using System;
using System.Collections.Generic;
using System.Linq;
using NTERA.Core;
using NTERA.EmuEra.Game.EraEmu.Content;
using NTERA.Engine.Compiler;

namespace NTERA.Engine.Runtime
{
	public class EraRuntime : IScriptEngine
	{
		public IExecutionProvider ExecutionProvider { get; }
		public IConsole Console { get; protected set; }

		public Stack<ExecutionSet> ExecutionStack { get; } = new Stack<ExecutionSet>();

		public EraRuntime(IExecutionProvider executionProvider)
		{
			ExecutionProvider = executionProvider;
		}

		public bool Initialize(IConsole console)
		{
			Console = console;
			return true;
		}

		public void Start()
		{
			Console.PrintSystemLine("EraJIT x64 0.0.0.0");
			Console.PrintSystemLine("");

			try
			{
				Call(ExecutionProvider.DefinedProcedures.First(x => x.Name == "SYSTEM_TITLE"));
			}
			catch (Exception ex)
			{
				Console.PrintSystemLine($"Unhandled exception: {ex.Message}");
				Console.PrintSystemLine("Stack trace:");

				foreach (var stackMember in ExecutionStack)
					Console.PrintSystemLine($"  - @{stackMember.SelfDefinition.Name} ({stackMember.SelfDefinition.Position} > {stackMember.SelfDefinition.Filename})");

				throw;
			}

			System.Threading.Thread.Sleep(-1);
		}

		public void Call(FunctionDefinition function)
		{
			var executionContents = ExecutionProvider.GetExecutionNodes(function);

			var localVariables = new VariableDictionary();

			foreach (var variable in function.Variables)
				localVariables[variable.Name] = variable.CalculatedValue;

			var globalVariables = new VariableDictionary();

			foreach (var variable in BaseDefinitions.DefaultGlobalVariables)
				globalVariables[variable.Name] = variable.CalculatedValue;

			var executionSet = new ExecutionSet
			{
				Nodes = executionContents.ToList(),
				SelfDefinition = function,
				GlobalVariables = globalVariables,
				LocalVariables = localVariables
			};

			ExecutionStack.Push(executionSet);

			ExecuteSet(executionSet);

			ExecutionStack.Pop();
		}

		public void ExecuteSet(ExecutionSet set)
		{
			for (; set.Position < set.Nodes.Count; set.Position++)
			{
				ExecutionNode node = set.Nodes[set.Position];

				ExecuteNode(set, node);
			}
		}

		public void ExecuteNode(ExecutionSet set, ExecutionNode node)
		{
			switch (node.Type)
			{
				case "statement":
					string statement = node.Metadata["name"];

					if (!Base.Keywords.StaticKeywords.TryGetValue(statement, out var keywordAction))
						throw new Exception($"Unknown statement: '{statement}'");

					keywordAction(this, set, node);

					break;
				case "assignment":
					string variableName = node["variable"].Metadata["name"];

					if (set.LocalVariables.ContainsKey(variableName))
						set.LocalVariables[variableName] = ComputeExpression(set, node["value"].SubNodes.Single());
					else if (set.GlobalVariables.ContainsKey(variableName))
						set.GlobalVariables[variableName] = ComputeExpression(set, node["value"].SubNodes.Single());
					else
						throw new Exception($"Unknown variable: '{variableName}'");

					break;
				default:
					throw new Exception($"Unknown node type: '{node.Type}'");
			}
		}

		public Value ComputeExpression(ExecutionSet set, ExecutionNode expressionNode)
		{
			switch (expressionNode.Type)
			{
				case "constant":
					ValueType type = (ValueType)Enum.Parse(typeof(ValueType), expressionNode.Metadata["type"]);

					string strValue = expressionNode.Metadata["value"];

					return type == ValueType.String ? (Value)strValue : (Value)double.Parse(strValue);
				default:
					throw new Exception($"Unknown expression type: '{expressionNode.Type}'");
			}
		}

		public void InputString(string input)
		{
			throw new NotImplementedException();
		}

		public void InputInteger(long input)
		{
			throw new NotImplementedException();
		}

		public void InputSystemInteger(long input)
		{
			throw new NotImplementedException();
		}

		public CroppedImage GetImage(string name)
		{
			throw new NotImplementedException();
		}
	}
}