implemented natural gas provider detection

Co-authored-by: dwindleduck <[email protected]>
Co-authored-by: eriksynn <[email protected]>
Co-authored-by: Debajyoti Debnath <[email protected]>
Co-authored-by: AdamFinkle <[email protected]>

rules-engine/src/rules_engine/parser.py

@@ -4,6 +4,7 @@
 """
 import csv
 import io
+import re
 from datetime import datetime, timedelta
 from enum import StrEnum
 
@@ -15,6 +16,19 @@ class NaturalGasCompany(StrEnum):
     NATIONAL_GRID = "national_grid"
 
 
+class _NaturalGasCompanyBillRegex:
+    """
+    The regex for which to search a natural gas bill to determine its company.
+    """
+
+    EVERSOURCE = re.compile(
+        r"Read Date,Usage,Number of Days,Usage per day,Charge,Average Temperature"
+    )
+    NATIONAL_GRID = re.compile(
+        r"Name,.*,,,,,\nAddress,.*,,,,,\nAccount Number,.*,,,,,\nService,.*,,,,,\n"
+    )
+
+
 class _GasBillRowEversource:
     """
     Holds data for one row of an Eversource gas bill CSV.
@@ -57,20 +71,43 @@ def __init__(self, row):
         self.usage = row["USAGE"]
 
 
-def parse_gas_bill(data: str, company: NaturalGasCompany) -> NaturalGasBillingInput:
+def _detect_gas_company(data: str) -> NaturalGasCompany:
+    """
+    Return which natural gas company issued this bill.
+    """
+    if _NaturalGasCompanyBillRegex.NATIONAL_GRID.search(data):
+        return NaturalGasCompany.NATIONAL_GRID
+    elif _NaturalGasCompanyBillRegex.EVERSOURCE.search(data):
+        return NaturalGasCompany.EVERSOURCE
+    else:
+        raise ValueError(
+            """Could not detect which company this bill was from:\n 
+                           Regular expressions matched not."""
+        )
+
+
+def parse_gas_bill(
+    data: str, company: NaturalGasCompany | None = None
+) -> NaturalGasBillingInput:
     """
     Parse a natural gas bill from a given natural gas company.
+
+    Tries to automatically detect the company that sent the bill.
+    Otherwise, requires the company be passed as an argument.
     """
+    if company == None:
+        company = _detect_gas_company(data)
+
     match company:
         case NaturalGasCompany.EVERSOURCE:
-            return parse_gas_bill_eversource(data)
+            return _parse_gas_bill_eversource(data)
         case NaturalGasCompany.NATIONAL_GRID:
-            return parse_gas_bill_national_grid(data)
+            return _parse_gas_bill_national_grid(data)
         case _:
             raise ValueError("Wrong CSV format selected: select another format.")
 
 
-def parse_gas_bill_eversource(data: str) -> NaturalGasBillingInput:
+def _parse_gas_bill_eversource(data: str) -> NaturalGasBillingInput:
     """
     Return a list of gas bill data parsed from an Eversource CSV
     received as a string.
@@ -103,7 +140,7 @@ def parse_gas_bill_eversource(data: str) -> NaturalGasBillingInput:
     return NaturalGasBillingInput(records=records)
 
 
-def parse_gas_bill_national_grid(data: str) -> NaturalGasBillingInput:
+def _parse_gas_bill_national_grid(data: str) -> NaturalGasBillingInput:
     """
     Return a list of gas bill data parsed from an National Grid CSV
     received as a string.

rules-engine/tests/test_rules_engine/test_engine.py

@@ -3,7 +3,6 @@
 
 import pytest
 from pytest import approx
-
 from rules_engine import engine
 from rules_engine.pydantic_models import (
     AnalysisType,

rules-engine/tests/test_rules_engine/test_examples.py

@@ -8,8 +8,6 @@
 import pytest
 from pydantic import BaseModel
 from pytest import approx
-from typing_extensions import Annotated
-
 from rules_engine import engine
 from rules_engine.pydantic_models import (
     NaturalGasBillingInput,
@@ -18,6 +16,7 @@
     SummaryOutput,
     TemperatureInput,
 )
+from typing_extensions import Annotated
 
 # Test inputs are provided as separate directory within the "cases/examples" directory
 # Each subdirectory contains a JSON file (named summary.json) which specifies the inputs for the test runner

rules-engine/tests/test_rules_engine/test_parser.py

@@ -1,6 +1,7 @@
 import pathlib
 from datetime import date
 
+import pytest
 from rules_engine import parser
 from rules_engine.pydantic_models import NaturalGasBillingRecordInput
 
@@ -10,13 +11,13 @@
 # of refactoring elsewhere in the codebase.
 
 
-def _read_gas_bill_eversource():
+def _read_gas_bill_eversource() -> str:
     """Read a test natural gas bill from a test Eversource CSV"""
     with open(ROOT_DIR / "feldman" / "natural-gas-eversource.csv") as f:
         return f.read()
 
 
-def _read_gas_bill_national_grid():
+def _read_gas_bill_national_grid() -> str:
     """Read a test natural gas bill from a test National Grid CSV"""
     with open(ROOT_DIR / "quateman" / "natural-gas-national-grid.csv") as f:
         return f.read()
@@ -76,11 +77,32 @@ def test_parse_gas_bill():
 
 def test_parse_gas_bill_eversource():
     """Tests parsing a natural gas bill from Eversource."""
-    _validate_eversource(parser.parse_gas_bill_eversource(_read_gas_bill_eversource()))
+    _validate_eversource(parser._parse_gas_bill_eversource(_read_gas_bill_eversource()))
 
 
 def test_parse_gas_bill_national_grid():
     """Tests parsing a natural gas bill from National Grid."""
     _validate_national_grid(
-        parser.parse_gas_bill_national_grid(_read_gas_bill_national_grid())
+        parser._parse_gas_bill_national_grid(_read_gas_bill_national_grid())
     )
+
+
+def test_detect_natural_gas_company():
+    """Tests if the natural gas company is correctly detected from the parsed csv."""
+    read_eversource = _read_gas_bill_eversource()
+    read_nationalgrid = _read_gas_bill_national_grid()
+    assert (
+        parser._detect_gas_company(read_eversource)
+        == parser.NaturalGasCompany.EVERSOURCE
+    )
+    assert (
+        parser._detect_gas_company(read_nationalgrid)
+        == parser.NaturalGasCompany.NATIONAL_GRID
+    )
+
+
+def test_detect_natural_gas_company_with_error():
+    """Tests if an error is raised if the natural gas company is incorrect in the csv."""
+    read_csv_string = r"Some bogus string input"
+    with pytest.raises(ValueError):
+        parser._detect_gas_company(read_csv_string)