using System;
using System.Collections.Generic;

namespace luaaaaah;

class Parser
{
	public class ChunkNode(BlockNode block, CodeRegion startRegion, CodeRegion endRegion)
	{
		public BlockNode block = block;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class BlockNode(List<StatNode> stats, CodeRegion startRegion, CodeRegion endRegion)
	{
		public List<StatNode> stats = stats;
		public RetstatNode? retstat;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public abstract class StatNode(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class Semicolon(CodeRegion region) : StatNode(region, region) { }
		public class Assignment(AssignmentNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public AssignmentNode node = node;
		}
		public class Functioncall(FunctioncallNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public FunctioncallNode node = node;
		}
		public class Label(string label, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public string label = label;
		}
		public class Break(CodeRegion region) : StatNode(region, region) { }
		public class Goto(string label, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public string label = label;
		}
		public class Do(BlockNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public BlockNode node = node;
		}
		public class While(WhileNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public WhileNode node = node;
		}
		public class Repeat(RepeatNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public RepeatNode node = node;
		}
		public class If(IfNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public IfNode node = node;
		}
		public class ForNumerical(ForNumericalNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public ForNumericalNode node = node;
		}
		public class ForGeneric(ForGenericNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public ForGenericNode node = node;
		}
		public class Function(FunctionNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public FunctionNode node = node;
		}
		public class LocalFunction(LocalFunctionNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public LocalFunctionNode node = node;
		}
		public class Local(LocalNode node, CodeRegion startRegion, CodeRegion endRegion) : StatNode(startRegion, endRegion)
		{
			public LocalNode node = node;
		}
	}
	public class RetstatNode(CodeRegion startRegion, CodeRegion endRegion)
	{
		public ExplistNode? values;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class AssignmentNode(VarlistNode lhs, ExplistNode rhs, CodeRegion startRegion, CodeRegion endRegion)
	{
		public VarlistNode lhs = lhs;
		public ExplistNode rhs = rhs;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class FunctioncallNode(SuffixexpNode function, string? objectArg, ArgsNode args, CodeRegion startRegion, CodeRegion endRegion)
	{
		public SuffixexpNode function = function;
		public string? objectArg = objectArg;
		public ArgsNode args = args;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class WhileNode(ExpNode condition, BlockNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public ExpNode condition = condition;
		public BlockNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class RepeatNode(ExpNode condition, BlockNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public ExpNode condition = condition;
		public BlockNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class IfNode(ExpNode condition, BlockNode body, List<ElseifNode> elseifs, CodeRegion startRegion, CodeRegion endRegion)
	{
		public ExpNode condition = condition;
		public BlockNode body = body;
		public List<ElseifNode> elseifs = elseifs;
		public BlockNode? else_;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class ForNumericalNode(string variable, ExpNode start, ExpNode end, ExpNode? change, BlockNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public string variable = variable;
		public ExpNode start = start;
		public ExpNode end = end;
		public ExpNode? change = change;
		public BlockNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class ForGenericNode(List<string> vars, ExplistNode exps, BlockNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public List<string> vars = vars;
		public ExplistNode exps = exps;
		public BlockNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class FunctionNode(FuncnameNode name, FuncbodyNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public FuncnameNode name = name;
		public FuncbodyNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class LocalFunctionNode(string name, FuncbodyNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public string name = name;
		public FuncbodyNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class LocalNode(AttnamelistNode attnames, ExplistNode? values, CodeRegion startRegion, CodeRegion endRegion)
	{
		public AttnamelistNode attnames = attnames;
		public ExplistNode? values = values;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class ExplistNode(List<ExpNode> exps, CodeRegion startRegion, CodeRegion endRegion)
	{
		public List<ExpNode> exps = exps;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class VarlistNode(List<VarNode> vars, CodeRegion startRegion, CodeRegion endRegion)
	{
		public List<VarNode> vars = vars;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public abstract class SuffixexpNode(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class Normal(NormalSuffixNode node, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpNode(startRegion, endRegion)
		{
			public NormalSuffixNode node = node;
		}
		public class Functioncall(FunctioncallNode node, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpNode(startRegion, endRegion)
		{
			public FunctioncallNode node = node;
		}
	}
	public abstract class ArgsNode(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class Bracketed(ExplistNode? node, CodeRegion startRegion, CodeRegion endRegion) : ArgsNode(startRegion, endRegion)
		{
			public ExplistNode? node = node;
		}
		public class Tableconstructor(TableconstructorNode node, CodeRegion startRegion, CodeRegion endRegion) : ArgsNode(startRegion, endRegion)
		{
			public TableconstructorNode node = node;
		}
		public class Literal(string name, CodeRegion startRegion, CodeRegion endRegion) : ArgsNode(startRegion, endRegion)
		{
			public string name = name;
		}
	}
	public abstract class ExpNode(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class Nil(CodeRegion region) : ExpNode(region, region) { }
		public class False(CodeRegion region) : ExpNode(region, region) { }
		public class True(CodeRegion region) : ExpNode(region, region) { }
		public class Numeral(INumeral value, CodeRegion region) : ExpNode(region, region)
		{
			public INumeral value = value;
		}
		public class LiteralString(string value, CodeRegion region) : ExpNode(region, region)
		{
			public string value = value;
		}
		public class Varargs(CodeRegion region) : ExpNode(region, region) { }
		public class Functiondef(FuncbodyNode node, CodeRegion startRegion, CodeRegion endRegion) : ExpNode(startRegion, endRegion)
		{
			public FuncbodyNode node = node;
		}
		public class Suffixexp(SuffixexpNode node, CodeRegion startRegion, CodeRegion endRegion) : ExpNode(startRegion, endRegion)
		{
			public SuffixexpNode node = node;
		}
		public class Tableconstructor(TableconstructorNode node, CodeRegion startRegion, CodeRegion endRegion) : ExpNode(startRegion, endRegion)
		{
			public TableconstructorNode node = node;
		}
		public class Unop(UnopNode node, CodeRegion startRegion, CodeRegion endRegion) : ExpNode(startRegion, endRegion)
		{
			public UnopNode node = node;
		}
		public class Binop(BinopNode node, CodeRegion startRegion, CodeRegion endRegion) : ExpNode(startRegion, endRegion)
		{
			public BinopNode node = node;
		}
	}
	public class ElseifNode(ExpNode condition, BlockNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public ExpNode condition = condition;
		public BlockNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class FuncnameNode(string name, List<string> dottedNames, string? firstArg, CodeRegion startRegion, CodeRegion endRegion)
	{
		public string name = name;
		public List<string> dottedNames = dottedNames;
		public string? firstArg = firstArg;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class FuncbodyNode(ParlistNode? pars, BlockNode body, CodeRegion startRegion, CodeRegion endRegion)
	{
		public ParlistNode? pars = pars;
		public BlockNode body = body;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class AttnamelistNode(List<AttnameNode> attnames, CodeRegion startRegion, CodeRegion endRegion)
	{
		public List<AttnameNode> attnames = attnames;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public abstract class VarNode(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class Name(string name, CodeRegion startRegion, CodeRegion endRegion) : VarNode(startRegion, endRegion)
		{
			public string name = name;
		}
		public class Indexed(IndexedVarNode node, CodeRegion startRegion, CodeRegion endRegion) : VarNode(startRegion, endRegion)
		{
			public IndexedVarNode node = node;
		}
		public class Member(MemberVarNode node, CodeRegion startRegion, CodeRegion endRegion) : VarNode(startRegion, endRegion)
		{
			public MemberVarNode node = node;
		}
	}
	public class NormalSuffixNode(SuffixexpFirstPart firstPart, List<SuffixexpSuffix> suffixes, CodeRegion startRegion, CodeRegion endRegion)
	{
		public SuffixexpFirstPart firstPart = firstPart;
		public List<SuffixexpSuffix> suffixes = suffixes;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class TableconstructorNode(FieldlistNode? exps, CodeRegion startRegion, CodeRegion endRegion)
	{
		public FieldlistNode? exps = exps;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class UnopNode(UnopType type, ExpNode exp, CodeRegion startRegion, CodeRegion endRegion)
	{
		public UnopType type = type;
		public ExpNode exp = exp;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public enum UnopType
	{
		Minus, LogicalNot, Length, BinaryNot,
	}
	public class BinopNode(ExpNode lhs, BinopType type, ExpNode rhs, CodeRegion startRegion, CodeRegion endRegion)
	{
		public ExpNode lhs = lhs;
		public BinopType type = type;
		public ExpNode rhs = rhs;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public enum BinopType
	{
		LogicalOr,
		LogicalAnd,
		Lt, Gt, LtEquals, GtEquals, NotEquals, Equals,
		BinaryOr,
		BinaryNot,
		BinaryAnd,
		Shl, Shr,
		Concat,
		Add, Sub,
		Mul, Div, IntDiv, Mod,
		Exp,
	}
	public class ParlistNode(List<string> names, bool hasVarargs, CodeRegion startRegion, CodeRegion endRegion)
	{
		public List<string> names = names;
		public bool hasVarargs = hasVarargs;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class AttnameNode(string name, string? attribute, CodeRegion startRegion, CodeRegion endRegion)
	{
		public string name = name;
		public string? attribute = attribute;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class IndexedVarNode(SuffixexpNode value, ExpNode index, CodeRegion startRegion, CodeRegion endRegion)
	{
		public SuffixexpNode value = value;
		public ExpNode index = index;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class MemberVarNode(SuffixexpNode value, string name, CodeRegion startRegion, CodeRegion endRegion)
	{
		public SuffixexpNode value = value;
		public string name = name;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public abstract class SuffixexpFirstPart(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class Name(string name, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpFirstPart(startRegion, endRegion)
		{
			public string name = name;
		}
		public class BracketedExp(ExpNode node, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpFirstPart(startRegion, endRegion)
		{
			public ExpNode node = node;
		}
	}
	public abstract class SuffixexpSuffix(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class Dot(string name, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpSuffix(startRegion, endRegion)
		{
			public string name = name;
		}
		public class Indexed(ExpNode node, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpSuffix(startRegion, endRegion)
		{
			public ExpNode node = node;
		}
		public class Args(ArgsNode node, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpSuffix(startRegion, endRegion)
		{
			public ArgsNode node = node;
		}
		public class ArgsFirstArg(ArgsFirstArgNode node, CodeRegion startRegion, CodeRegion endRegion) : SuffixexpSuffix(startRegion, endRegion)
		{
			public ArgsFirstArgNode node = node;
		}
	}
	public class FieldlistNode(List<FieldNode> exps, CodeRegion startRegion, CodeRegion endRegion)
	{
		public List<FieldNode> exps = exps;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class ArgsFirstArgNode(string name, ArgsNode rest, CodeRegion startRegion, CodeRegion endRegion)
	{
		public string name = name;
		public ArgsNode rest = rest;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public abstract class FieldNode(CodeRegion startRegion, CodeRegion endRegion)
	{
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
		public class IndexedAssignment(IndexedAssignmentNode node, CodeRegion startRegion, CodeRegion endRegion) : FieldNode(startRegion, endRegion)
		{
			public IndexedAssignmentNode node = node;
		}
		public class Assignment(FieldAssignmentNode node, CodeRegion startRegion, CodeRegion endRegion) : FieldNode(startRegion, endRegion)
		{
			public FieldAssignmentNode node = node;
		}
		public class Exp(ExpNode node, CodeRegion startRegion, CodeRegion endRegion) : FieldNode(startRegion, endRegion)
		{
			public ExpNode node = node;
		}
	}
	public class IndexedAssignmentNode(ExpNode index, ExpNode rhs, CodeRegion startRegion, CodeRegion endRegion)
	{
		public ExpNode index = index;
		public ExpNode rhs = rhs;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}
	public class FieldAssignmentNode(string lhs, ExpNode rhs, CodeRegion startRegion, CodeRegion endRegion)
	{
		public string lhs = lhs;
		public ExpNode rhs = rhs;
		public CodeRegion startRegion = startRegion, endRegion = endRegion;
	}

	public int index;

	public ChunkNode Parse(Token[] tokens)
	{
		return ParseChunk(tokens);
	}

	public ChunkNode ParseChunk(Token[] tokens)
	{
		BlockNode body = ParseBlock(tokens);
		return new ChunkNode(block: body, startRegion: body.startRegion, endRegion: body.endRegion);
	}

	public BlockNode ParseBlock(Token[] tokens)
	{
		CodeRegion startRegion = tokens[index].region;
		List<StatNode> stats = [];
		while(index < tokens.Length &&
			tokens[index].type != TokenType.Return &&
			tokens[index].type != TokenType.End &&
			tokens[index].type != TokenType.Elseif &&
			tokens[index].type != TokenType.Else)
		{
			stats.Add(ParseStat(tokens));
		}
		BlockNode ret = new(stats: stats, startRegion: startRegion, endRegion: stats[^1].endRegion);
		if(index < tokens.Length && tokens[index].type == TokenType.Return)
		{
			ret.retstat = ParseRetstat(tokens);
		}
		return ret;
	}

	public StatNode ParseStat(Token[] tokens)
	{
		if(index >= tokens.Length)
		{
			throw new Exception($"Index {index} out of bounds of {tokens.Length}");
		}
		CodeRegion startRegion = tokens[index].region;
		switch(tokens[index].type)
		{
			case TokenType.Semicolon:
			{
				index += 1;
				return new StatNode.Semicolon(startRegion);
			}
			case TokenType.Break:
			{
				index += 1;
				return new StatNode.Break(startRegion);
			}
			case TokenType.Goto:
			{
				index += 1;
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected name for goto at {startRegion}");
				}
				if(tokens[index].type != TokenType.Name)
				{
					throw new Exception($"{tokens[index].region}: Expected name for goto, got {tokens[index].type}");
				}
				StatNode.Goto ret = new(label: ((Token.StringData)tokens[index].data!).data, startRegion: startRegion, endRegion: tokens[index].region);
				index += 1;
				return ret;
			}
			case TokenType.Do:
			{
				index += 1;
				BlockNode body = ParseBlock(tokens);
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected end for `do` at {startRegion}");
				}
				if(tokens[index].type != TokenType.End)
				{
					throw new Exception($"{tokens[index].region}: Expected `end` to close `do` at {startRegion}, got {tokens[index].type}");
				}
				StatNode.Do ret = new(node: body, startRegion: startRegion, endRegion: tokens[index].region);
				index += 1;
				return ret;
			}
			case TokenType.While:
			{
				index += 1;
				ExpNode condition = ParseExp(tokens);
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `do` after condition of while loop starting at {startRegion}");
				}
				if(tokens[index].type != TokenType.Do)
				{
					throw new Exception($"{tokens[index].region}: Expected `do` after condition of while starting at {startRegion}, got {tokens[index].type}");
				}
				index += 1;
				BlockNode body = ParseBlock(tokens);
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `end` after body of while loop starting at {startRegion}");
				}
				CodeRegion endRegion = tokens[index].region;
				index += 1;
				return new StatNode.While(new(condition: condition, body: body, startRegion: startRegion, endRegion: endRegion), startRegion: startRegion, endRegion: endRegion);
			}
			case TokenType.Repeat:
			{
				index += 1;
				BlockNode body = ParseBlock(tokens);
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `until` after body of until loop starting at {startRegion}");
				}
				if(tokens[index].type != TokenType.Until)
				{
					throw new Exception($"{tokens[index].region}: Expected `until` after block of until loop starting at {startRegion}, got {tokens[index].type}");
				}
				index += 1;
				ExpNode conditon = ParseExp(tokens);
				return new StatNode.Repeat(new(condition: conditon, body: body, startRegion: startRegion, endRegion: conditon.endRegion), startRegion: startRegion, endRegion: conditon.endRegion);
			}
			case TokenType.If:
			{
				index += 1;
				ExpNode condition = ParseExp(tokens);
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `then` after condition of if starting at {startRegion}");
				}
				if(tokens[index].type != TokenType.Then)
				{
					throw new Exception($"{tokens[index].region}: Expected `then` after condition of if starting at {startRegion}, got {tokens[index].type}");
				}
				index += 1;
				BlockNode body = ParseBlock(tokens);
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `end` after body of if starting at {startRegion}");
				}
				List<ElseifNode> elseifs = [];
				while(tokens[index].type == TokenType.Elseif)
				{
					CodeRegion elseifStartRegion = tokens[index].region;
					index += 1;
					ExpNode elseifCondition = ParseExp(tokens);
					if(index >= tokens.Length)
					{
						throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `then` after condition of elseif starting at {elseifStartRegion}");
					}
					if(tokens[index].type != TokenType.Then)
					{
						throw new Exception($"{tokens[index].region}: Expected `then` after condition of elseif starting at {elseifStartRegion}, got {tokens[index].type}");
					}
					index += 1;
					BlockNode elseifBody = ParseBlock(tokens);
					elseifs.Add(new(condition: elseifCondition, body: elseifBody, startRegion: elseifStartRegion, endRegion: elseifBody.endRegion));
				}
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `end` after else-ifs of if starting at {startRegion}");
				}
				IfNode ret = new(condition: condition, body: body, elseifs: elseifs, startRegion: startRegion, endRegion: tokens[index - 1].region);
				if(tokens[index].type == TokenType.Then)
				{
					index += 1;
					ret.else_ = ParseBlock(tokens);
				}
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `end` to close if starting at {startRegion}");
				}
				if(tokens[index].type != TokenType.End)
				{
					throw new Exception($"{tokens[index].region}: Expected `end` to close if starting at {startRegion}, got {tokens[index].type}");
				}
				ret.endRegion = tokens[index].region;
				index += 1;
				return new StatNode.If(node: ret, startRegion: startRegion, endRegion: ret.endRegion);
			}
			case TokenType.For:
			{
				index += 1;
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected name after for at {startRegion}");
				}
				if(tokens[index].type != TokenType.Name)
				{
					throw new Exception($"{tokens[index].region}: Expected name after for at {startRegion}, got {tokens[index].type}");
				}
				string variable = ((Token.StringData)tokens[index].data!).data;
				index += 1;
				switch(tokens[index].type)
				{
					case TokenType.Equals:
					{
						index += 1;
						ExpNode start = ParseExp(tokens);
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `,` after start value of numerical for loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.Comma)
						{
							throw new Exception($"{tokens[index].region}: Expected `,` after start value of for loop starting at {startRegion}, got {tokens[index].type}");
						}
						index += 1;
						ExpNode end = ParseExp(tokens);
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `do` or `,` after end value of numerical for loop starting at {startRegion}");
						}
						ExpNode? change = null;
						if(tokens[index].type == TokenType.Comma)
						{
							index += 1;
							change = ParseExp(tokens);
						}
						if(index >= tokens.Length)
						{
							string t = (change == null) ? "`do` or `,` after end value" : "`do` after change value";
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected {t} of numerical for loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.Do)
						{
							string t = (change == null) ? "`do` or `,` after end value" : "`do` after change value";
							throw new Exception($"{tokens[index].region}: Expected {t} of numerical for loop starting at {startRegion}, got {tokens[index].type}");
						}
						index += 1;
						BlockNode body = ParseBlock(tokens);
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `end` to close numerical for loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.End)
						{
							throw new Exception($"{tokens[index].region}: Expected `end` to close numerical for loop starting at {startRegion}, got {tokens[index].type}");
						}
						CodeRegion endRegion = tokens[index].region;
						index += 1;
						return new StatNode.ForNumerical(new(variable: variable, start: start, end: end, change: change, body: body, startRegion: startRegion, endRegion: endRegion), startRegion: startRegion, endRegion: endRegion);
					}
					case TokenType.Comma:
					{
						List<string> names = [variable];
						while(tokens[index].type == TokenType.Comma)
						{
							index += 1;
							if(index >= tokens.Length)
							{
								throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected another name in name list of for-in loop starting at {startRegion}");
							}
							if(tokens[index].type != TokenType.Name)
							{
								throw new Exception($"{tokens[index].region}: Expected another name in name list of for-in loop starting at {startRegion}, got {tokens[index].type}");
							}
							names.Add(((Token.StringData)tokens[index].data!).data);
							index += 1;
							if(index >= tokens.Length)
							{
								throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `,` or `in` in for-in loop starting at {startRegion}");
							}
						}
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `in` after name list of for-in loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.In)
						{
							throw new Exception($"{tokens[index].region}: Expected `in` after name list of for-in loop starting at {startRegion}, got {tokens[index].type}");
						}
						index += 1;
						ExplistNode exps = ParseExplist(tokens);
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `do` after exp list of for-in loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.Do)
						{
							throw new Exception($"{tokens[index].region}: Expected `do` after exp list of for-in loop starting at {startRegion}, got {tokens[index].type}");
						}
						index += 1;
						BlockNode body = ParseBlock(tokens);
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `end` to close for-in loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.End)
						{
							throw new Exception($"{tokens[index].region}: Expected `end` to close for-in loop starting at {startRegion}, got {tokens[index].type}");
						}
						CodeRegion endRegion = tokens[index].region;
						index += 1;
						return new StatNode.ForGeneric(new(vars: names, exps: exps, body: body, startRegion: startRegion, endRegion: endRegion), startRegion: startRegion, endRegion: endRegion);
					}
					case TokenType.In:
					{
						index += 1;
						ExplistNode exps = ParseExplist(tokens);
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `do` after exp list of for-in loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.Do)
						{
							throw new Exception($"{tokens[index].region}: Expected `do` after exp list of for-in loop starting at {startRegion}, got {tokens[index].type}");
						}
						index += 1;
						BlockNode body = ParseBlock(tokens);
						if(index >= tokens.Length)
						{
							throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `end` to close for-in loop starting at {startRegion}");
						}
						if(tokens[index].type != TokenType.End)
						{
							throw new Exception($"{tokens[index].region}: Expected `end` to close for-in loop starting at {startRegion}, got {tokens[index].type}");
						}
						CodeRegion endRegion = tokens[index].region;
						index += 1;
						return new StatNode.ForGeneric(new(vars: [variable], exps: exps, body: body, startRegion: startRegion, endRegion: endRegion), startRegion: startRegion, endRegion: endRegion);
					}
					default:
					{
						throw new Exception($"{tokens[index].type}: Expected either `=`, `,` or `in` after first name of for loop {startRegion}, got {tokens[index].type}");
					}
				}
			}
			case TokenType.Function:
			{
				index += 1;
				FuncnameNode name = ParseFuncname(tokens);
				FuncbodyNode body = ParseFuncbody(tokens);
				return new StatNode.Function(new(name: name, body: body, startRegion: startRegion, endRegion: body.endRegion), startRegion: startRegion, endRegion: body.endRegion);
			}
			case TokenType.Local:
			{
				index += 1;
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length} after `local` at {startRegion}");
				}
				if(tokens[index].type == TokenType.Function)
				{
					index += 1;
					if(index >= tokens.Length)
					{
						throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected name of local function starting at {startRegion}");
					}
					if(tokens[index].type != TokenType.Name)
					{
						throw new Exception($"{tokens[index].region}: Expected name of local function starting at {startRegion}, got {tokens[index].type}");
					}
					string name = ((Token.StringData)tokens[index].data!).data;
					index += 1;
					FuncbodyNode body = ParseFuncbody(tokens);
					return new StatNode.LocalFunction(new(name: name, body: body, startRegion: startRegion, endRegion: body.endRegion), startRegion: startRegion, endRegion: body.endRegion);
				}
				else
				{
					AttnamelistNode attnames = ParseAttnamelist(tokens);
					LocalNode ret = new(attnames: attnames, values: null, startRegion: startRegion, endRegion: attnames.endRegion);
					if(index < tokens.Length && tokens[index].type == TokenType.Equals)
					{
						index += 1;
						ret.values = ParseExplist(tokens);
						ret.endRegion = ret.values.endRegion;
					}
					return new StatNode.Local(ret, startRegion: startRegion, endRegion: ret.endRegion);
				}
			}
			case TokenType.ColonColon:
			{
				index += 1;
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected name of label starting at {startRegion}");
				}
				if(tokens[index].type != TokenType.Name)
				{
					throw new Exception($"{tokens[index].region}: Expected name of label starting at {startRegion}, got {tokens[index].type}");
				}
				string name = ((Token.StringData)tokens[index].data!).data;
				index += 1;
				if(index >= tokens.Length)
				{
					throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `::` after label name starting at {startRegion}");
				}
				if(tokens[index].type != TokenType.Name)
				{
					throw new Exception($"{tokens[index].region}: Expected `::` after label name starting at {startRegion}, got {tokens[index].type}");
				}
				CodeRegion endRegion = tokens[index].region;
				index += 1;
				return new StatNode.Label(label: name, startRegion: startRegion, endRegion: endRegion);
			}
			case TokenType.Name:
			case TokenType.RoundOpen:
			{
				SuffixexpNode suffixExp = ParseSuffixExp(tokens);
				if(index >= tokens.Length)
				{
					if(suffixExp is SuffixexpNode.Normal)
					{
						throw new Exception($"{startRegion}: Expected function call, got normal suffix expression");
					}
					if(suffixExp is SuffixexpNode.Functioncall functioncall)
					{
						return new StatNode.Functioncall(node: functioncall.node, startRegion: functioncall.startRegion, endRegion: functioncall.endRegion);
					}
				}
				else
				{
					switch(tokens[index].type)
					{
						case TokenType.Equals:
						{
							index += 1;
							List<VarNode> lhs = [SuffixExpToVar(suffixExp)];
							ExplistNode rhs = ParseExplist(tokens);
							return new StatNode.Assignment(new(lhs: new(vars: lhs, startRegion: startRegion, endRegion: suffixExp.endRegion), rhs: rhs, startRegion: startRegion, endRegion: rhs.endRegion), startRegion: startRegion, endRegion: rhs.endRegion);
						}
						case TokenType.Comma:
						{
							List<VarNode> vars = [SuffixExpToVar(suffixExp)];
							while(index < tokens.Length && tokens[index].type == TokenType.Comma)
							{
								index += 1;
								vars.Add(ParseVar(tokens));
							}
							if(index >= tokens.Length)
							{
								throw new Exception($"Index {index} out of bounds of {tokens.Length}, expected `=` for assignment starting at {startRegion}");
							}
							if(tokens[index].type != TokenType.Equals)
							{
								throw new Exception($"{tokens[index].region}: Expected `=` for assignment starting at {startRegion}, got {tokens[index].type}");
							}
							index += 1;
							VarlistNode varlistNode = new(vars: vars, startRegion: startRegion, endRegion: vars[^1].endRegion);
							ExplistNode rhs = ParseExplist(tokens);
							return new StatNode.Assignment(new(lhs: varlistNode, rhs: rhs, startRegion: startRegion, endRegion: rhs.endRegion), startRegion: startRegion, endRegion: rhs.endRegion);
						}
					}
					if(suffixExp is SuffixexpNode.Normal)
					{
						throw new Exception($"{startRegion}: Expected function call, got normal suffix expression");
					}
					if(suffixExp is SuffixexpNode.Functioncall functioncall)
					{
						return new StatNode.Functioncall(node: functioncall.node, startRegion: functioncall.startRegion, endRegion: functioncall.endRegion);
					}
				}
			}
			break;
			default:
			{
				throw new Exception($"Unexpected token {tokens[index]} at {startRegion}");
			}
		}
		throw new NotImplementedException();
	}

	private VarNode ParseVar(Token[] tokens)
	{
		throw new NotImplementedException();
	}

	private VarNode SuffixExpToVar(SuffixexpNode suffixExp)
	{
		throw new NotImplementedException();
	}

	private SuffixexpNode ParseSuffixExp(Token[] tokens)
	{
		throw new NotImplementedException();
	}

	private AttnamelistNode ParseAttnamelist(Token[] tokens)
	{
		throw new NotImplementedException();
	}

	private FuncbodyNode ParseFuncbody(Token[] tokens)
	{
		throw new NotImplementedException();
	}

	private FuncnameNode ParseFuncname(Token[] tokens)
	{
		throw new NotImplementedException();
	}

	private ExplistNode ParseExplist(Token[] tokens)
	{
		throw new NotImplementedException();
	}

	private ExpNode ParseExp(Token[] tokens)
	{
		throw new NotImplementedException();
	}

	private RetstatNode ParseRetstat(Token[] tokens)
	{
		throw new NotImplementedException();
	}
}