using System;

using System.Collections.Generic;

using System.Text.RegularExpressions;

​

public class Program

{

    // Dictionary to map field names to their types

    public static Dictionary<string, string> fieldTypes = new Dictionary<string, string>

    {

        { "LeaveType", "choice" },  // example complex type

        { "duration", "decimal" }  // example simple type

        // Add more field types as needed

    };

​

    public static void Main()

    {

        string jsExpression1 = "$LeaveType$ == '1'";

        string jsExpression2 = "$duration$ == \"0\"";

        string jsExpression3 = "$LeaveType$ != '2'";

        string jsExpression4 = "$duration$ >= \"1\"";

        string jsExpression5 = "$LeaveType$ < '3'";

​

        string fhirExpression1 = ConvertToFhirSdcExpression(jsExpression1);

        string fhirExpression2 = ConvertToFhirSdcExpression(jsExpression2);

        string fhirExpression3 = ConvertToFhirSdcExpression(jsExpression3);

        string fhirExpression4 = ConvertToFhirSdcExpression(jsExpression4);

        string fhirExpression5 = ConvertToFhirSdcExpression(jsExpression5);

​

        Console.WriteLine(fhirExpression1);

        Console.WriteLine(fhirExpression2);

        Console.WriteLine(fhirExpression3);

        Console.WriteLine(fhirExpression4);

        Console.WriteLine(fhirExpression5);

    }

​

    public static string ConvertToFhirSdcExpression(string jsExpression)

    {

        // Regex to match $field$

        string pattern = @"\$(\w+)\$";

        string fhirExpression = Regex.Replace(jsExpression, pattern, match =>

        {

            string fieldName = match.Groups[1].Value;

            string fieldType = fieldTypes.ContainsKey(fieldName) ? fieldTypes[fieldName] : "unknown";

            string valuePath = fieldType == "choice" ? ".answer.value.code" : ".answer.value";

            return $"%resource.item.where(linkId='{fieldName}'){valuePath}";

        });

​

        // Match comparison operators and their values

        pattern = @"(\s*(==|!=|>=|<=|>|<)\s*)""([^""]*)""";

        string replacement = "$1'$3'";

        fhirExpression = Regex.Replace(fhirExpression, pattern, replacement);

        fhirExpression = fhirExpression.Replace("==", "=");

​

        return fhirExpression;

    }

}

​