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

package gengo

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

// hasXBaseCommands checks if the file contains any xBase commands.
func hasXBaseCommands(file *ast.File) bool {
	for _, d := range file.Decls {
		switch decl := d.(type) {
		case *ast.FuncDecl:
			if scanStmtsForXBase(decl.Body) {
				return true
			}
		case *ast.MethodDecl:
			if scanStmtsForXBase(decl.Body) {
				return true
			}
		}
	}
	return false
}

// xbaseFuncNames is the set of RTL functions that require the hbrdd import
// in the generated Go code. When a PRG only uses these via function-call
// syntax (no xBase commands like USE), the compiler still needs hbrdd.
var xbaseFuncNames = map[string]bool{
	"DBUSEAREA": true, "DBCREATE": true, "DBAPPEND": true, "DBSKIP": true,
	"DBGOTO": true, "DBGOTOP": true, "DBGOBOTTOM": true, "DBSEEK": true,
	"DBDELETE": true, "DBRECALL": true, "DBCLOSEAREA": true, "DBCLOSEALL": true,
	"DBSELECTAREA": true, "DBCOMMIT": true, "DBPACK": true, "DBZAP": true,
	"DBRLOCK": true, "DBRUNLOCK": true, "FLOCK": true, "DBUNLOCK": true,
	"FIELDGET": true, "FIELDPUT": true, "FIELDPOS": true, "FIELDNAME": true,
	"FCOUNT": true, "RECNO": true, "RECCOUNT": true, "EOF": true, "BOF": true,
	"FOUND": true, "DELETED": true, "LASTREC": true, "ALIAS": true,
	"ORDSETFOCUS": true, "ORDCOUNT": true, "ORDNAME": true, "ORDKEY": true,
	"USED": true, "SELECT": true, "SETDELETED": true,
	"FIVE_SQL": true, // FiveSql2 entry point also needs hbrdd
}

func scanExprForXBase(expr ast.Expr) bool {
	if expr == nil {
		return false
	}
	switch e := expr.(type) {
	case *ast.CallExpr:
		if ident, ok := e.Func.(*ast.IdentExpr); ok {
			if xbaseFuncNames[strings.ToUpper(ident.Name)] {
				return true
			}
		}
		for _, arg := range e.Args {
			if scanExprForXBase(arg) {
				return true
			}
		}
	case *ast.BinaryExpr:
		return scanExprForXBase(e.Left) || scanExprForXBase(e.Right)
	case *ast.AssignExpr:
		return scanExprForXBase(e.Right)
	case *ast.AliasExpr:
		// FIELD->NAME always needs hbrdd
		return true
	}
	return false
}

// countLocalsInStmts walks a statement list (recursively into IF /
// FOR / WHILE / DO CASE / SWITCH / SEQUENCE / WITH bodies) and totals
// every `LOCAL` declaration found. Function-entry frame allocation
// must include these so a mid-function or nested LOCAL doesn't get
// assigned a slot index past the runtime's allocated count — that
// previously surfaced as silent NIL reads / out-of-range writes
// (e.g. frb_demo Section 4 with `LOCAL ch := Channel(1)` inside an
// IF block returning NIL on receive).
func countLocalsInStmts(stmts []ast.Stmt) int {
	n := 0
	for _, s := range stmts {
		switch v := s.(type) {
		case *ast.VarDecl:
			if v.Scope == ast.ScopeLocal {
				n += len(v.Vars)
			}
		case *ast.IfStmt:
			n += countLocalsInStmts(v.Body)
			for _, ei := range v.ElseIfs {
				n += countLocalsInStmts(ei.Body)
			}
			n += countLocalsInStmts(v.ElseBody)
		case *ast.ForStmt:
			n += countLocalsInStmts(v.Body)
		case *ast.ForEachStmt:
			n += countLocalsInStmts(v.Body)
		case *ast.DoWhileStmt:
			n += countLocalsInStmts(v.Body)
		case *ast.SeqStmt:
			n += countLocalsInStmts(v.Body)
			n += countLocalsInStmts(v.RecoverBody)
		case *ast.SwitchStmt:
			for _, c := range v.Cases {
				n += countLocalsInStmts(c.Body)
			}
			n += countLocalsInStmts(v.Otherwise)
		case *ast.WatchStmt:
			// `WATCH ... CASE ... CASE ... OTHERWISE ... END WATCH`
			// — each CASE body and OTHERWISE may declare LOCALs.
			for _, c := range v.Cases {
				n += countLocalsInStmts(c.Body)
			}
			n += countLocalsInStmts(v.Otherwise)
		case *ast.TimeoutStmt:
			// `WITH TIMEOUT n SECONDS ... END` — body may declare LOCALs.
			n += countLocalsInStmts(v.Body)
		case *ast.ParallelForStmt:
			// `PARALLEL FOR i := ... NEXT` — body may declare LOCALs.
			n += countLocalsInStmts(v.Body)
		}
	}
	return n
}

func scanStmtsForXBase(stmts []ast.Stmt) bool {
	for _, s := range stmts {
		switch v := s.(type) {
		case *ast.UseCmd, *ast.GoCmd, *ast.SkipCmd, *ast.SeekCmd,
			*ast.ReplaceCmd, *ast.AppendCmd, *ast.DeleteCmd,
			*ast.SelectCmd, *ast.IndexCmd, *ast.SetCmd:
			return true
		case *ast.ExprStmt:
			if scanExprForXBase(v.X) {
				return true
			}
		case *ast.IfStmt:
			if scanStmtsForXBase(v.Body) || scanStmtsForXBase(v.ElseBody) {
				return true
			}
			for _, ei := range v.ElseIfs {
				if scanStmtsForXBase(ei.Body) {
					return true
				}
			}
		case *ast.ForStmt:
			if scanStmtsForXBase(v.Body) {
				return true
			}
		case *ast.ForEachStmt:
			if scanStmtsForXBase(v.Body) {
				return true
			}
		case *ast.DoWhileStmt:
			if scanStmtsForXBase(v.Body) {
				return true
			}
		case *ast.SeqStmt:
			if scanStmtsForXBase(v.Body) || scanStmtsForXBase(v.RecoverBody) {
				return true
			}
		case *ast.SwitchStmt:
			for _, c := range v.Cases {
				if scanStmtsForXBase(c.Body) {
					return true
				}
			}
		}
	}
	return false
}