use iced::Element;

use super::{Message, Navigation};

pub enum SetOptionsResult<TOption> {
    SetOptionsAndKeptSelection,
    SetOptionsAndSetSelectedOption(TOption),
}

impl<'a, TOption> Navigation<TOption>
where
    TOption: Clone + PartialEq + 'a,
    Element<'a, Message<TOption>>: From<&'a TOption>,
{
    pub fn set_options(&mut self, options: Vec<TOption>) -> SetOptionsResult<TOption> {
        let active_option_index =
            self.active_option
                .clone()
                .map_or(Option::None, |active_option| {
                    options
                        .iter()
                        .position(|option| active_option == option.clone())
                });
        if let Some(active_option_index) = active_option_index {
            let split = options.split_at(active_option_index);
            self.options_before_active = split.0.to_vec();
            self.options_after_active = split.1.split_at(1).1.to_vec();
            SetOptionsResult::SetOptionsAndKeptSelection
        } else {
            self.options_before_active = options
                .split_last()
                .map_or_else(Vec::new, |(_last, rest)| rest.to_vec());
            self.active_option = options.last().cloned();
            options.last().cloned().map_or(
                SetOptionsResult::SetOptionsAndKeptSelection,
                SetOptionsResult::SetOptionsAndSetSelectedOption,
            )
        }
    }
}