// Copyright (c) Microsoft. All rights reserved.

using System.Text.Json;
using System.Text.RegularExpressions;
using Microsoft.Agents.AI.Workflows;

namespace SingleAgent;

/// <summary>
/// This executor parses survey responses and produces structured output.
/// Example input: "Rating: 8. The app is good but checkout process is confusing."
/// </summary>
[System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1812:Avoid uninstantiated internal classes", Justification = "Instantiated by workflow framework")]
internal sealed partial class SurveyResponseParserExecutor() : Executor<string, string>("SurveyResponseParserExecutor")
{
    private static readonly JsonSerializerOptions s_jsonOptions = new()
    {
        WriteIndented = true
    };

    [GeneratedRegex(@"Rating:\s*(\d+)", RegexOptions.IgnoreCase)]
    private static partial Regex RatingRegex();

    public override ValueTask<string> HandleAsync(string message, IWorkflowContext context, CancellationToken cancellationToken = default)
    {
        SurveyResponse response = ParseSurveyResponse(message);
        string jsonResult = JsonSerializer.Serialize(response, s_jsonOptions);
        return ValueTask.FromResult(jsonResult);
    }

    private static SurveyResponse ParseSurveyResponse(string message)
    {
        // Parse the message to extract rating and comment
        int? rating = null;
        string comment = message;

        // Try to extract rating using pattern "Rating: {number}"
        Match ratingMatch = RatingRegex().Match(message);
        if (ratingMatch.Success && int.TryParse(ratingMatch.Groups[1].Value, out int parsedRating))
        {
            rating = parsedRating;

            // Remove the rating part from the message to get the comment
            // Find the position after the rating number
            int ratingEndIndex = ratingMatch.Index + ratingMatch.Length;

            // Skip any separators (period, comma, dash, etc.) and whitespace
            while (ratingEndIndex < message.Length &&
                   (char.IsWhiteSpace(message[ratingEndIndex]) ||
                    message[ratingEndIndex] == '.' ||
                    message[ratingEndIndex] == ',' ||
                    message[ratingEndIndex] == '-'))
            {
                ratingEndIndex++;
            }

            if (ratingEndIndex < message.Length)
            {
                comment = message[ratingEndIndex..].Trim();
            }
            else
            {
                comment = string.Empty;
            }
        }

        // Create and return the structured response
        return new SurveyResponse
        {
            Rating = rating,
            Comment = comment,
            OriginalMessage = message
        };
    }

    private sealed class SurveyResponse
    {
        public int? Rating { get; set; }
        public string Comment { get; set; } = string.Empty;
        public string OriginalMessage { get; set; } = string.Empty;
    }
}