using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace FrameworkBLL.ActionProcessor
{
    /// <summary>
    /// Evaluates MEVENTTYPEACTIONDETAIL.EVALCONDITION expressions.
    /// Supported syntax: {FieldName}==value  or  {FieldName}!=value
    /// Returns true (pass) when expression is null/empty.
    /// </summary>
    public interface IEvalConditionService
    {
        bool Evaluate(string? expression, IDictionary<string, string?> fields);
    }

    public sealed class EvalConditionService : IEvalConditionService
    {
        // Matches: {FieldName}==value  or  {FieldName}!=value
        private static readonly Regex _regex = new(
            @"^\{(?<field>[^}]+)\}(?<op>==|!=)(?<value>.*)$",
            RegexOptions.Compiled | RegexOptions.Singleline);

        public bool Evaluate(string? expression, IDictionary<string, string?> fields)
        {
            if (string.IsNullOrWhiteSpace(expression))
                return true;

            var match = _regex.Match(expression.Trim());
            if (!match.Success)
                return true; // unknown syntax — pass through

            var fieldName  = match.Groups["field"].Value;
            var op         = match.Groups["op"].Value;
            var expected   = match.Groups["value"].Value;

            fields.TryGetValue(fieldName, out var actual);
            var actualStr = actual ?? string.Empty;

            return op switch
            {
                "==" => string.Equals(actualStr, expected, StringComparison.OrdinalIgnoreCase),
                "!=" => !string.Equals(actualStr, expected, StringComparison.OrdinalIgnoreCase),
                _    => true
            };
        }
    }
}