Collaborative session implementation, 1

synctoy/data_model.py

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+from enum import Enum, StrEnum
+from typing import Literal, NewType
+
+from pydantic import BaseModel, JsonValue
+
+from synctoy.state_machine import StateMachine
+
+
+class Type(StrEnum):
+    Null = "null"
+    User = "user"
+    Message = "message"
+
+ObjectId = NewType("ObjectId", str)
+
+class RNull(BaseModel):
+    type: Literal[Type.Null] = Type.Null
+    id: ObjectId
+
+    def equivalent_to(self, other: StateMachine):
+        return self == other
+
+    def can_transition_from(self, old: StateMachine):
+        return True
+
+    def can_transition_to(self, new: StateMachine):
+        return True
+
+class RUser(BaseModel):
+    type: Literal[Type.User] = Type.User
+    id: ObjectId
+    name: str
+
+    def equivalent_to(self, other: StateMachine):
+        return self == other
+
+    def can_transition_from(self, old: StateMachine):
+        if isinstance(old, RNull):
+            return True
+        return False
+
+    def can_transition_to(self, new: StateMachine):
+        return False
+
+class RMessage(BaseModel):
+    type: Literal[Type.Message] = Type.Message
+    id: ObjectId
+    sender: ObjectId
+    content: str
+
+    def equivalent_to(self, other: StateMachine):
+        return self == other
+
+    def can_transition_from(self, old: StateMachine):
+        if isinstance(old, RNull):
+            return True
+        if isinstance(old, RMessage):
+            return True
+        return False
+
+    def can_transition_to(self, new: StateMachine):
+        if isinstance(new, RMessage):
+            return new.sender == self.sender
+        return True
+
+NonNullRecord = RUser | RMessage
+Record = RNull | NonNullRecord
+
+
+
+def as_state_machine(r: Record) -> StateMachine:
+    return r
+
+
+class ConditionType(StrEnum):
+    True_ = "true"
+    EquivalentTo = "equivalent_to"
+
+
+class CTrue(BaseModel):
+    type: Literal[ConditionType.True_] = ConditionType.True_
+
+    def is_met(self, old: Record, new: Record):
+        return True
+
+class CEquivalentTo(BaseModel):
+    type: Literal[ConditionType.EquivalentTo] = ConditionType.EquivalentTo
+
+    expected: Record
+
+    def is_met(self, old: Record, new: Record):
+        return old.equivalent_to(self.expected)
+
+Condition = CTrue | CEquivalentTo