using System.Data;
using System.Globalization;
using System.Text.RegularExpressions;

namespace Admin.NET.Plugin.AiDOP.Infrastructure.FormulaExpr;

/// <summary>
/// 结构化公式运行时求值器 v1。
/// 当前用于打通“可执行计算”的工程落点：调用方负责提供 @指标 与 $事实 的数值上下文。
/// </summary>
public static class FormulaRuntimeEvaluator
{
    private static readonly Regex MetricRefRe = new(@"@([A-Za-z][A-Za-z0-9_]*)", RegexOptions.Compiled);
    private static readonly Regex FactRefRe = new(@"\$([A-Za-z][A-Za-z0-9_]*)", RegexOptions.Compiled);

    public sealed class RuntimeResult
    {
        public decimal? Value { get; init; }
        public List<string> Errors { get; } = new();
        public bool Success => Errors.Count == 0 && Value.HasValue;
    }

    public static RuntimeResult TryEvaluate(
        string? formulaExpr,
        IReadOnlyDictionary<string, decimal?> metricValues,
        IReadOnlyDictionary<string, decimal?> factValues)
    {
        var parsed = FormulaParser.Parse(formulaExpr);
        var result = new RuntimeResult();
        if (parsed.IsEmpty)
        {
            result.Errors.Add("公式为空");
            return result;
        }
        foreach (var error in parsed.Errors) result.Errors.Add(error);
        if (result.Errors.Count > 0) return result;

        var expr = formulaExpr!.Trim().Replace("%", "/100", StringComparison.Ordinal);
        expr = MetricRefRe.Replace(expr, m =>
        {
            var code = m.Groups[1].Value;
            if (!metricValues.TryGetValue(code, out var value) || value == null)
            {
                result.Errors.Add($"缺少指标值 @{code}");
                return "0";
            }
            return value.Value.ToString(CultureInfo.InvariantCulture);
        });
        expr = FactRefRe.Replace(expr, m =>
        {
            var code = m.Groups[1].Value;
            if (!factValues.TryGetValue(code, out var value) || value == null)
            {
                result.Errors.Add($"缺少事实值 ${code}");
                return "0";
            }
            return value.Value.ToString(CultureInfo.InvariantCulture);
        });
        if (result.Errors.Count > 0) return result;

        try
        {
            var computed = new DataTable().Compute(expr, "");
            return new RuntimeResult { Value = Convert.ToDecimal(computed, CultureInfo.InvariantCulture) };
        }
        catch (Exception ex)
        {
            result.Errors.Add("公式计算失败：" + ex.Message);
            return result;
        }
    }
}