using MarketAlly.AIPlugin;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

namespace MarketAlly.AIPlugin.Analysis.Plugins
{
	[AIPlugin("ComplexityAnalyzer", "Measures cyclomatic and cognitive complexity with refactoring suggestions")]
	public class ComplexityAnalyzerPlugin : IAIPlugin
	{
		[AIParameter("Full path to the file or directory to analyze", required: true)]
		public string Path { get; set; } = string.Empty;

		[AIParameter("Calculate cyclomatic complexity", required: false)]
		public bool CalculateCyclomatic { get; set; } = true;

		[AIParameter("Calculate cognitive complexity", required: false)]
		public bool CalculateCognitive { get; set; } = true;

		[AIParameter("Maximum acceptable cyclomatic complexity", required: false)]
		public int MaxCyclomaticComplexity { get; set; } = 10;

		[AIParameter("Maximum acceptable cognitive complexity", required: false)]
		public int MaxCognitiveComplexity { get; set; } = 15;

		[AIParameter("Generate complexity reduction suggestions", required: false)]
		public bool GenerateSuggestions { get; set; } = true;

		[AIParameter("Include method-level complexity breakdown", required: false)]
		public bool IncludeMethodBreakdown { get; set; } = true;

		public IReadOnlyDictionary<string, Type> SupportedParameters => new Dictionary<string, Type>
		{
			["path"] = typeof(string),
			["calculateCyclomatic"] = typeof(bool),
			["calculateCognitive"] = typeof(bool),
			["maxCyclomaticComplexity"] = typeof(int),
			["maxCognitiveComplexity"] = typeof(int),
			["generateSuggestions"] = typeof(bool),
			["includeMethodBreakdown"] = typeof(bool)
		};

		public async Task<AIPluginResult> ExecuteAsync(IReadOnlyDictionary<string, object> parameters)
		{
			try
			{
				// Extract parameters
				string path = parameters["path"]?.ToString() ?? string.Empty;
				bool calculateCyclomatic = GetBoolParameter(parameters, "calculateCyclomatic", true);
				bool calculateCognitive = GetBoolParameter(parameters, "calculateCognitive", true);
				int maxCyclomatic = GetIntParameter(parameters, "maxCyclomaticComplexity", 10);
				int maxCognitive = GetIntParameter(parameters, "maxCognitiveComplexity", 15);
				bool generateSuggestions = GetBoolParameter(parameters, "generateSuggestions", true);
				bool includeMethodBreakdown = GetBoolParameter(parameters, "includeMethodBreakdown", true);

				// Validate path
				if (!File.Exists(path) && !Directory.Exists(path))
				{
					return new AIPluginResult(
						new FileNotFoundException($"Path not found: {path}"),
						"Path not found"
					);
				}

				// Get files to analyze
				var filesToAnalyze = GetFilesToAnalyze(path);
				if (!filesToAnalyze.Any())
				{
					return new AIPluginResult(
						new InvalidOperationException("No C# files found to analyze"),
						"No files found"
					);
				}

				// Analyze complexity for each file
				var fileResults = new List<FileComplexityResult>();
				var overallMetrics = new ComplexityMetrics();
				var highComplexityMethods = new List<MethodComplexityInfo>();
				var violations = new List<ComplexityViolation>();

				foreach (string filePath in filesToAnalyze)
				{
					var fileResult = await AnalyzeFileComplexity(
						filePath, calculateCyclomatic, calculateCognitive,
						maxCyclomatic, maxCognitive, includeMethodBreakdown);

					fileResults.Add(fileResult);
					overallMetrics.Add(fileResult.Metrics);
					highComplexityMethods.AddRange(fileResult.HighComplexityMethods);
					violations.AddRange(fileResult.Violations);
				}

				// Generate suggestions if requested
				var suggestions = new List<string>();
				if (generateSuggestions)
				{
					suggestions = GenerateComplexityReductionSuggestions(highComplexityMethods, violations);
				}

				// Calculate overall complexity score (0-100, higher is better)
				int overallScore = CalculateOverallComplexityScore(overallMetrics, maxCyclomatic, maxCognitive);

				var result = new
				{
					Path = path,
					FilesAnalyzed = filesToAnalyze.Count,
					CyclomaticComplexity = calculateCyclomatic ? new
					{
						Average = overallMetrics.AverageCyclomaticComplexity,
						Maximum = overallMetrics.MaxCyclomaticComplexity,
						Total = overallMetrics.TotalCyclomaticComplexity,
						MethodsAboveThreshold = overallMetrics.CyclomaticViolations
					} : null,
					CognitiveComplexity = calculateCognitive ? new
					{
						Average = overallMetrics.AverageCognitiveComplexity,
						Maximum = overallMetrics.MaxCognitiveComplexity,
						Total = overallMetrics.TotalCognitiveComplexity,
						MethodsAboveThreshold = overallMetrics.CognitiveViolations
					} : null,
					HighComplexityMethods = highComplexityMethods.Take(10).Select(m => new
					{
						m.MethodName,
						m.ClassName,
						m.FilePath,
						m.LineNumber,
						m.CyclomaticComplexity,
						m.CognitiveComplexity,
						m.ParameterCount,
						m.LinesOfCode
					}).ToList(),
					ComplexityViolations = violations.Select(v => new
					{
						v.MethodName,
						v.ClassName,
						v.FilePath,
						v.LineNumber,
						v.ViolationType,
						v.ActualValue,
						v.ThresholdValue,
						v.Severity
					}).ToList(),
					ReductionSuggestions = suggestions,
					MethodBreakdown = includeMethodBreakdown ? fileResults.SelectMany(f => f.MethodDetails).ToList() : null,
					OverallComplexityScore = overallScore,
					Summary = new
					{
						TotalMethods = overallMetrics.TotalMethods,
						HighComplexityMethods = highComplexityMethods.Count,
						TotalViolations = violations.Count,
						AverageMethodComplexity = Math.Round(overallMetrics.AverageCyclomaticComplexity, 2),
						RecommendedActions = violations.Count > 0 ? "Refactor high-complexity methods" : "Complexity within acceptable limits"
					}
				};

				return new AIPluginResult(result, $"Complexity analysis completed for {filesToAnalyze.Count} files");
			}
			catch (Exception ex)
			{
				return new AIPluginResult(ex, "Failed to analyze complexity");
			}
		}

		private async Task<FileComplexityResult> AnalyzeFileComplexity(
			string filePath, bool calculateCyclomatic, bool calculateCognitive,
			int maxCyclomatic, int maxCognitive, bool includeMethodBreakdown)
		{
			var sourceCode = await File.ReadAllTextAsync(filePath);
			var syntaxTree = CSharpSyntaxTree.ParseText(sourceCode, path: filePath);
			var root = await syntaxTree.GetRootAsync();

			var methods = root.DescendantNodes().OfType<MethodDeclarationSyntax>().ToList();
			var constructors = root.DescendantNodes().OfType<ConstructorDeclarationSyntax>().ToList();
			var properties = root.DescendantNodes().OfType<PropertyDeclarationSyntax>()
				.Where(p => p.AccessorList?.Accessors.Any(a => a.Body != null || a.ExpressionBody != null) == true)
				.ToList();

			var result = new FileComplexityResult
			{
				FilePath = filePath,
				FileName = System.IO.Path.GetFileName(filePath),
				Metrics = new ComplexityMetrics(),
				HighComplexityMethods = new List<MethodComplexityInfo>(),
				Violations = new List<ComplexityViolation>(),
				MethodDetails = new List<object>()
			};

			// Analyze methods
			foreach (var method in methods)
			{
				var methodInfo = AnalyzeMethod(method, filePath, calculateCyclomatic, calculateCognitive);
				result.Metrics.Add(methodInfo);

				if (methodInfo.CyclomaticComplexity > maxCyclomatic || methodInfo.CognitiveComplexity > maxCognitive)
				{
					result.HighComplexityMethods.Add(methodInfo);
				}

				// Check for violations
				if (calculateCyclomatic && methodInfo.CyclomaticComplexity > maxCyclomatic)
				{
					result.Violations.Add(new ComplexityViolation
					{
						MethodName = methodInfo.MethodName,
						ClassName = methodInfo.ClassName,
						FilePath = filePath,
						LineNumber = methodInfo.LineNumber,
						ViolationType = "CyclomaticComplexity",
						ActualValue = methodInfo.CyclomaticComplexity,
						ThresholdValue = maxCyclomatic,
						Severity = methodInfo.CyclomaticComplexity > maxCyclomatic * 1.5 ? "High" : "Medium"
					});
				}

				if (calculateCognitive && methodInfo.CognitiveComplexity > maxCognitive)
				{
					result.Violations.Add(new ComplexityViolation
					{
						MethodName = methodInfo.MethodName,
						ClassName = methodInfo.ClassName,
						FilePath = filePath,
						LineNumber = methodInfo.LineNumber,
						ViolationType = "CognitiveComplexity",
						ActualValue = methodInfo.CognitiveComplexity,
						ThresholdValue = maxCognitive,
						Severity = methodInfo.CognitiveComplexity > maxCognitive * 1.5 ? "High" : "Medium"
					});
				}

				if (includeMethodBreakdown)
				{
					result.MethodDetails.Add(new
					{
						methodInfo.MethodName,
						methodInfo.ClassName,
						methodInfo.CyclomaticComplexity,
						methodInfo.CognitiveComplexity,
						methodInfo.ParameterCount,
						methodInfo.LinesOfCode,
						methodInfo.LineNumber
					});
				}
			}

			// Analyze constructors
			foreach (var constructor in constructors)
			{
				var methodInfo = AnalyzeConstructor(constructor, filePath, calculateCyclomatic, calculateCognitive);
				result.Metrics.Add(methodInfo);

				if (methodInfo.CyclomaticComplexity > maxCyclomatic || methodInfo.CognitiveComplexity > maxCognitive)
				{
					result.HighComplexityMethods.Add(methodInfo);
				}
			}

			return result;
		}

		private MethodComplexityInfo AnalyzeMethod(MethodDeclarationSyntax method, string filePath,
			bool calculateCyclomatic, bool calculateCognitive)
		{
			var className = GetContainingClassName(method);
			var lineNumber = method.GetLocation().GetLineSpan().StartLinePosition.Line + 1;

			var info = new MethodComplexityInfo
			{
				MethodName = method.Identifier.ValueText,
				ClassName = className,
				FilePath = filePath,
				LineNumber = lineNumber,
				ParameterCount = method.ParameterList.Parameters.Count,
				LinesOfCode = CalculateLinesOfCode(method)
			};

			if (calculateCyclomatic)
			{
				info.CyclomaticComplexity = CalculateCyclomaticComplexity(method);
			}

			if (calculateCognitive)
			{
				info.CognitiveComplexity = CalculateCognitiveComplexity(method);
			}

			return info;
		}

		private MethodComplexityInfo AnalyzeConstructor(ConstructorDeclarationSyntax constructor, string filePath,
			bool calculateCyclomatic, bool calculateCognitive)
		{
			var className = GetContainingClassName(constructor);
			var lineNumber = constructor.GetLocation().GetLineSpan().StartLinePosition.Line + 1;

			var info = new MethodComplexityInfo
			{
				MethodName = $"{className} (constructor)",
				ClassName = className,
				FilePath = filePath,
				LineNumber = lineNumber,
				ParameterCount = constructor.ParameterList.Parameters.Count,
				LinesOfCode = CalculateLinesOfCode(constructor)
			};

			if (calculateCyclomatic)
			{
				info.CyclomaticComplexity = CalculateCyclomaticComplexity(constructor);
			}

			if (calculateCognitive)
			{
				info.CognitiveComplexity = CalculateCognitiveComplexity(constructor);
			}

			return info;
		}

		private int CalculateCyclomaticComplexity(SyntaxNode node)
		{
			int complexity = 1; // Base complexity

			var descendants = node.DescendantNodes();

			// Decision points that increase complexity
			complexity += descendants.OfType<IfStatementSyntax>().Count();
			complexity += descendants.OfType<WhileStatementSyntax>().Count();
			complexity += descendants.OfType<ForStatementSyntax>().Count();
			complexity += descendants.OfType<ForEachStatementSyntax>().Count();
			complexity += descendants.OfType<DoStatementSyntax>().Count();
			complexity += descendants.OfType<SwitchStatementSyntax>().Count();
			complexity += descendants.OfType<SwitchExpressionSyntax>().Count();
			complexity += descendants.OfType<ConditionalExpressionSyntax>().Count(); // Ternary operator
			complexity += descendants.OfType<CatchClauseSyntax>().Count();

			// Case statements in switch
			foreach (var switchStmt in descendants.OfType<SwitchStatementSyntax>())
			{
				complexity += switchStmt.Sections.Count - 1; // Subtract 1 because switch already counted
			}

			// Switch expression arms
			foreach (var switchExpr in descendants.OfType<SwitchExpressionSyntax>())
			{
				complexity += switchExpr.Arms.Count - 1; // Subtract 1 because switch already counted
			}

			// Logical operators (&& and ||)
			var binaryExpressions = descendants.OfType<BinaryExpressionSyntax>();
			foreach (var expr in binaryExpressions)
			{
				if (expr.OperatorToken.IsKind(SyntaxKind.AmpersandAmpersandToken) ||
					expr.OperatorToken.IsKind(SyntaxKind.BarBarToken))
				{
					complexity++;
				}
			}

			return complexity;
		}

		private int CalculateCognitiveComplexity(SyntaxNode node)
		{
			var calculator = new CognitiveComplexityCalculator();
			return calculator.Calculate(node);
		}

		private int CalculateLinesOfCode(SyntaxNode node)
		{
			var span = node.GetLocation().GetLineSpan();
			return span.EndLinePosition.Line - span.StartLinePosition.Line + 1;
		}

		private string GetContainingClassName(SyntaxNode node)
		{
			var classDeclaration = node.Ancestors().OfType<ClassDeclarationSyntax>().FirstOrDefault();
			if (classDeclaration != null)
			{
				return classDeclaration.Identifier.ValueText;
			}

			var structDeclaration = node.Ancestors().OfType<StructDeclarationSyntax>().FirstOrDefault();
			if (structDeclaration != null)
			{
				return structDeclaration.Identifier.ValueText;
			}

			return "Unknown";
		}

		private List<string> GetFilesToAnalyze(string path)
		{
			var files = new List<string>();

			if (File.Exists(path))
			{
				if (path.EndsWith(".cs", StringComparison.OrdinalIgnoreCase))
				{
					files.Add(path);
				}
			}
			else if (Directory.Exists(path))
			{
				files.AddRange(Directory.GetFiles(path, "*.cs", SearchOption.AllDirectories));
			}

			return files;
		}

		private List<string> GenerateComplexityReductionSuggestions(
			List<MethodComplexityInfo> highComplexityMethods,
			List<ComplexityViolation> violations)
		{
			var suggestions = new List<string>();

			if (!highComplexityMethods.Any())
			{
				suggestions.Add("✅ All methods have acceptable complexity levels.");
				return suggestions;
			}

			// General suggestions
			suggestions.Add("🔧 Consider the following complexity reduction strategies:");

			// Method extraction suggestions
			var methodsWithHighCyclomatic = highComplexityMethods.Where(m => m.CyclomaticComplexity > 15).ToList();
			if (methodsWithHighCyclomatic.Any())
			{
				suggestions.Add($"📝 Extract smaller methods from {methodsWithHighCyclomatic.Count} method(s) with high cyclomatic complexity (>15)");
				suggestions.Add("   • Break down large conditional blocks into separate methods");
				suggestions.Add("   • Extract loop bodies into dedicated methods");
				suggestions.Add("   • Use early returns to reduce nesting levels");
			}

			// Parameter count suggestions
			var methodsWithManyParams = highComplexityMethods.Where(m => m.ParameterCount > 5).ToList();
			if (methodsWithManyParams.Any())
			{
				suggestions.Add($"📦 Reduce parameter count for {methodsWithManyParams.Count} method(s) with >5 parameters");
				suggestions.Add("   • Consider using parameter objects or DTOs");
				suggestions.Add("   • Use builder pattern for complex object creation");
			}

			// Large method suggestions
			var largeMethods = highComplexityMethods.Where(m => m.LinesOfCode > 50).ToList();
			if (largeMethods.Any())
			{
				suggestions.Add($"📏 Break down {largeMethods.Count} large method(s) (>50 lines)");
				suggestions.Add("   • Apply Single Responsibility Principle");
				suggestions.Add("   • Extract helper methods for specific tasks");
			}

			// Specific method suggestions
			var topComplexMethods = highComplexityMethods
				.OrderByDescending(m => m.CyclomaticComplexity + m.CognitiveComplexity)
				.Take(3);

			suggestions.Add("🎯 Priority refactoring targets:");
			foreach (var method in topComplexMethods)
			{
				suggestions.Add($"   • {method.ClassName}.{method.MethodName} " +
							  $"(Cyclomatic: {method.CyclomaticComplexity}, Cognitive: {method.CognitiveComplexity})");
			}

			return suggestions;
		}

		private int CalculateOverallComplexityScore(ComplexityMetrics metrics, int maxCyclomatic, int maxCognitive)
		{
			if (metrics.TotalMethods == 0) return 100;

			// Calculate percentage of methods within acceptable limits
			var cyclomaticScore = metrics.TotalMethods > 0
				? (double)(metrics.TotalMethods - metrics.CyclomaticViolations) / metrics.TotalMethods * 100
				: 100;

			var cognitiveScore = metrics.TotalMethods > 0
				? (double)(metrics.TotalMethods - metrics.CognitiveViolations) / metrics.TotalMethods * 100
				: 100;

			// Weighted average (cognitive complexity is slightly more important)
			var overallScore = (cyclomaticScore * 0.4 + cognitiveScore * 0.6);

			// Penalty for extremely high complexity methods
			var avgComplexity = metrics.AverageCyclomaticComplexity;
			if (avgComplexity > maxCyclomatic * 2)
			{
				overallScore *= 0.7; // 30% penalty
			}
			else if (avgComplexity > maxCyclomatic * 1.5)
			{
				overallScore *= 0.85; // 15% penalty
			}

			return Math.Max(0, Math.Min(100, (int)Math.Round(overallScore)));
		}

		private bool GetBoolParameter(IReadOnlyDictionary<string, object> parameters, string key, bool defaultValue)
		{
			return parameters.TryGetValue(key, out var value) ? Convert.ToBoolean(value) : defaultValue;
		}

		private int GetIntParameter(IReadOnlyDictionary<string, object> parameters, string key, int defaultValue)
		{
			return parameters.TryGetValue(key, out var value) ? Convert.ToInt32(value) : defaultValue;
		}
	}

	// Supporting classes for complexity analysis
	public class ComplexityMetrics
	{
		public int TotalMethods { get; set; }
		public int TotalCyclomaticComplexity { get; set; }
		public int TotalCognitiveComplexity { get; set; }
		public int MaxCyclomaticComplexity { get; set; }
		public int MaxCognitiveComplexity { get; set; }
		public int CyclomaticViolations { get; set; }
		public int CognitiveViolations { get; set; }

		public double AverageCyclomaticComplexity => TotalMethods > 0 ? (double)TotalCyclomaticComplexity / TotalMethods : 0;
		public double AverageCognitiveComplexity => TotalMethods > 0 ? (double)TotalCognitiveComplexity / TotalMethods : 0;

		public void Add(MethodComplexityInfo method)
		{
			TotalMethods++;
			TotalCyclomaticComplexity += method.CyclomaticComplexity;
			TotalCognitiveComplexity += method.CognitiveComplexity;

			if (method.CyclomaticComplexity > MaxCyclomaticComplexity)
				MaxCyclomaticComplexity = method.CyclomaticComplexity;

			if (method.CognitiveComplexity > MaxCognitiveComplexity)
				MaxCognitiveComplexity = method.CognitiveComplexity;
		}

		public void Add(ComplexityMetrics other)
		{
			TotalMethods += other.TotalMethods;
			TotalCyclomaticComplexity += other.TotalCyclomaticComplexity;
			TotalCognitiveComplexity += other.TotalCognitiveComplexity;

			if (other.MaxCyclomaticComplexity > MaxCyclomaticComplexity)
				MaxCyclomaticComplexity = other.MaxCyclomaticComplexity;

			if (other.MaxCognitiveComplexity > MaxCognitiveComplexity)
				MaxCognitiveComplexity = other.MaxCognitiveComplexity;

			CyclomaticViolations += other.CyclomaticViolations;
			CognitiveViolations += other.CognitiveViolations;
		}
	}

	public class MethodComplexityInfo
	{
		public string MethodName { get; set; } = string.Empty;
		public string ClassName { get; set; } = string.Empty;
		public string FilePath { get; set; } = string.Empty;
		public int LineNumber { get; set; }
		public int CyclomaticComplexity { get; set; }
		public int CognitiveComplexity { get; set; }
		public int ParameterCount { get; set; }
		public int LinesOfCode { get; set; }
	}

	public class ComplexityViolation
	{
		public string MethodName { get; set; } = string.Empty;
		public string ClassName { get; set; } = string.Empty;
		public string FilePath { get; set; } = string.Empty;
		public int LineNumber { get; set; }
		public string ViolationType { get; set; } = string.Empty;
		public int ActualValue { get; set; }
		public int ThresholdValue { get; set; }
		public string Severity { get; set; } = string.Empty;
	}

	public class FileComplexityResult
	{
		public string FilePath { get; set; } = string.Empty;
		public string FileName { get; set; } = string.Empty;
		public ComplexityMetrics Metrics { get; set; } = new();
		public List<MethodComplexityInfo> HighComplexityMethods { get; set; } = new();
		public List<ComplexityViolation> Violations { get; set; } = new();
		public List<object> MethodDetails { get; set; } = new();
	}

	// Cognitive Complexity Calculator (implements the cognitive complexity algorithm)
	public class CognitiveComplexityCalculator
	{
		private int _complexity;
		private int _nestingLevel;

		public int Calculate(SyntaxNode node)
		{
			_complexity = 0;
			_nestingLevel = 0;
			Visit(node);
			return _complexity;
		}

		private void Visit(SyntaxNode node)
		{
			switch (node)
			{
				case IfStatementSyntax _:
				case WhileStatementSyntax _:
				case ForStatementSyntax _:
				case ForEachStatementSyntax _:
				case DoStatementSyntax _:
					_complexity += 1 + _nestingLevel;
					_nestingLevel++;
					VisitChildren(node);
					_nestingLevel--;
					break;

				case SwitchStatementSyntax switchStmt:
					_complexity += 1 + _nestingLevel;
					_nestingLevel++;
					VisitChildren(node);
					_nestingLevel--;
					break;

				case ConditionalExpressionSyntax _:
					_complexity += 1 + _nestingLevel;
					VisitChildren(node);
					break;

				case CatchClauseSyntax _:
					_complexity += 1 + _nestingLevel;
					_nestingLevel++;
					VisitChildren(node);
					_nestingLevel--;
					break;

				case BinaryExpressionSyntax binary when
					binary.OperatorToken.IsKind(SyntaxKind.AmpersandAmpersandToken) ||
					binary.OperatorToken.IsKind(SyntaxKind.BarBarToken):
					_complexity += 1;
					VisitChildren(node);
					break;

				default:
					VisitChildren(node);
					break;
			}
		}

		private void VisitChildren(SyntaxNode node)
		{
			foreach (var child in node.ChildNodes())
			{
				Visit(child);
			}
		}
	}
}