_eq!(
+            from_str_at_date(date, "2 hours").unwrap(),
+            Duration::days(days_diff) + Duration::hours(2)
+        );
+    }
+
+    #[test]
+    fn test_invalid_input_at_date() {
+        let date = Date::from_calendar_date(2014, Month::September, 5).unwrap();
+        assert!(matches!(
+            from_str_at_date(date, "invalid"),
+            Err(ParseDurationError::InvalidInput)
+        ));
+    }
 }

tests/simple.rs

@@ -1,5 +1,5 @@
-use humantime_to_duration::{from_str, ParseDurationError};
-use time::Duration;
+use humantime_to_duration::{from_str, from_str_at_date, ParseDurationError};
+use time::{Duration, OffsetDateTime};
 
 #[test]
 fn test_invalid_input() {
@@ -135,3 +135,30 @@ fn test_display_should_fail() {
         "Invalid input string: cannot be parsed as a relative time"
     );
 }
+
+#[test]
+fn test_from_str_at_date_day() {
+    let today = OffsetDateTime::now_utc().date();
+    let yesterday = today - Duration::days(1);
+    assert_eq!(
+        from_str_at_date(yesterday, "2 days").unwrap(),
+        Duration::days(1)
+    );
+}
+
+#[test]
+fn test_invalid_input_at_date() {
+    let today = OffsetDateTime::now_utc().date();
+    let result = from_str_at_date(today, "foobar");
+    println!("{result:?}");
+    match result {
+        Err(ParseDurationError::InvalidInput) => assert!(true),
+        _ => assert!(false),
+    }
+
+    let result = from_str_at_date(today, "invalid 1r");
+    match result {
+        Err(ParseDurationError::InvalidInput) => assert!(true),
+        _ => assert!(false),
+    }
+}