move home to fallback/via_home.py

my/location/fallback/via_home.py

@@ -0,0 +1,72 @@
+'''
+Simple location provider, serving as a fallback when more detailed data isn't available
+'''
+
+from dataclasses import dataclass
+from datetime import datetime, time, timezone
+from functools import lru_cache
+from typing import Sequence, Tuple, Union, cast
+
+from my.config import location as user_config
+
+from my.location.common import LatLon, DateIsh
+
+@dataclass
+class Config(user_config):
+    home: Union[
+        LatLon,         # either single, 'current' location
+        Sequence[Tuple[ # or, a sequence of location history
+            DateIsh,    # date when you moved to
+            LatLon,     # the location
+        ]]
+    ]
+    # TODO could make current Optional and somehow determine from system settings?
+    @property
+    def _history(self) -> Sequence[Tuple[datetime, LatLon]]:
+        home1 = self.home
+        # todo ugh, can't test for isnstance LatLon, it's a tuple itself
+        home2: Sequence[Tuple[DateIsh, LatLon]]
+        if isinstance(home1[0], tuple):
+            # already a sequence
+            home2 = cast(Sequence[Tuple[DateIsh, LatLon]], home1)
+        else:
+            # must be a pair of coordinates. also doesn't really matter which date to pick?
+            loc = cast(LatLon, home1)
+            home2 = [(datetime.min, loc)]
+
+        # todo cache?
+        res = []
+        for x, loc in home2:
+            dt: datetime
+            if isinstance(x, str):
+                dt = datetime.fromisoformat(x)
+            elif isinstance(x, datetime):
+                dt = x
+            else:
+                dt = datetime.combine(x, time.min)
+            # todo not sure about doing it here, but makes it easier to compare..
+            if dt.tzinfo is None:
+                dt = dt.replace(tzinfo=timezone.utc)
+            res.append((dt, loc))
+        res = list(sorted(res, key=lambda p: p[0]))
+        return res
+
+
+from ...core.cfg import make_config
+config = make_config(Config)
+
+
+@lru_cache(maxsize=None)
+def get_location(dt: datetime) -> LatLon:
+    '''
+    Interpolates the location at dt
+    '''
+    if dt.tzinfo is None:
+        dt = dt.replace(tzinfo=timezone.utc)
+    hist = list(reversed(config._history))
+    for pdt, loc in hist:
+        if dt >= pdt:
+            return loc
+    else:
+        # I guess the most reasonable is to fallback on the first location
+        return hist[-1][1]