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

namespace GeViSetEditor.Core.Parsers
{
    /// <summary>
    /// Complete binary parser that understands the entire .set file structure
    /// Parses ALL sections, items, and rules for full JSON serialization
    /// </summary>
    public class CompleteBinaryParser
    {
        private byte[] _data;
        private int _position;
        private Dictionary<int, string> _debugLog = new();

        public SetFileComplete Parse(byte[] data)
        {
            _data = data;
            _position = 0;

            var setFile = new SetFileComplete
            {
                FileSize = data.Length,
                RawData = data // Keep original for verification
            };

            Console.WriteLine($"=== Complete Binary Parser ===");
            Console.WriteLine($"File size: {data.Length:N0} bytes\n");

            try
            {
                // Parse header
                ParseHeader(setFile);

                // Parse all sections
                ParseAllSections(setFile);

                Console.WriteLine($"\n=== Parsing Complete ===");
                Console.WriteLine($"Sections parsed: {setFile.Sections.Count}");
                Console.WriteLine($"Total items: {setFile.Sections.Sum(s => s.Items.Count)}");
                Console.WriteLine($"Total rules: {setFile.Sections.Sum(s => s.Rules.Count)}");

                return setFile;
            }
            catch (Exception ex)
            {
                Console.WriteLine($"\nERROR at position {_position} (0x{_position:X}): {ex.Message}");
                throw;
            }
        }

        private void ParseHeader(SetFileComplete setFile)
        {
            Console.WriteLine("Parsing header...");

            // Optional null byte
            if (_position < _data.Length && _data[_position] == 0x00)
            {
                setFile.HeaderNullByte = true;
                _position++;
            }

            // Header is length-prefixed string (NOT Pascal string with 0x07)
            if (_position + 2 > _data.Length)
                throw new Exception("File too short for header");

            byte headerLen = _data[_position++];
            if (headerLen == 0 || headerLen > 50 || _position + headerLen > _data.Length)
                throw new Exception($"Invalid header length: {headerLen}");

            setFile.Header = Encoding.UTF8.GetString(_data, _position, headerLen);
            _position += headerLen;

            Console.WriteLine($"  Header: '{setFile.Header}'");
            Console.WriteLine($"  Position after header: {_position} (0x{_position:X})\n");
        }

        private void ParseAllSections(SetFileComplete setFile)
        {
            Console.WriteLine("Parsing sections...\n");

            int sectionCount = 0;
            int maxIterations = 10000; // Safety limit

            while (_position < _data.Length - 10 && maxIterations-- > 0)
            {
                int sectionStart = _position;

                var section = TryParseSection();
                if (section != null)
                {
                    sectionCount++;
                    setFile.Sections.Add(section);

                    if (sectionCount <= 20 || section.Items.Count > 0 || section.Rules.Count > 0)
                    {
                        Console.WriteLine($"Section #{sectionCount}: '{section.Name}' " +
                            $"(offset {sectionStart}, {section.Items.Count} items, {section.Rules.Count} rules)");
                    }
                }
                else
                {
                    // Skip unknown byte
                    _position++;
                }
            }

            Console.WriteLine($"\nTotal sections parsed: {sectionCount}");
        }

        private SectionComplete TryParseSection()
        {
            int startPos = _position;

            try
            {
                // Try to read section name (Pascal string: 0x07 <len> <data>)
                string sectionName = TryReadPascalString();
                if (string.IsNullOrEmpty(sectionName) || sectionName.Length > 100)
                {
                    _position = startPos;
                    return null;
                }

                var section = new SectionComplete
                {
                    Name = sectionName,
                    FileOffset = startPos
                };

                // Parse section contents
                ParseSectionContents(section);

                section.FileEndOffset = _position;
                return section;
            }
            catch
            {
                _position = startPos;
                return null;
            }
        }

        private void ParseSectionContents(SectionComplete section)
        {
            int maxIterations = 1000;
            bool foundRules = false;

            while (_position < _data.Length - 10 && maxIterations-- > 0)
            {
                int itemStart = _position;

                // Check for "Rules" marker (length-prefixed, no 0x07)
                if (CheckForRulesMarker())
                {
                    foundRules = true;
                    ParseRulesSubsection(section);
                    break; // Rules typically end a section
                }

                // Try to parse a config item
                var item = TryParseConfigItem();
                if (item != null)
                {
                    section.Items.Add(item);
                    continue;
                }

                // Check if we've hit next section
                if (IsLikelyNextSection())
                {
                    break;
                }

                // Move forward
                _position++;
            }
        }

        private bool CheckForRulesMarker()
        {
            // Pattern: 05 52 75 6C 65 73 = "Rules" (length 5 + data)
            if (_position + 6 > _data.Length)
                return false;

            return _data[_position] == 0x05 &&
                   _data[_position + 1] == 0x52 && // 'R'
                   _data[_position + 2] == 0x75 && // 'u'
                   _data[_position + 3] == 0x6C && // 'l'
                   _data[_position + 4] == 0x65 && // 'e'
                   _data[_position + 5] == 0x73;   // 's'
        }

        private void ParseRulesSubsection(SectionComplete section)
        {
            // Skip "Rules" marker
            _position += 6;

            // Skip metadata bytes (counts, flags, etc.)
            while (_position < _data.Length && _data[_position] <= 0x04)
            {
                _position++;
            }

            // Parse action rules
            int ruleCount = 0;
            int maxRules = 100;
            int consecutiveFails = 0;

            while (maxRules-- > 0 && _position < _data.Length - 20)
            {
                var rule = TryParseActionRule();
                if (rule != null)
                {
                    rule.RuleId = ruleCount++;
                    section.Rules.Add(rule);
                    consecutiveFails = 0;
                }
                else
                {
                    _position++;
                    consecutiveFails++;
                    if (consecutiveFails > 100) break;
                }
            }
        }

        private ActionRuleComplete TryParseActionRule()
        {
            int startPos = _position;

            try
            {
                var rule = new ActionRuleComplete
                {
                    FileOffset = startPos
                };

                // Try to read action string (07 01 40 <len_2bytes> <data>)
                string actionString = TryReadActionString();
                if (!string.IsNullOrEmpty(actionString))
                {
                    rule.Actions.Add(actionString);
                    return rule;
                }

                _position = startPos;
                return null;
            }
            catch
            {
                _position = startPos;
                return null;
            }
        }

        private ConfigItemComplete TryParseConfigItem()
        {
            int startPos = _position;

            try
            {
                // Read key (Pascal string)
                string key = TryReadPascalString();
                if (string.IsNullOrEmpty(key) || key.Length > 200)
                {
                    _position = startPos;
                    return null;
                }

                // Read value (typed)
                var (value, type) = TryReadTypedValue();
                if (value == null)
                {
                    _position = startPos;
                    return null;
                }

                return new ConfigItemComplete
                {
                    Key = key,
                    Value = value,
                    ValueType = type,
                    FileOffset = startPos
                };
            }
            catch
            {
                _position = startPos;
                return null;
            }
        }

        private string TryReadPascalString()
        {
            if (_position + 2 > _data.Length || _data[_position] != 0x07)
                return null;

            byte length = _data[_position + 1];
            if (length == 0 || length > 200 || _position + 2 + length > _data.Length)
                return null;

            string result = Encoding.UTF8.GetString(_data, _position + 2, length);
            _position += 2 + length;
            return result;
        }

        private string TryReadActionString()
        {
            // Pattern: 07 01 40 <len_2bytes_LE> <data>
            if (_position + 5 > _data.Length)
                return null;

            if (_data[_position] != 0x07 ||
                _data[_position + 1] != 0x01 ||
                _data[_position + 2] != 0x40)
                return null;

            int length = BitConverter.ToUInt16(_data, _position + 3);
            if (length == 0 || length > 500 || _position + 5 + length > _data.Length)
                return null;

            string result = Encoding.UTF8.GetString(_data, _position + 5, length);
            _position += 5 + length;

            // Validate it looks like an action
            if (string.IsNullOrWhiteSpace(result) || result.Length < 3)
                return null;

            return result;
        }

        private (object value, string type) TryReadTypedValue()
        {
            if (_position >= _data.Length)
                return (null, null);

            byte typeMarker = _data[_position];

            switch (typeMarker)
            {
                case 0x01: // Boolean
                    if (_position + 2 <= _data.Length)
                    {
                        _position++;
                        bool value = _data[_position++] != 0;
                        return (value, "boolean");
                    }
                    break;

                case 0x04: // Integer (4 bytes, little-endian)
                    if (_position + 5 <= _data.Length)
                    {
                        _position++;
                        int value = BitConverter.ToInt32(_data, _position);
                        _position += 4;
                        return (value, "integer");
                    }
                    break;

                case 0x07: // String (Pascal string)
                    string value_str = TryReadPascalString();
                    if (value_str != null)
                    {
                        return (value_str, "string");
                    }
                    break;
            }

            return (null, null);
        }

        private bool IsLikelyNextSection()
        {
            // Check if next bytes look like a new section (Pascal string)
            if (_position + 3 >= _data.Length)
                return true;

            if (_data[_position] != 0x07)
                return false;

            byte length = _data[_position + 1];
            if (length < 3 || length > 50)
                return false;

            // Check if it's printable ASCII (likely a section name)
            for (int i = 0; i < Math.Min(5, (int)length); i++)
            {
                if (_position + 2 + i >= _data.Length)
                    return false;

                byte b = _data[_position + 2 + i];
                if (b < 32 || b > 126)
                    return false;
            }

            return true;
        }
    }
}