diff --git a/src/git/filter.rs b/src/git/filter.rs
new file mode 100644
index 0000000..182845e
--- /dev/null
+++ b/src/git/filter.rs
@@ -0,0 +1,200 @@
+use crate::git::Commit;
+use anyhow::{anyhow, bail, Result};
+use chrono::{DateTime, Duration, Local, NaiveDate, ParseError, Utc};
+
+#[derive(Debug, Clone, Copy)]
+pub enum TimePeriod {
+    Days(u32),
+    Weeks(u32),
+    Months(u32),
+    Years(u32),
+    Custom(DateTime<Utc>, DateTime<Utc>),
+}
+
+impl TimePeriod {
+    pub fn days(n: u32) -> Self {
+        Self::Days(n)
+    }
+
+    pub fn weeks(n: u32) -> Self {
+        Self::Weeks(n)
+    }
+
+    pub fn months(n: u32) -> Self {
+        Self::Months(n)
+    }
+
+    pub fn years(n: u32) -> Self {
+        Self::Years(n)
+    }
+
+    pub fn custom(start: DateTime<Utc>, end: DateTime<Utc>) -> Result<Self> {
+        if start > end {
+            bail!("Start date must be before end date");
+        }
+        Ok(Self::Custom(start, end))
+    }
+
+    pub fn to_range(&self) -> (DateTime<Utc>, DateTime<Utc>) {
+        let now = Utc::now();
+        match self {
+            TimePeriod::Days(n) => (now - Duration::days(*n as i64), now),
+            TimePeriod::Weeks(n) => (now - Duration::weeks(*n as i64), now),
+            TimePeriod::Months(n) => (now - Duration::days((*n as i64) * 30), now),
+            TimePeriod::Years(n) => (now - Duration::days((*n as i64) * 365), now),
+            TimePeriod::Custom(start, end) => (*start, *end),
+        }
+    }
+}
+
+impl std::str::FromStr for TimePeriod {
+    type Err = ParseError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if s.ends_with('d') {
+            let n: u32 = s[..s.len() - 1].parse()?;
+            Ok(TimePeriod::Days(n))
+        } else if s.ends_with('w') {
+            let n: u32 = s[..s.len() - 1].parse()?;
+            Ok(TimePeriod::Weeks(n))
+        } else if s.ends_with('m') {
+            let n: u32 = s[..s.len() - 1].parse()?;
+            Ok(TimePeriod::Months(n))
+        } else if s.ends_with('y') {
+            let n: u32 = s[..s.len() - 1].parse()?;
+            Ok(TimePeriod::Years(n))
+        } else if s.contains(':') {
+            let parts: Vec<&str> = s.split(':').collect();
+            if parts.len() == 2 {
+                let start = NaiveDate::parse_from_str(parts[0], "%Y-%m-%d")?
+                    .and_hms_opt(0, 0, 0)
+                    .unwrap();
+                let end = NaiveDate::parse_from_str(parts[1], "%Y-%m-%d")?
+                    .and_hms_opt(23, 59, 59)
+                    .unwrap();
+                return Ok(TimePeriod::Custom(
+                    DateTime::from_utc(start, Utc),
+                    DateTime::from_utc(end, Utc),
+                ));
+            }
+            Err(ParseError)
+        } else {
+            let date = NaiveDate::parse_from_str(s, "%Y-%m-%d")?
+                .and_hms_opt(0, 0, 0)
+                .unwrap();
+            let start = DateTime::from_utc(date, Utc);
+            let end = start + Duration::days(1);
+            Ok(TimePeriod::Custom(start, end))
+        }
+    }
+}
+
+pub struct TimeFilter {
+    since: Option<DateTime<Utc>>,
+    until: Option<DateTime<Utc>>,
+    period: Option<TimePeriod>,
+}
+
+impl TimeFilter {
+    pub fn new() -> Self {
+        Self {
+            since: None,
+            until: None,
+            period: None,
+        }
+    }
+
+    pub fn since(mut self, date: DateTime<Utc>) -> Self {
+        self.since = Some(date);
+        self
+    }
+
+    pub fn until(mut self, date: DateTime<Utc>) -> Self {
+        self.until = Some(date);
+        self
+    }
+
+    pub fn period(mut self, period: TimePeriod) -> Self {
+        self.period = Some(period);
+        self
+    }
+
+    pub fn days_back(mut self, days: u32) -> Self {
+        let now = Utc::now();
+        self.since = Some(now - Duration::days(days as i64));
+        self.until = Some(now);
+        self
+    }
+
+    pub fn build(self) -> TimeFilter {
+        let (since, until) = if let Some(period) = self.period {
+            let (start, end) = period.to_range();
+            (Some(start), Some(end))
+        } else {
+            (self.since, self.until)
+        };
+        TimeFilter {
+            since,
+            until,
+            period: None,
+        }
+    }
+
+    pub fn contains(&self, commit: &Commit) -> bool {
+        let time = commit.time();
+        if let Some(since) = self.since {
+            if time < since {
+                return false;
+            }
+        }
+        if let Some(until) = self.until {
+            if time > until {
+                return false;
+            }
+        }
+        true
+    }
+}
+
+impl Default for TimeFilter {
+    fn default() -> Self {
+        Self::new().days_back(30)
+    }
+}
+
+pub fn parse_date(s: &str) -> Result<DateTime<Utc>> {
+    let formats = [
+        "%Y-%m-%d",
+        "%Y/%m/%d",
+        "%d-%m-%Y",
+        "%d/%m/%Y",
+        "%Y-%m-%dT%H:%M:%S",
+        "%Y-%m-%d %H:%M:%S",
+    ];
+
+    for fmt in &formats {
+        if let Ok(dt) = chrono::DateTime::parse_from_str(s, fmt) {
+            return Ok(dt.with_timezone(&Utc));
+        }
+    }
+
+    if s.ends_with('d') {
+        let n: u32 = s[..s.len() - 1].parse()?;
+        let now = Utc::now();
+        return Ok(now - Duration::days(n as i64));
+    } else if s.ends_with('w') {
+        let n: u32 = s[..s.len() - 1].parse()?;
+        let now = Utc::now();
+        return Ok(now - Duration::weeks(n as i64));
+    } else if s.ends_with('m') {
+        let n: u32 = s[..s.len() - 1].parse()?;
+        let now = Utc::now();
+        return Ok(now - Duration::days((n as i64) * 30));
+    } else if s.ends_with('y') {
+        let n: u32 = s[..s.len() - 1].parse()?;
+        let now = Utc::now();
+        return Ok(now - Duration::days((n as i64) * 365));
+    }
+
+    Err(anyhow!("Cannot parse date: {}", s))
+}