// fnode — fivenode_go build/run CLI.
//
// Reuses Five's compiler packages to turn PRG sources into Go, then
// builds them together with fivenode_go's own hbrtl_ext/* packages into
// a single self-contained binary. No FFI, no Apache, no Node.js.
//
// Usage:
//
//	fnode build <file.prg> [file2.prg ...] [-o output] [-I includedir ...] [--rtl pkg ...]
//	fnode run   <file.prg> [-I includedir ...] [--rtl pkg ...]
//	fnode version
//
// --rtl <pkg> blank-imports that fivenode_go package so its init()
// registers RTL functions. Default is the full hbrtl_ext set (currently
// just "hello"); pass --rtl explicitly to override.
package main

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"five/compiler/analyzer"
	"five/compiler/ast"
	"five/compiler/gengo"
	"five/compiler/parser"
	"five/compiler/pp"
)

const version = "fnode 0.1.0 — fivenode_go builder for Five"

// defaultRTL is the blank-import list used when --rtl is not specified.
// Order is irrelevant — each package's init() is independent.
var defaultRTL = []string{
	"fivenode_go/hbrtl_ext/hello",
	"fivenode_go/hbrtl_ext/httpserver",
	"fivenode_go/hbrtl_ext/bridge_capi",
	"fivenode_go/hbrtl_ext/pgrtl",
}

func main() {
	if len(os.Args) < 2 {
		printUsage()
		os.Exit(1)
	}
	switch os.Args[1] {
	case "build":
		cmdBuild(os.Args[2:])
	case "run":
		cmdRun(os.Args[2:])
	case "version", "-v", "--version":
		fmt.Println(version)
	case "help", "-h", "--help":
		printUsage()
	default:
		fmt.Fprintf(os.Stderr, "fnode: unknown command %q\n", os.Args[1])
		printUsage()
		os.Exit(1)
	}
}

func printUsage() {
	fmt.Fprintln(os.Stderr, version)
	fmt.Fprintln(os.Stderr, "")
	fmt.Fprintln(os.Stderr, "Usage:")
	fmt.Fprintln(os.Stderr, "  fnode build <file.prg>... [-o out] [-I dir]... [--rtl pkg]...")
	fmt.Fprintln(os.Stderr, "  fnode run   <file.prg>     [-I dir]... [--rtl pkg]...")
	fmt.Fprintln(os.Stderr, "  fnode version")
}

type buildOpts struct {
	prgFiles []string
	output   string
	includes []string
	rtlPkgs  []string
}

func parseCommon(args []string) buildOpts {
	var o buildOpts
	for i := 0; i < len(args); i++ {
		a := args[i]
		switch {
		case a == "-o" && i+1 < len(args):
			o.output = args[i+1]
			i++
		case a == "-I" && i+1 < len(args):
			o.includes = append(o.includes, args[i+1])
			i++
		case strings.HasPrefix(a, "-I"):
			o.includes = append(o.includes, a[2:])
		case a == "--rtl" && i+1 < len(args):
			o.rtlPkgs = append(o.rtlPkgs, args[i+1])
			i++
		default:
			o.prgFiles = append(o.prgFiles, a)
		}
	}
	if len(o.rtlPkgs) == 0 {
		o.rtlPkgs = append([]string{}, defaultRTL...)
	}
	return o
}

func cmdBuild(args []string) {
	o := parseCommon(args)
	if len(o.prgFiles) == 0 {
		fatal("build: no PRG files given")
	}
	if o.output == "" {
		base := strings.TrimSuffix(filepath.Base(o.prgFiles[0]), filepath.Ext(o.prgFiles[0]))
		o.output = base
	}
	absOut, err := filepath.Abs(o.output)
	if err != nil {
		fatal("cannot resolve output path: " + err.Error())
	}
	tmpDir := mkBuildDir()
	defer cleanupBuildDir(tmpDir)

	emitGeneratedSources(tmpDir, o)
	writeRootGo(tmpDir, o.rtlPkgs)
	writeGoMod(tmpDir)

	runGo(tmpDir, "mod", "tidy")
	runGo(tmpDir, "build", "-o", absOut, ".")
	fmt.Fprintf(os.Stderr, "Built: %s\n", absOut)
}

func cmdRun(args []string) {
	o := parseCommon(args)
	if len(o.prgFiles) == 0 {
		fatal("run: no PRG file given")
	}
	tmpDir := mkBuildDir()
	defer cleanupBuildDir(tmpDir)

	emitGeneratedSources(tmpDir, o)
	writeRootGo(tmpDir, o.rtlPkgs)
	writeGoMod(tmpDir)

	runGo(tmpDir, "mod", "tidy")
	runGoInteractive(tmpDir, "run", ".")
}

// emitGeneratedSources preprocesses, parses, analyzes, and emits Go for
// every PRG file. The first file is treated as the entry module
// (gengo.Generate emits a main()), the rest as library modules.
func emitGeneratedSources(tmpDir string, o buildOpts) {
	// Parse all files first so cross-file function references resolve.
	type parsed struct {
		file    *ast.File
		prgFile string
	}
	var ps []parsed
	crossFile := map[string]bool{}
	for _, f := range o.prgFiles {
		file := parseOne(f, o.includes)
		ps = append(ps, parsed{file: file, prgFile: f})
		for _, d := range file.Decls {
			switch decl := d.(type) {
			case *ast.FuncDecl:
				crossFile[strings.ToUpper(decl.Name)] = true
			case *ast.ClassDecl:
				crossFile[strings.ToUpper(decl.Name)] = true
			}
		}
	}
	for i, p := range ps {
		diags := analyzer.Analyze(p.file, crossFile)
		for _, d := range diags {
			if d.Severity <= analyzer.SevWarning {
				fmt.Fprintf(os.Stderr, "%s\n", d)
			}
		}
		var code string
		if i == 0 {
			code = gengo.Generate(p.file)
		} else {
			code = gengo.GenerateLibrary(p.file)
		}
		path := filepath.Join(tmpDir, fmt.Sprintf("prg_%d.go", i))
		writeFile(path, code)
	}
}

func parseOne(prgFile string, includes []string) *ast.File {
	src, err := os.ReadFile(prgFile)
	if err != nil {
		fatal("cannot read " + prgFile + ": " + err.Error())
	}
	pre := pp.New()
	pre.AddIncludeDir(filepath.Dir(prgFile))
	pre.AddIncludeDir(filepath.Join(filepath.Dir(prgFile), "include"))
	pre.AddIncludeDir(filepath.Join(fiveRoot(), "include"))
	for _, d := range includes {
		pre.AddIncludeDir(d)
	}
	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, ppErrs := pre.Process(prgFile, string(src))
	for _, e := range ppErrs {
		fmt.Fprintf(os.Stderr, "pp: %s\n", e)
	}
	if len(ppErrs) > 0 {
		fatal(fmt.Sprintf("%d preprocessor error(s) in %s", len(ppErrs), prgFile))
	}
	file, parseErrs := parser.ParseWithGoDumps(prgFile, processed, pre.GoDumps)
	if len(parseErrs) > 0 {
		for _, e := range parseErrs {
			fmt.Fprintf(os.Stderr, "%s\n", e)
		}
		fatal(fmt.Sprintf("%d parse error(s) in %s", len(parseErrs), prgFile))
	}
	return file
}

// writeRootGo writes the file that anchors the build's blank imports of
// hbrtl_ext packages. Each import's init() registers its RTL functions
// before the generated PRG main runs.
func writeRootGo(tmpDir string, rtlPkgs []string) {
	var sb strings.Builder
	sb.WriteString("package main\n\n")
	if len(rtlPkgs) > 0 {
		sb.WriteString("import (\n")
		for _, p := range rtlPkgs {
			fmt.Fprintf(&sb, "\t_ %q\n", p)
		}
		sb.WriteString(")\n")
	}
	writeFile(filepath.Join(tmpDir, "fnode_rtl.go"), sb.String())
}

func writeGoMod(tmpDir string) {
	five := mustAbs(fiveRoot())
	fnode := mustAbs(fnodeRoot())
	mod := fmt.Sprintf(`module fnode_build

go 1.21

require (
	five v0.0.0
	fivenode_go v0.0.0
)

replace five => %s

replace fivenode_go => %s
`, five, fnode)
	writeFile(filepath.Join(tmpDir, "go.mod"), mod)
}

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

func mkBuildDir() string {
	dir, err := os.MkdirTemp("", "fnode-build-*")
	if err != nil {
		fatal("mkdir temp: " + err.Error())
	}
	return dir
}

func cleanupBuildDir(dir string) {
	if os.Getenv("FNODE_KEEP_BUILD") != "" {
		fmt.Fprintln(os.Stderr, "[FNODE_KEEP_BUILD] keeping:", dir)
		return
	}
	os.RemoveAll(dir)
}

func runGo(dir string, args ...string) {
	cmd := exec.Command(goBin(), args...)
	cmd.Dir = dir
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		fatal("go " + strings.Join(args, " ") + " failed: " + err.Error())
	}
}

func runGoInteractive(dir string, args ...string) {
	cmd := exec.Command(goBin(), args...)
	cmd.Dir = dir
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		if ee, ok := err.(*exec.ExitError); ok {
			os.Exit(ee.ExitCode())
		}
		fatal("go " + strings.Join(args, " ") + " failed: " + err.Error())
	}
}

func goBin() string {
	if p, err := exec.LookPath("go"); err == nil {
		return p
	}
	for _, p := range []string{"/usr/local/go/bin/go", "/usr/bin/go", "/opt/homebrew/bin/go"} {
		if _, err := os.Stat(p); err == nil {
			return p
		}
	}
	return "go"
}

// fiveRoot resolves to Five's source tree (walk up from this binary or
// from cwd until a directory with module name "five" is found).
func fiveRoot() string {
	if d := walkUpForModule("five"); d != "" {
		return d
	}
	return "../../fivedev/five"
}

// fnodeRoot resolves to fivenode_go's source tree.
func fnodeRoot() string {
	if d := walkUpForModule("fivenode_go"); d != "" {
		return d
	}
	cwd, _ := os.Getwd()
	return cwd
}

func walkUpForModule(name string) string {
	starts := []string{}
	if cwd, err := os.Getwd(); err == nil {
		starts = append(starts, cwd)
	}
	if exe, err := os.Executable(); err == nil {
		starts = append(starts, filepath.Dir(exe))
	}
	for _, start := range starts {
		dir := start
		for {
			gm := filepath.Join(dir, "go.mod")
			if data, err := os.ReadFile(gm); err == nil {
				first := strings.SplitN(string(data), "\n", 2)[0]
				if strings.TrimSpace(first) == "module "+name {
					return dir
				}
			}
			parent := filepath.Dir(dir)
			if parent == dir {
				break
			}
			dir = parent
		}
	}
	return ""
}

func writeFile(path, content string) {
	if err := os.WriteFile(path, []byte(content), 0644); err != nil {
		fatal("write " + path + ": " + err.Error())
	}
}

func fatal(msg string) {
	fmt.Fprintln(os.Stderr, "fnode:", msg)
	os.Exit(1)
}