// Copyright (c) 2026 Charles KWON OhJun (charleskwonohjun@gmail.com)
// All rights reserved.

// Recursive descent parser for the Five language (Harbour-compatible).
//
// Design references:
//   - Harbour: harbour.y (Bison grammar, /mnt/d/harbour-core/src/compiler/harbour.y)
//     Key: operator precedence is mostly right-associative, = is both assign and compare
//   - tsgo: internal/parser/ — recursive descent with precedence climbing
//   - Pratt parser for expression parsing (precedence climbing)
//
// Harbour-specific rules enforced:
//   - LOCAL/STATIC/FIELD declarations must be at function top (before executable code)
//   - ? and ?? are QOut/QQOut shorthand
//   - (expr)->field is dynamic alias access
//   - &variable is macro expansion
package parser

import (
	"five/compiler/ast"
	"five/compiler/lexer"
	"five/compiler/token"
	"fmt"
	"strings"
)

// Parser parses Five/Harbour source into an AST.
type Parser struct {
	tokens  []token.Token
	pos     int
	current token.Token
	errors  []Error
	file    string
	GoDumps []string // inline Go code blocks from PP
}

// Error represents a parse error with position.
type Error struct {
	Pos     token.Position
	Message string
}

func (e Error) Error() string {
	return fmt.Sprintf("%s: %s", e.Pos, e.Message)
}

// Parse parses a source file and returns the AST.
func Parse(filename, source string) (*ast.File, []Error) {
	return ParseWithGoDumps(filename, source, nil)
}

// ParseWithGoDumps parses with inline Go code blocks from PP.
func ParseWithGoDumps(filename, source string, goDumps []string) (*ast.File, []Error) {
	tokens := lexer.Tokenize(filename, source)
	p := &Parser{
		tokens:  tokens,
		pos:     0,
		file:    filename,
		GoDumps: goDumps,
	}
	if len(tokens) > 0 {
		p.current = tokens[0]
	}

	file := p.parseFile()
	return file, p.errors
}

// --- Token navigation ---

func (p *Parser) peek() token.Kind {
	return p.current.Kind
}

// currentUpper returns the uppercased literal of the current token.
// Uses strings.EqualFold for comparisons where possible to avoid allocation.
func (p *Parser) currentUpper() string {
	return strings.ToUpper(p.current.Literal)
}

// peekAt returns the token kind at offset from current position.
// peekAt(0) = current, peekAt(1) = next, etc. Returns EOF if out of range.
func (p *Parser) peekAt(offset int) token.Kind {
	idx := p.pos + offset
	if idx >= 0 && idx < len(p.tokens) {
		return p.tokens[idx].Kind
	}
	return token.EOF
}

// peekLitAt returns the token literal at offset from current position.
func (p *Parser) peekLitAt(offset int) string {
	idx := p.pos + offset
	if idx >= 0 && idx < len(p.tokens) {
		return p.tokens[idx].Literal
	}
	return ""
}

// peekTokenAt returns the full token at offset. Safe for out-of-range.
func (p *Parser) peekTokenAt(offset int) token.Token {
	idx := p.pos + offset
	if idx >= 0 && idx < len(p.tokens) {
		return p.tokens[idx]
	}
	return token.Token{Kind: token.EOF}
}

func (p *Parser) advance() token.Token {
	tok := p.current
	p.pos++
	if p.pos < len(p.tokens) {
		p.current = p.tokens[p.pos]
	} else {
		p.current = token.Token{Kind: token.EOF}
	}
	return tok
}

func (p *Parser) match(kind token.Kind) bool {
	if p.current.Kind == kind {
		p.advance()
		return true
	}
	return false
}

func (p *Parser) expect(kind token.Kind) token.Token {
	if p.current.Kind == kind {
		return p.advance()
	}
	p.error(fmt.Sprintf("expected %v, got %v %q", kind, p.current.Kind, p.current.Literal))
	// Error recovery: return a synthetic token and try to continue
	return token.Token{Kind: kind, Pos: p.current.Pos}
}

func (p *Parser) at(kind token.Kind) bool {
	return p.current.Kind == kind
}

func (p *Parser) atAny(kinds ...token.Kind) bool {
	for _, k := range kinds {
		if p.current.Kind == k {
			return true
		}
	}
	return false
}

// --- Error handling & recovery ---

func (p *Parser) error(msg string) {
	// Avoid duplicate errors at same position
	if len(p.errors) > 0 {
		last := p.errors[len(p.errors)-1]
		if last.Pos == p.current.Pos {
			return
		}
	}
	p.errors = append(p.errors, Error{
		Pos:     p.current.Pos,
		Message: msg,
	})
}

// syncStmt skips tokens until a statement boundary is found.
// Called after errors to prevent cascading parse failures.
func (p *Parser) syncStmt() {
	for p.current.Kind != token.EOF {
		// Newline = statement boundary in Harbour
		if p.current.Kind == token.NEWLINE {
			p.advance()
			return
		}
		// Statement-starting keywords = safe to resume
		switch p.current.Kind {
		case token.FUNCTION_KW, token.PROCEDURE, token.CLASS, token.METHOD,
			token.LOCAL, token.STATIC, token.PRIVATE, token.PUBLIC,
			token.IF, token.FOR, token.DO, token.WHILE, token.SWITCH,
			token.BEGIN, token.RETURN, token.QMARK, token.QQMARK:
			return
		}
		p.advance()
	}
}

// skipNewlines consumes consecutive NEWLINE tokens.
func (p *Parser) skipNewlines() {
	for p.current.Kind == token.NEWLINE {
		p.advance()
	}
}

// expectEndOfStmt expects a NEWLINE or EOF (statement terminator).
func (p *Parser) expectEndOfStmt() {
	if p.current.Kind == token.NEWLINE {
		p.advance()
		return
	}
	if p.current.Kind == token.EOF {
		return
	}
	// Don't error for some keywords that start new statements
	// (Harbour allows missing newline before certain keywords)
}

// --- File parsing ---

func (p *Parser) parseFile() *ast.File {
	file := &ast.File{Name: p.file}
	p.skipNewlines()

	for p.current.Kind != token.EOF {
		switch p.current.Kind {
		case token.FUNCTION_KW, token.PROCEDURE:
			file.Decls = append(file.Decls, p.parseFuncDecl())
		case token.EXIT:
			// EXIT PROCEDURE/FUNCTION at top level
			p.advance()
			if p.current.Kind == token.PROCEDURE || p.current.Kind == token.FUNCTION_KW {
				file.Decls = append(file.Decls, p.parseFuncDecl())
			} else {
				p.skipToEndOfLine()
			}
		case token.CLASS:
			file.Decls = append(file.Decls, p.parseClassDecl())
		case token.METHOD:
			file.Decls = append(file.Decls, p.parseMethodDecl())
		case token.STATIC:
			// STATIC FUNCTION/PROCEDURE → function declaration with static scope
			if p.peekAt(1) == token.FUNCTION_KW || p.peekAt(1) == token.PROCEDURE {
				p.advance() // skip STATIC
				file.Decls = append(file.Decls, p.parseFuncDecl())
			} else {
				// Top-level STATIC declaration (module-level variable)
				file.Decls = append(file.Decls, p.parseVarDecl())
			}
		case token.IDENT:
			upper := p.currentUpper()
			if upper == "THREAD" && p.peekAt(1) == token.STATIC {
				// THREAD STATIC → treat as STATIC
				p.advance() // skip THREAD
				file.Decls = append(file.Decls, p.parseVarDecl())
			} else if upper == "CREATE" && p.peekAt(1) == token.CLASS {
				// CREATE CLASS → treat as CLASS
				p.advance() // skip CREATE
				file.Decls = append(file.Decls, p.parseClassDecl())
			} else if upper == "EXTERNAL" || upper == "EXTERN" || upper == "REQUEST" || upper == "ANNOUNCE" || upper == "DYNAMIC" || upper == "DECLARE" {
				p.skipToEndOfLine()
			} else if upper == "INIT" || upper == "EXIT" {
				// INIT PROCEDURE/FUNCTION or EXIT PROCEDURE/FUNCTION
				p.advance() // skip INIT/EXIT
				if p.current.Kind == token.PROCEDURE || p.current.Kind == token.FUNCTION_KW {
					file.Decls = append(file.Decls, p.parseFuncDecl())
				} else {
					p.skipToEndOfLine()
				}
			} else if upper == "SET" {
				// Top-level SET commands (SET PROCEDURE TO, etc.)
				p.skipToEndOfLine()
			} else if upper == "FIVE_GODUMP__" {
				// Inline Go code block from #pragma BEGINDUMP
				file.Decls = append(file.Decls, p.parseGoDump())
			} else {
				// Unknown IDENT at top level — PP residual or bare expression, skip
				p.skipToEndOfLine()
			}
		case token.MEMVAR, token.DECLARE:
			// File-level MEMVAR/DECLARE declaration — skip
			p.skipToEndOfLine()
		case token.IMPORT:
			file.Imports = append(file.Imports, p.parseImport())
		case token.PP_INCLUDE, token.PP_DEFINE, token.PP_IFDEF, token.PP_IFNDEF,
			token.PP_ELSE, token.PP_ENDIF, token.PP_PRAGMA, token.PP_UNDEF,
			token.PP_COMMAND, token.PP_TRANSLATE:
			p.skipToEndOfLine() // skip preprocessor for now
		default:
			// Bare expression or PP residual at top level — skip to EOL
			// This handles: PP #command residuals, bare function calls, etc.
			p.skipToEndOfLine()
		}
		p.skipNewlines()
	}

	return file
}

func (p *Parser) skipToEndOfLine() {
	for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		p.advance()
	}
	if p.current.Kind == token.NEWLINE {
		p.advance()
	}
}

// consumeFileExtension handles filename.ext (e.g. test.dbf, test.idx)
// where the dot+extension was parsed as separate tokens after parseExpr.
func (p *Parser) consumeFileExtension(fileExpr ast.Expr) {
	for p.current.Kind == token.DOT &&
		(p.peekAt(1) == token.IDENT || p.peekAt(1) == token.INT) {
		p.advance() // skip .
		ext := p.advance() // skip extension
		if ident, ok := fileExpr.(*ast.IdentExpr); ok {
			ident.Name = ident.Name + "." + ext.Literal
		}
	}
}

// parseGoDump parses FIVE_GODUMP__ <index> marker from PP.
func (p *Parser) parseGoDump() *ast.GoDumpDecl {
	pos := p.advance().Pos // consume FIVE_GODUMP__
	idx := 0
	if p.current.Kind == token.INT {
		fmt.Sscanf(p.current.Literal, "%d", &idx)
		p.advance()
	}
	p.expectEndOfStmt()
	code := ""
	if idx >= 0 && idx < len(p.GoDumps) {
		code = p.GoDumps[idx]
	}
	return &ast.GoDumpDecl{DumpPos: pos, Code: code}
}

// --- IMPORT ---

func (p *Parser) parseImport() *ast.ImportDecl {
	pos := p.expect(token.IMPORT).Pos
	alias := ""
	// IMPORT _ "pkg" — blank import
	// IMPORT alias "pkg" — aliased import
	if p.current.Kind == token.IDENT && p.peekAt(1) == token.STRING {
		alias = p.advance().Literal
	}
	pathTok := p.expect(token.STRING)
	p.expectEndOfStmt()
	return &ast.ImportDecl{ImportPos: pos, Alias: alias, Path: pathTok.Literal}
}

// --- FUNCTION / PROCEDURE ---

func (p *Parser) parseFuncDecl() *ast.FuncDecl {
	tok := p.advance() // FUNCTION or PROCEDURE
	isProc := tok.Kind == token.PROCEDURE

	// Allow keywords as function names (GOTO, END, etc.)
	nameTok := p.expectMethodName()

	// Parameters
	var params []*ast.ParamDecl
	if p.match(token.LPAREN) {
		params = p.parseParamList()
		p.expect(token.RPAREN)
	}

	// Skip CLASS className qualifier (PROCEDURE name CLASS className)
	if p.current.Kind == token.CLASS {
		p.advance() // skip CLASS
		p.expectMethodName() // skip className
	}
	p.expectEndOfStmt()

	// Declarations (LOCAL, STATIC, FIELD — must come first)
	var decls []ast.Decl
	p.skipNewlines()
	for p.atAny(token.LOCAL, token.STATIC, token.FIELD, token.MEMVAR, token.PARAMETERS) {
		decls = append(decls, p.parseVarDecl())
		p.skipNewlines()
	}

	// Body (executable statements until RETURN or end)
	body := p.parseStmtBlock(token.RETURN, token.FUNCTION_KW, token.PROCEDURE, token.CLASS, token.METHOD, token.EOF)

	// Consume RETURN if present
	var endPos token.Position
	if p.current.Kind == token.RETURN {
		retStmt := p.parseReturn()
		body = append(body, retStmt)
		endPos = retStmt.Pos()
	} else {
		endPos = p.current.Pos
	}

	return &ast.FuncDecl{
		FuncPos: tok.Pos,
		Name:    nameTok.Literal,
		IsProc:  isProc,
		Params:  params,
		Decls:   decls,
		Body:    body,
		EndPos:  endPos,
	}
}

func (p *Parser) parseParamList() []*ast.ParamDecl {
	var params []*ast.ParamDecl
	if p.at(token.RPAREN) {
		return params
	}
	// Variadic: FUNCTION Foo(...) — skip dots, use PCount() at runtime
	if p.at(token.DOT) {
		for p.at(token.DOT) {
			p.advance()
		}
		return params
	}
	for {
		byRef := p.match(token.AT)
		// Handle trailing ... after named params: FUNCTION Foo(a, b, ...)
		if p.at(token.DOT) {
			for p.at(token.DOT) {
				p.advance()
			}
			break
		}
		name := p.expectMethodName() // allow keywords as param names (e.g. data, type)
		var asType string
		if p.match(token.AS) {
			asType = p.expectMethodName().Literal
		}
		params = append(params, &ast.ParamDecl{
			NamePos: name.Pos,
			Name:    name.Literal,
			ByRef:   byRef,
			AsType:  asType,
		})
		if !p.match(token.COMMA) {
			break
		}
	}
	return params
}

// --- Variable declarations ---

func (p *Parser) parseVarDecl() *ast.VarDecl {
	tok := p.advance() // LOCAL, STATIC, FIELD, MEMVAR
	var scope ast.VarScope
	switch tok.Kind {
	case token.LOCAL:
		scope = ast.ScopeLocal
	case token.STATIC:
		scope = ast.ScopeStatic
	case token.FIELD:
		scope = ast.ScopeField
	case token.MEMVAR:
		// MEMVAR declares field aliases, treated like FIELD
		scope = ast.ScopeField
	default:
		scope = ast.ScopeLocal
	}

	var vars []*ast.VarInit
	for {
		// Allow keywords as variable names (data, field, etc.)
		name := p.expectMethodName()
		var init ast.Expr
		var asType string

		// LOCAL a[10] or LOCAL a[5,3] — array declaration
		if p.at(token.LBRACKET) {
			p.advance() // skip [
			sizeExpr := p.parseExpr()
			// Multi-dim: a[5,3]
			for p.match(token.COMMA) {
				p.parseExpr() // consume additional dimensions (simplified)
			}
			p.expect(token.RBRACKET)
			// Generate init as Array(size)
			init = &ast.CallExpr{
				Func: &ast.IdentExpr{Name: "Array"},
				Args: []ast.Expr{sizeExpr},
			}
		}
		// AS type (may come before or after :=)
		if p.match(token.AS) {
			// Skip type: AS STRING, AS NUMERIC, AS CLASS ClassName, AS ARRAY OF type
			for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF &&
				p.current.Kind != token.ASSIGN && p.current.Kind != token.COMMA {
				p.advance()
			}
		}
		if p.match(token.ASSIGN) { // :=
			init = p.parseExpr()
		}
		// AS type after := (alternative order)
		if p.match(token.AS) {
			asType = p.expectMethodName().Literal
			// Skip complex AS: AS CLASS ClassName, AS ARRAY OF...
			for p.current.Kind == token.IDENT {
				upper := p.currentUpper()
				if upper == "OF" || upper == "CLASS" {
					p.advance()
					if p.current.Kind == token.IDENT || p.current.Literal != "" {
						p.advance()
					}
				} else {
					break
				}
			}
		}

		vars = append(vars, &ast.VarInit{
			NamePos: name.Pos,
			Name:    name.Literal,
			Init:    init,
			AsType:  asType,
		})

		if !p.match(token.COMMA) {
			break
		}
	}

	p.expectEndOfStmt()
	return &ast.VarDecl{DeclPos: tok.Pos, Scope: scope, Vars: vars}
}

// --- CLASS ---

func (p *Parser) parseClassDecl() *ast.ClassDecl {
	classPos := p.expect(token.CLASS).Pos
	name := p.expect(token.IDENT).Literal

	var parent string
	if p.match(token.INHERIT) {
		p.match(token.FROM) // optional FROM
		parent = p.expectMethodName().Literal
	}
	// Alternative: FROM without INHERIT
	if parent == "" && p.match(token.FROM) {
		parent = p.expectMethodName().Literal
	}
	// Multiple inheritance: FROM class1, class2, class3 — skip extra parents
	for p.match(token.COMMA) {
		p.expectMethodName() // skip additional parent class name
	}
	p.expectEndOfStmt()

	var members []ast.Decl
	p.skipNewlines()
	for !p.atAny(token.ENDCLASS, token.END, token.EOF) {
		switch p.current.Kind {
		case token.DATA:
			members = append(members, p.parseDataDecl())
		case token.METHOD:
			members = append(members, p.parseClassMethodDecl())
		case token.ACCESS:
			members = append(members, p.parseAccessDecl())
		case token.ASSIGN_KW:
			members = append(members, p.parseAssignDecl())
		case token.CLASS:
			// CLASS VAR / CLASS METHOD / CLASS DATA inside class body
			p.advance() // skip CLASS
			if p.current.Kind == token.DATA {
				members = append(members, p.parseDataDecl())
			} else if p.current.Kind == token.METHOD {
				members = append(members, p.parseClassMethodDecl())
			} else if p.current.Kind == token.IDENT && p.currentUpper() == "VAR" {
				p.tokens[p.pos].Kind = token.DATA
				p.current = p.tokens[p.pos]
				members = append(members, p.parseDataDecl())
			} else {
				p.skipToEndOfLine()
			}
		case token.INLINE_KW, token.ON, token.DESTRUCTOR, token.OPERATOR_KW:
			// Stray INLINE, ON ERROR, DESTRUCTOR, OPERATOR — skip to EOL
			p.skipToEndOfLine()
			p.skipNewlines()
			continue
		case token.IDENT:
			upper := p.currentUpper()
			// FRIEND FUNCTION/CLASS — skip declaration
			if upper == "FRIEND" {
				p.advance() // skip FRIEND
				p.skipToEndOfLine()
				p.skipNewlines()
				continue
			}
			// VAR = DATA synonym
			if upper == "VAR" {
				// Rewrite as DATA token
				p.tokens[p.pos].Kind = token.DATA
				p.current = p.tokens[p.pos]
				members = append(members, p.parseDataDecl())
			} else if (upper == "PROTECTED" || upper == "EXPORTED" || upper == "HIDDEN" ||
				upper == "VISIBLE" || upper == "EXPORT" || upper == "SYNC") &&
				p.peekAt(1) == token.COLON {
				// Scope qualifier — skip it (Five doesn't enforce visibility)
				p.advance() // skip keyword
				p.advance() // skip :
				p.skipNewlines()
			} else if upper == "CLASS" {
				// CLASS VAR — class-level variable
				p.advance() // skip CLASS
				if p.current.Kind == token.IDENT && p.currentUpper() == "VAR" {
					p.tokens[p.pos].Kind = token.DATA
					p.current = p.tokens[p.pos]
					members = append(members, p.parseDataDecl())
				} else if p.current.Kind == token.DATA {
					members = append(members, p.parseDataDecl())
				} else if p.current.Kind == token.METHOD {
					members = append(members, p.parseClassMethodDecl())
				} else {
					p.skipToEndOfLine()
				}
			} else if upper == "ON" || upper == "OPERATOR" || upper == "DESTRUCTOR" ||
				upper == "DELEGATE" || upper == "ERROR" || upper == "MESSAGE" ||
				upper == "VIRTUAL" || upper == "DEFERRED" {
				// ON ERROR, OPERATOR "+" ARG, DESTRUCTOR, DELEGATE — skip to EOL
				p.skipToEndOfLine()
				p.skipNewlines()
				continue
			} else {
				p.error(fmt.Sprintf("unexpected in CLASS body: %v %q", p.current.Kind, p.current.Literal))
				p.advance()
			}
		default:
			p.error(fmt.Sprintf("unexpected in CLASS body: %v", p.current.Kind))
			p.advance()
		}
		p.skipNewlines()
	}

	endPos := p.current.Pos
	if p.match(token.ENDCLASS) {
		// ok
	} else if p.match(token.END) {
		// END CLASS — skip optional CLASS keyword
		p.match(token.CLASS)
	}
	p.expectEndOfStmt()

	return &ast.ClassDecl{
		ClassPos:   classPos,
		Name:       name,
		ParentName: parent,
		Members:    members,
		EndPos:     endPos,
	}
}

func (p *Parser) parseDataDecl() *ast.DataDecl {
	dataPos := p.expect(token.DATA).Pos
	name := p.expectMethodName().Literal // allow keywords as data names

	var init ast.Expr
	var asType string

	// Parse AS, INIT, commas, and qualifiers in any order
	for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		if p.match(token.AS) {
			if p.current.Kind == token.IDENT || p.current.Literal != "" {
				p.advance() // type name
			}
			continue
		}
		if p.match(token.COMMA) {
			// VAR One, Two, Three — skip additional names
			if p.current.Kind == token.IDENT || p.current.Literal != "" {
				p.advance() // skip additional name
			}
			continue
		}
		if p.current.Kind == token.IDENT {
			upper := p.currentUpper()
			if upper == "INIT" {
				p.advance()
				init = p.parseExpr()
				continue
			}
			// Skip visibility/attribute qualifiers
			if upper == "READONLY" || upper == "EXPORTED" || upper == "PROTECTED" ||
				upper == "HIDDEN" || upper == "SYNC" || upper == "USUAL" ||
				upper == "PROPERTY" || upper == "PERSISTENT" || upper == "SHARED" {
				p.advance()
				continue
			}
		}
		if p.current.Kind == token.INLINE_KW {
			p.skipToEndOfLine()
			break
		}
		break
	}
	p.expectEndOfStmt()

	return &ast.DataDecl{DataPos: dataPos, Name: name, Init: init, AsType: asType}
}

// expectMethodName: method names can be keywords (end, home, left, right, etc.)
func (p *Parser) expectMethodName() token.Token {
	if p.current.Kind == token.IDENT {
		return p.advance()
	}
	// Allow keywords as method names
	if p.current.Literal != "" {
		return p.advance()
	}
	return p.expect(token.IDENT)
}

func (p *Parser) parseClassMethodDecl() *ast.MethodDecl {
	methodPos := p.expect(token.METHOD).Pos

	// Skip optional FUNCTION/PROCEDURE qualifier
	if p.current.Kind == token.FUNCTION_KW || p.current.Kind == token.PROCEDURE {
		p.advance()
	}

	name := p.expectMethodName().Literal

	var params []*ast.ParamDecl
	if p.match(token.LPAREN) {
		params = p.parseParamList()
		p.expect(token.RPAREN)
	}

	// Check for SETGET keyword
	isSetGet := false
	if p.current.Kind == token.IDENT && p.currentUpper() == "SETGET" {
		p.advance()
		isSetGet = true
	}

	// Skip trailing qualifiers: OPERATOR, VIRTUAL, CONSTRUCTOR, etc.
	if p.current.Kind == token.IDENT {
		upper := p.currentUpper()
		if upper == "OPERATOR" || upper == "VIRTUAL" || upper == "DEFERRED" {
			p.skipToEndOfLine()
		}
	}
	if p.current.Kind == token.OPERATOR_KW || p.current.Kind == token.CONSTRUCTOR {
		p.skipToEndOfLine()
	}

	// Skip INLINE + rest of line (METHOD ... INLINE expr)
	p.skipClassInline()

	p.expectEndOfStmt()

	return &ast.MethodDecl{
		MethodPos: methodPos,
		Name:      name,
		Params:    params,
		IsSetGet:  isSetGet,
		EndPos:    methodPos,
	}
}

// skipClassInline skips INLINE keyword and the rest of the line (used in CLASS body)
func (p *Parser) skipClassInline() {
	if p.current.Kind == token.INLINE_KW ||
		(p.current.Kind == token.IDENT && p.currentUpper() == "INLINE") {
		p.skipToEndOfLine()
	}
}

// ACCESS name METHOD getterName
func (p *Parser) parseAccessDecl() *ast.MethodDecl {
	pos := p.expect(token.ACCESS).Pos
	propName := p.expectMethodName().Literal

	// Skip optional (params)
	if p.match(token.LPAREN) {
		for !p.atAny(token.RPAREN, token.EOF) {
			p.advance()
		}
		p.match(token.RPAREN)
	}

	methodName := propName
	if p.match(token.METHOD) {
		methodName = p.expectMethodName().Literal
		if p.match(token.LPAREN) {
			for !p.atAny(token.RPAREN, token.EOF) {
				p.advance()
			}
			p.match(token.RPAREN)
		}
	}
	// Skip INLINE + rest of line
	p.skipClassInline()
	p.expectEndOfStmt()

	return &ast.MethodDecl{
		MethodPos:  pos,
		Name:       methodName,
		IsAccess:   true,
		AccessName: propName,
		EndPos:     pos,
	}
}

// ASSIGN name METHOD setterName
func (p *Parser) parseAssignDecl() *ast.MethodDecl {
	pos := p.expect(token.ASSIGN_KW).Pos
	propName := p.expectMethodName().Literal

	// Skip optional (params)
	if p.match(token.LPAREN) {
		for !p.atAny(token.RPAREN, token.EOF) {
			p.advance()
		}
		p.match(token.RPAREN)
	}

	methodName := "_" + propName
	if p.match(token.METHOD) {
		methodName = p.expectMethodName().Literal
		if p.match(token.LPAREN) {
			for !p.atAny(token.RPAREN, token.EOF) {
				p.advance()
			}
			p.match(token.RPAREN)
		}
	}
	// Skip INLINE + rest of line
	p.skipClassInline()
	p.expectEndOfStmt()

	return &ast.MethodDecl{
		MethodPos:  pos,
		Name:       methodName,
		IsAssign:   true,
		AccessName: propName,
		EndPos:     pos,
	}
}

// parseMethodDecl parses standalone: METHOD [FUNCTION|PROCEDURE] name(...) CLASS classname
func (p *Parser) parseMethodDecl() *ast.MethodDecl {
	methodPos := p.expect(token.METHOD).Pos

	// Skip optional FUNCTION/PROCEDURE qualifier
	if p.current.Kind == token.FUNCTION_KW || p.current.Kind == token.PROCEDURE {
		p.advance()
	}

	name := p.expectMethodName().Literal

	var params []*ast.ParamDecl
	if p.match(token.LPAREN) {
		params = p.parseParamList()
		p.expect(token.RPAREN)
	}

	var className string
	if p.match(token.CLASS) {
		className = p.expect(token.IDENT).Literal
	}
	p.expectEndOfStmt()

	// Declarations
	var decls []ast.Decl
	p.skipNewlines()
	for p.atAny(token.LOCAL, token.STATIC) {
		decls = append(decls, p.parseVarDecl())
		p.skipNewlines()
	}

	// Body
	body := p.parseStmtBlock(token.RETURN, token.FUNCTION_KW, token.PROCEDURE, token.CLASS, token.METHOD, token.EOF)

	var endPos token.Position
	if p.current.Kind == token.RETURN {
		retStmt := p.parseReturn()
		body = append(body, retStmt)
		endPos = retStmt.Pos()
	} else {
		endPos = p.current.Pos
	}

	return &ast.MethodDecl{
		MethodPos: methodPos,
		Name:      name,
		ClassName: className,
		Params:    params,
		Decls:     decls,
		Body:      body,
		EndPos:    endPos,
	}
}

// --- Statement parsing ---

// parseStmtBlock parses statements until one of the stop tokens.
func (p *Parser) parseStmtBlock(stopTokens ...token.Kind) []ast.Stmt {
	var stmts []ast.Stmt
	for {
		p.skipNewlines()
		if p.current.Kind == token.EOF {
			break
		}
		for _, stop := range stopTokens {
			if p.current.Kind == stop {
				// Don't stop at RETURN if it's used as variable: return := ...
				if stop == token.RETURN &&
					p.peekAt(1) == token.ASSIGN {
					break // continue parsing as statement
				}
				return stmts
			}
		}
		stmt := p.parseStmt()
		if stmt != nil {
			stmts = append(stmts, stmt)
		}
	}
	return stmts
}

func (p *Parser) parseStmt() ast.Stmt {
	// Registry lookup — O(1) dispatch
	if fn := p.lookupStmtParser(); fn != nil {
		return fn(p)
	}

	// IDENT-based commands (xBase multi-word: COPY, SORT, etc.)
	if p.current.Kind == token.IDENT {
		return p.parseIdentStmt()
	}

	// Multi-assign: a, b := expr
	if p.looksLikeMultiAssign() {
		return p.parseMultiAssign()
	}

	// Default: expression statement
	return p.parseExprStmt()
}


// parseIdentStmt handles IDENT-based commands (xBase multi-word: COPY, SORT, etc.)
func (p *Parser) parseIdentStmt() ast.Stmt {
	upper := p.currentUpper()

	// WITH TIMEOUT → timeout context
	if upper == "WITH" && p.peekAt(1) == token.TIMEOUT_KW {
		return p.parseWithTimeout()
	}

	// xBase commands that consume entire line
	switch upper {
	case "COPY", "SORT", "COUNT", "SUM", "AVERAGE", "TOTAL", "UPDATE",
		"LABEL", "REPORT", "ACCEPT", "INPUT", "LOCATE", "CONTINUE",
		"JOIN", "RELEASE", "SAVE", "RESTORE", "ERASE", "RENAME",
		"RUN", "DIR", "STORE", "NOTE", "TEXT", "ENDTEXT",
		"WITH", "KEYBOARD", "CLEAR", "DISPLAY", "LIST", "REINDEX":
		p.advance()
		for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
			p.advance()
		}
		p.expectEndOfStmt()
		return &ast.ExprStmt{X: &ast.LiteralExpr{Kind: token.NIL_LIT, Value: "NIL"}}

	case "COMMIT":
		p.advance()
		p.expectEndOfStmt()
		return &ast.ExprStmt{X: &ast.CallExpr{
			Func: &ast.IdentExpr{Name: "DbCommit"},
		}}

	case "FIVE_GODUMP__":
		// GoDump is a Decl, wrap as ExprStmt for statement context
		p.advance() // consume FIVE_GODUMP__
		idx := 0
		if p.current.Kind == token.INT {
			fmt.Sscanf(p.current.Literal, "%d", &idx)
			p.advance()
		}
		p.expectEndOfStmt()
		// Store as nil statement — gengo handles GoDumpDecl at file level
		return &ast.ExprStmt{X: &ast.LiteralExpr{Kind: token.NIL_LIT, Value: "NIL"}}
	}

	// Multi-assign check: a, b := expr
	if p.looksLikeMultiAssign() {
		return p.parseMultiAssign()
	}

	// Default: expression statement (function call, assignment, etc.)
	return p.parseExprStmt()
}

func (p *Parser) parseExprStmt() ast.Stmt {
	// READ [SAVE] [MSG AT ...] [MSG COLOR ...] — special case
	if p.current.Kind == token.IDENT && p.currentUpper() == "READ" {
		pos := p.advance().Pos
		save := false
		if p.current.Kind == token.IDENT && p.currentUpper() == "SAVE" {
			save = true
			p.advance()
		}
		// Skip optional clauses: MSG AT row,col,col2 / MSG COLOR "..." etc.
		if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
			p.skipToEndOfLine()
		}
		p.expectEndOfStmt()
		return &ast.ReadCmd{ReadPos: pos, Save: save}
	}
	// TRY / CATCH [oErr] / END — Harbour extension, maps to BEGIN SEQUENCE / RECOVER
	if p.current.Kind == token.IDENT && p.currentUpper() == "TRY" {
		return p.parseTryCatch()
	}
	// CLOSE [DATABASES|ALL] — close work areas
	if p.current.Kind == token.IDENT && p.currentUpper() == "CLOSE" {
		p.advance()
		// Skip optional DATABASES/ALL keyword
		if p.current.Kind == token.IDENT {
			p.advance()
		}
		p.expectEndOfStmt()
		return &ast.ExprStmt{X: &ast.CallExpr{
			Func: &ast.IdentExpr{Name: "DbCloseArea"},
		}}
	}
	// xBase commands that consume entire line (COPY, SORT, COUNT, SUM, etc.)
	if p.current.Kind == token.IDENT {
		// WITH TIMEOUT n / body / ENDWITH
		if p.currentUpper() == "WITH" &&
			p.peekAt(1) == token.TIMEOUT_KW {
			return p.parseWithTimeout()
		}
		switch p.currentUpper() {
		case "COPY", "SORT", "COUNT", "SUM", "AVERAGE", "TOTAL", "UPDATE",
			"LABEL", "REPORT", "ACCEPT", "INPUT", "LOCATE", "CONTINUE",
			"JOIN", "RELEASE", "SAVE", "RESTORE", "ERASE", "RENAME",
			"RUN", "DIR", "STORE", "NOTE", "TEXT", "ENDTEXT",
			"WITH", "KEYBOARD", "CLEAR", "DISPLAY", "LIST", "REINDEX":
			// Consume entire line — these are complex multi-word commands
			p.advance()
			for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
				p.advance()
			}
			p.expectEndOfStmt()
			return &ast.ExprStmt{X: &ast.LiteralExpr{Kind: token.NIL_LIT, Value: "NIL"}}
		}
	}

	// COMMIT — flush work area
	if p.current.Kind == token.IDENT && p.currentUpper() == "COMMIT" {
		p.advance()
		p.expectEndOfStmt()
		return &ast.ExprStmt{X: &ast.CallExpr{
			Func: &ast.IdentExpr{Name: "DbCommit"},
		}}
	}
	expr := p.parseExpr()

	// ch <- value (channel send)
	if p.at(token.ARROW_LEFT) {
		pos := p.advance().Pos
		val := p.parseExpr()
		p.expectEndOfStmt()
		return &ast.ChanSendStmt{ChanPos: pos, Chan: expr, Value: val}
	}

	p.expectEndOfStmt()
	return &ast.ExprStmt{X: expr}
}

// --- Control flow ---

func (p *Parser) parseIf() *ast.IfStmt {
	ifPos := p.expect(token.IF).Pos
	cond := p.parseExpr()
	p.expectEndOfStmt()

	body := p.parseStmtBlock(token.ELSEIF, token.ELSE, token.ENDIF, token.END)

	var elseIfs []*ast.ElseIfClause
	for p.current.Kind == token.ELSEIF {
		eiPos := p.advance().Pos
		eiCond := p.parseExpr()
		p.expectEndOfStmt()
		eiBody := p.parseStmtBlock(token.ELSEIF, token.ELSE, token.ENDIF, token.END)
		elseIfs = append(elseIfs, &ast.ElseIfClause{
			ElseIfPos: eiPos,
			Cond:      eiCond,
			Body:      eiBody,
		})
	}

	var elseBody []ast.Stmt
	if p.match(token.ELSE) {
		p.expectEndOfStmt()
		elseBody = p.parseStmtBlock(token.ENDIF, token.END)
	}

	endPos := p.current.Pos
	if !p.match(token.ENDIF) {
		p.match(token.END) // alternative
	}
	p.expectEndOfStmt()

	return &ast.IfStmt{
		IfPos:    ifPos,
		Cond:     cond,
		Body:     body,
		ElseIfs:  elseIfs,
		ElseBody: elseBody,
		EndPos:   endPos,
	}
}

// looksLikeIIF checks if IF( starts an IIF-style call: IF(cond, true, false)
// by scanning for commas inside the parenthesized expression.
func (p *Parser) looksLikeIIF() bool {
	// Start after IF token; expect ( at p.pos+1
	if p.pos+1 >= len(p.tokens) || p.peekAt(1) != token.LPAREN {
		return false
	}
	depth := 0
	commas := 0
	for i := p.pos + 2; i < len(p.tokens); i++ { // start INSIDE the parens
		switch p.tokens[i].Kind {
		case token.LPAREN, token.LBRACE, token.LBRACKET:
			depth++
		case token.RPAREN:
			if depth == 0 {
				return commas >= 2
			}
			depth--
		case token.RBRACE, token.RBRACKET:
			if depth > 0 {
				depth--
			}
		case token.COMMA:
			if depth == 0 {
				commas++
			}
		case token.NEWLINE, token.EOF:
			return false
		}
	}
	return false
}

// parseDoProc: DO funcname [WITH arg1, arg2, ...]
func (p *Parser) parseDoProc() ast.Stmt {
	p.advance() // skip DO
	funcName := p.expectMethodName().Literal

	var args []ast.Expr
	if p.current.Kind == token.WITH {
		p.advance() // skip WITH
		for {
			args = append(args, p.parseExpr())
			if !p.match(token.COMMA) {
				break
			}
		}
	}
	p.expectEndOfStmt()

	return &ast.ExprStmt{X: &ast.CallExpr{
		Func: &ast.IdentExpr{Name: funcName},
		Args: args,
	}}
}

func (p *Parser) parseDoWhile() *ast.DoWhileStmt {
	var doPos token.Position
	if p.current.Kind == token.DO {
		doPos = p.advance().Pos
		p.expect(token.WHILE)
	} else {
		// Bare WHILE (Clipper compatibility)
		doPos = p.expect(token.WHILE).Pos
	}
	cond := p.parseExpr()
	p.expectEndOfStmt()

	body := p.parseStmtBlock(token.ENDDO, token.END)

	endPos := p.current.Pos
	if !p.match(token.ENDDO) {
		p.match(token.END)
	}
	p.expectEndOfStmt()

	return &ast.DoWhileStmt{DoPos: doPos, Cond: cond, Body: body, EndPos: endPos}
}

func (p *Parser) parseFor() ast.Stmt {
	forPos := p.expect(token.FOR).Pos

	// FOR EACH var IN collection
	if p.match(token.EACH) {
		return p.parseForEach(forPos)
	}

	// FOR var := start TO end [STEP step]
	// Variable can be aliased: M->TEST or simple: i
	varTok := p.expectMethodName()
	varName := varTok.Literal
	// Handle M->varname
	if p.at(token.ARROW) {
		p.advance() // skip ->
		fieldTok := p.expectMethodName()
		varName = fieldTok.Literal
	}
	p.expect(token.ASSIGN) // :=
	start := p.parseExpr()
	p.expect(token.TO)
	toExpr := p.parseExpr()

	var step ast.Expr
	if p.match(token.STEP) {
		step = p.parseExpr()
	}
	p.expectEndOfStmt()

	body := p.parseStmtBlock(token.NEXT, token.END)
	nextPos := p.current.Pos
	if !p.match(token.NEXT) {
		p.match(token.END)
	}
	// Skip optional counter variable after NEXT (e.g. NEXT nVar)
	if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		p.skipToEndOfLine()
	}
	p.expectEndOfStmt()

	return &ast.ForStmt{
		ForPos: forPos, Var: varName, Start: start, To: toExpr,
		Step: step, Body: body, NextPos: nextPos,
	}
}

func (p *Parser) parseForEach(forPos token.Position) *ast.ForEachStmt {
	varName := p.expect(token.IDENT).Literal
	// Multi-variable FOR EACH: FOR EACH a, b, c IN x, y, z
	// Skip extra variables — use only first var and first collection
	var extraVars []string
	for p.match(token.COMMA) {
		extraVars = append(extraVars, p.expect(token.IDENT).Literal)
	}
	p.expect(token.IN)
	collection := p.parseExpr()
	// Skip extra collections
	for p.match(token.COMMA) {
		p.parseExpr() // consume and discard
	}
	descend := false
	if p.current.Kind == token.DESCENDING {
		p.advance()
		descend = true
	}
	p.expectEndOfStmt()

	body := p.parseStmtBlock(token.NEXT, token.END)
	nextPos := p.current.Pos
	if !p.match(token.NEXT) {
		p.match(token.END)
	}
	// Skip optional counter variable after NEXT
	if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		p.skipToEndOfLine()
	}
	p.expectEndOfStmt()

	return &ast.ForEachStmt{
		ForPos: forPos, Var: varName, Collection: collection,
		Descend: descend, Body: body, NextPos: nextPos,
	}
}

// parseDoCase: DO CASE / CASE cond / OTHERWISE / ENDCASE
// Harbour: equivalent to IF/ELSEIF/ELSE chain
func (p *Parser) parseDoCase() *ast.IfStmt {
	doPos := p.expect(token.DO).Pos
	p.expect(token.CASE) // consume CASE after DO
	p.expectEndOfStmt()
	p.skipNewlines()

	// First CASE
	if p.current.Kind != token.CASE {
		p.error("expected CASE after DO CASE")
		return &ast.IfStmt{IfPos: doPos, EndPos: doPos}
	}

	p.advance() // consume CASE
	cond := p.parseExpr()
	p.expectEndOfStmt()
	body := p.parseStmtBlock(token.CASE, token.OTHERWISE, token.ENDCASE, token.END)

	// Build as IfStmt with ElseIfs
	var elseIfs []*ast.ElseIfClause
	for p.current.Kind == token.CASE {
		eiPos := p.advance().Pos
		eiCond := p.parseExpr()
		p.expectEndOfStmt()
		eiBody := p.parseStmtBlock(token.CASE, token.OTHERWISE, token.ENDCASE, token.END)
		elseIfs = append(elseIfs, &ast.ElseIfClause{
			ElseIfPos: eiPos,
			Cond:      eiCond,
			Body:      eiBody,
		})
	}

	var elseBody []ast.Stmt
	if p.match(token.OTHERWISE) {
		p.expectEndOfStmt()
		elseBody = p.parseStmtBlock(token.ENDCASE, token.END)
	}

	endPos := p.current.Pos
	if !p.match(token.ENDCASE) {
		p.match(token.END)
	}
	p.expectEndOfStmt()

	return &ast.IfStmt{
		IfPos:    doPos,
		Cond:     cond,
		Body:     body,
		ElseIfs:  elseIfs,
		ElseBody: elseBody,
		EndPos:   endPos,
	}
}

func (p *Parser) parseSwitch() *ast.SwitchStmt {
	switchPos := p.expect(token.SWITCH).Pos
	expr := p.parseExpr()
	p.expectEndOfStmt()

	var cases []*ast.CaseClause
	var otherwise []ast.Stmt
	p.skipNewlines()

	for p.current.Kind == token.CASE {
		casePos := p.advance().Pos
		val := p.parseExpr()
		p.expectEndOfStmt()
		caseBody := p.parseStmtBlock(token.CASE, token.OTHERWISE, token.ENDSWITCH, token.ENDCASE, token.END)
		cases = append(cases, &ast.CaseClause{CasePos: casePos, Value: val, Body: caseBody})
	}

	if p.match(token.OTHERWISE) {
		p.expectEndOfStmt()
		otherwise = p.parseStmtBlock(token.ENDSWITCH, token.ENDCASE, token.END)
	}

	endPos := p.current.Pos
	if !p.match(token.ENDSWITCH) {
		if !p.match(token.ENDCASE) {
			p.match(token.END)
		}
	}
	p.expectEndOfStmt()

	return &ast.SwitchStmt{SwitchPos: switchPos, Expr: expr, Cases: cases, Otherwise: otherwise, EndPos: endPos}
}

func (p *Parser) parseBeginSequence() *ast.SeqStmt {
	beginPos := p.expect(token.BEGIN).Pos
	p.expect(token.SEQUENCE)
	p.expectEndOfStmt()

	body := p.parseStmtBlock(token.RECOVER, token.END)

	var recoverVar string
	var recoverBody []ast.Stmt
	if p.match(token.RECOVER) {
		if p.match(token.USING) {
			recoverVar = p.expect(token.IDENT).Literal
		}
		p.expectEndOfStmt()
		recoverBody = p.parseStmtBlock(token.END)
	}

	endPos := p.current.Pos
	p.match(token.END)
	p.match(token.SEQUENCE) // optional: END SEQUENCE
	p.expectEndOfStmt()

	return &ast.SeqStmt{
		BeginPos: beginPos, Body: body,
		RecoverVar: recoverVar, RecoverBody: recoverBody,
		EndPos: endPos,
	}
}

// parseTryCatch: TRY ... CATCH [oErr] ... END — maps to SeqStmt
func (p *Parser) parseTryCatch() *ast.SeqStmt {
	beginPos := p.advance().Pos // consume TRY
	p.expectEndOfStmt()

	// Parse body until CATCH or END
	var body []ast.Stmt
	for !p.atAny(token.EOF) {
		if p.current.Kind == token.IDENT && p.currentUpper() == "CATCH" {
			break
		}
		if p.current.Kind == token.END {
			break
		}
		body = append(body, p.parseStmt())
		p.skipNewlines()
	}

	var recoverVar string
	var recoverBody []ast.Stmt
	if p.current.Kind == token.IDENT && p.currentUpper() == "CATCH" {
		p.advance() // consume CATCH
		if p.current.Kind == token.IDENT && p.current.Kind != token.NEWLINE {
			recoverVar = p.advance().Literal
		}
		p.expectEndOfStmt()
		recoverBody = p.parseStmtBlock(token.END)
	}

	endPos := p.current.Pos
	p.match(token.END)
	if p.current.Kind == token.IDENT && p.currentUpper() == "TRY" {
		p.advance() // END TRY
	}
	p.expectEndOfStmt()

	return &ast.SeqStmt{
		BeginPos: beginPos, Body: body,
		RecoverVar: recoverVar, RecoverBody: recoverBody,
		EndPos: endPos,
	}
}

func (p *Parser) parseReturn() *ast.ReturnStmt {
	pos := p.expect(token.RETURN).Pos
	var val ast.Expr
	var vals []ast.Expr
	if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		val = p.parseExpr()
		// Multi-return: RETURN a, b, c
		if p.match(token.COMMA) {
			vals = append(vals, val)
			vals = append(vals, p.parseExpr())
			for p.match(token.COMMA) {
				vals = append(vals, p.parseExpr())
			}
			val = vals[0] // keep first for backward compat
		}
	}
	p.expectEndOfStmt()
	return &ast.ReturnStmt{ReturnPos: pos, Value: val, Values: vals}
}

func (p *Parser) parseQOut(isQQ bool) *ast.QOutStmt {
	pos := p.advance().Pos // consume ? or ??
	var exprs []ast.Expr
	if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		exprs = append(exprs, p.parseExpr())
		for p.match(token.COMMA) {
			exprs = append(exprs, p.parseExpr())
		}
	}
	p.expectEndOfStmt()
	return &ast.QOutStmt{QPos: pos, IsQQ: isQQ, Exprs: exprs}
}

func (p *Parser) parsePrivatePublic(scope ast.VarScope) ast.Stmt {
	tok := p.advance()
	var vars []*ast.VarInit
	for {
		// Handle &macro in PRIVATE/PUBLIC list
		if p.at(token.AMPERSAND) {
			macroExpr := p.parseMacro()
			var init ast.Expr
			if p.match(token.ASSIGN) {
				init = p.parseExpr()
			}
			name := "macro"
			if me, ok := macroExpr.(*ast.MacroExpr); ok {
				if id, ok2 := me.Expr.(*ast.IdentExpr); ok2 {
					name = id.Name
				}
			}
			vars = append(vars, &ast.VarInit{NamePos: macroExpr.Pos(), Name: name, Init: init})
			if !p.match(token.COMMA) {
				break
			}
			continue
		}
		name := p.expectMethodName() // allow keywords as var names (MEMVAR, etc.)
		var init ast.Expr
		// Skip AS type declaration
		if p.match(token.AS) {
			for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF &&
				p.current.Kind != token.ASSIGN && p.current.Kind != token.COMMA {
				p.advance()
			}
		}
		if p.match(token.ASSIGN) {
			init = p.parseExpr()
		}
		vars = append(vars, &ast.VarInit{NamePos: name.Pos, Name: name.Literal, Init: init})
		if !p.match(token.COMMA) {
			break
		}
	}
	p.expectEndOfStmt()
	return &ast.VarDecl{DeclPos: tok.Pos, Scope: scope, Vars: vars}
}

// --- xBase commands ---

func (p *Parser) parseUse() *ast.UseCmd {
	pos := p.expect(token.USE).Pos
	var file ast.Expr
	var via, alias string

	// USE without args = close
	if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		// If file starts with macro &, skip entire USE to EOL (complex macro syntax)
		if p.at(token.AMPERSAND) {
			p.skipToEndOfLine()
			p.expectEndOfStmt()
			return &ast.UseCmd{UsePos: pos}
		}
		file = p.parseExpr()
		p.consumeFileExtension(file)
	}

	// Parse optional clauses: VIA, ALIAS, EXCLUSIVE, SHARED, NEW, READONLY
	for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		if p.current.Kind == token.IDENT {
			upper := p.currentUpper()
			if upper == "VIA" {
				p.advance()
				via = p.expectMethodName().Literal
				continue
			}
			if upper == "ALIAS" {
				p.advance()
				if p.at(token.AMPERSAND) {
					p.parseMacro() // macro alias — skip
				} else {
					alias = p.expectMethodName().Literal
				}
				continue
			}
			if upper == "EXCLUSIVE" || upper == "SHARED" || upper == "NEW" || upper == "READONLY" ||
				upper == "ADDITIVE" {
				p.advance()
				continue
			}
			if upper == "INDEX" {
				// INDEX file1[, file2, ...] — skip to EOL
				p.skipToEndOfLine()
				break
			}
		}
		if p.current.Kind == token.ALIAS {
			p.advance()
			if p.at(token.AMPERSAND) {
				p.parseMacro()
			} else {
				alias = p.expectMethodName().Literal
			}
			continue
		}
		if p.current.Kind == token.INDEX {
			// INDEX file1, file2, ... — skip to EOL
			p.skipToEndOfLine()
			break
		}
		break
	}

	p.expectEndOfStmt()
	return &ast.UseCmd{UsePos: pos, File: file, Via: via, Alias: alias}
}

func (p *Parser) parseSelect() *ast.SelectCmd {
	pos := p.expect(token.SELECT).Pos
	area := p.parseExpr()
	p.expectEndOfStmt()
	return &ast.SelectCmd{SelectPos: pos, Area: area}
}

func (p *Parser) parseGo() *ast.GoCmd {
	pos := p.advance().Pos // GO or GOTO
	var dir string
	var recNo ast.Expr

	switch p.current.Kind {
	case token.TOP:
		dir = "TOP"
		p.advance()
	case token.BOTTOM:
		dir = "BOTTOM"
		p.advance()
	default:
		recNo = p.parseExpr()
	}
	p.expectEndOfStmt()
	return &ast.GoCmd{GoPos: pos, Direction: dir, RecNo: recNo}
}

func (p *Parser) parseSkip() *ast.SkipCmd {
	pos := p.expect(token.SKIP_KW).Pos
	var count ast.Expr
	if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		count = p.parseExpr()
	}
	p.expectEndOfStmt()
	return &ast.SkipCmd{SkipPos: pos, Count: count}
}

func (p *Parser) parseSeek() *ast.SeekCmd {
	pos := p.expect(token.SEEK).Pos
	key := p.parseExpr()
	softSeek := false
	if p.current.Kind == token.SOFTSEEK {
		p.advance()
		softSeek = true
	}
	p.expectEndOfStmt()
	return &ast.SeekCmd{SeekPos: pos, Key: key, SoftSeek: softSeek}
}

func (p *Parser) parseReplace() *ast.ReplaceCmd {
	pos := p.expect(token.REPLACE).Pos
	var fields []ast.ReplaceField
	for {
		field := p.parseExpr()
		p.expect(token.WITH)
		value := p.parseExpr()
		fields = append(fields, ast.ReplaceField{Field: field, Value: value})
		if !p.match(token.COMMA) {
			break
		}
	}
	p.expectEndOfStmt()
	return &ast.ReplaceCmd{ReplacePos: pos, Fields: fields}
}

func (p *Parser) parseAppend() *ast.AppendCmd {
	pos := p.expect(token.APPEND).Pos
	if p.match(token.FROM) {
		// APPEND FROM filename [DELIMITED|SDF|VIA ...] — skip to EOL
		p.skipToEndOfLine()
		p.expectEndOfStmt()
		return &ast.AppendCmd{AppendPos: pos}
	}
	p.expect(token.BLANK)
	p.expectEndOfStmt()
	return &ast.AppendCmd{AppendPos: pos}
}

func (p *Parser) parseIndex() *ast.IndexCmd {
	pos := p.expect(token.INDEX).Pos
	p.expect(token.ON)
	keyExpr := p.parseExpr()

	// INDEX ON expr TO file  OR  INDEX ON expr TAG tagname [TO file]
	var fileExpr ast.Expr
	if p.match(token.TO) {
		fileExpr = p.parseExpr()
		p.consumeFileExtension(fileExpr)
	} else if p.current.Kind == token.IDENT && p.currentUpper() == "TAG" {
		p.advance() // skip TAG
		tagExpr := p.parseExpr() // tag name
		if p.match(token.TO) {
			fileExpr = p.parseExpr()
		} else {
			fileExpr = tagExpr // use tag name as file
		}
	} else {
		fileExpr = p.parseExpr() // fallback
	}

	var forCond ast.Expr
	unique := false
	descending := false

	for {
		if p.match(token.FOR) {
			forCond = p.parseExpr()
		} else if p.match(token.UNIQUE) {
			unique = true
		} else if p.match(token.DESCENDING) {
			descending = true
		} else {
			break
		}
	}
	p.expectEndOfStmt()

	return &ast.IndexCmd{
		IndexPos: pos, KeyExpr: keyExpr, File: fileExpr,
		ForCond: forCond, Unique: unique, Descending: descending,
	}
}

func (p *Parser) parseSet() *ast.SetCmd {
	pos := p.expect(token.SET).Pos

	// Accept any token as SET keyword (COLOR, KEY, ORDER, FILTER, etc. may be keyword tokens)
	setting := p.expectMethodName().Literal

	var expr ast.Expr
	var extra string

	// SET commands: consume everything until end of line.
	// Boolean toggles: SET DELETED ON/OFF, SET EXACT ON/OFF, etc.
	// Value settings: SET FILTER TO expr, SET ORDER TO n, SET DATE TO fmt
	upperSetting := strings.ToUpper(setting)

	// Check for ON/OFF boolean toggle
	booleanSets := map[string]bool{
		"DELETED": true, "EXACT": true, "SOFTSEEK": true, "EXCLUSIVE": true,
		"FIXED": true, "CANCEL": true, "BELL": true, "CONFIRM": true,
		"INSERT": true, "ESCAPE": true, "WRAP": true, "INTENSITY": true,
		"SCOREBOARD": true, "CONSOLE": true, "ALTERNATE": true, "PRINTER": true,
	}

	if booleanSets[upperSetting] {
		if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
			extra = strings.ToUpper(p.expectMethodName().Literal)
		}
	} else if p.match(token.TO) {
		if upperSetting == "FILTER" || upperSetting == "RELATION" || upperSetting == "ORDER" || upperSetting == "INDEX" {
			if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
				expr = p.parseExpr()
			}
			if p.current.Kind == token.INTO {
				p.advance()
				extra = p.expectMethodName().Literal
			}
		} else if upperSetting == "DATE" || upperSetting == "DECIMALS" || upperSetting == "EPOCH" {
			if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
				expr = p.parseExpr()
			}
		}
	}

	// Consume remaining tokens (for COLOR TO, KEY TO, etc.)
	for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		p.advance()
	}
	p.expectEndOfStmt()
	return &ast.SetCmd{SetPos: pos, Setting: setting, Expr: expr, Extra: extra}
}

// parseAtCmd parses @ row, col SAY/GET/PROMPT commands.
func (p *Parser) parseAtCmd() ast.Stmt {
	pos := p.advance().Pos // consume @
	row := p.parseExpr()
	p.expect(token.COMMA)
	col := p.parseExpr()

	// Determine sub-command: SAY, GET, PROMPT
	if p.current.Kind == token.IDENT {
		switch p.currentUpper() {
		case "SAY":
			return p.parseAtSay(pos, row, col)
		case "GET":
			return p.parseAtGet(pos, row, col)
		case "PROMPT":
			return p.parseAtPrompt(pos, row, col)
		case "CLEAR":
			// @ row, col CLEAR [TO row2, col2] — clear region
			p.advance() // skip CLEAR
			if p.match(token.TO) {
				p.parseExpr() // row2
				p.expect(token.COMMA)
				p.parseExpr() // col2
			}
			p.expectEndOfStmt()
			return &ast.ExprStmt{X: &ast.CallExpr{
				Func: &ast.IdentExpr{Name: "SetPos"},
				Args: []ast.Expr{row, col},
			}}
		}
	}

	// @ row, col TO row2, col2 [DOUBLE] — box drawing
	if p.match(token.TO) {
		row2 := p.parseExpr()
		p.expect(token.COMMA)
		col2 := p.parseExpr()
		// Skip optional DOUBLE keyword or other modifiers
		for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
			p.advance()
		}
		p.expectEndOfStmt()
		return &ast.ExprStmt{X: &ast.CallExpr{
			Func: &ast.IdentExpr{Name: "DispBox"},
			Args: []ast.Expr{row, col, row2, col2},
		}}
	}

	// Bare @ row, col — just position cursor
	for p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		p.advance() // skip any remaining tokens
	}
	p.expectEndOfStmt()
	return &ast.ExprStmt{X: &ast.CallExpr{
		Func: &ast.IdentExpr{Name: "SetPos"},
		Args: []ast.Expr{row, col},
	}}
}

func (p *Parser) parseAtSay(pos token.Position, row, col ast.Expr) ast.Stmt {
	p.advance() // consume SAY
	sayExpr := p.parseExpr()

	// Check for GET after SAY
	if p.current.Kind == token.IDENT && p.currentUpper() == "GET" {
		return p.parseAtSayGet(pos, row, col, sayExpr)
	}

	// PICTURE clause
	var pic ast.Expr
	if p.current.Kind == token.IDENT && p.currentUpper() == "PICTURE" {
		p.advance()
		pic = p.parseExpr()
	}
	p.expectEndOfStmt()
	return &ast.AtSayCmd{AtPos: pos, Row: row, Col: col, SayExpr: sayExpr, Picture: pic}
}

func (p *Parser) parseAtGet(pos token.Position, row, col ast.Expr) *ast.AtGetCmd {
	p.advance() // consume GET
	varExpr := p.parseExpr()
	varName := ""
	if ident, ok := varExpr.(*ast.IdentExpr); ok {
		varName = ident.Name
	}

	var pic, valid, when ast.Expr
	for p.current.Kind == token.IDENT {
		switch p.currentUpper() {
		case "PICTURE":
			p.advance()
			pic = p.parseExpr()
		case "VALID":
			p.advance()
			valid = p.parseExpr()
		case "WHEN":
			p.advance()
			when = p.parseExpr()
		case "RANGE":
			// RANGE low, high — skip both values
			p.advance()
			p.parseExpr() // low
			p.expect(token.COMMA)
			p.parseExpr() // high
		case "COLOR", "COLOUR", "MESSAGE", "SEND", "GUISEND",
			"CAPTION", "CARGO", "COLORSPEC":
			// Skip keyword + value
			p.advance()
			p.parseExpr()
		default:
			goto done
		}
	}
done:
	p.expectEndOfStmt()
	return &ast.AtGetCmd{AtPos: pos, Row: row, Col: col, Var: varExpr, VarName: varName, Picture: pic, Valid: valid, When: when}
}

func (p *Parser) parseAtSayGet(pos token.Position, row, col ast.Expr, sayExpr ast.Expr) *ast.AtSayGetCmd {
	p.advance() // consume GET
	varExpr := p.parseExpr()
	varName := ""
	if ident, ok := varExpr.(*ast.IdentExpr); ok {
		varName = ident.Name
	}

	var pic, valid, when ast.Expr
	for p.current.Kind == token.IDENT {
		switch p.currentUpper() {
		case "PICTURE":
			p.advance()
			pic = p.parseExpr()
		case "VALID":
			p.advance()
			valid = p.parseExpr()
		case "WHEN":
			p.advance()
			when = p.parseExpr()
		case "RANGE":
			p.advance()
			p.parseExpr()
			p.expect(token.COMMA)
			p.parseExpr()
		case "COLOR", "COLOUR", "MESSAGE", "SEND", "GUISEND",
			"CAPTION", "CARGO", "COLORSPEC":
			p.advance()
			p.parseExpr()
		default:
			goto done
		}
	}
done:
	p.expectEndOfStmt()
	return &ast.AtSayGetCmd{AtPos: pos, Row: row, Col: col, SayExpr: sayExpr, Var: varExpr, VarName: varName, Picture: pic, Valid: valid, When: when}
}

func (p *Parser) parseAtPrompt(pos token.Position, row, col ast.Expr) ast.Stmt {
	p.advance() // consume PROMPT
	prompt := p.parseExpr()
	var msg ast.Expr
	if p.current.Kind == token.IDENT && p.currentUpper() == "MESSAGE" {
		p.advance()
		msg = p.parseExpr()
	}
	p.expectEndOfStmt()
	// Emit as: __AtPrompt(row, col, prompt [, msg])
	args := []ast.Expr{row, col, prompt}
	if msg != nil {
		args = append(args, msg)
	}
	return &ast.ExprStmt{X: &ast.CallExpr{
		Func: &ast.IdentExpr{Name: "__AtPrompt"},
		Args: args,
	}}
}

// === Five Go Extension Parsers ===

// looksLikeMultiAssign checks strictly: IDENT , IDENT [, IDENT...] :=
// Each token between start and := must be IDENT or COMMA only (no [ ( : etc.)
func (p *Parser) looksLikeMultiAssign() bool {
	// Must start with IDENT (or keyword-as-ident)
	if p.current.Kind != token.IDENT && p.current.Literal == "" {
		return false
	}
	// Next token must be COMMA for multi-assign
	if p.pos+1 >= len(p.tokens) || p.peekAt(1) != token.COMMA {
		return false
	}
	// Scan from after first IDENT: COMMA, IDENT, COMMA, IDENT, ..., ASSIGN
	expectComma := true // first IDENT already consumed, expect COMMA next
	for i := p.pos + 1; i < len(p.tokens); i++ {
		tk := p.tokens[i]
		if tk.Kind == token.ASSIGN {
			return expectComma == true // last was IDENT (expectComma=true), then :=
		}
		if tk.Kind == token.NEWLINE || tk.Kind == token.EOF {
			return false
		}
		if expectComma {
			if tk.Kind != token.COMMA {
				return false
			}
			expectComma = false
		} else {
			// Expect IDENT or keyword-as-ident (including "_")
			if tk.Kind != token.IDENT && tk.Literal == "" {
				return false
			}
			expectComma = true
		}
	}
	return false
}

// parseMultiAssign: a, b := Func()  or  a, b, c := x, y, z  or  _, b := Func()
func (p *Parser) parseMultiAssign() *ast.MultiAssignStmt {
	pos := p.current.Pos
	var targets []string

	// Parse target list: a, b, c or _, b
	for {
		name := "_"
		if p.current.Kind == token.IDENT && p.current.Literal == "_" {
			p.advance()
		} else {
			tok := p.expectMethodName()
			name = tok.Literal
		}
		targets = append(targets, name)
		if !p.match(token.COMMA) {
			break
		}
	}

	p.expect(token.ASSIGN) // :=

	// Parse value list
	var values []ast.Expr
	values = append(values, p.parseExpr())
	for p.match(token.COMMA) {
		values = append(values, p.parseExpr())
	}
	p.expectEndOfStmt()

	return &ast.MultiAssignStmt{AssignPos: pos, Targets: targets, Values: values}
}

// parseDefer: DEFER expr
func (p *Parser) parseDefer() *ast.DeferStmt {
	pos := p.expect(token.DEFER_KW).Pos
	// Parse the expression to defer (typically a method call: db:Close())
	call := p.parseExpr()
	p.expectEndOfStmt()
	return &ast.DeferStmt{DeferPos: pos, Call: call}
}

// parseConstBlock: CONST ... END CONST
func (p *Parser) parseConstBlock() ast.Stmt {
	pos := p.expect(token.CONST_KW).Pos
	p.expectEndOfStmt()

	var items []ast.ConstItem
	p.skipNewlines()

	for !p.atAny(token.END, token.ENDCASE, token.EOF) {
		if p.current.Kind == token.IDENT || p.current.Literal != "" {
			name := p.expectMethodName().Literal
			var val ast.Expr
			if p.match(token.ASSIGN) {
				val = p.parseExpr()
			}
			items = append(items, ast.ConstItem{Name: name, Value: val})
			p.expectEndOfStmt()
		} else {
			break
		}
		p.skipNewlines()
	}

	if p.match(token.END) {
		// Skip optional CONST after END
		if p.current.Kind == token.CONST_KW {
			p.advance()
		}
	}
	p.expectEndOfStmt()

	_ = pos
	return &ast.ExprStmt{X: &ast.LiteralExpr{Kind: token.NIL_LIT, Value: "NIL"}}
}

// parseShortIfAssign: IF var := expr ; condition ... ENDIF
// Detected inside parseIf when IF is followed by IDENT := expr ;
// === Five Concurrency Parsers ===

// parseWatch: WATCH / CASE msg := <- ch / CASE ch <- val / OTHERWISE / ENDWATCH
func (p *Parser) parseWatch() *ast.WatchStmt {
	watchPos := p.expect(token.WATCH_KW).Pos
	p.expectEndOfStmt()

	var cases []*ast.WatchCase
	var otherwise []ast.Stmt
	p.skipNewlines()

	for p.current.Kind == token.CASE {
		casePos := p.advance().Pos
		wc := &ast.WatchCase{CasePos: casePos}

		if p.at(token.ARROW_LEFT) {
			// CASE <- ch (receive, discard value)
			p.advance() // consume <-
			wc.RecvChan = p.parseExpr()
		} else {
			// CASE var := <- ch  OR  CASE ch <- val
			first := p.parseExpr()
			if p.at(token.ASSIGN) && p.peekAt(1) == token.ARROW_LEFT {
				// CASE var := <- ch
				p.advance() // consume :=
				p.advance() // consume <-
				wc.RecvChan = p.parseExpr()
				if ident, ok := first.(*ast.IdentExpr); ok {
					wc.RecvVar = ident.Name
				}
			} else if p.at(token.ARROW_LEFT) {
				// CASE ch <- val (send)
				p.advance() // consume <-
				wc.SendChan = first
				wc.SendVal = p.parseExpr()
			} else {
				// CASE expr (boolean guard — less common)
				wc.RecvChan = first
			}
		}
		p.expectEndOfStmt()
		wc.Body = p.parseStmtBlock(token.CASE, token.OTHERWISE, token.END)
		cases = append(cases, wc)
	}

	if p.match(token.OTHERWISE) {
		p.expectEndOfStmt()
		otherwise = p.parseStmtBlock(token.END)
	}

	endPos := p.current.Pos
	p.match(token.END)
	// Skip optional WATCH after END
	if p.current.Kind == token.WATCH_KW {
		p.advance()
	}
	p.expectEndOfStmt()

	return &ast.WatchStmt{WatchPos: watchPos, Cases: cases, Otherwise: otherwise, EndPos: endPos}
}

// parseParallelFor: PARALLEL FOR i := 1 TO n / body / NEXT
func (p *Parser) parseParallelFor() ast.Stmt {
	p.expect(token.PARALLEL_KW)

	if p.current.Kind != token.FOR {
		// Not PARALLEL FOR — skip
		p.skipToEndOfLine()
		p.expectEndOfStmt()
		return &ast.ExprStmt{X: &ast.LiteralExpr{Kind: token.NIL_LIT, Value: "NIL"}}
	}

	forPos := p.expect(token.FOR).Pos
	varTok := p.expectMethodName()
	varName := varTok.Literal
	if p.at(token.ARROW) {
		p.advance()
		fieldTok := p.expectMethodName()
		varName = fieldTok.Literal
	}
	p.expect(token.ASSIGN)
	start := p.parseExpr()
	p.expect(token.TO)
	toExpr := p.parseExpr()

	var step ast.Expr
	if p.match(token.STEP) {
		step = p.parseExpr()
	}
	p.expectEndOfStmt()

	body := p.parseStmtBlock(token.NEXT, token.END)
	endPos := p.current.Pos
	if !p.match(token.NEXT) {
		p.match(token.END)
	}
	if p.current.Kind != token.NEWLINE && p.current.Kind != token.EOF {
		p.skipToEndOfLine()
	}
	p.expectEndOfStmt()

	return &ast.ParallelForStmt{
		ForPos: forPos, Var: varName, Start: start, To: toExpr,
		Step: step, Body: body, EndPos: endPos,
	}
}

// parseWithTimeout: WITH TIMEOUT n / body / ENDWITH
func (p *Parser) parseWithTimeout() *ast.TimeoutStmt {
	withPos := p.advance().Pos // consume WITH
	p.expect(token.TIMEOUT_KW) // consume TIMEOUT
	duration := p.parseExpr()
	p.expectEndOfStmt()

	body := p.parseStmtBlock(token.END)
	endPos := p.current.Pos
	p.match(token.END)
	// Skip optional WITH after END
	if p.current.Kind == token.IDENT && p.currentUpper() == "WITH" {
		p.advance()
	}
	p.expectEndOfStmt()

	return &ast.TimeoutStmt{WithPos: withPos, Duration: duration, Body: body, EndPos: endPos}
}

func (p *Parser) isShortIfAssign() bool {
	// Look ahead: IF ident := expr ; condition
	if p.pos+3 >= len(p.tokens) {
		return false
	}
	// Check pattern: IDENT := ... ;
	for i := p.pos + 1; i < len(p.tokens); i++ {
		if p.tokens[i].Kind == token.SEMICOLON {
			// Found ; before newline — it's short if
			return true
		}
		if p.tokens[i].Kind == token.NEWLINE || p.tokens[i].Kind == token.EOF {
			return false
		}
	}
	return false
}