From 28ff5c95cf248e0d835108ca2c5a3b1ef6fa73fc Mon Sep 17 00:00:00 2001 From: Palash Tyagi <23239946+Magnus167@users.noreply.github.com> Date: Sun, 13 Apr 2025 00:39:08 +0100 Subject: [PATCH] Add BDateFreq enum and frequency-based date retrieval functions --- src/utils/bdates.rs | 365 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 365 insertions(+) create mode 100644 src/utils/bdates.rs diff --git a/src/utils/bdates.rs b/src/utils/bdates.rs new file mode 100644 index 0000000..0734ed5 --- /dev/null +++ b/src/utils/bdates.rs @@ -0,0 +1,365 @@ +use chrono::{Datelike, Duration, NaiveDate, Weekday}; +use std::error::Error; + +#[derive(Debug, Clone, Copy)] +pub enum BDateFreq { + Daily, + WeeklyMonday, + MonthStart, + QuarterStart, + YearStart, + MonthEnd, + QuarterEnd, + WeeklyFriday, + YearEnd, +} + +#[derive(Debug, Clone, Copy)] +pub enum AggregationType { + Start, // Indicates picking the first date in a group. + End, // Indicates picking the last date in a group. +} + +impl BDateFreq { + pub fn from_string(freq: String) -> Result> { + // use from_str to convert the string to a BDateFreq enum + Self::from_str(&freq) + } + pub fn from_str(freq: &str) -> Result> { + match freq { + "D" => Ok(BDateFreq::Daily), + "W" => Ok(BDateFreq::WeeklyMonday), + "M" => Ok(BDateFreq::MonthStart), + "Q" => Ok(BDateFreq::QuarterStart), + "A" => Ok(BDateFreq::YearStart), + "ME" => Ok(BDateFreq::MonthEnd), + "QE" => Ok(BDateFreq::QuarterEnd), + "WF" => Ok(BDateFreq::WeeklyFriday), + "YE" => Ok(BDateFreq::YearEnd), + _ => Err("Invalid frequency specified".into()), + } + } + pub fn agg_type(&self) -> AggregationType { + match self { + BDateFreq::Daily + | BDateFreq::WeeklyMonday + | BDateFreq::MonthStart + | BDateFreq::QuarterStart + | BDateFreq::YearStart => AggregationType::Start, + + BDateFreq::WeeklyFriday + | BDateFreq::MonthEnd + | BDateFreq::QuarterEnd + | BDateFreq::YearEnd => AggregationType::End, + } + } +} + +/// Returns only the business dates (Mon-Fri) between start_date and end_date +/// that match the desired frequency. +pub fn get_bdates_list_with_freq( + start_date_str: &str, + end_date_str: &str, + freq: BDateFreq, +) -> Result, Box> { + let start_date = NaiveDate::parse_from_str(start_date_str, "%Y-%m-%d")?; + let end_date = NaiveDate::parse_from_str(end_date_str, "%Y-%m-%d")?; + + if start_date > end_date { + return Ok(Vec::new()); + } + + let mut dates = match freq { + BDateFreq::Daily => collect_daily(start_date, end_date), + + BDateFreq::WeeklyMonday => collect_weekly(start_date, end_date, Weekday::Mon), + BDateFreq::WeeklyFriday => collect_weekly(start_date, end_date, Weekday::Fri), + + BDateFreq::MonthStart => collect_monthly(start_date, end_date, /*start=*/ true), + BDateFreq::MonthEnd => collect_monthly(start_date, end_date, /*start=*/ false), + + BDateFreq::QuarterStart => collect_quarterly(start_date, end_date, /*start=*/ true), + BDateFreq::QuarterEnd => collect_quarterly(start_date, end_date, /*start=*/ false), + + BDateFreq::YearStart => collect_yearly(start_date, end_date, /*start=*/ true), + BDateFreq::YearEnd => collect_yearly(start_date, end_date, /*start=*/ false), + }; + + // Filter out any weekend days that might slip in edge cases (e.g. if the + // computed "start of month" fell on Sat/Sun). + dates.retain(|d| d.weekday() != Weekday::Sat && d.weekday() != Weekday::Sun); + + Ok(dates) +} + +/* ------------------------------ Helpers ------------------------------ */ + +/// Return all business days, day-by-day. +fn collect_daily(start_date: NaiveDate, end_date: NaiveDate) -> Vec { + let mut result = Vec::new(); + let mut current = start_date; + while current <= end_date { + if is_weekday(current) { + result.push(current); + } + current = current.succ_opt().unwrap(); + } + result +} + +/// Return the specified weekday (e.g. Monday, Friday) in each week of the range. +fn collect_weekly( + start_date: NaiveDate, + end_date: NaiveDate, + target_weekday: Weekday, +) -> Vec { + let mut result = Vec::new(); + + // Find the first `target_weekday` on or after `start_date`. + // If `start_date` is already e.g. Monday, we can use it as is. + // Otherwise, jump ahead until we get that weekday. + let mut current = move_to_weekday_on_or_after(start_date, target_weekday); + + // Step in 7-day increments (full weeks). + while current <= end_date { + result.push(current); + current = current + Duration::days(7); + } + result +} + +/// Return either first or last business day in each month of the range. +fn collect_monthly( + start_date: NaiveDate, + end_date: NaiveDate, + want_first_day: bool, +) -> Vec { + let mut result = Vec::new(); + + // We'll iterate month by month, from (start_year, start_month) up to + // (end_year, end_month). + let mut year = start_date.year(); + let mut month = start_date.month(); + + // A small helper that updates year/month by +1 month. + let next_month = |(yr, mo): (i32, u32)| -> (i32, u32) { + if mo == 12 { + (yr + 1, 1) + } else { + (yr, mo + 1) + } + }; + + // Move `(year, month)` backward if necessary so that `(year, month)` + // definitely covers the entire period from `start_date` onward. + // Actually, it’s simpler to start from the actual (year, month) of start_date + // and go up. We'll just skip if the computed "day" < start_date. + + // Continue while we haven't passed (end_year, end_month). + while year < end_date.year() || (year == end_date.year() && month <= end_date.month()) { + // Compute the date that represents either first or last business day + // for this (year, month). + let candidate = if want_first_day { + first_business_day_of_month(year, month) + } else { + last_business_day_of_month(year, month) + }; + if candidate >= start_date && candidate <= end_date { + result.push(candidate); + } + + // Move to the next month. + let (ny, nm) = next_month((year, month)); + year = ny; + month = nm; + } + + result +} + +/// Return either the first or last business day in each quarter of the range. +fn collect_quarterly( + start_date: NaiveDate, + end_date: NaiveDate, + want_first_day: bool, +) -> Vec { + let mut result = Vec::new(); + + // We'll figure out which quarter `start_date` is in, then jump quarter-by-quarter. + // Quarters are: Q1 = months 1–3, Q2 = 4–6, Q3 = 7–9, Q4 = 10–12. + // Start by computing the (year, quarter_index) for start_date. + let mut year = start_date.year(); + let mut q = month_to_quarter(start_date.month()); + + while quarter_to_first_date(year, q) > end_date { + // If even the earliest day in that quarter is > end_date, we’re done. + return result; + } + + // Move backward if the quarter’s last day < start_date, etc. + // But simpler: we’ll do a loop that increments quarter by quarter, and + // pick the appropriate date each time. We break when we pass end_date. + + loop { + // For the current year+quarter, compute the date that’s either the first or last + // business day of that quarter: + let candidate = if want_first_day { + first_business_day_of_quarter(year, q) + } else { + last_business_day_of_quarter(year, q) + }; + + if candidate > end_date { + break; + } + if candidate >= start_date { + result.push(candidate); + } + + // Move to next quarter. + if q == 4 { + year += 1; + q = 1; + } else { + q += 1; + } + } + + result +} + +/// Return either the first or last business day in each year of the range. +fn collect_yearly( + start_date: NaiveDate, + end_date: NaiveDate, + want_first_day: bool, +) -> Vec { + let mut result = Vec::new(); + let mut year = start_date.year(); + + // Step year-by-year from `start_date.year()` up to `end_date.year()`. + while year <= end_date.year() { + let candidate = if want_first_day { + first_business_day_of_year(year) + } else { + last_business_day_of_year(year) + }; + if candidate >= start_date && candidate <= end_date { + result.push(candidate); + } + year += 1; + } + result +} + +/* ---------------------- Low-Level Utility Functions ---------------------- */ + +/// Is this a weekday (Mon-Fri)? +fn is_weekday(date: NaiveDate) -> bool { + match date.weekday() { + Weekday::Sat | Weekday::Sun => false, + _ => true, + } +} + +/// Given a date and a `target_weekday`, returns the date that is the first +/// `target_weekday` on or after the given date. +fn move_to_weekday_on_or_after(date: NaiveDate, target: Weekday) -> NaiveDate { + let mut current = date; + while current.weekday() != target { + current = current.succ_opt().unwrap(); + } + current +} + +/// Return the earliest business day of (year, month). +fn first_business_day_of_month(year: i32, month: u32) -> NaiveDate { + // Start with the 1st of the month. + let mut d = NaiveDate::from_ymd_opt(year, month, 1).expect("invalid year-month"); + // If it’s Sat/Sun, move forward until we get a weekday. + while !is_weekday(d) { + d = d.succ_opt().unwrap(); + } + d +} + +/// Return the latest business day of (year, month). +fn last_business_day_of_month(year: i32, month: u32) -> NaiveDate { + let last_dom = days_in_month(year, month); + let mut d = NaiveDate::from_ymd_opt(year, month, last_dom).expect("invalid year-month"); + // If it’s Sat/Sun, move backward until we get a weekday. + while !is_weekday(d) { + d = d.pred_opt().unwrap(); + } + d +} + +/// Number of days in a month (not considering leap years *beyond* chrono's normal handling). +fn days_in_month(year: i32, month: u32) -> u32 { + // Chrono can handle this if we do a little trick: + // Construct the 1st of the next month, then subtract 1 day. + // For example: + // if month == 12 => next = (year+1, 1, 1) + // else => next = (year, month+1, 1) + let (ny, nm) = if month == 12 { + (year + 1, 1) + } else { + (year, month + 1) + }; + let first_of_next = NaiveDate::from_ymd_opt(ny, nm, 1).unwrap(); + let last_of_this = first_of_next.pred_opt().unwrap(); + last_of_this.day() +} + +/// Convert a month (1..12) to a quarter (1..4). +fn month_to_quarter(m: u32) -> u32 { + (m - 1) / 3 + 1 +} + +/// Returns 1st day of a given (year, quarter). +fn quarter_to_first_date(year: i32, quarter: u32) -> NaiveDate { + let month = match quarter { + 1 => 1, + 2 => 4, + 3 => 7, + 4 => 10, + _ => panic!("invalid quarter"), + }; + NaiveDate::from_ymd_opt(year, month, 1).unwrap() +} + +/// Return the earliest business day in (year, quarter). +fn first_business_day_of_quarter(year: i32, quarter: u32) -> NaiveDate { + let mut d = quarter_to_first_date(year, quarter); + while !is_weekday(d) { + d = d.succ_opt().unwrap(); + } + d +} + +/// Return the last business day in (year, quarter). +fn last_business_day_of_quarter(year: i32, quarter: u32) -> NaiveDate { + // The last month in the quarter is quarter_to_first_date(...) + 2 months + // Then we find the last day of that month. + let start = quarter_to_first_date(year, quarter); + let last_month = start.month() + 2; // e.g. Q1 => month=1 => +2=3 => March + last_business_day_of_month(year, last_month) +} + +/// Returns Jan 1st of a given year (adjust if weekend). +fn first_business_day_of_year(year: i32) -> NaiveDate { + let mut d = NaiveDate::from_ymd_opt(year, 1, 1).unwrap(); + while !is_weekday(d) { + d = d.succ_opt().unwrap(); + } + d +} + +/// Returns Dec 31st of a given year (adjust if weekend). +fn last_business_day_of_year(year: i32) -> NaiveDate { + let mut d = NaiveDate::from_ymd_opt(year, 12, 31).unwrap(); + while !is_weekday(d) { + d = d.pred_opt().unwrap(); + } + d +}