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

use crate::{
    AppState,
    assembly,
    assembly::{
        ElementKey,
        Regulator,
        RegulatorKey
    },
    specified::SpecifiedValue
};

// an editable view of a regulator
#[component(inline_props)]
fn RegulatorInput(regulator: Regulator) -> View {
    let valid = create_signal(true);
    let value = create_signal(
        regulator.set_point.with_untracked(|set_pt| set_pt.spec.clone())
    );
    
    // this closure resets the input value to the regulator's set point
    // specification
    let reset_value = move || {
        batch(|| {
            valid.set(true);
            value.set(regulator.set_point.with(|set_pt| set_pt.spec.clone()));
        })
    };
    
    // reset the input value whenever the regulator's set point specification
    // is updated
    create_effect(reset_value);
    
    view! {
        input(
            r#type="text",
            class=move || {
                if valid.get() {
                    regulator.set_point.with(|set_pt| {
                        if set_pt.is_present() {
                            "regulator-input constraint"
                        } else {
                            "regulator-input"
                        }
                    })
                } else {
                    "regulator-input invalid"
                }
            },
            placeholder=regulator.measurement.with(|result| result.to_string()),
            bind:value=value,
            on:change=move |_| {
                valid.set(
                    match SpecifiedValue::try_from(value.get_clone_untracked()) {
                        Ok(set_pt) => {
                            regulator.set_point.set(set_pt);
                            true
                        }
                        Err(_) => false
                    }
                )
            },
            on:keydown={
                move |event: KeyboardEvent| {
                    match event.key().as_str() {
                        "Escape" => reset_value(),
                        _ => ()
                    }
                }
            }
        )
    }
}

// a list item that shows a regulator in an outline view of an element
#[component(inline_props)]
fn RegulatorOutlineItem(regulator_key: RegulatorKey, element_key: ElementKey) -> View {
    let state = use_context::<AppState>();
    let assembly = &state.assembly;
    let regulator = assembly.regulators.with(|regs| regs[regulator_key]);
    let other_subject = if regulator.subjects.0 == element_key {
        regulator.subjects.1
    } else {
        regulator.subjects.0
    };
    let other_subject_label = assembly.elements.with(|elts| elts[other_subject].label.clone());
    view! {
        li(class="regulator") {
            div(class="regulator-label") { (other_subject_label) }
            div(class="regulator-type") { "Inversive distance" }
            RegulatorInput(regulator=regulator)
            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 regulated = element.regulators.map(|regs| regs.len() > 0);
    let regulator_list = element.regulators.map(
        |regs| regs.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 regulated.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="regulators") {
                    Keyed(
                        list=regulator_list,
                        view=move |reg_key| view! {
                            RegulatorOutlineItem(
                                regulator_key=reg_key,
                                element_key=key
                            )
                        },
                        key=|reg_key| reg_key.clone()
                    )
                }
            }
        }
    }
}

// a component that lists the elements of the current assembly, showing each
// element's regulators in 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
            )
        }
    }
}