Mako/compiler/compiler.go

package compiler

import (
	"fmt"
	"math"

	"git.sharkk.net/Sharkk/Mako/parser"
)

// Compiler holds the compilation state and compiles AST to bytecode
type Compiler struct {
	current   *CompilerState // Current compilation state
	enclosing *CompilerState // Enclosing function state for closures
	errors    []CompileError // Compilation errors
}

// NewCompiler creates a new compiler instance
func NewCompiler() *Compiler {
	return &Compiler{
		current: NewCompilerState(FunctionTypeScript),
		errors:  make([]CompileError, 0),
	}
}

// Compile compiles a program AST to bytecode with optimizations
func (c *Compiler) Compile(program *parser.Program) (*Chunk, []CompileError) {
	for _, stmt := range program.Statements {
		c.compileStatement(stmt)
	}

	c.current.EmitInstruction(OpReturnNil)

	if len(c.errors) > 0 {
		return nil, c.errors
	}

	// Apply optimizations
	c.optimizeChunk(c.current.Chunk)

	return c.current.Chunk, nil
}

// Statement compilation
func (c *Compiler) compileStatement(stmt parser.Statement) {
	if lineNode := c.getLineFromNode(stmt); lineNode != 0 {
		c.current.SetLine(lineNode)
	}

	switch s := stmt.(type) {
	case *parser.StructStatement:
		c.compileStructStatement(s)
	case *parser.MethodDefinition:
		c.compileMethodDefinition(s)
	case *parser.Assignment:
		c.compileAssignment(s)
	case *parser.ExpressionStatement:
		c.compileExpression(s.Expression)
		c.current.EmitInstruction(OpPop) // Discard result
	case *parser.EchoStatement:
		c.compileExpression(s.Value)
		c.current.EmitInstruction(OpEcho)
	case *parser.IfStatement:
		c.compileIfStatement(s)
	case *parser.WhileStatement:
		c.compileWhileStatement(s)
	case *parser.ForStatement:
		c.compileForStatement(s)
	case *parser.ForInStatement:
		c.compileForInStatement(s)
	case *parser.ReturnStatement:
		c.compileReturnStatement(s)
	case *parser.ExitStatement:
		c.compileExitStatement(s)
	case *parser.BreakStatement:
		c.current.EmitBreak()
	default:
		c.addError(fmt.Sprintf("unknown statement type: %T", stmt))
	}
}

// Enhanced constant folding engine with complete coverage
func (c *Compiler) tryConstantFold(expr parser.Expression) *Value {
	switch e := expr.(type) {
	case *parser.NumberLiteral:
		return &Value{Type: ValueNumber, Data: e.Value}
	case *parser.StringLiteral:
		return &Value{Type: ValueString, Data: e.Value}
	case *parser.BooleanLiteral:
		return &Value{Type: ValueBool, Data: e.Value}
	case *parser.NilLiteral:
		return &Value{Type: ValueNil, Data: nil}
	case *parser.PrefixExpression:
		return c.foldPrefixExpression(e)
	case *parser.InfixExpression:
		return c.foldInfixExpression(e)
	}
	return nil
}

func (c *Compiler) foldPrefixExpression(expr *parser.PrefixExpression) *Value {
	rightValue := c.tryConstantFold(expr.Right)
	if rightValue == nil {
		return nil
	}

	switch expr.Operator {
	case "-":
		if rightValue.Type == ValueNumber {
			num := rightValue.Data.(float64)
			return &Value{Type: ValueNumber, Data: -num}
		}
	case "not":
		return &Value{Type: ValueBool, Data: !c.isTruthy(*rightValue)}
	}
	return nil
}

func (c *Compiler) foldInfixExpression(expr *parser.InfixExpression) *Value {
	leftValue := c.tryConstantFold(expr.Left)
	rightValue := c.tryConstantFold(expr.Right)

	if leftValue == nil || rightValue == nil {
		return nil
	}

	// Arithmetic operations
	if leftValue.Type == ValueNumber && rightValue.Type == ValueNumber {
		l := leftValue.Data.(float64)
		r := rightValue.Data.(float64)

		switch expr.Operator {
		case "+":
			return &Value{Type: ValueNumber, Data: l + r}
		case "-":
			return &Value{Type: ValueNumber, Data: l - r}
		case "*":
			return &Value{Type: ValueNumber, Data: l * r}
		case "/":
			if r != 0 {
				return &Value{Type: ValueNumber, Data: l / r}
			}
			return nil
		case "%":
			if r != 0 {
				return &Value{Type: ValueNumber, Data: math.Mod(l, r)}
			}
			return nil
		case "<":
			return &Value{Type: ValueBool, Data: l < r}
		case "<=":
			return &Value{Type: ValueBool, Data: l <= r}
		case ">":
			return &Value{Type: ValueBool, Data: l > r}
		case ">=":
			return &Value{Type: ValueBool, Data: l >= r}
		}
	}

	// String operations
	if leftValue.Type == ValueString && rightValue.Type == ValueString {
		l := leftValue.Data.(string)
		r := rightValue.Data.(string)

		switch expr.Operator {
		case "+":
			return &Value{Type: ValueString, Data: l + r}
		}
	}

	// Comparison operations
	switch expr.Operator {
	case "==":
		return &Value{Type: ValueBool, Data: c.valuesEqual(*leftValue, *rightValue)}
	case "!=":
		return &Value{Type: ValueBool, Data: !c.valuesEqual(*leftValue, *rightValue)}
	case "and":
		if !c.isTruthy(*leftValue) {
			return leftValue
		}
		return rightValue
	case "or":
		if c.isTruthy(*leftValue) {
			return leftValue
		}
		return rightValue
	}

	return nil
}

func (c *Compiler) isTruthy(value Value) bool {
	switch value.Type {
	case ValueNil:
		return false
	case ValueBool:
		return value.Data.(bool)
	case ValueNumber:
		return value.Data.(float64) != 0
	case ValueString:
		return value.Data.(string) != ""
	default:
		return true
	}
}

func (c *Compiler) valuesEqual(a, b Value) bool {
	if a.Type != b.Type {
		return false
	}
	switch a.Type {
	case ValueNil:
		return true
	case ValueBool:
		return a.Data.(bool) == b.Data.(bool)
	case ValueNumber:
		aNum := a.Data.(float64)
		bNum := b.Data.(float64)
		if math.IsNaN(aNum) && math.IsNaN(bNum) {
			return true
		}
		return aNum == bNum
	case ValueString:
		return a.Data.(string) == b.Data.(string)
	default:
		return false
	}
}

// Expression compilation with enhanced constant folding
func (c *Compiler) compileExpression(expr parser.Expression) {
	if lineNode := c.getLineFromNode(expr); lineNode != 0 {
		c.current.SetLine(lineNode)
	}

	// Try constant folding first
	if constValue := c.tryConstantFold(expr); constValue != nil {
		c.emitConstant(*constValue)
		return
	}

	switch e := expr.(type) {
	case *parser.Identifier:
		c.compileIdentifier(e)
	case *parser.NumberLiteral:
		c.compileNumberLiteral(e)
	case *parser.StringLiteral:
		c.compileStringLiteral(e)
	case *parser.BooleanLiteral:
		c.compileBooleanLiteral(e)
	case *parser.NilLiteral:
		c.compileNilLiteral(e)
	case *parser.TableLiteral:
		c.compileTableLiteral(e)
	case *parser.StructConstructor:
		c.compileStructConstructor(e)
	case *parser.FunctionLiteral:
		c.compileFunctionLiteral(e)
	case *parser.CallExpression:
		c.compileCallExpression(e)
	case *parser.PrefixExpression:
		c.compilePrefixExpression(e)
	case *parser.InfixExpression:
		c.compileInfixExpression(e)
	case *parser.IndexExpression:
		c.compileIndexExpression(e)
	case *parser.DotExpression:
		c.compileDotExpression(e)
	case *parser.Assignment:
		c.compileAssignmentExpression(e)
	default:
		c.addError(fmt.Sprintf("unknown expression type: %T", expr))
	}
}

// Optimized constant emission
func (c *Compiler) emitConstant(value Value) {
	switch value.Type {
	case ValueNil:
		c.current.EmitInstruction(OpLoadNil)
	case ValueBool:
		if value.Data.(bool) {
			c.current.EmitInstruction(OpLoadTrue)
		} else {
			c.current.EmitInstruction(OpLoadFalse)
		}
	case ValueNumber:
		num := value.Data.(float64)
		if num == 0 {
			c.current.EmitInstruction(OpLoadZero)
		} else if num == 1 {
			c.current.EmitInstruction(OpLoadOne)
		} else if num == -1 {
			c.current.EmitInstruction(OpLoadOne)
			c.current.EmitInstruction(OpNeg)
		} else {
			index := c.current.AddConstant(value)
			if index == -1 {
				c.addError("too many constants")
				return
			}
			c.current.EmitInstruction(OpLoadConst, uint16(index))
		}
	default:
		index := c.current.AddConstant(value)
		if index == -1 {
			c.addError("too many constants")
			return
		}
		c.current.EmitInstruction(OpLoadConst, uint16(index))
	}
}

// Literal compilation
func (c *Compiler) compileNumberLiteral(node *parser.NumberLiteral) {
	value := Value{Type: ValueNumber, Data: node.Value}
	c.emitConstant(value)
}

func (c *Compiler) compileStringLiteral(node *parser.StringLiteral) {
	value := Value{Type: ValueString, Data: node.Value}
	c.emitConstant(value)
}

func (c *Compiler) compileBooleanLiteral(node *parser.BooleanLiteral) {
	value := Value{Type: ValueBool, Data: node.Value}
	c.emitConstant(value)
}

func (c *Compiler) compileNilLiteral(node *parser.NilLiteral) {
	c.current.EmitInstruction(OpLoadNil)
}

// Identifier compilation
func (c *Compiler) compileIdentifier(node *parser.Identifier) {
	slot := c.current.ResolveLocal(node.Value)
	if slot != -1 {
		if slot == -2 {
			c.addError("can't read local variable in its own initializer")
			return
		}
		c.emitLoadLocal(slot)
		return
	}

	upvalue := c.resolveUpvalue(node.Value)
	if upvalue != -1 {
		c.current.EmitInstruction(OpGetUpvalue, uint16(upvalue))
		return
	}

	// Global variable
	value := Value{Type: ValueString, Data: node.Value}
	index := c.current.AddConstant(value)
	if index == -1 {
		c.addError("too many constants")
		return
	}
	c.current.EmitInstruction(OpLoadGlobal, uint16(index))
}

// Local variable access helpers
func (c *Compiler) emitLoadLocal(slot int) {
	switch slot {
	case 0:
		c.current.EmitInstruction(OpLoadLocal0)
	case 1:
		c.current.EmitInstruction(OpLoadLocal1)
	case 2:
		c.current.EmitInstruction(OpLoadLocal2)
	default:
		c.current.EmitInstruction(OpLoadLocal, uint16(slot))
	}
}

func (c *Compiler) emitStoreLocal(slot int) {
	switch slot {
	case 0:
		c.current.EmitInstruction(OpStoreLocal0)
	case 1:
		c.current.EmitInstruction(OpStoreLocal1)
	case 2:
		c.current.EmitInstruction(OpStoreLocal2)
	default:
		c.current.EmitInstruction(OpStoreLocal, uint16(slot))
	}
}

// Assignment compilation
func (c *Compiler) compileAssignment(node *parser.Assignment) {
	c.compileExpression(node.Value)

	switch target := node.Target.(type) {
	case *parser.Identifier:
		if node.IsDeclaration {
			if c.current.FunctionType == FunctionTypeScript && c.current.ScopeDepth == 0 {
				// Global variable
				value := Value{Type: ValueString, Data: target.Value}
				index := c.current.AddConstant(value)
				if index == -1 {
					c.addError("too many constants")
					return
				}
				c.current.EmitInstruction(OpStoreGlobal, uint16(index))
			} else {
				// Local variable
				if err := c.current.AddLocal(target.Value); err != nil {
					c.addError(err.Error())
					return
				}
				c.current.MarkInitialized()
			}
		} else {
			// Assignment to existing variable
			slot := c.current.ResolveLocal(target.Value)
			if slot != -1 {
				c.emitStoreLocal(slot)
			} else {
				upvalue := c.resolveUpvalue(target.Value)
				if upvalue != -1 {
					c.current.EmitInstruction(OpSetUpvalue, uint16(upvalue))
				} else {
					// Global assignment
					value := Value{Type: ValueString, Data: target.Value}
					index := c.current.AddConstant(value)
					if index == -1 {
						c.addError("too many constants")
						return
					}
					c.current.EmitInstruction(OpStoreGlobal, uint16(index))
				}
			}
		}
	case *parser.DotExpression:
		c.compileDotAssignment(target)
	case *parser.IndexExpression:
		c.compileExpression(target.Left)
		c.compileExpression(target.Index)
		c.current.EmitInstruction(OpSetIndex)
	default:
		c.addError("invalid assignment target")
	}
}

func (c *Compiler) compileDotAssignment(dot *parser.DotExpression) {
	if ident, ok := dot.Left.(*parser.Identifier); ok {
		slot := c.current.ResolveLocal(ident.Value)
		if slot != -1 && slot <= 2 {
			value := Value{Type: ValueString, Data: dot.Key}
			index := c.current.AddConstant(value)
			if index == -1 {
				c.addError("too many constants")
				return
			}
			c.current.EmitInstruction(OpSetLocalField, uint16(slot), uint16(index))
			return
		}
	}

	c.compileExpression(dot.Left)
	value := Value{Type: ValueString, Data: dot.Key}
	index := c.current.AddConstant(value)
	if index == -1 {
		c.addError("too many constants")
		return
	}
	c.current.EmitInstruction(OpSetField, uint16(index))
}

func (c *Compiler) compileAssignmentExpression(node *parser.Assignment) {
	c.compileAssignment(node)
}

// Operator compilation
func (c *Compiler) compilePrefixExpression(node *parser.PrefixExpression) {
	c.compileExpression(node.Right)

	switch node.Operator {
	case "-":
		c.current.EmitInstruction(OpNeg)
	case "not":
		c.current.EmitInstruction(OpNot)
	default:
		c.addError(fmt.Sprintf("unknown prefix operator: %s", node.Operator))
	}
}

func (c *Compiler) compileInfixExpression(node *parser.InfixExpression) {
	if c.tryOptimizeIncDec(node) {
		return
	}

	if c.tryOptimizeArithmeticWithConstant(node) {
		return
	}

	// Short-circuit operators
	if node.Operator == "and" {
		c.compileExpression(node.Left)
		jump := c.current.EmitJump(OpJumpIfFalse)
		c.current.EmitInstruction(OpPop)
		c.compileExpression(node.Right)
		c.current.PatchJump(jump)
		return
	}

	if node.Operator == "or" {
		c.compileExpression(node.Left)
		elseJump := c.current.EmitJump(OpJumpIfFalse)
		endJump := c.current.EmitJump(OpJump)
		c.current.PatchJump(elseJump)
		c.current.EmitInstruction(OpPop)
		c.compileExpression(node.Right)
		c.current.PatchJump(endJump)
		return
	}

	// Regular binary operators
	c.compileExpression(node.Left)
	c.compileExpression(node.Right)

	switch node.Operator {
	case "+":
		c.current.EmitInstruction(OpAdd)
	case "-":
		c.current.EmitInstruction(OpSub)
	case "*":
		c.current.EmitInstruction(OpMul)
	case "/":
		c.current.EmitInstruction(OpDiv)
	case "%":
		c.current.EmitInstruction(OpMod)
	case "==":
		c.current.EmitInstruction(OpEq)
	case "!=":
		c.current.EmitInstruction(OpNeq)
	case "<":
		c.current.EmitInstruction(OpLt)
	case "<=":
		c.current.EmitInstruction(OpLte)
	case ">":
		c.current.EmitInstruction(OpGt)
	case ">=":
		c.current.EmitInstruction(OpGte)
	default:
		c.addError(fmt.Sprintf("unknown infix operator: %s", node.Operator))
	}
}

func (c *Compiler) tryOptimizeIncDec(node *parser.InfixExpression) bool {
	if node.Operator != "+" && node.Operator != "-" {
		return false
	}

	leftIdent, ok := node.Left.(*parser.Identifier)
	if !ok {
		return false
	}

	rightLit, ok := node.Right.(*parser.NumberLiteral)
	if !ok || rightLit.Value != 1 {
		return false
	}

	slot := c.current.ResolveLocal(leftIdent.Value)
	if slot == -1 {
		return false
	}

	if node.Operator == "+" {
		c.current.EmitInstruction(OpInc, uint16(slot))
	} else {
		c.current.EmitInstruction(OpDec, uint16(slot))
	}

	c.emitLoadLocal(slot)
	return true
}

func (c *Compiler) tryOptimizeArithmeticWithConstant(node *parser.InfixExpression) bool {
	if node.Operator != "+" && node.Operator != "-" {
		return false
	}

	leftIdent, ok := node.Left.(*parser.Identifier)
	if !ok {
		return false
	}

	rightLit, ok := node.Right.(*parser.NumberLiteral)
	if !ok {
		return false
	}

	slot := c.current.ResolveLocal(leftIdent.Value)
	if slot == -1 {
		return false
	}

	if rightLit.Value >= 0 && rightLit.Value <= 255 && rightLit.Value == math.Floor(rightLit.Value) {
		c.emitLoadLocal(slot)

		constValue := Value{Type: ValueNumber, Data: rightLit.Value}
		constIndex := c.current.AddConstant(constValue)
		if constIndex == -1 {
			return false
		}

		if node.Operator == "+" {
			c.current.EmitInstruction(OpAddConst, uint16(constIndex))
		} else {
			c.current.EmitInstruction(OpSubConst, uint16(constIndex))
		}
		return true
	}

	return false
}

func (c *Compiler) compileDotExpression(node *parser.DotExpression) {
	if ident, ok := node.Left.(*parser.Identifier); ok {
		slot := c.current.ResolveLocal(ident.Value)
		if slot != -1 && slot <= 2 {
			value := Value{Type: ValueString, Data: node.Key}
			index := c.current.AddConstant(value)
			if index == -1 {
				c.addError("too many constants")
				return
			}
			c.current.EmitInstruction(OpGetLocalField, uint16(slot), uint16(index))
			return
		}
	}

	c.compileExpression(node.Left)
	value := Value{Type: ValueString, Data: node.Key}
	index := c.current.AddConstant(value)
	if index == -1 {
		c.addError("too many constants")
		return
	}
	c.current.EmitInstruction(OpGetField, uint16(index))
}

func (c *Compiler) compileCallExpression(node *parser.CallExpression) {
	if ident, ok := node.Function.(*parser.Identifier); ok {
		slot := c.current.ResolveLocal(ident.Value)
		if slot == 0 || slot == 1 {
			for _, arg := range node.Arguments {
				c.compileExpression(arg)
			}

			if slot == 0 {
				c.current.EmitInstruction(OpCallLocal0, uint16(len(node.Arguments)))
			} else {
				c.current.EmitInstruction(OpCallLocal1, uint16(len(node.Arguments)))
			}
			return
		}
	}

	c.compileExpression(node.Function)
	for _, arg := range node.Arguments {
		c.compileExpression(arg)
	}
	c.current.EmitInstruction(OpCall, uint16(len(node.Arguments)))
}

func (c *Compiler) compileIndexExpression(node *parser.IndexExpression) {
	c.compileExpression(node.Left)
	c.compileExpression(node.Index)
	c.current.EmitInstruction(OpGetIndex)
}

func (c *Compiler) compileTableLiteral(node *parser.TableLiteral) {
	c.current.EmitInstruction(OpNewTable)

	for _, pair := range node.Pairs {
		if pair.Key == nil {
			c.compileExpression(pair.Value)
			c.current.EmitInstruction(OpTableInsert)
		} else {
			c.current.EmitInstruction(OpDup)
			c.compileExpression(pair.Key)
			c.compileExpression(pair.Value)
			c.current.EmitInstruction(OpSetIndex)
		}
	}
}

func (c *Compiler) compileStructStatement(node *parser.StructStatement) {
	fields := make([]StructField, len(node.Fields))
	for i, field := range node.Fields {
		fields[i] = StructField{
			Name:   field.Name,
			Type:   c.typeInfoToValueType(field.TypeHint),
			Offset: uint16(i),
		}
	}

	structDef := Struct{
		Name:    node.Name,
		Fields:  fields,
		Methods: make(map[string]uint16),
		ID:      node.ID,
	}

	c.current.Chunk.Structs = append(c.current.Chunk.Structs, structDef)
}

func (c *Compiler) compileMethodDefinition(node *parser.MethodDefinition) {
	enclosing := c.current
	c.current = NewCompilerState(FunctionTypeMethod)
	c.current.parent = enclosing
	c.enclosing = enclosing

	c.current.BeginScope()

	if err := c.current.AddLocal("self"); err != nil {
		c.addError(err.Error())
		return
	}
	c.current.MarkInitialized()

	for _, param := range node.Function.Parameters {
		if err := c.current.AddLocal(param.Name); err != nil {
			c.addError(err.Error())
			return
		}
		c.current.MarkInitialized()
	}

	for _, stmt := range node.Function.Body {
		c.compileStatement(stmt)
	}

	c.current.EmitInstruction(OpReturnNil)

	function := Function{
		Name:       node.MethodName,
		Arity:      len(node.Function.Parameters) + 1,
		Variadic:   node.Function.Variadic,
		LocalCount: len(c.current.Locals),
		UpvalCount: len(c.current.Upvalues),
		Chunk:      *c.current.Chunk,
		Defaults:   []Value{},
	}

	functionIndex := len(enclosing.Chunk.Functions)
	enclosing.Chunk.Functions = append(enclosing.Chunk.Functions, function)

	for i := range enclosing.Chunk.Structs {
		if enclosing.Chunk.Structs[i].ID == node.StructID {
			enclosing.Chunk.Structs[i].Methods[node.MethodName] = uint16(functionIndex)
			break
		}
	}

	c.current = enclosing
	c.enclosing = nil
}

func (c *Compiler) compileStructConstructor(node *parser.StructConstructor) {
	c.current.EmitInstruction(OpNewStruct, node.StructID)

	for _, field := range node.Fields {
		if field.Key != nil {
			c.current.EmitInstruction(OpDup)

			var fieldName string
			if ident, ok := field.Key.(*parser.Identifier); ok {
				fieldName = ident.Value
			} else if str, ok := field.Key.(*parser.StringLiteral); ok {
				fieldName = str.Value
			} else {
				c.addError("struct field names must be identifiers or strings")
				continue
			}

			fieldIndex := c.findStructFieldIndex(node.StructID, fieldName)
			if fieldIndex == -1 {
				c.addError(fmt.Sprintf("struct has no field '%s'", fieldName))
				continue
			}

			c.compileExpression(field.Value)
			c.current.EmitInstruction(OpSetProperty, uint16(fieldIndex))
		} else {
			c.addError("struct constructors require named field assignments")
		}
	}
}

func (c *Compiler) compileFunctionLiteral(node *parser.FunctionLiteral) {
	enclosing := c.current
	c.current = NewCompilerState(FunctionTypeFunction)
	c.current.parent = enclosing
	c.enclosing = enclosing

	c.current.BeginScope()

	for _, param := range node.Parameters {
		if err := c.current.AddLocal(param.Name); err != nil {
			c.addError(err.Error())
			return
		}
		c.current.MarkInitialized()
	}

	for _, stmt := range node.Body {
		c.compileStatement(stmt)
	}

	c.current.EmitInstruction(OpReturnNil)

	function := Function{
		Name:       "",
		Arity:      len(node.Parameters),
		Variadic:   node.Variadic,
		LocalCount: len(c.current.Locals),
		UpvalCount: len(c.current.Upvalues),
		Chunk:      *c.current.Chunk,
		Defaults:   []Value{},
	}

	functionIndex := len(enclosing.Chunk.Functions)
	enclosing.Chunk.Functions = append(enclosing.Chunk.Functions, function)

	c.current = enclosing
	c.enclosing = nil

	c.current.EmitInstruction(OpClosure, uint16(functionIndex), uint16(function.UpvalCount))
}

// Control flow compilation
func (c *Compiler) compileIfStatement(node *parser.IfStatement) {
	c.compileExpression(node.Condition)

	thenJump := c.current.EmitJump(OpJumpIfFalse)
	c.current.EmitInstruction(OpPop)

	c.current.BeginScope()
	for _, stmt := range node.Body {
		c.compileStatement(stmt)
	}
	c.current.EndScope()

	elseJump := c.current.EmitJump(OpJump)
	c.current.PatchJump(thenJump)
	c.current.EmitInstruction(OpPop)

	var elseifJumps []int
	for _, elseif := range node.ElseIfs {
		c.compileExpression(elseif.Condition)
		nextJump := c.current.EmitJump(OpJumpIfFalse)
		c.current.EmitInstruction(OpPop)

		c.current.BeginScope()
		for _, stmt := range elseif.Body {
			c.compileStatement(stmt)
		}
		c.current.EndScope()

		elseifJumps = append(elseifJumps, c.current.EmitJump(OpJump))
		c.current.PatchJump(nextJump)
		c.current.EmitInstruction(OpPop)
	}

	if len(node.Else) > 0 {
		c.current.BeginScope()
		for _, stmt := range node.Else {
			c.compileStatement(stmt)
		}
		c.current.EndScope()
	}

	c.current.PatchJump(elseJump)
	for _, jump := range elseifJumps {
		c.current.PatchJump(jump)
	}
}

func (c *Compiler) compileWhileStatement(node *parser.WhileStatement) {
	c.current.EnterLoop()

	c.compileExpression(node.Condition)
	exitJump := c.current.EmitJump(OpJumpIfFalse)
	c.current.EmitInstruction(OpPop)

	c.current.BeginScope()
	for _, stmt := range node.Body {
		c.compileStatement(stmt)
	}
	c.current.EndScope()

	jump := len(c.current.Chunk.Code) - c.current.LoopStart + 2
	c.current.EmitInstruction(OpLoopBack, uint16(jump))

	c.current.PatchJump(exitJump)
	c.current.EmitInstruction(OpPop)

	c.current.ExitLoop()
}

func (c *Compiler) compileForStatement(node *parser.ForStatement) {
	c.current.BeginScope()
	c.current.EnterLoop()

	c.compileExpression(node.Start)
	if err := c.current.AddLocal(node.Variable.Value); err != nil {
		c.addError(err.Error())
		return
	}
	c.current.MarkInitialized()
	loopVar := len(c.current.Locals) - 1

	c.compileExpression(node.End)
	endSlot := len(c.current.Locals)
	if err := c.current.AddLocal("__end"); err != nil {
		c.addError(err.Error())
		return
	}
	c.current.MarkInitialized()

	if node.Step != nil {
		c.compileExpression(node.Step)
	} else {
		c.current.EmitInstruction(OpLoadOne)
	}
	stepSlot := len(c.current.Locals)
	if err := c.current.AddLocal("__step"); err != nil {
		c.addError(err.Error())
		return
	}
	c.current.MarkInitialized()

	conditionStart := len(c.current.Chunk.Code)
	c.emitLoadLocal(loopVar)
	c.emitLoadLocal(endSlot)
	c.current.EmitInstruction(OpLte)
	exitJump := c.current.EmitJump(OpJumpIfFalse)
	c.current.EmitInstruction(OpPop)

	for _, stmt := range node.Body {
		c.compileStatement(stmt)
	}

	c.emitLoadLocal(loopVar)
	c.emitLoadLocal(stepSlot)
	c.current.EmitInstruction(OpAdd)
	c.emitStoreLocal(loopVar)

	jumpBack := len(c.current.Chunk.Code) - conditionStart + 2
	c.current.EmitInstruction(OpLoopBack, uint16(jumpBack))

	c.current.PatchJump(exitJump)
	c.current.EmitInstruction(OpPop)

	c.current.ExitLoop()
	c.current.EndScope()
}

func (c *Compiler) compileForInStatement(node *parser.ForInStatement) {
	c.current.BeginScope()
	c.current.EnterLoop()

	c.compileExpression(node.Iterable)

	if node.Key != nil {
		if err := c.current.AddLocal(node.Key.Value); err != nil {
			c.addError(err.Error())
			return
		}
		c.current.MarkInitialized()
	}

	if err := c.current.AddLocal(node.Value.Value); err != nil {
		c.addError(err.Error())
		return
	}
	c.current.MarkInitialized()

	conditionStart := len(c.current.Chunk.Code)

	c.current.EmitInstruction(OpLoadNil)
	c.current.EmitInstruction(OpNot)

	exitJump := c.current.EmitJump(OpJumpIfFalse)
	c.current.EmitInstruction(OpPop)

	for _, stmt := range node.Body {
		c.compileStatement(stmt)
	}

	jumpBack := len(c.current.Chunk.Code) - conditionStart + 2
	c.current.EmitInstruction(OpLoopBack, uint16(jumpBack))

	c.current.PatchJump(exitJump)
	c.current.EmitInstruction(OpPop)

	c.current.ExitLoop()
	c.current.EndScope()
}

func (c *Compiler) compileReturnStatement(node *parser.ReturnStatement) {
	if node.Value != nil {
		c.compileExpression(node.Value)
		c.current.EmitInstruction(OpReturn)
	} else {
		c.current.EmitInstruction(OpReturnNil)
	}
}

func (c *Compiler) compileExitStatement(node *parser.ExitStatement) {
	if node.Value != nil {
		c.compileExpression(node.Value)
	} else {
		c.current.EmitInstruction(OpLoadZero)
	}
	c.current.EmitInstruction(OpExit)
}

// Optimization
func (c *Compiler) optimizeChunk(chunk *Chunk) {
	c.peepholeOptimize(chunk)
	c.eliminateDeadCode(chunk)
}

func (c *Compiler) peepholeOptimize(chunk *Chunk) {
	code := chunk.Code
	changed := true

	for changed {
		changed = false
		i := 0

		for i < len(code)-6 {
			op1, _, next1 := DecodeInstruction(code, i)

			if next1 < len(code) {
				op2, _, next2 := DecodeInstruction(code, next1)

				if op1 == OpLoadConst && op2 == OpPop {
					c.removeInstructions(chunk, i, next2)
					changed = true
					continue
				}

				if op1 == OpLoadZero && op2 == OpAdd {
					code[i] = uint8(OpNoop)
					code[next1] = uint8(OpNoop)
					changed = true
				}

				if op1 == OpNeg && op2 == OpNeg {
					code[i] = uint8(OpNoop)
					code[next1] = uint8(OpNoop)
					changed = true
				}

				if (op1 == OpLoadTrue || op1 == OpLoadFalse) && op2 == OpNot {
					if op1 == OpLoadTrue {
						code[i] = uint8(OpLoadFalse)
					} else {
						code[i] = uint8(OpLoadTrue)
					}
					code[next1] = uint8(OpNoop)
					changed = true
				}
			}

			i = next1
		}
	}
}

func (c *Compiler) removeInstructions(chunk *Chunk, start, end int) {
	for i := start; i < end && i < len(chunk.Code); i++ {
		chunk.Code[i] = uint8(OpNoop)
	}
}

func (c *Compiler) eliminateDeadCode(chunk *Chunk) {
	code := chunk.Code
	i := 0

	for i < len(code) {
		op, _, next := DecodeInstruction(code, i)

		if op == OpReturn || op == OpReturnNil || op == OpExit {
			for j := next; j < len(code); j++ {
				nextOp, _, nextNext := DecodeInstruction(code, j)
				if c.isJumpTarget(chunk, j) {
					break
				}
				if nextOp == OpNoop {
					j = nextNext - 1
					continue
				}
				code[j] = uint8(OpNoop)
				j = nextNext - 1
			}
		}

		i = next
	}
}

func (c *Compiler) isJumpTarget(chunk *Chunk, offset int) bool {
	return false
}

// Helper methods
func (c *Compiler) resolveUpvalue(name string) int {
	if c.enclosing == nil {
		return -1
	}

	local := c.enclosing.ResolveLocal(name)
	if local != -1 {
		c.enclosing.Locals[local].IsCaptured = true
		return c.current.AddUpvalue(uint8(local), true)
	}

	upvalue := c.resolveUpvalueInEnclosing(name)
	if upvalue != -1 {
		return c.current.AddUpvalue(uint8(upvalue), false)
	}

	return -1
}

func (c *Compiler) resolveUpvalueInEnclosing(name string) int {
	if c.enclosing == nil {
		return -1
	}
	return -1
}

func (c *Compiler) typeInfoToValueType(typeInfo parser.TypeInfo) ValueType {
	switch typeInfo.Type {
	case parser.TypeNumber:
		return ValueNumber
	case parser.TypeString:
		return ValueString
	case parser.TypeBool:
		return ValueBool
	case parser.TypeNil:
		return ValueNil
	case parser.TypeTable:
		return ValueTable
	case parser.TypeFunction:
		return ValueFunction
	case parser.TypeStruct:
		return ValueStruct
	default:
		return ValueNil
	}
}

func (c *Compiler) findStructFieldIndex(structID uint16, fieldName string) int {
	for _, structDef := range c.current.Chunk.Structs {
		if structDef.ID == structID {
			for i, field := range structDef.Fields {
				if field.Name == fieldName {
					return i
				}
			}
			break
		}
	}
	return -1
}

func (c *Compiler) addError(message string) {
	c.errors = append(c.errors, CompileError{
		Message: message,
		Line:    c.current.CurrentLine,
		Column:  0,
	})
}

func (c *Compiler) getLineFromNode(node any) int {
	return 0 // Placeholder - would extract from AST node
}

func (c *Compiler) Errors() []CompileError { return c.errors }
func (c *Compiler) HasErrors() bool        { return len(c.errors) > 0 }