1 files changed, 87 insertions, 0 deletions
diff --git a/game.py b/game.py
new file mode 100644
index 0000000..fd9aba0
--- /dev/null
+++ b/game.py
@@ -0,0 +1,87 @@
+import re
+from enum import Enum
+from dataclasses import dataclass
+
+from distribution import Distribution
+
+def d(edge_count):
+    res = Distribution()
+    if edge_count == 0:
+        res.insert(0, 1)
+        return res
+    prob = 1/edge_count
+    for val in range(1, edge_count+1):
+        res.insert(val, prob)
+    return res
+
+
+class Roll:
+    Fumble = -1
+    Fail = 0
+    Success = 1
+    Crit = 2
+
+    @staticmethod
+    def get_natural_success_mod(value):
+        if value <= 1:
+            return -1
+        if value >= 20:
+            return 1
+        return 0
+
+    @staticmethod
+    def check(value, dc, bonus=0):
+        res = 0
+        rolled = value + bonus
+        if rolled >= dc + 10:
+            res = Roll.Crit
+        elif rolled >= dc:
+            res = Roll.Success
+        elif rolled <= dc - 10:
+            res = Roll.Fumble
+        res += Roll.get_natural_success_mod(value)
+        return Roll.clamp(res)
+
+    @staticmethod
+    def clamp(value):
+        return max(Roll.Fumble, min(Roll.Crit, value))
+
+
+class Difficulty(Enum):
+    Terrible = -2
+    Low = -1
+    Moderate = 0
+    High = 1
+    Extreme = 2
+
+    @classmethod
+    def from_str(cls, name):
+        name = name.strip().lower()
+        for member in cls:
+            if member.name.lower() == name:
+                return member
+        raise ValueError(f"{name!r} is not a valid {cls.__name__}")
+
+@dataclass
+class RollInfo:
+    die_size: int
+    dice_count: int = 1
+    bonus: int = 0
+
+    @classmethod
+    def parse(cls, str_data):
+        # match strings like 2d6+8 (15)
+        match = re.fullmatch(r"^(\d+)d(\d+)\s*(\+\s*\d+)?\s*(\s*\(\s*\d+\s*\))?",
+                             str_data)
+        if not match:
+            raise ValueError(f"{str_data!r} is not a valid RollInfo")
+        res = RollInfo(int(match.group(2).strip()))
+        res.dice_count = int(match.group(1).strip())
+        bonus = match.group(3)
+        if bonus:
+            res.bonus = int(bonus.strip(" +"))
+        return res
+    
+    def distribution(self):
+        return self.dice_count * d(self.die_size) + self.bonus
+