vertigo-forms 0.1.3

use either::Either;
use std::{collections::HashMap, hash::Hash};
use vertigo::{
    AttrGroup, Computed, KeyDownEvent, Value, bind, component, computed_tuple, css, dom,
    dom_element, transaction,
};

pub struct SelectSearchParams {
    /// Minimum number of letters to open dropdown
    pub min_chars: usize,
    pub input_title: String,
}

impl Default for SelectSearchParams {
    fn default() -> Self {
        Self {
            min_chars: 3,
            input_title: "Enter phrase".to_string(),
        }
    }
}

/// Input that searches for entered query in provided item list, based on `HashMap<K, V>`.
#[component]
pub fn SelectSearch<K, V>(
    /// Currently selected value
    value: Value<K>,
    /// List of possible values
    options: Computed<HashMap<K, V>>,
    /// Component behavior/display parameters
    params: SelectSearchParams,
    /// Add attributes to the container
    c: AttrGroup,
    /// Add attributes to the input
    i: AttrGroup,
) where
    K: Clone + ToString + PartialEq + Eq + Hash + 'static,
    V: Clone + ToString + PartialEq + 'static,
{
    // Filter currently typed by user
    let filter = Value::<Option<String>>::default();
    // Toggle for dropdown visibility
    let dropdown_opened = Value::<bool>::default();
    // Item selected in dropdown using keyboard
    let item_selected = Value::<Option<K>>::default();

    // Items list for dropdown display
    let items = computed_tuple!(options, filter).map(move |(inner_options, inner_filter)| {
        if let Some(inner_filter) = inner_filter {
            let inner_filter = inner_filter.to_lowercase();
            if inner_filter.len() >= params.min_chars {
                // Filter options
                inner_options
                    .into_iter()
                    .filter(|(_, opt_value)| {
                        opt_value.to_string().to_lowercase().contains(&inner_filter)
                    })
                    .collect::<Vec<_>>()
            } else {
                vec![]
            }
        } else {
            vec![]
        }
    });

    let dropdown_css = |visible| {
        let display_value = if visible { "block" } else { "none" };
        css! {"
            display: {display_value};
            position: absolute;
            background-color: white;
            box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.4);
            border: 1px black solid;
            z-index: 1;
        "}
    };

    // Render list
    let list_deps = computed_tuple!(dropdown_opened, items, item_selected);
    let list = bind!(
        value,
        filter,
        dropdown_opened,
        list_deps.render_value(move |(inner_dropdown_opened, inner_items, item_selected)| {
            let item_css = |selected: bool| {
                let bg_color = if selected { "#ccc" } else { "inherit" };

                css! {"
                        cursor: pointer;
                        padding: 2px 4px;
                        background-color: {bg_color};

                        :hover {
                            background-color: #ccc;
                        };
                    "}
            };

            let list = dom_element! {
                <div css={dropdown_css(inner_dropdown_opened)} />
            };

            if inner_dropdown_opened {
                for (opt_key, opt_value) in &inner_items {
                    // Prevent on blur on input
                    let on_mouse_down = || true;
                    let on_click = bind!(value, filter, dropdown_opened, opt_key, |_| {
                        value.set(opt_key.clone());
                        filter.set(None);
                        dropdown_opened.set(false);
                    });
                    list.add_child(dom! {
                        <div
                            id={opt_key.to_string()}
                            css={item_css(item_selected.as_ref() == Some(opt_key))}
                            {on_mouse_down} {on_click}
                        >
                            {opt_value.to_string()}
                        </div>
                    });
                }
            }

            list.into()
        })
    );

    // Render input
    let input_deps = computed_tuple!(value, options);
    let input = input_deps.render_value(move |(inner_value, options_inner)| {
        let i = i.clone();
        // Displayed value is filter, or value label if no filter typed in
        let displayed_value = filter.to_computed().map(move |inner_filter| {
            if let Some(inner_filter) = inner_filter {
                inner_filter
            } else {
                options_inner
                    .get(&inner_value)
                    .map(|val| val.to_string())
                    .unwrap_or_default()
            }
        });

        let on_input = bind!(filter, dropdown_opened, |new_value: String| {
            if new_value.len() >= params.min_chars {
                dropdown_opened.set(true);
            }
            filter.set(Some(new_value));
        });

        let on_blur = bind!(dropdown_opened, || dropdown_opened.set(false));

        // Make items selectable by keyboard arrows
        let hook_key_down = bind!(
            value,
            item_selected,
            filter,
            options,
            items,
            dropdown_opened,
            |key_down: KeyDownEvent| {
                if key_down.key == "ArrowDown" || key_down.key == "ArrowUp" {
                    transaction(|ctx| {
                        if filter.get(ctx).is_some() {
                            // Create iterator over dropdown, reversed if arrow up
                            let mut items_iter = {
                                let iter = items.get(ctx).into_iter();
                                if key_down.key == "ArrowUp" {
                                    Either::Left(iter.rev())
                                } else {
                                    Either::Right(iter)
                                }
                            }
                            .peekable();

                            // Save first element for eventual later use
                            let first_key = items_iter.peek().map(|(key, _)| key).cloned();

                            if let Some(inner_item_selected) = item_selected.get(ctx) {
                                // If some item already selected, advance
                                if let Some((next_key, _)) = items_iter
                                    .skip_while(|(opt_key, _)| opt_key != &inner_item_selected)
                                    .nth(1)
                                {
                                    item_selected.set(Some(next_key));
                                } else {
                                    // Not found, probably last value was filtered out, just set the first one
                                    item_selected.set(first_key);
                                }
                            } else if let Some((opt_key, _)) = items_iter.next() {
                                // If nothing selected just take first one
                                item_selected.set(Some(opt_key));
                            }
                        }
                    });
                    true
                } else if key_down.key == "Enter" {
                    transaction(|ctx| {
                        if let Some(item_selected) = item_selected.get(ctx) {
                            // Close dropdown
                            dropdown_opened.set(false);
                            // Set input text to chosen item
                            if let Some(opt_value) = options.get(ctx).get(&item_selected) {
                                filter.set(Some(opt_value.to_string()));
                            }
                            // Set the value itself
                            value.set(item_selected);
                        }
                    });
                    true
                } else {
                    false
                }
            }
        );

        dom! {
            <input
                required="required"
                title={&params.input_title}
                value={displayed_value}
                {on_input} {on_blur} {hook_key_down} {..i}
            />
        }
    });

    let dropdown_css = css! {"
        position: relative;
    "};

    dom! {
        <div css={dropdown_css} {..c}>
            {input}
            {list}
        </div>
    }
}