package shell

type State interface {
	Variable(string) string
	Command(string) CommandExecutor
	Env(string) string

	Pushd(string) error
	Popd() error
	Cwd() string

	SetVariable(string, string)
	SetCommand(string, CommandExecutor)
	SetEnv(string, string)

	Clone() State
}

func NewShellState() *ShellState {
	return &ShellState{
		variables: map[string]string{},
		commands:  map[string]CommandExecutor{},
		env:       map[string]string{},
		dirstack:  []string{},
	}
}

type ShellState struct {
	variables map[string]string
	commands  map[string]CommandExecutor
	env       map[string]string
	dirstack  []string
}

func (s *ShellState) Variable(n string) string {
	if v, ok := s.variables[n]; ok {
		return v
	}

	return ""
}

func (s *ShellState) Command(n string) CommandExecutor {
	if v, ok := s.commands[n]; ok {
		return v
	}

	return nil
}

func (s *ShellState) Env(n string) string {
	if v, ok := s.env[n]; ok {
		return v
	}

	return ""
}

func (s *ShellState) SetVariable(n string, v string) {
	s.variables[n] = v
}

func (s *ShellState) SetCommand(n string, e CommandExecutor) {
	s.commands[n] = e
}

func (s *ShellState) SetEnv(n string, v string) {
	s.env[n] = v
}

func (s *ShellState) Pushd(dir string) error {
	s.dirstack = append([]string{dir}, s.dirstack...)
	return nil
}

func (s *ShellState) Popd() error {
	if len(s.dirstack) == 0 {
		return nil
	}

	s.dirstack = s.dirstack[1:]
	return nil
}

func (s *ShellState) Cwd() string {
	if len(s.dirstack) == 0 {
		return ""
	}

	return s.dirstack[0]
}

func (s *ShellState) Clone() State {
	state := NewShellState()

	for k, v := range s.commands {
		state.SetCommand(k, v)
	}

	for k, v := range s.variables {
		state.SetVariable(k, v)
	}

	for k, v := range s.env {
		state.SetEnv(k, v)
	}

	state.dirstack = make([]string, len(s.dirstack))
	copy(s.dirstack, state.dirstack)

	return state
}