five/cmd/five/main.go

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

// Five CLI — the Harbour + Go fusion language tool.
//
// Usage:
//   five run <file.prg>           Compile and run a PRG file
//   five build <file.prg> [-o out] Compile to native binary
//   five gen <file.prg>           Generate Go source (for debugging)
package main

import (
	"five/compiler/analyzer"
	"five/compiler/ast"
	"five/compiler/gengo"
	"five/compiler/genpc"
	"five/compiler/parser"
	"five/compiler/pp"
	"five/hbrt"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

func main() {
	if len(os.Args) < 2 {
		printUsage()
		os.Exit(1)
	}

	cmd := os.Args[1]
	switch cmd {
	case "run":
		if len(os.Args) < 3 {
			fatal("usage: five run <file.prg>")
		}
		runPRG(os.Args[2])
	case "build":
		if len(os.Args) < 3 {
			fatal("usage: five build <file.prg> [file2.prg ...] [-o output] [-I includedir]")
		}
		output := ""
		var prgFiles []string
		var includeDirs []string
		for i := 2; i < len(os.Args); i++ {
			if os.Args[i] == "-o" && i+1 < len(os.Args) {
				output = os.Args[i+1]
				i++
			} else if os.Args[i] == "-I" && i+1 < len(os.Args) {
				includeDirs = append(includeDirs, os.Args[i+1])
				i++
			} else if strings.HasPrefix(os.Args[i], "-I") {
				includeDirs = append(includeDirs, os.Args[i][2:])
			} else {
				prgFiles = append(prgFiles, os.Args[i])
			}
		}
		if len(prgFiles) == 1 {
			buildPRGWithIncludes(prgFiles[0], output, includeDirs)
		} else {
			buildMultiPRGWithIncludes(prgFiles, output, includeDirs)
		}
	case "gen":
		if len(os.Args) < 3 {
			fatal("usage: five gen <file.prg>")
		}
		genPRG(os.Args[2])
	case "debug":
		if len(os.Args) < 3 {
			fatal("usage: five debug <file.prg>")
		}
		debugPRG(os.Args[2])
	case "frb":
		if len(os.Args) < 3 {
			fatal("usage: five frb <file.prg> [-o output.frb] [--pcode]")
		}
		output := ""
		prgFile := os.Args[2]
		pcodeMode := false
		for i := 3; i < len(os.Args); i++ {
			if os.Args[i] == "-o" && i+1 < len(os.Args) {
				output = os.Args[i+1]
				i++
			} else if os.Args[i] == "--pcode" {
				pcodeMode = true
			}
		}
		if output == "" {
			base := strings.TrimSuffix(filepath.Base(prgFile), filepath.Ext(prgFile))
			output = base + ".frb"
		}
		if pcodeMode {
			buildFRBPcode(prgFile, output)
		} else {
			buildFRB(prgFile, output)
		}
	case "version":
		fmt.Println("Five 0.1.0 — Harbour + Go fusion language")
		fmt.Println("Copyright (c) 2026 Charles KWON OhJun")
	default:
		fmt.Fprintf(os.Stderr, "unknown command: %s\n", cmd)
		printUsage()
		os.Exit(1)
	}
}

func printUsage() {
	fmt.Fprintln(os.Stderr, "Five — Harbour + Go fusion language")
	fmt.Fprintln(os.Stderr, "")
	fmt.Fprintln(os.Stderr, "Usage:")
	fmt.Fprintln(os.Stderr, "  five run <file.prg>           Compile and run")
	fmt.Fprintln(os.Stderr, "  five build <file.prg> [-o out] Compile to binary")
	fmt.Fprintln(os.Stderr, "  five gen <file.prg>           Show generated Go code")
	fmt.Fprintln(os.Stderr, "  five debug <file.prg>         Debug with interactive debugger")
	fmt.Fprintln(os.Stderr, "  five frb <file.prg> [-o out]  Compile to FRB module")
	fmt.Fprintln(os.Stderr, "  five version                  Show version")
}

// runPRG compiles a PRG file and runs it immediately.
func runPRG(prgFile string) {
	goCode := compilePRG(prgFile)

	// Create temp build directory
	tmpDir, err := os.MkdirTemp("", "five-build-*")
	if err != nil {
		fatal("failed to create temp dir: " + err.Error())
	}
	if os.Getenv("FIVE_KEEP_BUILD") == "" {
		defer os.RemoveAll(tmpDir)
	} else {
		fmt.Fprintln(os.Stderr, "[FIVE_KEEP_BUILD] keeping:", tmpDir)
	}

	writeGoProject(tmpDir, prgFile, goCode)

	// go run
	cmd := exec.Command(goPath(), "run", ".")
	cmd.Dir = tmpDir
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		if exitErr, ok := err.(*exec.ExitError); ok {
			os.Exit(exitErr.ExitCode())
		}
		fatal("run failed: " + err.Error())
	}
}

// buildPRG compiles a PRG file to a native binary.
func buildPRG(prgFile, output string) {
	goCode := compilePRG(prgFile)

	if output == "" {
		base := strings.TrimSuffix(filepath.Base(prgFile), filepath.Ext(prgFile))
		output = base
	}

	// Create temp build directory
	tmpDir, err := os.MkdirTemp("", "five-build-*")
	if err != nil {
		fatal("failed to create temp dir: " + err.Error())
	}
	if os.Getenv("FIVE_KEEP_BUILD") == "" {
		defer os.RemoveAll(tmpDir)
	} else {
		fmt.Fprintln(os.Stderr, "[FIVE_KEEP_BUILD] keeping:", tmpDir)
	}

	writeGoProject(tmpDir, prgFile, goCode)

	// Resolve absolute path for output
	absOutput, err := filepath.Abs(output)
	if err != nil {
		fatal("cannot resolve output path: " + err.Error())
	}

	// go build
	cmd := exec.Command(goPath(), "build", "-o", absOutput, ".")
	cmd.Dir = tmpDir
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		fatal("build failed: " + err.Error())
	}

	fmt.Fprintf(os.Stderr, "Built: %s\n", absOutput)
}

// genPRG generates Go source and prints it to stdout.
func genPRG(prgFile string) {
	goCode := compilePRG(prgFile)
	fmt.Print(goCode)
}

// buildMultiPRG compiles multiple PRG files into one binary.
func buildMultiPRG(prgFiles []string, output string) {
	if output == "" {
		base := strings.TrimSuffix(filepath.Base(prgFiles[0]), filepath.Ext(prgFiles[0]))
		output = base
	}

	tmpDir, err := os.MkdirTemp("", "five-build-*")
	if err != nil {
		fatal("failed to create temp dir: " + err.Error())
	}
	if os.Getenv("FIVE_KEEP_BUILD") == "" {
		defer os.RemoveAll(tmpDir)
	} else {
		fmt.Fprintln(os.Stderr, "[FIVE_KEEP_BUILD] keeping:", tmpDir)
	}

	// Phase 1: Parse all files and collect cross-file function names
	type parsedFile struct {
		file    *ast.File
		prgFile string
	}
	var parsed []parsedFile
	crossFileFuncs := make(map[string]bool)

	for _, prgFile := range prgFiles {
		f := parsePRGFile(prgFile)
		parsed = append(parsed, parsedFile{file: f, prgFile: prgFile})
		for _, d := range f.Decls {
			switch decl := d.(type) {
			case *ast.FuncDecl:
				crossFileFuncs[strings.ToUpper(decl.Name)] = true
			case *ast.ClassDecl:
				crossFileFuncs[strings.ToUpper(decl.Name)] = true
			}
		}
	}

	// Phase 2: Analyze and generate each file with cross-file function awareness
	for i, pf := range parsed {
		diags := analyzer.Analyze(pf.file, crossFileFuncs)
		for _, d := range diags {
			if d.Severity <= analyzer.SevWarning {
				fmt.Fprintf(os.Stderr, "%s\n", d)
			}
		}

		var goCode string
		if i > 0 {
			goCode = gengo.GenerateLibrary(pf.file)
		} else {
			goCode = gengo.Generate(pf.file)
		}
		goFile := fmt.Sprintf("prg_%d.go", i)
		writeFile(filepath.Join(tmpDir, goFile), goCode)
	}

	// Write go.mod
	fiveRoot := findFiveRoot()
	goMod := fmt.Sprintf("module five-generated\n\ngo 1.21\n\nrequire five v0.0.0\n\nreplace five => %s\n", fiveRoot)
	writeFile(filepath.Join(tmpDir, "go.mod"), goMod)

	// go mod tidy
	tidy := exec.Command(goPath(), "mod", "tidy")
	tidy.Dir = tmpDir
	tidy.Stderr = os.Stderr
	if err := tidy.Run(); err != nil {
		fmt.Fprintf(os.Stderr, "warning: go mod tidy: %v\n", err)
	}

	// go build
	absOutput, err := filepath.Abs(output)
	if err != nil {
		fatal("cannot resolve output path: " + err.Error())
	}
	cmd := exec.Command(goPath(), "build", "-o", absOutput, ".")
	cmd.Dir = tmpDir
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		fatal("build failed: " + err.Error())
	}
	fmt.Fprintf(os.Stderr, "Built: %s\n", absOutput)
}

// Global user include dirs (set by build command, used by compilePRGMode)
var userIncludeDirs []string

// buildPRGWithIncludes is buildPRG with -I support.
func buildPRGWithIncludes(prgFile, output string, includes []string) {
	userIncludeDirs = includes
	buildPRG(prgFile, output)
}

// buildMultiPRGWithIncludes is buildMultiPRG with -I support.
func buildMultiPRGWithIncludes(prgFiles []string, output string, includes []string) {
	userIncludeDirs = includes
	buildMultiPRG(prgFiles, output)
}

// parsePRGFile preprocesses and parses a PRG file, returning the AST.
func parsePRGFile(prgFile string) *ast.File {
	source, err := os.ReadFile(prgFile)
	if err != nil {
		fatal("cannot read file: " + err.Error())
	}

	pre := pp.New()
	pre.AddIncludeDir(filepath.Dir(prgFile))
	pre.AddIncludeDir(filepath.Join(filepath.Dir(prgFile), "include"))
	fiveRoot := findFiveRoot()
	pre.AddIncludeDir(filepath.Join(fiveRoot, "include"))
	if exePath, err := os.Executable(); err == nil {
		pre.AddIncludeDir(filepath.Join(filepath.Dir(exePath), "include"))
	}
	for _, dir := range userIncludeDirs {
		pre.AddIncludeDir(dir)
	}
	if hbInc := os.Getenv("HB_INC"); hbInc != "" {
		pre.AddIncludeDir(hbInc)
	}
	for _, p := range []string{"/usr/local/include/harbour", "/usr/include/harbour"} {
		if _, err := os.Stat(p); err == nil {
			pre.AddIncludeDir(p)
		}
	}

	processed, ppErrors := pre.Process(prgFile, string(source))
	for _, e := range ppErrors {
		fmt.Fprintf(os.Stderr, "pp: %s\n", e)
	}

	file, errs := parser.ParseWithGoDumps(prgFile, processed, pre.GoDumps)
	if len(errs) > 0 {
		for _, e := range errs {
			fmt.Fprintf(os.Stderr, "%s\n", e)
		}
		fatal(fmt.Sprintf("%d parse error(s) in %s", len(errs), prgFile))
	}
	return file
}

// compilePRGMode compiles with library flag support.
func compilePRGMode(prgFile string, isLibrary bool) string {
	source, err := os.ReadFile(prgFile)
	if err != nil {
		fatal("cannot read file: " + err.Error())
	}

	pre := pp.New()
	pre.AddIncludeDir(filepath.Dir(prgFile))
	pre.AddIncludeDir(filepath.Join(filepath.Dir(prgFile), "include"))
	// Five's own include directory (from project root) — must come BEFORE Harbour system includes
	fiveRoot := findFiveRoot()
	pre.AddIncludeDir(filepath.Join(fiveRoot, "include"))
	if exePath, err := os.Executable(); err == nil {
		pre.AddIncludeDir(filepath.Join(filepath.Dir(exePath), "include"))
	}
	// User-specified -I directories — before Harbour system includes
	for _, dir := range userIncludeDirs {
		pre.AddIncludeDir(dir)
	}
	// Harbour include paths from environment or standard locations (LAST)
	if hbInc := os.Getenv("HB_INC"); hbInc != "" {
		pre.AddIncludeDir(hbInc)
	}
	for _, p := range []string{"/usr/local/include/harbour", "/usr/include/harbour"} {
		if _, err := os.Stat(p); err == nil {
			pre.AddIncludeDir(p)
		}
	}

	processed, ppErrors := pre.Process(prgFile, string(source))
	for _, e := range ppErrors {
		fmt.Fprintf(os.Stderr, "pp: %s\n", e)
	}

	file, errs := parser.ParseWithGoDumps(prgFile, processed, pre.GoDumps)
	if len(errs) > 0 {
		for _, e := range errs {
			fmt.Fprintf(os.Stderr, "%s\n", e)
		}
		fatal(fmt.Sprintf("%d parse error(s) in %s", len(errs), prgFile))
	}

	// Semantic analysis (warnings — non-fatal)
	diags := analyzer.Analyze(file)
	for _, d := range diags {
		if d.Severity <= analyzer.SevWarning {
			fmt.Fprintf(os.Stderr, "%s\n", d)
		}
	}

	if isLibrary {
		return gengo.GenerateLibrary(file)
	}
	return gengo.Generate(file)
}

// compilePRG preprocesses, parses, and generates Go source.
func compilePRG(prgFile string) string {
	source, err := os.ReadFile(prgFile)
	if err != nil {
		fatal("cannot read file: " + err.Error())
	}

	// Phase 1: Preprocessor (#include, #define, #ifdef)
	pre := pp.New()
	pre.AddIncludeDir(filepath.Dir(prgFile))
	pre.AddIncludeDir(filepath.Join(filepath.Dir(prgFile), "include"))
	// Five's own include directory — MUST come before Harbour system includes
	fiveRoot := findFiveRoot()
	pre.AddIncludeDir(filepath.Join(fiveRoot, "include"))
	if exePath, err := os.Executable(); err == nil {
		pre.AddIncludeDir(filepath.Join(filepath.Dir(exePath), "include"))
	}
	// User-specified -I directories
	for _, dir := range userIncludeDirs {
		pre.AddIncludeDir(dir)
	}
	// Harbour include paths (LAST — Five's own headers take priority)
	if harbourInc := os.Getenv("HB_INC"); harbourInc != "" {
		pre.AddIncludeDir(harbourInc)
	}
	for _, p := range []string{"/usr/local/include/harbour", "/usr/include/harbour"} {
		if _, err := os.Stat(p); err == nil {
			pre.AddIncludeDir(p)
		}
	}

	processed, ppErrors := pre.Process(prgFile, string(source))
	for _, e := range ppErrors {
		fmt.Fprintf(os.Stderr, "pp: %s\n", e)
	}

	// Phase 2: Parse
	file, errs := parser.ParseWithGoDumps(prgFile, processed, pre.GoDumps)
	if len(errs) > 0 {
		for _, e := range errs {
			fmt.Fprintf(os.Stderr, "%s\n", e)
		}
		fatal(fmt.Sprintf("%d parse error(s)", len(errs)))
	}

	// Phase 2.5: Analyze (warnings — non-fatal)
	diags := analyzer.Analyze(file)
	for _, d := range diags {
		if d.Severity <= analyzer.SevWarning {
			fmt.Fprintf(os.Stderr, "%s\n", d)
		}
	}

	// Phase 3: Generate
	return gengo.Generate(file)
}

// writeGoProject creates a temporary Go project with the generated code.
func writeGoProject(dir, prgFile, goCode string) {
	// Find the Five module path (where go.mod is)
	fiveRoot := findFiveRoot()

	// go.mod with replace directive pointing to Five source
	goMod := fmt.Sprintf(`module five-generated

go 1.21

require five v0.0.0

replace five => %s
`, fiveRoot)

	writeFile(filepath.Join(dir, "go.mod"), goMod)
	writeFile(filepath.Join(dir, "main.go"), goCode)

	// Run go mod tidy to resolve dependencies
	tidy := exec.Command(goPath(), "mod", "tidy")
	tidy.Dir = dir
	tidy.Stderr = os.Stderr
	if err := tidy.Run(); err != nil {
		// Non-fatal — some environments may not need it
		_ = err
	}
}

// findFiveRoot finds the root directory of the Five project (where go.mod is).
// findFiveRoot finds the Five project root (directory containing go.mod with "module five").
// Tries: 1) walk up from cwd, 2) walk up from executable. Fallback: cwd.
func findFiveRoot() string {
	if root := walkUpForGoMod(""); root != "" {
		return root
	}
	if exe, err := os.Executable(); err == nil {
		if root := walkUpForGoMod(filepath.Dir(exe)); root != "" {
			return root
		}
	}
	abs, _ := filepath.Abs(".")
	return abs
}

// walkUpForGoMod walks up from startDir (or cwd if empty) looking for go.mod.
func walkUpForGoMod(startDir string) string {
	dir := startDir
	if dir == "" {
		dir, _ = os.Getwd()
	}
	for {
		modPath := filepath.Join(dir, "go.mod")
		if _, err := os.Stat(modPath); err == nil {
			return dir
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			break
		}
		dir = parent
	}
	return ""
}

// goPath is an alias for findGoBin (deduplicated).
func goPath() string { return findGoBin() }

func writeFile(path, content string) {
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		fatal("cannot write " + path + ": " + err.Error())
	}
}

// buildFRB compiles a PRG to Five Runtime Binary (.frb).
// FRB = Go plugin (.so) wrapped in FRB header for runtime loading.
func buildFRB(prgFile, outputFile string) {
	source, err := os.ReadFile(prgFile)
	if err != nil {
		fatal("cannot read file: " + err.Error())
	}

	// Phase 1: Preprocess
	pre := pp.New()
	pre.AddIncludeDir(filepath.Dir(prgFile))
	pre.AddIncludeDir(filepath.Join(filepath.Dir(prgFile), "include"))
	if exePath, err := os.Executable(); err == nil {
		pre.AddIncludeDir(filepath.Join(filepath.Dir(exePath), "include"))
	}
	processed, ppErrors := pre.Process(prgFile, string(source))
	for _, e := range ppErrors {
		fmt.Fprintf(os.Stderr, "pp: %s\n", e)
	}

	// Phase 2: Parse
	file, parseErrors := parser.ParseWithGoDumps(prgFile, processed, pre.GoDumps)
	if len(parseErrors) > 0 {
		for _, e := range parseErrors {
			fmt.Fprintf(os.Stderr, "%s\n", e)
		}
		fatal(fmt.Sprintf("%d parse error(s)", len(parseErrors)))
	}

	// Phase 3: Generate Go source as library
	goSrc := gengo.GenerateLibrary(file)

	// Phase 4: Build as Go plugin
	tmpDir, err := os.MkdirTemp("", "five-frb-*")
	if err != nil {
		fatal("cannot create temp dir: " + err.Error())
	}
	if os.Getenv("FIVE_KEEP_BUILD") == "" {
		defer os.RemoveAll(tmpDir)
	} else {
		fmt.Fprintln(os.Stderr, "[FIVE_KEEP_BUILD] keeping:", tmpDir)
	}

	// Write go.mod — point to Five's module root
	fiveRoot := mustAbs(".")
	if exePath, err := os.Executable(); err == nil {
		fiveRoot = filepath.Dir(exePath)
	}
	// Find go.mod in fiveRoot or parent directories
	for d := fiveRoot; ; d = filepath.Dir(d) {
		if _, err := os.Stat(filepath.Join(d, "go.mod")); err == nil {
			fiveRoot = d
			break
		}
		if d == filepath.Dir(d) {
			break
		}
	}
	modName := fmt.Sprintf("frbmod_%d_%d", os.Getpid(), time.Now().UnixNano())
	goModContent := fmt.Sprintf("module %s\n\ngo 1.21.13\n\nrequire five v0.0.0\n\nreplace five => %s\n", modName, fiveRoot)
	writeFile(filepath.Join(tmpDir, "go.mod"), goModContent)

	// Write Go source (no additional exports needed — init() handles registration)
	writeFile(filepath.Join(tmpDir, "module.go"), goSrc)

	// Find go binary
	goBin := findGoBin()

	// go mod tidy
	tidyCmd := exec.Command(goBin, "mod", "tidy")
	tidyCmd.Dir = tmpDir
	if output, err := tidyCmd.CombinedOutput(); err != nil {
		fmt.Fprintf(os.Stderr, "tidy error: %s\n%s\n", err, string(output))
		fatal("go mod tidy failed")
	}

	// Build plugin
	soFile := filepath.Join(tmpDir, "module.so")
	buildCmd := exec.Command(goBin, "build", "-buildmode=plugin", "-o", soFile, ".")
	buildCmd.Dir = tmpDir
	if output, err := buildCmd.CombinedOutput(); err != nil {
		fmt.Fprintf(os.Stderr, "%s\n", string(output))
		fatal("plugin build failed")
	}

	// Phase 5: Package as FRB
	soData, err := os.ReadFile(soFile)
	if err != nil {
		fatal("cannot read .so: " + err.Error())
	}

	frbData := make([]byte, hbrt.FrbHeaderSize+len(soData))
	frbData[0] = hbrt.FrbMagic0
	frbData[1] = hbrt.FrbMagic1
	frbData[2] = hbrt.FrbMagic2
	frbData[3] = hbrt.FrbMagic3
	frbData[4] = hbrt.FrbVersion1
	frbData[5] = 0 // flags
	// Flags: 0
	frbData[6] = 0
	frbData[7] = 0
	// SymCount: 0 (symbols are self-registering via init())
	frbData[8] = 0
	frbData[9] = 0
	frbData[10] = 0
	frbData[11] = 0
	copy(frbData[12:], soData)

	if err := os.WriteFile(outputFile, frbData, 0755); err != nil {
		fatal("cannot write FRB: " + err.Error())
	}

	fmt.Fprintf(os.Stderr, "FRB: %s (%d bytes)\n", outputFile, len(frbData))
}

// debugPRG compiles PRG with debug info and runs with interactive debugger.
func debugPRG(prgFile string) {
	source, err := os.ReadFile(prgFile)
	if err != nil {
		fatal("cannot read file: " + err.Error())
	}

	// Phase 1: Preprocess
	pre := pp.New()
	pre.AddIncludeDir(filepath.Dir(prgFile))
	pre.AddIncludeDir(filepath.Join(filepath.Dir(prgFile), "include"))
	if exePath, err := os.Executable(); err == nil {
		pre.AddIncludeDir(filepath.Join(filepath.Dir(exePath), "include"))
	}
	processed, ppErrors := pre.Process(prgFile, string(source))
	for _, e := range ppErrors {
		fmt.Fprintf(os.Stderr, "pp: %s\n", e)
	}

	// Phase 2: Parse
	file, parseErrors := parser.ParseWithGoDumps(prgFile, processed, pre.GoDumps)
	if len(parseErrors) > 0 {
		for _, e := range parseErrors {
			fmt.Fprintf(os.Stderr, "%s\n", e)
		}
		fatal(fmt.Sprintf("%d parse error(s)", len(parseErrors)))
	}

	// Phase 3: Generate Go with debug info
	goSrc := gengo.GenerateWithDebug(file)

	// Phase 4: Build and run (same as runPRG but with debug setup)
	tmpDir, err := os.MkdirTemp("", "five-debug-*")
	if err != nil {
		fatal("cannot create temp dir: " + err.Error())
	}
	if os.Getenv("FIVE_KEEP_BUILD") == "" {
		defer os.RemoveAll(tmpDir)
	} else {
		fmt.Fprintln(os.Stderr, "[FIVE_KEEP_BUILD] keeping:", tmpDir)
	}

	fiveRoot := findProjectRoot()
	goMod := fmt.Sprintf("module five-generated\n\ngo 1.21.13\n\nrequire five v0.0.0\n\nreplace five => %s\n", fiveRoot)
	writeFile(filepath.Join(tmpDir, "go.mod"), goMod)

	// Add debug setup to main (use %q for safe path escaping)
	debugSetup := fmt.Sprintf(
		"vm.Debugger = hbrt.NewDebugger()\n\tvm.Debugger.SourceDir = %s\n\tvm.Debugger.Callback = hbrt.TUIDebugger()\n\tvm.Run(\"MAIN\")",
		fmt.Sprintf("%q", mustAbs(".")))
	goSrc = strings.Replace(goSrc, "vm.Run(\"MAIN\")", debugSetup, 1)
	// Remove unused fmt import if added
	// (no longer needed since we don't use fmt.Println in generated code)

	writeFile(filepath.Join(tmpDir, "main.go"), goSrc)

	goBin := findGoBin()
	tidyCmd := exec.Command(goBin, "mod", "tidy")
	tidyCmd.Dir = tmpDir
	if out, err := tidyCmd.CombinedOutput(); err != nil {
		fmt.Fprintf(os.Stderr, "warning: go mod tidy: %v\n%s", err, out)
	}

	runCmd := exec.Command(goBin, "run", ".")
	runCmd.Dir = tmpDir
	runCmd.Stdin = os.Stdin
	runCmd.Stdout = os.Stdout
	runCmd.Stderr = os.Stderr
	runCmd.Run()
}

// findProjectRoot is an alias for findFiveRoot (deduplicated).
func findProjectRoot() string { return findFiveRoot() }

// buildFRBPcode compiles PRG to pcode FRB (no Go compiler needed to run).
func buildFRBPcode(prgFile, outputFile string) {
	source, err := os.ReadFile(prgFile)
	if err != nil {
		fatal("cannot read file: " + err.Error())
	}

	// Phase 1: Preprocess
	pre := pp.New()
	pre.AddIncludeDir(filepath.Dir(prgFile))
	pre.AddIncludeDir(filepath.Join(filepath.Dir(prgFile), "include"))
	if exePath, err := os.Executable(); err == nil {
		pre.AddIncludeDir(filepath.Join(filepath.Dir(exePath), "include"))
	}
	processed, _ := pre.Process(prgFile, string(source))

	// Phase 2: Parse
	file, parseErrors := parser.ParseWithGoDumps(prgFile, processed, pre.GoDumps)
	if len(parseErrors) > 0 {
		for _, e := range parseErrors {
			fmt.Fprintf(os.Stderr, "%s\n", e)
		}
		fatal(fmt.Sprintf("%d parse error(s)", len(parseErrors)))
	}

	// Phase 3: Generate pcode
	pcMod := genpc.Generate(file)

	// Phase 4: Serialize
	pcData := hbrt.SerializePcodeModule(pcMod)

	// Phase 5: Write FRB
	frbData := make([]byte, hbrt.FrbHeaderSize+len(pcData))
	frbData[0] = hbrt.FrbMagic0
	frbData[1] = hbrt.FrbMagic1
	frbData[2] = hbrt.FrbMagic2
	frbData[3] = hbrt.FrbMagic3
	frbData[4] = hbrt.FrbVersion1
	frbData[5] = 0
	frbData[6] = hbrt.FrbModePcode
	frbData[7] = 0
	// func count
	frbData[8] = byte(len(pcMod.Funcs))
	frbData[9] = byte(len(pcMod.Funcs) >> 8)
	frbData[10] = 0
	frbData[11] = 0
	frbData = append(frbData[:12], pcData...)

	if err := os.WriteFile(outputFile, frbData, 0755); err != nil {
		fatal("cannot write FRB: " + err.Error())
	}

	fmt.Fprintf(os.Stderr, "FRB (pcode): %s (%d bytes, %d functions)\n", outputFile, len(frbData), len(pcMod.Funcs))
}


func findGoBin() string {
	// Try PATH first
	if p, err := exec.LookPath("go"); err == nil {
		return p
	}
	// Common locations
	for _, p := range []string{"/usr/local/go/bin/go", "/usr/bin/go", "/snap/bin/go"} {
		if _, err := os.Stat(p); err == nil {
			return p
		}
	}
	return "go"
}

func mustAbs(path string) string {
	abs, err := filepath.Abs(path)
	if err != nil {
		return path
	}
	return abs
}

func fatal(msg string) {
	fmt.Fprintf(os.Stderr, "five: %s\n", msg)
	os.Exit(1)
}