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

// analyzer.go — Semantic analysis pass for Five AST.
//
// Runs AFTER parsing, BEFORE code generation.
// Checks:
//   1. Variable declaration: all LOCAL vars declared before use
//   2. Scope analysis: LOCAL vs PRIVATE vs PUBLIC vs FIELD
//   3. Undeclared variable warnings
//   4. Unused variable warnings
//   5. Function signature validation
//   6. Type hints (when available)

package analyzer

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

// Diagnostic represents an analysis warning or error.
type Diagnostic struct {
	Pos      token.Position
	Message  string
	Severity Severity
}

type Severity int

const (
	SevError   Severity = iota // Must fix
	SevWarning                 // Should fix
	SevHint                    // Optional improvement
)

func (d Diagnostic) String() string {
	prefix := "HINT"
	switch d.Severity {
	case SevError:
		prefix = "ERROR"
	case SevWarning:
		prefix = "WARN"
	}
	return fmt.Sprintf("%s:%d:%d: %s: %s", d.Pos.File, d.Pos.Line, d.Pos.Col, prefix, d.Message)
}

// Scope tracks declared variables in a function.
type Scope struct {
	Name     string            // function name
	Declared map[string]VarInfo // upper(name) → info
	Used     map[string]bool   // upper(name) → was used
	Parent   *Scope            // outer scope (for blocks)
}

// VarInfo holds info about a declared variable.
type VarInfo struct {
	Name    string
	Pos     token.Position
	Kind    ast.VarScope // LOCAL, STATIC, FIELD, etc.
	IsParam bool
}

// Analyzer performs semantic analysis on a parsed AST file.
type Analyzer struct {
	file          *ast.File
	diagnostics   []Diagnostic
	scope         *Scope
	funcNames     map[string]bool // declared function names (this file + external)
	moduleStatics map[string]VarInfo // module-level STATIC variables
}

// Analyze runs semantic analysis and returns diagnostics.
// externalFuncs (optional) provides function names from other files in multi-file builds.
func Analyze(file *ast.File, externalFuncs ...map[string]bool) []Diagnostic {
	a := &Analyzer{
		file:          file,
		funcNames:     make(map[string]bool),
		moduleStatics: make(map[string]VarInfo),
	}

	// Phase 1: Collect all function names from this file
	for _, d := range file.Decls {
		switch decl := d.(type) {
		case *ast.FuncDecl:
			a.funcNames[strings.ToUpper(decl.Name)] = true
		case *ast.ClassDecl:
			a.funcNames[strings.ToUpper(decl.Name)] = true
		}
	}

	// Merge external function names (from other PRG files in multi-file build)
	for _, ext := range externalFuncs {
		for name := range ext {
			a.funcNames[name] = true
		}
	}

	// Phase 1.5: Collect module-level STATIC variables
	for _, d := range file.Decls {
		if vd, ok := d.(*ast.VarDecl); ok && vd.Scope == ast.ScopeStatic {
			for _, v := range vd.Vars {
				a.moduleStatics[strings.ToUpper(v.Name)] = VarInfo{
					Name: v.Name,
					Pos:  v.NamePos,
					Kind: ast.ScopeStatic,
				}
			}
		}
	}

	// Phase 2: Analyze each function and class method body
	for _, d := range file.Decls {
		switch decl := d.(type) {
		case *ast.FuncDecl:
			a.analyzeFunc(decl)
		case *ast.MethodDecl:
			a.analyzeMethod(decl)
		}
	}

	return a.diagnostics
}

func (a *Analyzer) analyzeFunc(fn *ast.FuncDecl) {
	a.scope = &Scope{
		Name:     fn.Name,
		Declared: make(map[string]VarInfo),
		Used:     make(map[string]bool),
	}

	// Register module-level STATIC variables (visible to all functions in this file)
	for name, info := range a.moduleStatics {
		a.scope.Declared[name] = info
	}

	// Register parameters as declared
	for _, p := range fn.Params {
		a.scope.Declared[strings.ToUpper(p.Name)] = VarInfo{
			Name:    p.Name,
			Pos:     p.NamePos,
			IsParam: true,
		}
	}

	// Register LOCAL/STATIC declarations
	for _, d := range fn.Decls {
		if vd, ok := d.(*ast.VarDecl); ok {
			for _, v := range vd.Vars {
				a.scope.Declared[strings.ToUpper(v.Name)] = VarInfo{
					Name: v.Name,
					Pos:  v.NamePos,
					Kind: vd.Scope,
				}
			}
		}
	}

	// Analyze body statements
	for _, stmt := range fn.Body {
		a.analyzeStmt(stmt)
	}

	// Check for unused variables
	for name, info := range a.scope.Declared {
		if !a.scope.Used[name] && !info.IsParam {
			// Skip common patterns: loop vars, error vars
			lower := strings.ToLower(info.Name)
			if lower == "i" || lower == "j" || lower == "k" || lower == "n" ||
				lower == "err" || lower == "_" {
				continue
			}
			a.hint(info.Pos, "unused variable '%s'", info.Name)
		}
	}
}

// analyzeMethod walks a class-method body (`METHOD Foo() CLASS TBar`)
// applying the same undeclared-variable and unused-variable checks
// that analyzeFunc performs on standalone functions. Without this,
// unresolved identifiers inside CLASS methods silently fell through
// to gengo's memvar fallback (NIL at runtime) — e.g. a missing
// `#include "dbinfo.ch"` leaving DBI_FULLPATH undefined in a method.
func (a *Analyzer) analyzeMethod(m *ast.MethodDecl) {
	a.scope = &Scope{
		Name:     m.Name,
		Declared: make(map[string]VarInfo),
		Used:     make(map[string]bool),
	}

	// Module-level STATICs are visible to class methods too
	for name, info := range a.moduleStatics {
		a.scope.Declared[name] = info
	}

	// Parameters
	for _, p := range m.Params {
		a.scope.Declared[strings.ToUpper(p.Name)] = VarInfo{
			Name:    p.Name,
			Pos:     p.NamePos,
			IsParam: true,
		}
	}

	// LOCAL / STATIC declarations inside the method
	for _, d := range m.Decls {
		if vd, ok := d.(*ast.VarDecl); ok {
			for _, v := range vd.Vars {
				a.scope.Declared[strings.ToUpper(v.Name)] = VarInfo{
					Name: v.Name,
					Pos:  v.NamePos,
					Kind: vd.Scope,
				}
			}
		}
	}

	for _, stmt := range m.Body {
		a.analyzeStmt(stmt)
	}

	// Unused-variable hints (same exclusions as analyzeFunc)
	for name, info := range a.scope.Declared {
		if !a.scope.Used[name] && !info.IsParam {
			lower := strings.ToLower(info.Name)
			if lower == "i" || lower == "j" || lower == "k" || lower == "n" ||
				lower == "err" || lower == "_" {
				continue
			}
			a.hint(info.Pos, "unused variable '%s'", info.Name)
		}
	}
}

func (a *Analyzer) analyzeStmt(stmt ast.Stmt) {
	if stmt == nil {
		return
	}
	switch s := stmt.(type) {
	case *ast.ExprStmt:
		a.analyzeExpr(s.X)
	case *ast.ReturnStmt:
		if s.Value != nil {
			a.analyzeExpr(s.Value)
		}
		for _, v := range s.Values {
			a.analyzeExpr(v)
		}
	case *ast.IfStmt:
		a.analyzeExpr(s.Cond)
		for _, st := range s.Body {
			a.analyzeStmt(st)
		}
		for _, ei := range s.ElseIfs {
			a.analyzeExpr(ei.Cond)
			for _, st := range ei.Body {
				a.analyzeStmt(st)
			}
		}
		for _, st := range s.ElseBody {
			a.analyzeStmt(st)
		}
	case *ast.DoWhileStmt:
		a.analyzeExpr(s.Cond)
		for _, st := range s.Body {
			a.analyzeStmt(st)
		}
	case *ast.ForStmt:
		a.markUsed(s.Var)
		a.analyzeExpr(s.Start)
		a.analyzeExpr(s.To)
		if s.Step != nil {
			a.analyzeExpr(s.Step)
		}
		for _, st := range s.Body {
			a.analyzeStmt(st)
		}
	case *ast.ForEachStmt:
		a.markUsed(s.Var)
		a.analyzeExpr(s.Collection)
		for _, st := range s.Body {
			a.analyzeStmt(st)
		}
	case *ast.SwitchStmt:
		a.analyzeExpr(s.Expr)
		for _, c := range s.Cases {
			a.analyzeExpr(c.Value)
			for _, st := range c.Body {
				a.analyzeStmt(st)
			}
		}
		for _, st := range s.Otherwise {
			a.analyzeStmt(st)
		}
	case *ast.SeqStmt:
		for _, st := range s.Body {
			a.analyzeStmt(st)
		}
		// RECOVER USING var — declare the variable in scope
		if s.RecoverVar != "" {
			a.scope.Declared[strings.ToUpper(s.RecoverVar)] = VarInfo{
				Name: s.RecoverVar,
				Pos:  s.BeginPos,
				Kind: ast.ScopeLocal,
			}
		}
		for _, st := range s.RecoverBody {
			a.analyzeStmt(st)
		}
	case *ast.QOutStmt:
		for _, e := range s.Exprs {
			a.analyzeExpr(e)
		}
	case *ast.VarDecl:
		// Mid-function LOCAL — register
		for _, v := range s.Vars {
			a.scope.Declared[strings.ToUpper(v.Name)] = VarInfo{
				Name: v.Name,
				Pos:  v.NamePos,
				Kind: s.Scope,
			}
			if v.Init != nil {
				a.analyzeExpr(v.Init)
			}
		}
	case *ast.MultiAssignStmt:
		for _, name := range s.Targets {
			if name != "_" {
				a.markUsed(name)
			}
		}
		for _, v := range s.Values {
			a.analyzeExpr(v)
		}
	case *ast.DeferStmt:
		a.analyzeExpr(s.Call)
	case *ast.ChanSendStmt:
		a.analyzeExpr(s.Chan)
		a.analyzeExpr(s.Value)
	case *ast.WatchStmt:
		for _, c := range s.Cases {
			if c.RecvChan != nil {
				a.analyzeExpr(c.RecvChan)
			}
			if c.SendChan != nil {
				a.analyzeExpr(c.SendChan)
			}
			if c.SendVal != nil {
				a.analyzeExpr(c.SendVal)
			}
			if c.RecvVar != "" {
				a.markUsed(c.RecvVar)
			}
			for _, st := range c.Body {
				a.analyzeStmt(st)
			}
		}
		for _, st := range s.Otherwise {
			a.analyzeStmt(st)
		}
	case *ast.ParallelForStmt:
		a.markUsed(s.Var)
		a.analyzeExpr(s.Start)
		a.analyzeExpr(s.To)
		for _, st := range s.Body {
			a.analyzeStmt(st)
		}
	case *ast.TimeoutStmt:
		a.analyzeExpr(s.Duration)
		for _, st := range s.Body {
			a.analyzeStmt(st)
		}
	}
}

func (a *Analyzer) analyzeExpr(expr ast.Expr) {
	if expr == nil {
		return
	}
	switch e := expr.(type) {
	case *ast.IdentExpr:
		a.checkVarUsage(e.Name, e.NamePos)
	case *ast.BinaryExpr:
		a.analyzeExpr(e.Left)
		a.analyzeExpr(e.Right)
	case *ast.UnaryExpr:
		a.analyzeExpr(e.X)
	case *ast.PostfixExpr:
		a.analyzeExpr(e.X)
	case *ast.AssignExpr:
		a.analyzeExpr(e.Left)
		a.analyzeExpr(e.Right)
	case *ast.CallExpr:
		a.analyzeExpr(e.Func)
		for _, arg := range e.Args {
			a.analyzeExpr(arg)
		}
	case *ast.SendExpr:
		a.analyzeExpr(e.Object)
		for _, arg := range e.Args {
			a.analyzeExpr(arg)
		}
	case *ast.IndexExpr:
		a.analyzeExpr(e.X)
		a.analyzeExpr(e.Index)
	case *ast.SliceExpr:
		a.analyzeExpr(e.X)
		if e.Low != nil {
			a.analyzeExpr(e.Low)
		}
		if e.High != nil {
			a.analyzeExpr(e.High)
		}
	case *ast.DotExpr:
		a.analyzeExpr(e.X)
	case *ast.ArrayLitExpr:
		for _, item := range e.Items {
			a.analyzeExpr(item)
		}
	case *ast.HashLitExpr:
		for i := range e.Keys {
			a.analyzeExpr(e.Keys[i])
			a.analyzeExpr(e.Values[i])
		}
	case *ast.BlockExpr:
		// Register block parameters (e.g., {|x,y| x + y})
		for _, p := range e.Params {
			a.scope.Declared[strings.ToUpper(p)] = VarInfo{
				Name:    p,
				Pos:     e.LBrace,
				IsParam: true,
			}
		}
		a.analyzeExpr(e.Body)
	case *ast.AliasExpr:
		a.analyzeExpr(e.Alias)
		a.analyzeExpr(e.Field)
	case *ast.MacroExpr:
		a.analyzeExpr(e.Expr)
	case *ast.RefExpr:
		a.analyzeExpr(e.X)
	case *ast.NilSafeExpr:
		a.analyzeExpr(e.X)
		for _, arg := range e.Args {
			a.analyzeExpr(arg)
		}
	case *ast.ChanRecvExpr:
		a.analyzeExpr(e.Chan)
	case *ast.AsyncExpr:
		a.analyzeExpr(e.Call)
	case *ast.AwaitExpr:
		a.analyzeExpr(e.Future)
	}
}

// checkVarUsage verifies a variable is declared and marks it used.
func (a *Analyzer) checkVarUsage(name string, pos token.Position) {
	upper := strings.ToUpper(name)

	// Skip well-known RTL functions and constants
	if a.isKnownFunction(upper) || a.isBuiltinConstant(upper) {
		return
	}

	// Mark as used
	a.markUsed(name)

	// Check if declared in current scope
	if _, ok := a.scope.Declared[upper]; ok {
		return
	}

	// Check if it's an IMPORT package name
	for _, imp := range a.file.Imports {
		parts := strings.Split(imp.Path, "/")
		pkgName := parts[len(parts)-1]
		if strings.EqualFold(pkgName, name) || (imp.Alias != "" && imp.Alias == name) {
			return
		}
	}

	// Not declared — warn (could be MEMVAR, FIELD, or typo)
	a.warn(pos, "undeclared variable '%s' (missing LOCAL?)", name)
}

func (a *Analyzer) markUsed(name string) {
	if a.scope != nil {
		a.scope.Used[strings.ToUpper(name)] = true
	}
}

// rtlFunctions contains all 479 RTL functions registered in hbrtl/register.go.
// Generated from: grep -o 'hbrt.Sym("[^"]*"' hbrtl/register.go
var rtlFunctions = map[string]bool{
	// Console
	"QOUT": true, "QQOUT": true,
	// String/Conversion
	"STR": true, "VAL": true, "LEN": true, "SUBSTR": true, "UPPER": true, "LOWER": true,
	"ALLTRIM": true, "LTRIM": true, "RTRIM": true, "TRIM": true, "SPACE": true,
	"PADR": true, "PADL": true, "PADC": true, "REPLICATE": true,
	// Type/Conversion
	"VALTYPE": true, "EMPTY": true, "ABS": true, "INT": true,
	// Array
	"AADD": true, "ADEL": true, "AINS": true, "ASIZE": true, "ACLONE": true,
	"ACOPY": true, "AFILL": true, "ASORT": true, "AEVAL": true, "ASCAN": true, "ATAIL": true,
	// Hash
	"HB_HASH": true, "HB_HGET": true, "HB_HSET": true, "HB_HDEL": true,
	"HB_HHASKEY": true, "HB_HKEYS": true, "HB_HVALUES": true,
	"HB_HPOS": true, "HB_HKEYAT": true, "HB_HVALUEAT": true, "HB_HCLONE": true,
	// Date/Time
	"DATE": true, "TIME": true, "YEAR": true, "MONTH": true, "DAY": true, "DOW": true,
	"SECONDS": true, "DTOC": true, "DTOS": true, "STOD": true, "CTOD": true,
	"CDOW": true, "CMONTH": true, "DAYS": true, "ELAPTIME": true, "AMPM": true, "SECS": true,
	// Eval
	"EVAL": true,
	// String Extended
	"AT": true, "LEFT": true, "RIGHT": true, "ASC": true, "CHR": true,
	"STRTRAN": true, "STUFF": true, "RAT": true, "HARDCR": true,
	"HB_STRREPLACE": true, "HB_NTOS": true, "DESCEND": true,
	"HB_VALTOSTR": true, "HB_VALTOEXP": true, "HB_CSTR": true,
	// Math
	"ROUND": true, "MAX": true, "MIN": true, "SQRT": true, "LOG": true, "EXP": true, "MOD": true,
	// Misc
	"TYPE": true, "PCOUNT": true, "BREAK": true, "ARRAY": true, "FCOUNT": true,
	"FIELDNAME": true, "SELECT": true, "FILE": true, "INKEY": true, "TRANSFORM": true,
	"SETDATEFORMAT": true, "SETEPOCH": true, "SETCENTURY": true,
	"IIF": true, "IF": true, "STRZERO": true, "OUTSTD": true, "OUTERR": true,
	"CENTER": true, "SOUNDEX": true, "TONE": true,
	// Terminal
	"SETPOS": true, "ROW": true, "COL": true, "DEVPOS": true, "DEVOUT": true,
	"DISPOUT": true, "DEVOUTPICT": true, "DISPBOX": true, "CLS": true, "SCROLL": true,
	"SETCOLOR": true, "SETCURSOR": true, "MAXROW": true, "MAXCOL": true,
	// dbEdit/Browse
	"DBEDIT": true, "TBROWSEDB": true, "TBROWSENEW": true, "TBCOLUMNNEW": true,
	// RDD
	"EOF": true, "BOF": true, "FOUND": true, "RECNO": true, "RECCOUNT": true,
	"LASTREC": true, "DELETED": true, "FIELDGET": true, "FIELDPUT": true,
	"FIELDPOS": true, "FIELDBLOCK": true, "FIELDWBLOCK": true, "AFIELDS": true,
	"DBSTRUCT": true,
	// Database
	"ALIAS": true, "DBEVAL": true, "USED": true, "DBUSEAREA": true,
	"DBCLOSEAREA": true, "DBCLOSEALL": true, "DBGOTO": true, "DBSKIP": true,
	"DBGOTOP": true, "DBGOBOTTOM": true, "DBAPPEND": true, "DBDELETE": true,
	"DBRECALL": true, "DBCOMMIT": true, "DBRLOCK": true, "DBRUNLOCK": true,
	"DBSEEK": true, "DBSELECTAREA": true, "DBPACK": true, "DBZAP": true,
	"DBCREATE": true, "DBINFO": true, "DBORDERINFO": true, "DBSETINDEX": true,
	// FiveSql2 hybrid hot-path RTL (pcode + Go-native scan)
	"PCCOMPILE": true, "PCEVAL": true, "SQLSCAN": true, "SQLEACH": true,
	"SQLHASHBUILD": true, "SQLHASHJOIN": true,
	"SQLORDERBY": true, "SQLGROUPBY": true,
	// Field metadata + index creation
	"FIELDTYPE": true, "FIELDLEN": true, "FIELDDEC": true,
	"ORDCREATE": true, "DBCREATEINDEX": true, "DBCLEARINDEX": true,
	"RECALL": true, "PACK": true, "ZAP": true,
	"FLOCK": true, "DBUNLOCK": true,
	"__DBPACK": true, "__DBZAP": true,
	// Locate/Filter
	"DBLOCATE": true, "__DBLOCATE": true, "__DBCONTINUE": true,
	"DBSETFILTER": true, "DBCLEARFILTER": true, "DBFILTER": true,
	// Encoding/Hashing
	"HB_MD5": true, "HB_SHA256": true, "HB_BASE64ENCODE": true,
	"HB_BASE64DECODE": true, "HB_CRC32": true,
	// Bit Operations
	"HB_BITAND": true, "HB_BITOR": true, "HB_BITXOR": true, "HB_BITNOT": true,
	"HB_BITSHIFT": true, "HB_BITTEST": true, "HB_BITSET": true, "HB_BITRESET": true,
	// Regex
	"HB_REGEXCOMP": true, "HB_REGEXMATCH": true, "HB_REGEXSPLIT": true,
	"HB_REGEXALL": true, "HB_REGEXREPLACE": true,
	// Memo
	"MEMOREAD": true, "MEMOWRIT": true, "MEMOTRAN": true, "MEMOLINE": true, "MLCOUNT": true,
	// Binary Conversion
	"BIN2I": true, "BIN2L": true, "BIN2W": true, "I2BIN": true, "L2BIN": true, "W2BIN": true,
	// Keyboard
	"LASTKEY": true, "NEXTKEY": true, "READKEY": true, "SETKEY": true,
	"KEYBOARD": true, "HB_KEYPUT": true, "HB_KEYCHAR": true, "HB_KEYINS": true,
	// Display
	"DISPBEGIN": true, "DISPEND": true, "DISPCOUNT": true,
	"SAVESCREEN": true, "RESTSCREEN": true, "ALERT": true,
	// Error Handling
	"ERRORBLOCK": true, "ERRORNEW": true, "DOSERROR": true, "FERROR": true, "ERRORSYS": true,
	// SET Commands
	"SET": true, "__SETDATEFORMAT": true, "__SETDECIMALS": true, "__SETEPOCH": true,
	"SETDELETED": true, "SETEXACT": true, "SETSOFTSEEK": true, "SETEXCLUSIVE": true,
	"SETFIXED": true, "SETCANCEL": true, "SETBELL": true, "SETCONFIRM": true,
	"SETINSERT": true, "SETESCAPE": true, "SETWRAP": true,
	"_SET_EXACT": true, "_SET_DELETED": true, "_SET_SOFTSEEK": true,
	"_SET_EXCLUSIVE": true, "_SET_DATEFORMAT": true, "_SET_DECIMALS": true, "_SET_EPOCH": true,
	// File I/O
	"FOPEN": true, "FCREATE": true, "FCLOSE": true, "FREAD": true, "FWRITE": true,
	"FSEEK": true, "FERASE": true, "FRENAME": true, "HB_FILEEXISTS": true,
	// Directory/Disk
	"CURDIR": true, "DIRCHANGE": true, "DIRECTORY": true, "DIRMAKE": true,
	"DIRREMOVE": true, "DISKSPACE": true,
	// Type Checking
	"HB_ISARRAY": true, "HB_ISBLOCK": true, "HB_ISCHAR": true, "HB_ISSTRING": true,
	"HB_ISDATE": true, "HB_ISDATETIME": true, "HB_ISLOGICAL": true, "HB_ISNUMERIC": true,
	"HB_ISOBJECT": true, "HB_ISHASH": true, "HB_ISNIL": true, "HB_ISPOINTER": true,
	"HB_ISEVALITEM": true, "HB_ISNULL": true,
	// OS/Environment
	"GETENV": true, "HB_GETENV": true, "SETENV": true, "HB_SETENV": true,
	"OS": true, "VERSION": true, "HB_RUN": true,
	"HB_FNAMEDIR": true, "HB_FNAMEEXT": true, "HB_FNAMENAME": true, "HB_FNAMEMERGE": true,
	"HB_FNAMESPLIT": true, "HB_FNAMEEXISTS": true, "HB_FNAMEEXTSET": true, "HB_FNAMENAMEEXT": true,
	// Character Classification
	"ISDIGIT": true, "ISALPHA": true, "ISALNUM": true,
	"ISUPPER": true, "ISLOWER": true, "ISSPACE": true,
	// Harbour Extensions
	"HB_ASCIIUPPER": true, "HB_ASCIILOWER": true,
	"HB_DEFAULT": true, "HB_DEFAULTVALUE": true,
	"HB_DISPOUTAT": true, "HB_DISPOUTATBOX": true, "HB_DISPBOX": true,
	"HB_COLORINDEX": true, "HB_LEFTEQ": true, "HB_LEFTEQI": true,
	"HB_VAL": true, "HB_TOKENGET": true, "HB_TOKENCOUNT": true,
	"__DEFAULTNIL": true, "MEMVARBLOCK": true,
	// Bitmap/Rushmore
	"BM_DBSETFILTER": true, "BM_DBSEEKWILD": true, "BM_TURBO": true,
	"BM_DBGETFILTERARRAY": true, "BM_DBSETFILTERARRAY": true,
	"BM_DBSETFILTERARRAYADD": true, "BM_DBSETFILTERARRAYDEL": true,
	// HBSIX Compatibility
	"SX_SETTAG": true, "SX_INDEXTAG": true, "SX_TAGORDER": true,
	"SX_TAGCOUNT": true, "SX_TAGS": true, "SX_SETFILEORD": true,
	"SX_ISDBT": true, "SX_ISFPT": true, "SX_ISSMT": true,
	"SX_AUTOOPEN": true, "SX_AUTOSHARE": true, "SX_BLOB2FILE": true,
	"SX_FILE2BLOB": true, "SX_SETTRIGGER": true, "SX_VFGET": true,
	"SX_DBFENCRYPT": true, "SX_DBFDECRYPT": true, "SX_COMPRESS": true,
	"SX_DECOMPRESS": true, "RDDINFO": true, "RDDNAME": true, "RDDLIST": true,
	// Timestamp
	"HB_DATETIME": true, "HB_HOUR": true, "HB_MINUTE": true, "HB_SEC": true,
	"HB_TTOC": true, "HB_CTOT": true, "HB_SECOND": true, "HB_ATOKENS": true,
	"HB_CDPSELECT": true, "HB_TTOS": true, "HB_STOT": true, "HB_MILLISECONDS": true,
	"HB_DATE": true, "HB_CTOD": true, "HB_DTOC": true, "HB_STOD": true,
	"HB_DTOT": true, "HB_TTOD": true, "HB_TTOHOUR": true, "HB_TTOMIN": true,
	"HB_TTOSEC": true, "HB_TTOMSEC": true, "HB_TTON": true, "HB_NTOT": true,
	"HB_NTOHOUR": true, "HB_NTOMIN": true, "HB_NTOSEC": true,
	"HB_WEEK": true, "HB_CDAY": true,
	// Index/DB Introspection
	"INDEXORD": true, "INDEXKEY": true, "ORDSETFOCUS": true, "ORDCOUNT": true,
	"ORDNAME": true, "ORDKEY": true, "ORDFOR": true, "ORDINFO": true,
	"ORDSCOPE": true, "RDDSETDEFAULT": true,
	// Directory/Temp
	"HB_DIREXISTS": true, "HB_DIRCREATE": true, "HB_FTEMPCREATE": true, "HB_DIRTEMP": true,
	// File Extended
	"HB_FSIZE": true, "HB_FCOPY": true, "HB_FEOF": true, "HB_FCOMMIT": true,
	"HB_FREADLEN": true, "HB_FGETATTR": true, "HB_FSETATTR": true,
	"HB_FGETDATETIME": true, "HB_FSETDATETIME": true, "HB_FLOCK": true, "HB_FUNLOCK": true,
	"HB_FILEDELETE": true, "HB_FILEMATCH": true,
	"HB_MEMOREAD": true, "HB_MEMOWRIT": true, "HB_DISKSPACE": true,
	// String Extended 2
	"HB_AT": true, "HB_RAT": true, "HB_ATI": true, "HB_ATX": true,
	"HB_ASCIIISALPHA": true, "HB_ASCIIISDIGIT": true,
	"HB_ASCIIISLOWER": true, "HB_ASCIIISUPPER": true,
	"HB_STRISUTF8": true, "HB_STRDECODESCAPE": true, "HB_STRXOR": true,
	"HB_WILDMATCH": true, "HB_WILDMATCHI": true,
	"HB_STRTOHEX": true, "HB_HEXTOSTR": true, "HB_STRFORMAT": true,
	// Hex Conversion
	"HB_NUMTOHEX": true, "HB_HEXTONUM": true,
	// Token
	"TOKEN": true, "NUMTOKEN": true,
	// Stack Introspection
	"PROCNAME": true, "PROCLINE": true, "PROCFILE": true, "ERRORLEVEL": true,
	// JSON
	"HB_JSONENCODE": true, "HB_JSONDECODE": true,
	"JSONPRETTY": true, "JSONTO": true, "JSONFROM": true, "JSONPATH": true,
	"JSONMERGE": true, "JSONTYPE": true, "JSONVALID": true,
	"JSONHTTPGET": true, "JSONHTTPPOST": true,
	// Random
	"HB_RANDOM": true, "HB_RANDOMINT": true, "HB_RANDOMSEED": true, "HB_RANDSTR": true,
	// OS Info
	"HB_VERSION": true, "HB_COMPILER": true, "HB_OSNEWLINE": true,
	"HB_OSPATHSEPARATOR": true, "HB_CWD": true, "HB_DIRBASE": true,
	"HB_PROGNAME": true, "HB_USERNAME": true, "HB_GETHOSTNAME": true,
	// Process
	"HB_PROCESSRUN": true, "WAIT": true,
	// UTF-8
	"HB_UTF8TOSTR": true, "HB_STRTOUTF8": true, "HB_UTF8LEN": true,
	"HB_UTF8SUBSTR": true, "HB_UTF8LEFT": true, "HB_UTF8RIGHT": true, "HB_UTF8AT": true,
	// FRB
	"FRBLOAD": true, "FRBDO": true, "FRBUNLOAD": true, "FRBRUN": true,
	"FRBCOMPILE": true, "FRBEXEC": true,
	// Concurrency
	"GO": true, "CHANNEL": true, "CHSEND": true, "CHRECEIVE": true, "CHCLOSE": true,
	"WAITGROUP": true, "WGDONE": true, "WGWAIT": true, "WGADD": true,
	"MUTEX": true, "LOCK": true, "UNLOCK": true, "SLEEP": true,
	// Harbour compat aliases
	"HB_SYMBOL_UNUSED": true, "HB_IDLEADD": true, "HB_IDLESLEEP": true,
	"HB_PS": true, "HB_EOL": true,
}

func (a *Analyzer) isKnownFunction(name string) bool {
	// Check declared functions in this file (and external files)
	if a.funcNames[name] {
		return true
	}
	return rtlFunctions[name]
}

func (a *Analyzer) isBuiltinConstant(name string) bool {
	constants := map[string]bool{
		"NIL": true, "TRUE": true, "FALSE": true,
		"SELF": true, "SUPER": true,
		// Harbour commands treated as identifiers
		"QUIT": true, "ERRORLEVEL": true,
		// Field/Memvar alias prefixes
		"FIELD": true, "_FIELD": true, "M": true, "MEMVAR": true,
		// Keyboard constants
		"K_ESC": true, "K_ENTER": true, "K_UP": true, "K_DOWN": true,
		"K_LEFT": true, "K_RIGHT": true, "K_PGUP": true, "K_PGDN": true,
		// Alternate source (SET ALTERNATE)
		"ALTSRC": true,
	}
	return constants[name]
}

// --- Diagnostic helpers ---

func (a *Analyzer) diag(sev Severity, pos token.Position, format string, args ...interface{}) {
	a.diagnostics = append(a.diagnostics, Diagnostic{
		Pos:      pos,
		Message:  fmt.Sprintf(format, args...),
		Severity: sev,
	})
}

func (a *Analyzer) errorf(pos token.Position, format string, args ...interface{}) {
	a.diag(SevError, pos, format, args...)
}

func (a *Analyzer) warn(pos token.Position, format string, args ...interface{}) {
	a.diag(SevWarning, pos, format, args...)
}

func (a *Analyzer) hint(pos token.Position, format string, args ...interface{}) {
	a.diag(SevHint, pos, format, args...)
}