using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AIK.Common.StompNet
{
    /// <summary>
    /// STOMP帧结构
    /// </summary>
    public static class StompFrameHelper
    {
        private static readonly byte[] NullByte = { 0 };

        public static byte[] BuildFrame(string command, Dictionary<string, string>? headers = null, string? body = null)
        {
            var sb = new StringBuilder();
            sb.Append(command).Append('\n');

            if (headers != null)
            {
                foreach (var header in headers)
                {
                    sb.Append($"{header.Key}:{header.Value}").Append("\n");
                }
            }

            sb.Append("\n"); // 空行
            sb.Append("\u0000"); // 结束符
            var headerBytes = Encoding.UTF8.GetBytes(sb.ToString());

            return headerBytes;
        }

        public static (string command, Dictionary<string, string> headers, string body)? ParseFrame(byte[] data)
        {
            if (data.Length == 0 || data[data.Length - 1] != 0) return null;

            var text = Encoding.UTF8.GetString(data, 0, data.Length - 1); // 去掉 
            var parts = text.Split(new[] { "\r\n\r\n", "\n\n" }, 2, StringSplitOptions.None);

            if (parts.Length < 1) return null;

            var headerSection = parts[0];
            var body = parts.Length > 1 ? parts[1] : "";

            var lines = headerSection.Split(new[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
            if (lines.Length == 0) return null;

            var command = lines[0].Trim();
            var headers = new Dictionary<string, string>();

            for (int i = 1; i < lines.Length; i++)
            {
                var line = lines[i];
                var idx = line.IndexOf(':');
                if (idx > 0)
                {
                    var key = line.Substring(0, idx).Trim();
                    var value = line.Substring(idx + 1).Trim();
                    headers[key] = value;
                }
            }

            return (command, headers, body);
        }
    }
}