Weight string to grams

BritishHorseRacingApi.Tests/DataConverterHelperTests.cs

@@ -80,5 +80,24 @@ namespace BritishHorseRacingApi.Tests
             //Assert
             Assert.Equal(decimalExpectedValue, result);
         }
+
+        [Theory()]
+        [InlineData("9st 4lbs", 58967.00662)]
+        [InlineData("11st 3lbs", 71214.00098)]
+        [InlineData("10lbs", 4535.92000)]
+        [InlineData("9st", 57152.63862)]
+        [InlineData("9st 0lbs", 57152.63862)]
+        [InlineData("", null)]
+        [InlineData(" ", null)]
+        [InlineData(null, null)]
+        public void TestWeightStringToGrams(string value, double? expectedResult)
+        {
+            //Arrange
+            var decimalExpectedValue = (decimal?)expectedResult;
+            //Act
+            var result = DataConverterHelper.WeightStringToGrams(value);
+            //Assert
+            Assert.Equal(decimalExpectedValue, result);
+        }
     }
 }

BritishHorseRacingApi/Helpers/DataConverterHelper.cs

@@ -81,5 +81,22 @@ namespace BritishHorseRacingApi.Helpers
             var denominator = Decimal.Parse(match.Groups["Denominator"].Value);
             return (numerator / denominator) + 1;
         }
+        private static readonly Regex _weightStringRegex = new Regex("((?'stone'[0-9]+)?st)? ?((?'pounds'[0-9]+)lbs)?", RegexOptions.Compiled);
+        public static decimal? WeightStringToGrams(string value)
+        {
+            if (String.IsNullOrWhiteSpace(value))
+                return null;
+
+            var result = _weightStringRegex.Match(value);
+
+            var stoneGroup = result.Groups["stone"];
+            var stone = stoneGroup.Success ? Decimal.Parse(stoneGroup.Value) : 0;
+
+            var poundsGroup = result.Groups["pounds"];
+            var pounds = poundsGroup.Success ? Decimal.Parse(poundsGroup.Value) : 0;
+
+            var grams = (stone * 6350.29318m) + (pounds * 453.592m);
+            return grams;
+        }
     }
 }

BritishHorseRacingApi/Models/Runner.cs

@@ -139,5 +139,6 @@ namespace BritishHorseRacingApi.Models
 
         public decimal? DecimalOdds() => DataConverterHelper.FractionOddsToDecimal(Odds);
         public string RacehorseNameWithoutCountry => RacehorseName.Split('(')[0].Trim();
+        public decimal? WeightInGrams => DataConverterHelper.WeightStringToGrams(WeightText);
     }
 }