Move database utilities to database.py

It may not be a good idea to scatter database utilities around utils.py.
With this in mind, I moved them to database.py as static methods under
the class Database.

1 files changed, 38 insertions, 3 deletions

diff --git a/jimbrella/database.py b/jimbrella/database.py
index 3d835a8..7f10c55 100644
--- a/jimbrella/database.py
+++ b/jimbrella/database.py
@@ -1,6 +1,8 @@
 import csv
 import os
-from datetime import datetime
+from datetime import datetime, timedelta
+from .utils import human_timedelta
+from .config import DUE_HOURS
 
 
 class Database:
@@ -154,8 +156,41 @@ class Database:
                 return umb
 
     def read(self) -> list:
-        """Currently an alias for `_read()`."""
-        return self._read()
+        """An interface to `_read()` with supplemental data included.
+
+        All exposed methods with a return value should use this method instead of `_read()`.
+
+        Supplemental data:
+        - lent_time_ago:        time since umbrella was taken away by tenant. if umbrella is not
+                                taken away, its value is None.
+        - lent_time_ago_str:    lent_time_ago as a string representation.
+        """
+        umbrellas = self._read()
+        now = datetime.now()
+        for idx, umb in enumerate(umbrellas):
+            if umb["status"] == "lent":
+                lent_time_ago = now - umb["lent_at"]
+                umbrellas[idx]["lent_time_ago"] = lent_time_ago
+                umbrellas[idx]["lent_time_ago_str"] = human_timedelta(lent_time_ago)
+        return umbrellas
+
+    def group_by_status(umbrellas) -> dict:
+        """(static method) Returns umbrellas grouped into a dict by their status."""
+        keys = set([umb["status"] for umb in umbrellas])
+        statuses = {}
+        for key in keys:
+            statuses[key] = [umb for umb in umbrellas if umb["status"] == key]
+        return statuses
+
+    def find_overdue(umbrellas) -> list:
+        """(static method) Returns umbrellas in possession of their tenant for too long."""
+        now = datetime.now()
+        return [
+            umb
+            for umb in umbrellas
+            if umb["lent_at"] is not None
+            and now - umb["lent_at"] > timedelta(hours=DUE_HOURS)
+        ]
 
     def take_away(
         self, serial, tenant_name, tenant_id, tenant_phone="", tenant_email=""