package pnyx

type PermissionLevel int
const (
  PERMISSION_FALLTHROUGH PermissionLevel = iota
  PERMISSION_ALLOW
  PERMISSION_DENY
  PERMISSION_ALLOW_ALL
  PERMISSION_DENY_ALL
)

type Role string
type Action string

type Permissions map[Action]Permission
type Permission struct {
  Level PermissionLevel
  Next Permissions
}

func(permissions Permissions) Allowed(action []Action, def bool) bool {
  if len(action) == 0 {
    return def
  } else if permissions == nil {
    return def
  }

  perm, exists := permissions[action[0]]
  if exists == false {
    return def
  } else if len(action) == 1 {
    return perm.Level == PERMISSION_ALLOW || perm.Level == PERMISSION_ALLOW_ALL
  } else {
    switch perm.Level {
    case PERMISSION_ALLOW_ALL:
      return perm.Next.Allowed(action[1:], true)
    case PERMISSION_DENY_ALL:
      return perm.Next.Allowed(action[1:], false)
    default:
      return perm.Next.Allowed(action[1:], def)
    }
  }
}

func(permissions Permissions) Copy() Permissions {
  if permissions == nil {
    return nil
  }

  new_permissions := Permissions{}
  for action, permission := range(permissions) {
    new_permissions[action] = Permission{
      Level: permission.Level,
      Next: permission.Next.Copy(),
    }
  }
  return new_permissions
}