//go:build windows

package vncspawner

import (
	"os"
	"path/filepath"
)

// detectWindows looks for UltraVNC and TightVNC in common install locations,
// in a project-local "vnc" folder, and in WEBVNC_VNC_DIR.
func candidates() []Candidate {
	var cands []Candidate

	// 1. Project-local vnc/ folder (current working directory) — used by get-vnc.ps1.
	cands = append(cands, scanDir(filepath.Join(mustCwd(), "vnc"))...)
	// 2. Explicit env override.
	if dir := os.Getenv("WEBVNC_VNC_DIR"); dir != "" {
		cands = append(cands, scanDir(dir)...)
	}
	// 3. Standard install paths.
	for _, base := range []string{
		`C:\Program Files\uvnc bvba\UltraVNC\winvnc.exe`,
		`C:\Program Files (x86)\uvnc bvba\UltraVNC\winvnc.exe`,
		`C:\Program Files\UltraVNC\winvnc.exe`,
		`C:\Program Files (x86)\UltraVNC\winvnc.exe`,
		`C:\Program Files\TightVNC\tvnserver.exe`,
		`C:\Program Files (x86)\TightVNC\tvnserver.exe`,
	} {
		if fileExists(base) {
			cands = append(cands, Candidate{Path: base, Args: []string{"-run"}, Desc: filepath.Base(base)})
		}
	}
	// 4. Scan Program Files dirs (covers custom install paths).
	for _, d := range programDirs() {
		for _, pat := range []string{"UltraVNC*\\winvnc.exe", "TightVNC*\\tvnserver.exe"} {
			matches, _ := filepath.Glob(filepath.Join(d, pat))
			for _, m := range matches {
				if fileExists(m) {
					cands = append(cands, Candidate{Path: m, Args: []string{"-run"}, Desc: filepath.Base(m)})
				}
			}
		}
	}
	return cands
}

// scanDir looks for winvnc.exe / tvnserver.exe in dir.
func scanDir(dir string) []Candidate {
	var out []Candidate
	for _, name := range []string{"winvnc.exe", "tvnserver.exe"} {
		p := filepath.Join(dir, name)
		if fileExists(p) {
			out = append(out, Candidate{Path: p, Args: []string{"-run"}, Desc: name})
		}
	}
	return out
}

func mustCwd() string {
	wd, err := os.Getwd()
	if err != nil {
		return "."
	}
	return wd
}

func programDirs() []string {
	var dirs []string
	for _, env := range []string{"ProgramFiles", "ProgramFiles(x86)", "ProgramW6432"} {
		if v := os.Getenv(env); v != "" {
			dirs = append(dirs, v)
		}
	}
	return dirs
}

func fileExists(p string) bool {
	_, err := os.Stat(p)
	return err == nil
}