package oauth

import (
	"fmt"
	"os/exec"
	"runtime"
)

// CommandExecutor is an interface for executing system commands.
// This allows for dependency injection and mocking in tests.
type CommandExecutor interface {
	Execute(name string, args ...string) error
}

// realCommandExecutor is the production implementation that actually executes commands.
type realCommandExecutor struct{}

func (e *realCommandExecutor) Execute(name string, args ...string) error {
	return exec.Command(name, args...).Start()
}

// buildBrowserCommand returns the command and arguments needed to open a browser on the given OS.
// This is a pure function with no side effects, making it easily testable.
func buildBrowserCommand(goos, url string) (string, []string, error) {
	switch goos {
	case "darwin":
		return "open", []string{url}, nil
	case "linux":
		return "xdg-open", []string{url}, nil
	case "windows":
		return "rundll32", []string{"url.dll,FileProtocolHandler", url}, nil
	default:
		return "", nil, fmt.Errorf("unsupported platform: %s", goos)
	}
}

// openBrowserWithExecutor opens the browser using the provided executor.
// This allows for dependency injection in tests.
func openBrowserWithExecutor(goos, url string, executor CommandExecutor) error {
	cmd, args, err := buildBrowserCommand(goos, url)
	if err != nil {
		return err
	}
	return executor.Execute(cmd, args...)
}

// OpenBrowser opens the default browser to the given URL.
// This is the public API that maintains backward compatibility.
func OpenBrowser(url string) error {
	return openBrowserWithExecutor(runtime.GOOS, url, &realCommandExecutor{})
}