Implement draft of ElectricMultipoleParameters

Author: EZoni

src/pals/parameters/ElectricMultipoleParameters.py

@@ -1,11 +1,63 @@
-from pydantic import BaseModel, ConfigDict
+from pydantic import BaseModel, ConfigDict, model_validator
+from typing import Any
+
+# Valid parameter prefixes, their expected format and description
+_PARAMETER_PREFIXES = {
+    "tilt": ("tiltN", "Tilt"),
+    "En": ("EnN", "Normal component"),
+    "Es": ("EsN", "Skew component"),
+}
+
+
+def _validate_order(
+    key_num: str, parameter_name: str, prefix: str, expected_format: str
+) -> None:
+    """Validate that the order number is a non-negative integer without leading zeros."""
+    error_msg = (
+        f"Invalid {parameter_name}: '{prefix}{key_num}'. "
+        f"Parameter must be of the form '{expected_format}', where 'N' is a non-negative integer without leading zeros."
+    )
+    if not key_num.isdigit() or (key_num.startswith("0") and key_num != "0"):
+        raise ValueError(error_msg)
 
 
 class ElectricMultipoleParameters(BaseModel):
-    """Electric multipole parameters"""
+    """Electric multipole parameters
+
+    Valid parameter formats:
+    - tiltN: Tilt of Nth order multipole
+    - EnN: Normal component of Nth order multipole
+    - EsN: Skew component of Nth order multipole
+    - *NL: Length-integrated versions of components (e.g., En3L, EsNL)
+
+    Where N is a positive integer without leading zeros (except "0" itself).
+    """
 
-    # Allow arbitrary fields (TODO: remove this)
     model_config = ConfigDict(extra="allow")
 
-    # TODO: add ElectricMultipoleParameters in a follow-up RP
-    # https://pals-project.readthedocs.io/en/latest/element-parameters.html#electricmultipolep-electric-multipole-parameters
+    @model_validator(mode="before")
+    @classmethod
+    def validate(cls, values: dict[str, Any]) -> dict[str, Any]:
+        """Validate all parameter names match the expected multipole format."""
+        for key in values:
+            # Check if key ends with 'L' for length-integrated values
+            is_length_integrated = key.endswith("L")
+            base_key = key[:-1] if is_length_integrated else key
+
+            # No length-integrated values allowed for tilt parameter
+            if is_length_integrated and base_key.startswith("tilt"):
+                raise ValueError(f"Invalid electric multipole parameter: '{key}'. ")
+
+            # Find matching prefix
+            for prefix, (expected_format, description) in _PARAMETER_PREFIXES.items():
+                if base_key.startswith(prefix):
+                    key_num = base_key[len(prefix) :]
+                    _validate_order(key_num, description, prefix, expected_format)
+                    break
+            else:
+                raise ValueError(
+                    f"Invalid electric multipole parameter: '{key}'. "
+                    f"Parameters must be of the form 'tiltN', 'EnN', or 'EsN' "
+                    f"(with optional 'L' suffix for length-integrated), where 'N' is a non-negative integer."
+                )
+        return values