def show_fail(self, reason):
    """
    Method called if OptiPass failed.

    Arguments:
      reason:  string containing the error message
    """
    self.clear()
    text = self.fail_text.format(reason)
    if str(reason) == 'No solution':
        text += '\n * try increasing the maximum budget'
    self.append(pn.pane.Alert(text, alert_type = 'danger'))
    self.template.open_modal()

def show_invalid_weights(self, w: list[str]):
    """
    Method called when weighted targets are being used and one of the
    text boxes does not have a valid entry (must be a number between 1 and 5).

    Arguments:
      w: the list of strings read from the text entry widgets
    """
    text = self.invalid_weights_text.format(w)
    self.clear()
    self.append(pn.pane.Alert(text, alert_type = 'warning'))
    self.template.open_modal()

def show_missing(self, rlist, bmax, tlist):
    """
    Method called by the OP class when it detects missing parameters (e.g.
    if the user did not select a region or a target).
    """
    text = self.missing_params_text
    if len(rlist) == 0:
        text += ' * one or more geographic regions\n'
    if bmax == 0:
        text += ' * a maximum budget\n'
    if len(tlist) == 0:
        text += ' * one or more targets\n'
    self.clear()
    self.append(pn.pane.Alert(text, alert_type = 'warning'))
    self.template.open_modal()

def show_params(self, regions, bmax, bstep, targets, weights, climate):
    """
    Method called to allow the user to review the optimization parameters read from the
    various widgets.  Displays each parameter and two buttons ("Cancel" and "Continue").

    Arguments:
      regions:  list of region names
      bmax:  maximum budget amount
      bstep:  incremwnt in budget amounts
      targets:  list of restoration target names
      weights:  list of target weights
      climate:  climate scenario
    """
    n = bmax // bstep
    fbmax = OP.format_budget_amount(bmax)
    fbstep = OP.format_budget_amount(bstep)
    text = self.preview_message_text
    text += f'  * Regions: {", ".join(regions)}\n\n'
    if n > 1:
        text += f'  * {n} budget levels from {fbstep} up to {fbmax} in increments of {fbstep}\n\n'
    else:
        text += f'  * a single budget of {fbmax}\n\n'
    targets = [t.split(':')[-1] for t in targets]
    if weights:
        targets = [f'{targets[i]} ⨉ {weights[i]}' for i in range(len(targets))]
    text += f'  * Targets: {", ".join(targets)}\n' 
    text += f'  * Climate: {climate}\n\n'
    self.clear()
    self.append(pn.pane.Alert(text, alert_type = 'secondary'))
    self.append(pn.Row(self.cancel_button, self.continue_button))
    self.template.open_modal()

def show_success(self):
    """
    Method called after OptiPass has finished running and the results have been
    parsed successfully.
    """
    self.clear()
    self.append(pn.pane.Alert(self.success_text, alert_type = 'success'))
    self.template.open_modal()