add streak-releted basic functionality

common/time.py

@@ -1,8 +1,10 @@
 import re
-from datetime import datetime, timedelta
+from datetime import date, datetime, timedelta
 
 from django.utils import timezone
 
+from common.utils import generate_split_ranges
+
 dateformat: str = "%d/%m/%Y"
 datetimeformat: str = "%d/%m/%Y %H:%M"
 timeformat: str = "%H:%M"
@@ -84,3 +86,80 @@ def local_strftime(datetime: datetime, format: str = datetimeformat) -> str:
     return timezone.localtime(datetime).strftime(format)
 
 
+def daterange(start: date, end: date, end_inclusive: bool = False) -> list[date]:
+    time_between: timedelta = end - start
+    if (days_between := time_between.days) < 1:
+        raise ValueError("start and end have to be at least 1 day apart.")
+    if end_inclusive:
+        print(f"{end_inclusive=}")
+        print(f"{days_between=}")
+        days_between += 1
+    print(f"{days_between=}")
+    return [start + timedelta(x) for x in range(days_between)]
+
+
+def streak(datelist: list[date]) -> dict[str, int | tuple[date, date]]:
+    if len(datelist) == 1:
+        return {"days": 1, "dates": (datelist[0], datelist[0])}
+    else:
+        print(f"Processing {len(datelist)} dates.")
+        missing = sorted(
+            set(
+                datelist[0] + timedelta(x)
+                for x in range((datelist[-1] - datelist[0]).days)
+            )
+            - set(datelist)
+        )
+        print(f"{len(missing)} days missing.")
+        datelist_with_missing = sorted(datelist + missing)
+        ranges = list(generate_split_ranges(datelist_with_missing, missing))
+        print(f"{len(ranges)} ranges calculated.")
+        longest_consecutive_days = timedelta(0)
+        longest_range: tuple[date, date] = (date(1970, 1, 1), date(1970, 1, 1))
+        for start, end in ranges:
+            if (current_streak := end - start) > longest_consecutive_days:
+                longest_consecutive_days = current_streak
+                longest_range = (start, end)
+        return {"days": longest_consecutive_days.days + 1, "dates": longest_range}
+
+
+def streak_bruteforce(datelist: list[date]) -> dict[str, int | tuple[date, date]]:
+    if (datelist_length := len(datelist)) == 0:
+        raise ValueError("Number of dates in the list is 0.")
+    datelist.sort()
+    current_streak = 1
+    current_start = datelist[0]
+    current_end = datelist[0]
+    current_date = datelist[0]
+    highest_streak = 1
+    highest_streak_daterange = (current_start, current_end)
+
+    def update_highest_streak():
+        nonlocal highest_streak, highest_streak_daterange
+        if current_streak > highest_streak:
+            highest_streak = current_streak
+            highest_streak_daterange = (current_start, current_end)
+
+    def reset_streak():
+        nonlocal current_start, current_end, current_streak
+        current_start = current_end = current_date
+        current_streak = 1
+
+    def increment_streak():
+        nonlocal current_end, current_streak
+        current_end = current_date
+        current_streak += 1
+
+    for i, datelist_item in enumerate(datelist, start=1):
+        current_date = datelist_item
+        if current_date == current_start or current_date == current_end:
+            continue
+        if current_date - timedelta(1) != current_end and i != datelist_length:
+            update_highest_streak()
+            reset_streak()
+        elif current_date - timedelta(1) == current_end and i == datelist_length:
+            increment_streak()
+            update_highest_streak()
+        else:
+            increment_streak()
+    return {"days": highest_streak, "dates": highest_streak_daterange}

common/utils.py

@@ -1,6 +1,7 @@
+from datetime import date
 from random import choices
 from string import ascii_lowercase
-from typing import Any, Callable
+from typing import Any, Callable, Generator, TypeVar
 
 from django.template.loader import render_to_string
 from django.urls import NoReverseMatch, reverse
@@ -145,3 +146,23 @@ def truncate_with_popover(input_string: str) -> str:
 
 def randomid(seed: str = "", length: int = 10) -> str:
     return seed + "".join(choices(ascii_lowercase, k=length))
+
+
+T = TypeVar("T", str, int, date)
+
+
+def generate_split_ranges(
+    value_list: list[T], split_points: list[T]
+) -> Generator[tuple[T, T], None, None]:
+    for x in range(0, len(split_points) + 1):
+        if x == 0:
+            start = 0
+        elif x >= len(split_points):
+            start = value_list.index(split_points[x - 1]) + 1
+        else:
+            start = value_list.index(split_points[x - 1]) + 1
+        try:
+            end = value_list.index(split_points[x])
+        except IndexError:
+            end = len(value_list)
+        yield (value_list[start], value_list[end - 1])