use itertools::Itertools;
use sycamore::prelude::*;
use web_sys::{
    Event,
    HtmlInputElement,
    KeyboardEvent,
    MouseEvent,
    wasm_bindgen::JsCast
};

use crate::{
    AppState,
    assembly,
    assembly::{
        Observable,
        ObservableKey,
        ObservableRole::*,
        ElementKey
    }
};

// an editable view of the Lorentz product representing an observable
#[component(inline_props)]
fn ObservableInput(observable: Observable) -> View {
    view! {
        input(
            r#type="text",
            placeholder=observable.measured.with(|result| result.to_string()),
            bind:value=observable.desired_text,
            on:change=move |event: Event| {
                let target: HtmlInputElement = event.target().unwrap().unchecked_into();
                let value = target.value();
                if value.is_empty() {
                    observable.role.set(Measure);
                } else {
                    match target.value().parse::<f64>() {
                        Ok(desired) => batch(|| {
                            observable.desired.set(desired);
                            observable.role.set(Constrain);
                        }),
                        Err(_) => observable.role.set(Invalid)
                    };
                }
            }
        )
    }
}

// a list item that shows an observable in an outline view of an element
#[component(inline_props)]
fn ObservableOutlineItem(observable_key: ObservableKey, element_key: ElementKey) -> View {
    let state = use_context::<AppState>();
    let assembly = &state.assembly;
    let observable = assembly.observables.with(|obsls| obsls[observable_key].clone());
    let other_subject = if observable.subjects.0 == element_key {
        observable.subjects.1
    } else {
        observable.subjects.0
    };
    let other_subject_label = assembly.elements.with(|elts| elts[other_subject].label.clone());
    let class = observable.role.map(
        |role| match role {
            Measure => "observable",
            Constrain => "observable constrained",
            Invalid => "observable invalid"
        }
    );
    view! {
        li(class=class.get()) {
            div(class="observable-label") { (other_subject_label) }
            ObservableInput(observable=observable)
            div(class="status")
        }
    }
}

// a list item that shows an element in an outline view of an assembly
#[component(inline_props)]
fn ElementOutlineItem(key: ElementKey, element: assembly::Element) -> View {
    let state = use_context::<AppState>();
    let class = state.selection.map(
        move |sel| if sel.contains(&key) { "selected" } else { "" }
    );
    let label = element.label.clone();
    let rep_components = move || {
        element.representation.with(
            |rep| rep.iter().map(
                |u| {
                    let u_str = format!("{:.3}", u).replace("-", "\u{2212}");
                    view! { div { (u_str) } }
                }
            ).collect::<Vec<_>>()
        )
    };
    let observed = element.observables.map(|obsls| obsls.len() > 0);
    let observable_list = element.observables.map(
        |obsls| obsls.clone().into_iter().collect()
    );
    let details_node = create_node_ref();
    view! {
        li {
            details(ref=details_node) {
                summary(
                    class=class.get(),
                    on:keydown={
                        move |event: KeyboardEvent| {
                            match event.key().as_str() {
                                "Enter" => {
                                    state.select(key, event.shift_key());
                                    event.prevent_default();
                                },
                                "ArrowRight" if observed.get() => {
                                    let _ = details_node
                                        .get()
                                        .unchecked_into::<web_sys::Element>()
                                        .set_attribute("open", "");
                                },
                                "ArrowLeft" => {
                                    let _ = details_node
                                        .get()
                                        .unchecked_into::<web_sys::Element>()
                                        .remove_attribute("open");
                                },
                                _ => ()
                            }
                        }
                    }
                ) {
                    div(
                        class="element-switch",
                        on:click=|event: MouseEvent| event.stop_propagation()
                    )
                    div(
                        class="element",
                        on:click={
                            move |event: MouseEvent| {
                                if event.shift_key() {
                                    state.selection.update(|sel| {
                                        if !sel.remove(&key) {
                                            sel.insert(key);
                                        }
                                    });
                                } else {
                                    state.selection.update(|sel| {
                                        sel.clear();
                                        sel.insert(key);
                                    });
                                }
                                event.stop_propagation();
                                event.prevent_default();
                            }
                        }
                    ) {
                        div(class="element-label") { (label) }
                        div(class="element-representation") { (rep_components) }
                        div(class="status")
                    }
                }
                ul(class="observables") {
                    Keyed(
                        list=observable_list,
                        view=move |obs_key| view! {
                            ObservableOutlineItem(
                                observable_key=obs_key,
                                element_key=key
                            )
                        },
                        key=|obs_key| obs_key.clone()
                    )
                }
            }
        }
    }
}

// a component that lists the elements of the current assembly, showing the
// observables associated with each element as a collapsible sub-list. its
// implementation is based on Kate Morley's HTML + CSS tree views:
//
//   https://iamkate.com/code/tree-views/
//
#[component]
pub fn Outline() -> View {
    let state = use_context::<AppState>();
    
    // list the elements alphabetically by ID
    let element_list = state.assembly.elements.map(
        |elts| elts
            .clone()
            .into_iter()
            .sorted_by_key(|(_, elt)| elt.id.clone())
            .collect()
    );
    
    view! {
        ul(
            id="outline",
            on:click={
                let state = use_context::<AppState>();
                move |_| state.selection.update(|sel| sel.clear())
            }
        ) {
            Keyed(
                list=element_list,
                view=|(key, elt)| view! {
                    ElementOutlineItem(key=key, element=elt)
                },
                key=|(_, elt)| elt.serial
            )
        }
    }
}