Begin building trade calculations

elite_engineering/materials.py

@@ -3,6 +3,7 @@ import csv
 import dataclasses
 import enum
 import fractions
+import functools
 import importlib.resources
 import typing
 
@@ -11,6 +12,7 @@ from elite_engineering import trade
 
 @dataclasses.dataclass
 class Material:
+    symbol: str
     name: str
     type_: str
     category: str
@@ -27,7 +29,7 @@ def _load() -> typing.Dict[str, Material]:
     lines = path.read_text().splitlines()
     reader = csv.reader(lines[1:])
     return {
-        symbol.lower(): Material(name, type_, category, int(grade))
+        symbol.lower(): Material(symbol.lower(), name, type_, category, int(grade))
         for fdevid, symbol, grade, type_, category, name in reader
     }
 
@@ -66,10 +68,22 @@ class Inventory(collections.UserDict):
         return all([self[name] >= quantity for name, quantity in items.items()])
 
     def __add__(self, other: "Inventory") -> "Inventory":
-        return Inventory({name: self[name] + qty for name, qty in other.items()})
+        return Inventory({name: self[name] + other[name] for name in materials})
 
     def __sub__(self, other: "Inventory") -> "Inventory":
-        return Inventory({name: self[name] - qty for name, qty in other.items()})
+        return Inventory({name: self[name] - other[name] for name in materials})
+
+    def trades(self, symbol: str, quantity: int) -> "Materials":
+        if self.has(Materials({symbol: quantity})):
+            return Materials({})
+        raise ValueError
+
+    def trade_for(self, other: "Inventory") -> "Inventory":
+        def accumulate(inv: "Inventory", mat: typing.Tuple[str, int]) -> "Inventory":
+            symbol, quantity = mat
+            return inv - inv.trades(symbol, quantity)
+
+        return functools.reduce(accumulate, other.items(), self)
 
     @classmethod
     def from_event(

tests/test_materials.py

@@ -25,8 +25,12 @@ class TradeCalculationTests(unittest.TestCase):
         actual = [
             [
                 self.format_ratio(
-                    materials.Material("name", "raw", "category", grade_in).trade_ratio(
-                        materials.Material("name", "raw", "category", grade_out)
+                    materials.Material(
+                        "symbol", "name", "raw", "category", grade_in
+                    ).trade_ratio(
+                        materials.Material(
+                            "symbol", "name", "raw", "category", grade_out
+                        )
                     )
                 )
                 for grade_in in [1, 2, 3, 4, 5]
@@ -47,8 +51,10 @@ class TradeCalculationTests(unittest.TestCase):
         actual = [
             [
                 self.format_ratio(
-                    materials.Material("name", "raw", "category", grade_in).trade_ratio(
-                        materials.Material("name", "raw", "other", grade_out)
+                    materials.Material(
+                        "symbol", "name", "raw", "category", grade_in
+                    ).trade_ratio(
+                        materials.Material("symbol", "name", "raw", "other", grade_out)
                     )
                 )
                 for grade_in in [1, 2, 3, 4, 5]
@@ -70,8 +76,12 @@ class TradeCalculationTests(unittest.TestCase):
         actual = [
             [
                 self.format_ratio(
-                    materials.Material("name", "raw", "category", grade_in).trade_ratio(
-                        materials.Material("name", "encoded", "other", grade_out)
+                    materials.Material(
+                        "symbol", "name", "raw", "category", grade_in
+                    ).trade_ratio(
+                        materials.Material(
+                            "symbol", "name", "encoded", "other", grade_out
+                        )
                     )
                 )
                 for grade_in in [1, 2, 3, 4, 5]
@@ -146,9 +156,6 @@ class InventoryTests(unittest.TestCase):
         self.assertEqual(exc.exception.args, (-1,))
 
     def test_load_from_materials_event(self) -> None:
-        event = json.loads(
-            pathlib.Path(__file__).parent.joinpath("events/materials.json").read_text()
-        )
         event = {
             "timestamp": "2022-01-23T02:58:12Z",
             "event": "Materials",
@@ -222,6 +229,25 @@ class InventoryTests(unittest.TestCase):
             self.from_event(event)
         self.assertEqual(exc.exception.args, ("Not a 'Materials' event",))
 
+    def test_trade_unnecessary(self) -> None:
+        inventory = self.make({"carbon": 3, "niobium": 1})
+        recipe = materials.Materials({"carbon": 3})
+        self.assertEqual(inventory, inventory.trade_for(recipe))
+
+    def test_trade_impossible(self) -> None:
+        inventory = self.make()
+        recipe = materials.Materials({"carbon": 3})
+        with self.assertRaises(ValueError):
+            inventory.trade_for(recipe)
+
+    @unittest.skip("Not implemented")
+    def test_trade_grade_2_for_grade_1(self) -> None:
+        inventory = self.make({"vanadium": 1, "niobium": 1})
+        recipe = materials.Materials({"carbon": 3})
+        self.assertEqual(
+            self.make({"carbon": 3, "niobium": 1}), inventory.trade_for(recipe)
+        )
+
 
 class MaterialsTests(InventoryTests):
     def make(