Add report range functions for chunking requests and diffing cache by…

… month

mpr/date.py

@@ -9,7 +9,6 @@
 date64 = dtype('datetime64[D]')
 Date = type(date64)
 DateInterval = Tuple[date, date]
-Quarter = Tuple[int, int]
 
 
 def from_string(date_string: str, date_format: str) -> date64:
@@ -22,14 +21,3 @@ def to_ordinal(it: date64) -> uint32:
 
 def from_ordinal(ordinal: uint32) -> date64:
     return datetime64(date.fromordinal(ordinal), 'D')
-
-
-def to_quarter(it: date) -> Quarter:
-    return it.year, (it.month - 1) // 3
-
-
-def from_quarter(year: int, quarter: int) -> DateInterval:
-    month = quarter * 3 + 1
-    start = date(year, month, 1)
-    end = date(year, month + 3, 1) if 0 <= quarter < 3 else date(year + 1, 1, 1)
-    return start, end

mpr/report_range.py

@@ -0,0 +1,64 @@
+from datetime import date
+from typing import Tuple
+from typing import NamedTuple
+from typing import Union
+from typing import Iterator
+from .date import DateInterval
+
+# Load Algorithm...
+# given a date range...
+#   create a ReportMonth for each month in the request range
+#   Retrieve report months from table's fetched attribute that match the requested ReportMonth
+#   Find the date difference between each requested report range and the corresponding fetched report range
+#   Request the report for those dates and save it into the table
+#   Replace the fetched report month with the requested report month in table's fetched attribute
+
+Month = Tuple[int, int]
+
+
+class ReportMonth(NamedTuple):
+    year: int
+    month: int
+    end: int = None
+
+    @property
+    def dates(self) -> DateInterval:
+        year = self.year
+        month = self.month
+        end = self.end
+        last = date(year, month, end) if end else min(date(*next_month(year, month), 1), date.today())
+        return date(year, month, 1), last
+
+    def __hash__(self) -> int:
+        return hash((self.year, self.month))
+
+    def __eq__(self, other) -> bool:
+        return isinstance(other, ReportMonth) and hash(self) == hash(other) and self.end == other.end
+
+
+def next_month(year: int, month: int) -> Month:
+    return (year, month + 1) if month < 12 else (year + 1, 1)
+
+
+def get_months(start: date, end: date) -> Iterator[Month]:
+    current = (start.year, start.month)
+    last = (end.year, end.month)
+
+    while current <= last:
+        yield current
+        current = next_month(*current)
+
+
+def report_months(start: date, end: date) -> Iterator[ReportMonth]:
+    return map(lambda it: ReportMonth(*it), get_months(start, end))
+
+
+def report_diff(requested: ReportMonth, fetched: ReportMonth) -> Union[DateInterval, None]:
+    assert requested.month == fetched.month, "Reports must be the same month"
+
+    if requested == fetched:
+        return None
+
+    first = fetched.dates[1]
+    second = requested.dates[1]
+    return min(first, second), max(first, second)

test/test_report_range.py

@@ -0,0 +1,46 @@
+from datetime import date
+from unittest import TestCase
+
+from mpr.report_range import ReportMonth, next_month, report_months, get_months, report_diff
+
+
+class ReportRangeTest(TestCase):
+    def test_equals(self):
+        first = ReportMonth(2019, 1)
+        second = ReportMonth(2019, 1)
+        self.assertEqual(first, second)
+
+    def test_not_equal(self):
+        first = ReportMonth(2019, 1)
+        second = ReportMonth(2019, 1, 15)
+        self.assertEqual(hash(first), hash(second))
+        self.assertNotEqual(first, second)
+
+    def test_next_month(self):
+        self.assertEqual(next_month(2018, 12), (2019, 1))
+        self.assertEqual(next_month(2019, 1), (2019, 2))
+
+    def test_months(self):
+        months = list(get_months(date(2018, 10, 1), date(2019, 2, 15)))
+        self.assertEqual(months, [(2018, 10), (2018, 11), (2018, 12), (2019, 1), (2019, 2)])
+
+    def test_report_months(self):
+        today = date.today()
+        year = today.year
+        month = today.month
+        first, *_, last = report_months(date(2019, 6, 1), today)
+
+        self.assertEqual(first, ReportMonth(2019, 6))
+        self.assertEqual(last.year, year)
+        self.assertEqual(last.month, month)
+        self.assertEqual(last.dates, (date(year, month, 1), today))
+
+    def test_report_diff(self):
+        with self.assertRaises(AssertionError):
+            report_diff(ReportMonth(2019, 1), ReportMonth(2019, 2))
+
+        self.assertIsNone(report_diff(ReportMonth(2019, 1), ReportMonth(2019, 1)))
+
+        start, end = report_diff(ReportMonth(2019, 1), ReportMonth(2019, 1, 15))
+        self.assertEqual(start, date(2019, 1, 15))
+        self.assertEqual(end, date(2019, 2, 1))