using System;
using System.IO;
using System.Text;
using System.Collections.Generic;
using GeViSetEditor.Core.Models;

namespace GeViSetEditor.Core.Parsers
{
    /// <summary>
    /// Writes ComprehensiveConfigFile back to binary .set format
    /// Enables edit/add/delete operations on configuration
    /// </summary>
    public class BinaryConfigWriter
    {
        /// <summary>
        /// Rebuild complete .set file from configuration nodes
        /// </summary>
        public byte[] Write(ComprehensiveConfigFile config)
        {
            using var ms = new MemoryStream();

            // Write header
            WriteHeader(ms, config);

            // Write all nodes sequentially
            foreach (var node in config.RootNodes)
            {
                WriteNode(ms, node);
            }

            return ms.ToArray();
        }

        private void WriteHeader(MemoryStream ms, ComprehensiveConfigFile config)
        {
            // Write null prefix if it was present
            if (config.HeaderNullPrefix)
            {
                ms.WriteByte(0x00);
            }

            // Write header string
            if (!string.IsNullOrEmpty(config.Header))
            {
                byte[] headerBytes = Encoding.UTF8.GetBytes(config.Header);
                ms.WriteByte((byte)headerBytes.Length);
                ms.Write(headerBytes, 0, headerBytes.Length);
            }
        }

        private void WriteNode(MemoryStream ms, ConfigNode node)
        {
            switch (node.NodeType)
            {
                case "boolean":
                    WriteBoolean(ms, node);
                    break;

                case "integer":
                    WriteInteger(ms, node);
                    break;

                case "string":
                    WriteString(ms, node);
                    break;

                case "property":
                    WriteProperty(ms, node);
                    break;

                case "marker":
                    WriteMarker(ms, node);
                    break;

                default:
                    throw new InvalidOperationException($"Unknown node type: {node.NodeType}");
            }
        }

        private void WriteBoolean(MemoryStream ms, ConfigNode node)
        {
            ms.WriteByte(0x01);  // Boolean marker

            bool value = Convert.ToBoolean(node.Value);
            ms.WriteByte(value ? (byte)1 : (byte)0);
        }

        private void WriteInteger(MemoryStream ms, ConfigNode node)
        {
            ms.WriteByte(0x04);  // Integer marker

            int value = Convert.ToInt32(node.Value);
            byte[] bytes = BitConverter.GetBytes(value);
            ms.Write(bytes, 0, bytes.Length);
        }

        private void WriteString(MemoryStream ms, ConfigNode node)
        {
            ms.WriteByte(0x07);  // String marker

            string value = node.Value?.ToString() ?? "";
            byte[] bytes = Encoding.UTF8.GetBytes(value);

            if (bytes.Length > 255)
                throw new InvalidOperationException($"String too long: {bytes.Length} bytes (max 255)");

            ms.WriteByte((byte)bytes.Length);
            ms.Write(bytes, 0, bytes.Length);
        }

        private void WriteProperty(MemoryStream ms, ConfigNode node)
        {
            // Write property name (07 <len> <name>)
            ms.WriteByte(0x07);
            byte[] nameBytes = Encoding.UTF8.GetBytes(node.Name ?? "");

            if (nameBytes.Length > 255)
                throw new InvalidOperationException($"Property name too long: {nameBytes.Length} bytes (max 255)");

            ms.WriteByte((byte)nameBytes.Length);
            ms.Write(nameBytes, 0, nameBytes.Length);

            // Write property value based on ValueType
            WriteTypedValue(ms, node.Value, node.ValueType);
        }

        private void WriteMarker(MemoryStream ms, ConfigNode node)
        {
            // Write marker (05 <len> <name>)
            ms.WriteByte(0x05);
            byte[] nameBytes = Encoding.UTF8.GetBytes(node.Name ?? "");

            if (nameBytes.Length > 255)
                throw new InvalidOperationException($"Marker name too long: {nameBytes.Length} bytes (max 255)");

            ms.WriteByte((byte)nameBytes.Length);
            ms.Write(nameBytes, 0, nameBytes.Length);

            // If it's a Rules marker with actions, write them
            if (node.Name == "Rules" && node.Value is List<string> actions)
            {
                WriteRulesActions(ms, actions);
            }
        }

        private void WriteRulesActions(MemoryStream ms, List<string> actions)
        {
            // Write action strings in the special format: 07 01 40 <len_2bytes_LE> <data>
            foreach (var action in actions)
            {
                ms.WriteByte(0x07);
                ms.WriteByte(0x01);
                ms.WriteByte(0x40);

                byte[] actionBytes = Encoding.UTF8.GetBytes(action);
                ushort length = (ushort)actionBytes.Length;

                byte[] lenBytes = BitConverter.GetBytes(length);
                ms.Write(lenBytes, 0, 2);  // Write length as 2-byte LE

                ms.Write(actionBytes, 0, actionBytes.Length);
            }
        }

        private void WriteTypedValue(MemoryStream ms, object? value, string? valueType)
        {
            if (value == null)
            {
                // Write null as empty string
                ms.WriteByte(0x07);
                ms.WriteByte(0x00);
                return;
            }

            switch (valueType)
            {
                case "boolean":
                    ms.WriteByte(0x01);
                    bool boolVal = Convert.ToBoolean(value);
                    ms.WriteByte(boolVal ? (byte)1 : (byte)0);
                    break;

                case "integer":
                    ms.WriteByte(0x04);
                    int intVal = Convert.ToInt32(value);
                    byte[] intBytes = BitConverter.GetBytes(intVal);
                    ms.Write(intBytes, 0, intBytes.Length);
                    break;

                case "string":
                    ms.WriteByte(0x07);
                    string strVal = value.ToString() ?? "";
                    byte[] strBytes = Encoding.UTF8.GetBytes(strVal);

                    if (strBytes.Length > 255)
                        throw new InvalidOperationException($"String value too long: {strBytes.Length} bytes (max 255)");

                    ms.WriteByte((byte)strBytes.Length);
                    ms.Write(strBytes, 0, strBytes.Length);
                    break;

                default:
                    // Default to string representation
                    WriteTypedValue(ms, value.ToString(), "string");
                    break;
            }
        }
    }
}