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

namespace GeViSetEditor.Core.Parsers
{
    /// <summary>
    /// Parser for GeViSet .set configuration files (binary format)
    /// Format: Proprietary binary with sections, rules, and action mappings
    /// </summary>
    public class SetFileParser
    {
        private byte[] _data;
        private int _position;

        public GeViSetConfiguration Parse(string filePath)
        {
            _data = File.ReadAllBytes(filePath);
            _position = 0;

            var config = new GeViSetConfiguration();

            // Read header
            if (_data[_position] == 0x00) _position++; // Skip initial marker
            config.Header = ReadPascalString() ?? "GeViSoft Parameters";

            Console.WriteLine($"Parsing {filePath} ({_data.Length:N0} bytes)");
            Console.WriteLine($"Header: {config.Header}\n");

            // Parse all sections until end of file
            int sectionCount = 0;
            while (_position < _data.Length - 20)
            {
                var section = TryParseSection();
                if (section != null)
                {
                    config.Sections.Add(section);
                    sectionCount++;
                    Console.WriteLine($"Section {sectionCount}: {section.Name} ({section.Items.Count} items, {section.Rules.Count} rules) - pos: {_position}");
                }
                else
                {
                    _position++; // Skip unknown byte
                }
            }

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

            // Second pass: Find all "Rules" markers and extract action mappings directly
            Console.WriteLine($"\nSearching for Rules sections...");
            ExtractRulesDirectly(config);

            return config;
        }

        private void ExtractRulesDirectly(GeViSetConfiguration config)
        {
            // Search for pattern: 05 52 75 6C 65 73 = "05 Rules"
            byte[] rulesPattern = new byte[] { 0x05, 0x52, 0x75, 0x6C, 0x65, 0x73 };

            for (int i = 0; i < _data.Length - rulesPattern.Length; i++)
            {
                bool match = true;
                for (int j = 0; j < rulesPattern.Length; j++)
                {
                    if (_data[i + j] != rulesPattern[j])
                    {
                        match = false;
                        break;
                    }
                }

                if (match)
                {
                    Console.WriteLine($"  Found Rules pattern at offset {i} (0x{i:X})");
                    _position = i + rulesPattern.Length;

                    // Create or find a section for these rules
                    var rulesSection = config.Sections.FirstOrDefault(s => s.Name == "ActionMappings");
                    if (rulesSection == null)
                    {
                        rulesSection = new Section { Name = "ActionMappings" };
                        config.Sections.Add(rulesSection);
                    }

                    // Try to parse rules from this location
                    ParseRulesSection(rulesSection);

                    Console.WriteLine($"    Extracted {rulesSection.Rules.Count} rules");
                }
            }
        }

        private Section TryParseSection()
        {
            int startPos = _position;

            // Try to read section name
            string sectionName = ReadPascalString();
            if (string.IsNullOrEmpty(sectionName) || sectionName.Length > 50)
            {
                _position = startPos;
                return null;
            }

            var section = new Section { Name = sectionName };

            // Parse section contents
            int maxIterations = 1000; // Safety limit
            while (_position < _data.Length - 10 && maxIterations-- > 0)
            {
                // Check for "Rules" subsection (can be Pascal string OR length-prefixed)
                int savePos = _position;

                // Try Pascal string first (0x07 marker)
                string possibleRules = ReadPascalString();
                if (possibleRules == "Rules")
                {
                    Console.WriteLine($"  Found Rules subsection (Pascal) at offset {savePos} in section '{sectionName}'");
                    ParseRulesSection(section);
                    break; // Rules typically end a section
                }

                // Rewind and try length-prefixed format (no 0x07 marker)
                _position = savePos;
                possibleRules = ReadLengthPrefixedString();
                if (possibleRules == "Rules")
                {
                    Console.WriteLine($"  Found Rules subsection (LenPrefix) at offset {savePos} in section '{sectionName}'");
                    ParseRulesSection(section);
                    break; // Rules typically end a section
                }

                // Neither worked, rewind
                _position = savePos;

                // Try to read a config item
                var item = TryReadConfigItem();
                if (item != null)
                {
                    section.Items.Add(item);
                }
                else
                {
                    // Check if we've hit the next section or end
                    if (IsLikelySectionStart())
                        break;
                    _position++;
                }
            }

            return section;
        }

        private void ParseRulesSection(Section section)
        {
            int startRuleCount = section.Rules.Count;
            int startPos = _position;

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

            Console.WriteLine($"      ParseRulesSection: start={startPos}, after skip={_position}, bytes: {BitConverter.ToString(_data, _position, Math.Min(20, _data.Length - _position))}");

            // Parse rules - keep trying until we stop finding action strings
            int maxRules = 100;
            int attempts = 0;
            int consecutiveFails = 0;

            while (maxRules-- > 0 && _position < _data.Length - 20)
            {
                int beforePos = _position;
                var rule = TryParseRule();
                attempts++;

                if (rule != null)
                {
                    section.Rules.Add(rule);
                    Console.WriteLine($"      Found rule at pos {beforePos}, now at {_position}");
                    consecutiveFails = 0;
                }
                else
                {
                    _position++;
                    consecutiveFails++;

                    // Stop if we've had too many consecutive failures
                    if (consecutiveFails > 100)
                    {
                        Console.WriteLine($"      Too many consecutive failures at {_position}, stopping");
                        break;
                    }
                }

                if (attempts > 200) break; // Safety limit
            }

            Console.WriteLine($"      ParseRulesSection complete: extracted {section.Rules.Count - startRuleCount} rules");
        }

        private ActionRule TryParseRule()
        {
            int startPos = _position;

            // Look for rule marker: 01 <id>
            if (_position + 2 >= _data.Length || _data[_position] != 0x01)
            {
                _position = startPos;
                return null;
            }

            var rule = new ActionRule
            {
                RuleId = _data[_position + 1]
            };
            _position += 2;

            // Skip size bytes (05 00 00 00 or 0a 00 00 00 patterns)
            if (_position + 4 < _data.Length && (_data[_position] == 0x05 || _data[_position] == 0x0a))
            {
                _position += 4;
            }

            // Read trigger properties (fields starting with .)
            for (int i = 0; i < 30; i++) // Max 30 properties
            {
                if (_position >= _data.Length) break;

                // Check for property field (01 <len> .<name>)
                if (_data[_position] == 0x01 && _position + 2 < _data.Length)
                {
                    int len = _data[_position + 1];
                    if (len > 0 && len < 50 && _position + 2 + len < _data.Length)
                    {
                        string propName = Encoding.UTF8.GetString(_data, _position + 2, len);
                        _position += 2 + len;

                        // Read boolean value
                        if (_position < _data.Length)
                        {
                            bool value = _data[_position++] != 0;
                            if (propName.StartsWith("."))
                            {
                                rule.TriggerProperties[propName] = value;
                            }
                        }
                    }
                    else
                    {
                        break;
                    }
                }
                else
                {
                    break;
                }
            }

            // Read main action string (07 01 40 <len_2bytes> <data>)
            string mainAction = ReadActionString();
            if (!string.IsNullOrEmpty(mainAction))
            {
                rule.MainAction = mainAction;
            }

            // Skip metadata (04 02 40... patterns)
            SkipMetadata();

            // Look for nested Rules section (action variations)
            int checkPos = _position;
            string nestedRules = ReadPascalString();
            if (nestedRules == "Rules")
            {
                ParseActionVariations(rule);
            }
            else
            {
                // Try length-prefixed format
                _position = checkPos;
                nestedRules = ReadLengthPrefixedString();
                if (nestedRules == "Rules")
                {
                    ParseActionVariations(rule);
                }
                else
                {
                    _position = checkPos; // Rewind if not "Rules"
                }
            }

            // Only return rule if it has meaningful data
            if (!string.IsNullOrEmpty(rule.MainAction) || rule.TriggerProperties.Count > 0)
            {
                return rule;
            }

            _position = startPos;
            return null;
        }

        private void ParseActionVariations(ActionRule rule)
        {
            // Skip count bytes
            while (_position < _data.Length && _data[_position] <= 0x04)
            {
                _position++;
            }

            // Parse each variation
            int maxVariations = 30;
            while (maxVariations-- > 0 && _position < _data.Length - 20)
            {
                var variation = TryParseActionVariation();
                if (variation != null)
                {
                    rule.ActionVariations.Add(variation);
                }
                else
                {
                    if (IsLikelySectionStart())
                        break;

                    // Look ahead for next variation
                    bool foundNext = false;
                    for (int i = 1; i < 20 && _position + i < _data.Length; i++)
                    {
                        if (_data[_position + i] == 0x01 && _position + i + 1 < _data.Length)
                        {
                            _position += i;
                            foundNext = true;
                            break;
                        }
                    }

                    if (!foundNext)
                        break;
                }
            }
        }

        private ActionVariation TryParseActionVariation()
        {
            int startPos = _position;

            // Look for variation marker: 01 <id>
            if (_position + 2 >= _data.Length || _data[_position] != 0x01)
            {
                _position = startPos;
                return null;
            }

            var variation = new ActionVariation
            {
                VariationId = _data[_position + 1]
            };
            _position += 2;

            // Skip size (05 00 00 00)
            if (_position + 4 < _data.Length && _data[_position] == 0x05)
            {
                _position += 4;
            }

            // Read action string
            variation.ActionString = ReadActionString() ?? "";

            // Skip metadata
            SkipMetadata();

            // Read action type (GscAction, GCoreAction, etc.)
            string actionType = ReadPascalString();
            if (actionType != null && actionType.Contains("Action"))
            {
                variation.ActionType = actionType;

                // Read full command (another action string)
                variation.FullCommand = ReadActionString() ?? "";

                // Read server type
                variation.ServerType = ReadPascalString() ?? "";

                // Try to read server name
                int savePos = _position;
                string serverName = ReadPascalString();
                if (!string.IsNullOrEmpty(serverName) && serverName.Length < 100 && !serverName.StartsWith("."))
                {
                    variation.ServerName = serverName;
                }
                else
                {
                    _position = savePos; // Rewind if not a valid server name
                }
            }

            // Only return if we got meaningful data
            if (!string.IsNullOrEmpty(variation.ActionString))
            {
                return variation;
            }

            _position = startPos;
            return null;
        }

        private ConfigItem TryReadConfigItem()
        {
            int startPos = _position;

            string name = ReadPascalString();
            if (string.IsNullOrEmpty(name) || name.Length > 100)
            {
                _position = startPos;
                return null;
            }

            // Try to read value
            object value = ReadValue();
            if (value == null)
            {
                _position = startPos;
                return null;
            }

            return new ConfigItem
            {
                Name = name,
                Value = value,
                Type = value switch
                {
                    bool => ConfigValueType.Boolean,
                    int => ConfigValueType.Integer,
                    string => ConfigValueType.String,
                    _ => ConfigValueType.Binary
                }
            };
        }

        // Helper methods for reading binary data

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

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

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

        private string ReadLengthPrefixedString()
        {
            // Simpler format: just <length_byte> <string_data> (no 0x07 marker)
            if (_position + 1 > _data.Length)
                return null;

            byte length = _data[_position];
            if (length == 0 || length > 50 || _position + 1 + length > _data.Length)
                return null;

            string result = Encoding.UTF8.GetString(_data, _position + 1, length);
            _position += 1 + length;
            return result;
        }

        private string ReadActionString()
        {
            // Action strings: 07 01 40 <len_2bytes> <data>
            if (_position + 5 > _data.Length ||
                _data[_position] != 0x07 ||
                _data[_position + 1] != 0x01 ||
                _data[_position + 2] != 0x40)
                return null;

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

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

        private object ReadValue()
        {
            if (_position >= _data.Length)
                return null;

            byte type = _data[_position];

            switch (type)
            {
                case 0x01: // Boolean
                    if (_position + 2 <= _data.Length)
                    {
                        _position++;
                        return _data[_position++] != 0;
                    }
                    break;

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

                case 0x07: // String
                    return ReadPascalString();
            }

            return null;
        }

        private void SkipMetadata()
        {
            // Skip common metadata patterns (04 02 40... and 04 0a...)
            while (_position + 5 < _data.Length && _data[_position] == 0x04)
            {
                _position += 5;
            }
        }

        private string PeekString(int length)
        {
            if (_position + length > _data.Length)
                return "";
            return Encoding.UTF8.GetString(_data, _position, length);
        }

        private bool IsLikelySectionStart()
        {
            if (_position + 10 >= _data.Length)
                return true;

            // Check for multiple nulls (section boundary)
            int nullCount = 0;
            for (int i = 0; i < Math.Min(10, _data.Length - _position); i++)
            {
                if (_data[_position + i] == 0x00)
                    nullCount++;
            }

            return nullCount >= 4;
        }
    }
}