ClaudeDo/src/ClaudeDo.Ui/Helpers/StreamLineFormatter.cs

using System.Text;
using System.Text.Json;

namespace ClaudeDo.Ui.Helpers;

public class StreamLineFormatter
{
    private const int MaxLength = 50_000;

    public string? FormatLine(string line)
    {
        JsonDocument doc;
        try
        {
            doc = JsonDocument.Parse(line);
        }
        catch (JsonException)
        {
            return line;
        }

        using (doc)
        {
            var root = doc.RootElement;
            if (!root.TryGetProperty("type", out var typeProp))
                return null;

            var type = typeProp.GetString();

            switch (type)
            {
                case "stream_event":
                    return FormatStreamEvent(root);

                case "result":
                    if (root.TryGetProperty("result", out var resultProp))
                        return $"\n--- Result ---\n{resultProp.GetString()}\n";
                    return null;

                case "system":
                    if (root.TryGetProperty("subtype", out var subtypeProp) &&
                        subtypeProp.GetString() == "api_retry")
                        return "\n[Retrying API call...]\n";
                    return null;

                default:
                    return null;
            }
        }
    }

    private static string? FormatStreamEvent(JsonElement root)
    {
        if (!root.TryGetProperty("event", out var ev))
            return null;
        if (!ev.TryGetProperty("type", out var evTypeProp))
            return null;

        var evType = evTypeProp.GetString();

        switch (evType)
        {
            case "content_block_delta":
                if (!ev.TryGetProperty("delta", out var delta))
                    return null;
                if (!delta.TryGetProperty("type", out var deltaTypeProp))
                    return null;
                var deltaType = deltaTypeProp.GetString();
                if (deltaType == "text_delta")
                {
                    return delta.TryGetProperty("text", out var textProp)
                        ? textProp.GetString()
                        : null;
                }
                return null; // input_json_delta and others → skip

            case "content_block_stop":
                return "\n";

            case "content_block_start":
                if (!ev.TryGetProperty("content_block", out var cb))
                    return null;
                if (cb.TryGetProperty("type", out var cbTypeProp) &&
                    cbTypeProp.GetString() == "tool_use" &&
                    cb.TryGetProperty("name", out var nameProp))
                    return $"\n[Tool: {nameProp.GetString()}]\n";
                return null;

            default:
                return null; // message_start, message_delta, etc.
        }
    }

    public string FormatFile(string filePath)
    {
        var sb = new StringBuilder();
        foreach (var line in File.ReadLines(filePath))
        {
            var formatted = FormatLine(line);
            if (formatted is not null)
                sb.Append(formatted);
        }
        return Trim(sb.ToString());
    }

    public static string Trim(string text)
    {
        if (text.Length <= MaxLength) return text;
        var trimStart = text.Length - MaxLength;
        var newlineAfter = text.IndexOf('\n', trimStart);
        if (newlineAfter >= 0 && newlineAfter < trimStart + 200)
            trimStart = newlineAfter + 1;
        return text[trimStart..];
    }
}