// 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"
	"sort"
	"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",
	"fivenode_go/hbrtl_ext/dispatch",
	"fivenode_go/hbrtl_ext/labdb_state",
	"fivenode_go/hbrtl_ext/labdb_static",
}

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]... [--go-replace pkg=path]...")
	fmt.Fprintln(os.Stderr, "  fnode run   <file.prg>     [-I dir]... [--rtl pkg]... [--go-replace pkg=path]...")
	fmt.Fprintln(os.Stderr, "  fnode version")
}

type buildOpts struct {
	prgFiles    []string
	output      string
	includes    []string
	rtlPkgs     []string
	// goReplace maps a Go module path to a local filesystem path that
	// gets emitted as `replace <path> => <local>` in the temp go.mod.
	// Lets PRG #pragma BEGINDUMP blocks import private modules that
	// `go mod tidy` would otherwise fail to fetch (e.g. a sibling
	// project living outside any module proxy).
	goReplace map[string]string
	// goModule overrides the default temp-build module name
	// ("fnode_build"). Set this to a path inside an existing module
	// when the BEGINDUMP block needs to import that module's
	// internal/* packages — Go's internal-visibility rule only lets
	// callers whose own module path lives under the same parent see
	// internal/.
	//   --module gitea.fivego.org/kwon_ai/solmade/_fnode_build
	goModule string
}

func parseCommon(args []string) buildOpts {
	o := buildOpts{goReplace: map[string]string{}}
	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++
		case a == "--go-replace" && i+1 < len(args):
			// --go-replace gitea.fivego.org/kwon_ai/solmade=/abs/path
			spec := args[i+1]
			i++
			eq := strings.IndexByte(spec, '=')
			if eq <= 0 || eq == len(spec)-1 {
				fatal("--go-replace expects pkg=path, got: " + spec)
			}
			o.goReplace[spec[:eq]] = spec[eq+1:]
		case a == "--module" && i+1 < len(args):
			o.goModule = 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, o.goReplace, o.goModule)

	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, o.goReplace, o.goModule)

	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
			}
		}
	}
	// Auto-rename the Main() of each library file (i > 0) to a
	// unique name derived from its file basename so multiple .prg
	// files that all define `FUNCTION Main()` can be linked into
	// one binary. The dispatcher (FNODE_CALL or HTTP path router)
	// looks up the renamed symbol by the same convention:
	//   app/api/admin-stats.prg → ADMIN_STATS__MAIN
	for i := 1; i < len(ps); i++ {
		newName := mainNameFor(ps[i].prgFile)
		renameMain(ps[i].file, newName)
		crossFile[newName] = true
		delete(crossFile, "MAIN") // only the entry file owns MAIN
	}
	// Re-add MAIN if the entry file declares it (it almost always
	// does); without this the analyzer would warn about the entry
	// file's Main looking undeclared.
	for _, d := range ps[0].file.Decls {
		if fd, ok := d.(*ast.FuncDecl); ok && strings.EqualFold(fd.Name, "Main") {
			crossFile["MAIN"] = true
			break
		}
	}

	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)
	}
}

// renameMain finds the file's top-level FUNCTION Main (case-insensitive)
// and rewrites its Name to newName. Other functions / classes are left
// alone so cross-file calls keep working. Returns whether a Main was
// found and renamed.
func renameMain(f *ast.File, newName string) bool {
	for _, d := range f.Decls {
		if fd, ok := d.(*ast.FuncDecl); ok && strings.EqualFold(fd.Name, "Main") {
			fd.Name = newName
			return true
		}
	}
	return false
}

// mainNameFor derives the unique Main-symbol name from a .prg path.
// `app/api/admin-stats.prg` → `ADMIN_STATS__MAIN`. Hyphens become
// underscores so Harbour's identifier rules accept the result; the
// "__MAIN" suffix lets the dispatcher recognise these as entry points
// rather than helper functions.
func mainNameFor(prgPath string) string {
	base := strings.TrimSuffix(filepath.Base(prgPath), filepath.Ext(prgPath))
	base = strings.ReplaceAll(base, "-", "_")
	return strings.ToUpper(base) + "__MAIN"
}

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, extraReplace map[string]string, modName string) {
	five := mustAbs(fiveRoot())
	fnode := mustAbs(fnodeRoot())
	if modName == "" {
		modName = "fnode_build"
	}
	var sb strings.Builder
	fmt.Fprintf(&sb, `module %s

go 1.21

require (
	five v0.0.0
	fivenode_go v0.0.0
)

replace five => %s

replace fivenode_go => %s
`, modName, five, fnode)
	// Sorted iteration for stable go.mod output.
	keys := make([]string, 0, len(extraReplace))
	for k := range extraReplace {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	for _, pkg := range keys {
		path := extraReplace[pkg]
		if !filepath.IsAbs(path) {
			path = mustAbs(path)
		}
		fmt.Fprintf(&sb, "\nrequire %s v0.0.0\n", pkg)
		fmt.Fprintf(&sb, "replace %s => %s\n", pkg, path)
	}
	writeFile(filepath.Join(tmpDir, "go.mod"), sb.String())
}

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.
//
// Order of resolution:
//  1. Walk up looking for a go.mod with `module five` (works when
//     fnode was launched from inside the Five source tree).
//  2. Read fnodeRoot's go.mod for a `replace five => <path>` line —
//     this is the common case when fnode is invoked from somewhere
//     else (e.g. /Users/.../solmade) with the binary living in
//     fivenode_go's tree; the replace pin in fivenode_go/go.mod is
//     the source of truth for where Five lives.
//  3. Hard-coded relative fallback, resolved against the current
//     working directory. Only useful when fnode is run from inside
//     fivenode_go itself.
func fiveRoot() string {
	if d := walkUpForModule("five"); d != "" {
		return d
	}
	if p := fiveFromFnodeGoMod(); p != "" {
		return p
	}
	return "../../fivedev/five"
}

// fiveFromFnodeGoMod parses fivenode_go's own go.mod for a
//
//	replace five => <path>
//
// directive and returns the path resolved against fnodeRoot when it's
// relative. Empty when not found.
func fiveFromFnodeGoMod() string {
	fr := fnodeRoot()
	if fr == "" {
		return ""
	}
	data, err := os.ReadFile(filepath.Join(fr, "go.mod"))
	if err != nil {
		return ""
	}
	for _, raw := range strings.Split(string(data), "\n") {
		line := strings.TrimSpace(raw)
		if !strings.HasPrefix(line, "replace") {
			continue
		}
		// Match either `replace five => path` or `replace five v0.0.0 => path`.
		if !strings.Contains(line, " five ") && !strings.Contains(line, " five\t") &&
			!strings.HasSuffix(strings.TrimSpace(strings.SplitN(line, "=>", 2)[0]), " five") {
			continue
		}
		parts := strings.SplitN(line, "=>", 2)
		if len(parts) != 2 {
			continue
		}
		p := strings.TrimSpace(parts[1])
		if filepath.IsAbs(p) {
			return p
		}
		if abs, err := filepath.Abs(filepath.Join(fr, p)); err == nil {
			return abs
		}
	}
	return ""
}

// 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)
}