tools/publish/src/app.rs

use std::collections::HashMap;
use crate::rdf::ontology::{IndexEntry, LabeledIri, Ontology};
use crate::rdf::term_helper::{TermHelper, TermHelperMut};
use gl_search::{Schema, SearchDocument, SearchIndex, doc, Value};
use http::StatusCode;
use iced::alignment::Horizontal;
use iced::widget::button::Style;
use iced::widget::grid::Sizing;
use iced::widget::{button, center, column, combo_box, container, grid, mouse_area, opaque, operation, pick_list, row, scrollable, space, stack, table, text, text_input, toggler};
use iced::window::Settings;
use iced::{Background, Color, Element, Length, Subscription, Task, color, window};
use iced::widget::text::Wrapping;
use ldp::middleware::BasicAuthMiddleware;
use ldp::model::{KeyedDataset, QuadKey};
use ldp::reqwest::{Client, Url};
use ldp::reqwest_middleware::{ClientBuilder, ClientWithMiddleware};
use ldp::traverse::Traverse;
use ldp::{RdfSource, RdfSourceUpdateResponse, ResourceRequestBuilder, SerializationOptions};
use oxigraph::io::RdfFormat;
use oxigraph::model::vocab::{rdf, rdfs};
use oxigraph::model::{BaseDirection, Dataset, NamedNode, NamedOrBlankNode, Quad, Term};
use tracing::{debug_span, error, field, trace};
use crate::navigator::Navigator;
use crate::rdf::curie::CurieHelper;
use crate::rdf::language;
use crate::rdf::vocab::rda;
use crate::widget::iri_input::iri_input;
use crate::widget::navigation_area::navigation_area;

#[derive(Clone, Debug)]
pub(crate) enum Message {
    None,
    RebuildIndex,
    Traverse,
    AddRdfSource(RdfSource<Dataset>),
    ConcludeTraversal,
    IndexQueryResults(HashMap<NamedNode, IndexEntry>),
    WindowClosed(window::Id),
    URLInputChanged(String),
    URLInputSubmitted,
    NavigateTo(Url),
    FetchDocument(Url),
    LoadDocument(RdfSource<KeyedDataset<RowState>>),
    ShowNewDocumentButtons,
    HideNewDocumentButtons,
    ShowError(String),
    AddRow(Option<QuadKey>),
    DeleteRow(QuadKey),
    DeleteAllRows,
    OpenQueryWindow(SearchResultClickAction),
    HoverRow(QuadKey),
    UnhoverRow(QuadKey),
    QueryUpdated(String),
    SetSearchResults(Vec<SearchDocument>),
    QueryTypeUpdated(LabeledIri),
    SearchResultClicked(NamedNode),
    DatatypeUpdated(QuadKey, Option<String>),
    LanguageUpdated(QuadKey, Option<String>),
    SubjectUpdated(QuadKey, String),
    PredicateUpdated(QuadKey, String),
    ObjectUpdated(QuadKey, String),
    DirectionToggled(QuadKey, BaseDirection),
    SaveGraph(bool),
    ShowOverwriteConfirmationModal,
    HideOverwriteConfirmationModal,
    ConfirmOverwrite,
    NewDocument(NamedNode),
    NavigateToPredicate(QuadKey),
    NavigateToObject(QuadKey),
    NavigateBack,
    NavigateForward,
    ResetState,
}

#[derive(Default, Debug, Clone)]
pub(crate) struct RowState {
    read_only: bool,
    datatype_state: combo_box::State<String>,
}

#[derive(Debug, Clone)]
pub(crate) enum SearchResultClickAction {
    URLInput,
    Predicate(QuadKey),
    Object(QuadKey),
}

struct SearchState {
    window_id: window::Id,
    action: SearchResultClickAction,
    entity_selection: Option<LabeledIri>,
    query: String,
    results: Vec<SearchDocument>,
}

pub(crate) struct Publisher {
    http_client: ClientWithMiddleware,
    curie_helper: CurieHelper,
    ontology: Ontology,
    abbreviated_datatypes: Vec<String>,
    window_id: window::Id,
    url_input: String,
    navigator: Navigator<Url>,
    document: RdfSource<KeyedDataset<RowState>>,
    hovered_row: Option<QuadKey>,
    search_state: Option<SearchState>,
    index: SearchIndex,
    traversal: Option<Dataset>,
    show_overwrite_confirmation: bool,
    modified: bool,
    show_new_document_buttons: bool,
}

impl Publisher {
    pub(crate) fn new() -> (Self, Task<Message>) {
        let curie_helper = CurieHelper::new(Ontology::prefixes().clone());

        let ontology = debug_span!("Ontology Creation").in_scope(|| {
            Ontology::builder()
                .with_path("/home/alex/.local/share/org.graphofliberty.desktop/ontology")
                .build()
                .expect("Failed to build ontology")
        });

        let index = SearchIndex::builder()
            .with_path("/home/alex/.local/share/org.graphofliberty.desktop/index")
            .build()
            .expect("Failed to build search index");

        let mut abbreviated_datatypes = ontology
            .datatypes()
            .into_iter()
            .map(|node| curie_helper.abbreviate(None, node.as_str())
                .unwrap_or(node.as_str().to_string())
            ).collect::<Vec<_>>();
        abbreviated_datatypes.sort();

        let (id, task) = window::open(Settings::default());

        let client = Client::new();
        let http_client = ClientBuilder::new(client.clone())
            .with(BasicAuthMiddleware::new(
                "fedoraAdmin".to_string(),
                Some("fedoraAdmin".to_string()),
            ))
            .build();

        let starting_url = Url::parse("http://fedora.quill.lan/rest/").unwrap();
        let navigator = Navigator::new(starting_url.clone());
        let document = RdfSource::new(starting_url.clone());

        (
            Self {
                http_client,
                curie_helper,
                ontology,
                abbreviated_datatypes,
                window_id: id,
                url_input: starting_url.to_string(),
                navigator,
                document,
                hovered_row: None,
                search_state: None,
                index,
                traversal: None,
                show_overwrite_confirmation: false,
                modified: false,
                show_new_document_buttons: false,
            },
            task.map(|_| Message::None),
        )
    }

    pub(crate) fn update(&mut self, message: Message) -> Task<Message> {
        let mut task = Task::none();
        trace!(?message);

        match message {
            Message::RebuildIndex => {
                let mut writer = self.index.writer().expect("Unable to obtain index writer");
                let clear_index_task = Task::perform(tokio::task::spawn_blocking(move || {
                    let _span = debug_span!("Clear Index").entered();
                    writer.delete_all_documents().expect("Unable to clear index");
                    writer.commit().expect("Unable to commit index operation");
                }), |_| Message::None);

                let index_future = self.ontology
                    .query_for_indexable_triples(&*language::ENGLISH_OR_UNTAGGED, None);
                let index_task = Task::perform(index_future, |task_result| {
                    match task_result {
                        Ok(results) => Message::IndexQueryResults(results),
                        Err(err) => Message::ShowError(err.to_string()),
                    }
                });

                task = clear_index_task.chain(Task::batch([
                    index_task,
                    Task::done(Message::Traverse),
                ]));
            }
            Message::Traverse => {
                let client = self.http_client.clone();
                let root = Url::parse(&self.url_input).expect("Invalid URL");
                let stream = Traverse::new(client, root, None);

                task = Task::run(stream, |result| match result {
                    Ok(rdf_source) => Message::AddRdfSource(rdf_source),
                    Err(err) => Message::ShowError(format!("Unable to fetch RDF Source: {err}")),
                }).chain(Task::done(Message::ConcludeTraversal));

                self.traversal = Some(self.ontology.to_dataset());
            }
            Message::AddRdfSource(rdf_source) => {
                if let Some(traversal) = &mut self.traversal {
                    traversal.extend(rdf_source.dataset());
                }
            }
            Message::ConcludeTraversal => {
                if let Some(traversal) = self.traversal.take() {
                    let index_task = self.ontology
                        .query_for_indexable_triples(&*language::ENGLISH_OR_UNTAGGED, Some(traversal));
                    task = Task::perform(index_task, |task_result| {
                        match task_result {
                            Ok(results) => Message::IndexQueryResults(results),
                            Err(err) => Message::ShowError(err.to_string()),
                        }
                    });
                }
            }
            Message::IndexQueryResults(results) => {
                let mut writer = self.index.writer().expect("Unable to obtain index writer");
                let curie_helper = self.curie_helper.clone();
                task = Task::perform(tokio::task::spawn_blocking(move || {
                    let span = debug_span!("Index Query Results", documents = field::Empty).entered();
                    let mut counter = 0usize;
                    for (individual, entry) in results {
                        let mut document = doc!(
                        Schema::type_field() => entry.category_id,
                        Schema::iri_field() => individual.as_str(),
                    );

                        if let Some(curie) = curie_helper.abbreviate(None, individual.as_str()) {
                            document.add_text(Schema::curie_field(), curie);
                        }

                        for (key, value) in entry.fields {
                            document.add_text(Schema::field(&key, language::ENGLISH_PRIMARY), value.as_str());
                        }
                        writer.add_document(document).expect("Failed to add document to search index");
                        counter += 1;
                    }

                    span.record("documents", counter);
                    writer.commit()
                }), |result| {
                    if let Err(err) = result {
                        Message::ShowError(err.to_string())
                    } else {
                        Message::None
                    }
                });
            }
            Message::WindowClosed(id) => {
                if self.window_id == id {
                    task = iced::exit();
                } else {
                    self.search_state = None;
                }
            }
            Message::URLInputChanged(value) => {
                self.url_input = value;
            }
            Message::URLInputSubmitted => {
                let url = Url::parse(&self.url_input).expect("Invalid URL");
                if &url != self.navigator.current() {
                    self.navigator.goto(url.clone());
                }
                task = Task::done(Message::NavigateTo(url));
            }
            Message::NavigateTo(url) => {
                task = Task::done(Message::DeleteAllRows)
                    .chain(Task::done(Message::ResetState))
                    .chain(Task::done(Message::FetchDocument(url)));
            }
            Message::FetchDocument(url) => {
                let client = self.http_client.clone();
                task = Task::future(async {
                    let request = ResourceRequestBuilder::with_client_and_url(client, url)
                        .accept_rdf_format(RdfFormat::Turtle)
                        .follow_described_by(true)
                        .build();

                    match request.send().await {
                        Ok(resource) => match resource.into_rdf_source().await {
                            Ok(rdf_source) => Message::LoadDocument(rdf_source),
                            Err(err) => {
                                Message::ShowError(format!("Unable to parse response: {err}"))
                            }
                        },
                        Err(ldp::Error::Reqwest(err)) => {
                            if err.status() == Some(StatusCode::NOT_FOUND) {
                                Message::ShowNewDocumentButtons
                            } else {
                                Message::ShowError(err.to_string())
                            }
                        }
                        Err(err) => Message::ShowError(format!("Request failed: {err}")),
                    }
                });
            }
            Message::LoadDocument(document) => {
                let messages = document
                    .dataset()
                    .quads
                    .keys()
                    .map(|key| Message::AddRow(Some(key)));
                task = Task::batch(messages.map(Task::done)).chain(Task::done(Message::ResetState));

                self.document = document;
            }
            Message::ShowError(error) => {
                error!(error);
            }
            Message::AddRow(None) => {
                let mut quad = self.document.new_quad();
                let empty_node = NamedNode::new_unchecked("");
                quad.predicate = empty_node.clone();
                quad.object = Term::NamedNode(empty_node);

                let key = self.document.dataset_mut().quads.insert(quad);
                task = Task::done(Message::AddRow(Some(key)));
            }
            Message::AddRow(Some(key)) => {
                let quad = self
                    .document
                    .dataset()
                    .quads
                    .get(key)
                    .expect("Failed to get quad from document");
                let read_only = self.ontology.is_read_only(quad.as_ref());
                let term = TermHelper::new(&quad.object);
                let datatype = term
                    .datatype()
                    .map(|datatype| self.curie_helper.abbreviate(None, datatype.as_str())
                        .unwrap_or(datatype.as_str().to_string()));

                let datatype_state = combo_box::State::with_selection(
                    self.abbreviated_datatypes.clone(),
                    datatype.as_ref(),
                );
                let state = RowState {
                    read_only,
                    datatype_state,
                };
                self.document
                    .dataset_mut()
                    .associated_data
                    .insert(key, state);
                self.modified = true;
            }
            Message::DeleteRow(key) => {
                self.document.dataset_mut().remove(key);
                self.modified = true;
            }
            Message::DeleteAllRows => {
                self.document.dataset_mut().clear();
                self.modified = true;
            }
            Message::OpenQueryWindow(action) => {
                let selected_entity_class = match action {
                    SearchResultClickAction::Predicate(_) => Some(rdf::PROPERTY),
                    SearchResultClickAction::Object(key) => {
                        self.document
                            .dataset()
                            .quads
                            .get(key)
                            .and_then(|quad| if quad.predicate == rdf::TYPE {
                                Some(rdfs::CLASS)
                            } else { None })
                    },
                    SearchResultClickAction::URLInput => None,
                };

                if let Some(search_state) = &mut self.search_state {
                    search_state.action = action;
                } else {
                    let (id, window_task) = window::open(Settings::default());
                    self.search_state = Some(SearchState {
                        window_id: id,
                        action,
                        entity_selection: None,
                        query: String::new(),
                        results: Vec::new(),
                    });
                    task = window_task.then(|_| operation::focus("query"));
                }

                if let Some(selected_entity_class) = selected_entity_class {
                    let selection = self.ontology.info(&selected_entity_class.into_owned(), &*language::ENGLISH_OR_UNTAGGED);
                    task = task.chain(Task::done(Message::QueryTypeUpdated(selection)));
                }
            }
            Message::QueryTypeUpdated(type_) => {
                if let Some(search_state) = &mut self.search_state {
                    search_state.entity_selection = Some(type_);
                    task = Task::done(Message::QueryUpdated(search_state.query.clone()));
                }
            }
            Message::QueryUpdated(new_query) => {
                if let Some(search_state) = &mut self.search_state {
                    let category_id = search_state.entity_selection
                        .clone()
                        .and_then(|info| self.ontology.category_id(&info.iri));

                    let query = new_query.clone();
                    search_state.query = new_query;
                    let results = self.index.query(category_id, query.as_str(), Schema::all_fields(), 10)
                        .expect("Unable to complete search");
                    task = Task::done(Message::SetSearchResults(results));
                };
            }
            Message::SetSearchResults(results) => {
                if let Some(search_state) = &mut self.search_state {
                    search_state.results = results;
                }
            }
            Message::SearchResultClicked(node) => {
                if let Some(search_state) = &self.search_state {
                    match search_state.action {
                        SearchResultClickAction::URLInput => {
                            task = Task::done(Message::URLInputChanged(node.as_str().to_string()))
                                .chain(Task::done(Message::URLInputSubmitted));
                        }
                        SearchResultClickAction::Predicate(key) => {
                            if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                                quad.predicate = node;
                            }
                        }
                        SearchResultClickAction::Object(key) => {
                            if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                                quad.object = Term::NamedNode(node);
                            }
                        }
                    }
                    task = task.chain(window::close(search_state.window_id));
                    self.modified = true;
                }
            }
            Message::HoverRow(index) => {
                self.hovered_row = Some(index);
            }
            Message::UnhoverRow(index) if self.hovered_row == Some(index) => {
                self.hovered_row = None;
            }
            Message::DatatypeUpdated(key, Some(maybe_prefixed_iri)) => {
                let node = self
                    .curie_helper
                    .expand(None, &maybe_prefixed_iri)
                    .unwrap_or(maybe_prefixed_iri);

                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    let mut term = TermHelperMut::new(&mut quad.object);
                    term.set_datatype(Some(NamedNode::new_unchecked(node)));
                    self.modified = true;
                }
            }
            Message::DatatypeUpdated(key, None) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    let mut term = TermHelperMut::new(&mut quad.object);
                    term.set_datatype(None);
                    self.modified = true;
                }
            }
            Message::LanguageUpdated(key, Some(language)) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    let mut term = TermHelperMut::new(&mut quad.object);
                    term.set_language(language.as_str());
                    self.modified = true;
                }
            }
            Message::LanguageUpdated(key, None) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    let mut term = TermHelperMut::new(&mut quad.object);
                    term.set_language("en");
                    self.modified = true;
                }
            }
            Message::SubjectUpdated(key, value) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    quad.subject = NamedOrBlankNode::NamedNode(NamedNode::new_unchecked(value));
                    self.modified = true;
                }
            }
            Message::PredicateUpdated(key, value) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    quad.predicate = NamedNode::new_unchecked(value);
                    self.modified = true;
                }
            }
            Message::ObjectUpdated(key, value) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    let mut term = TermHelperMut::new(&mut quad.object);
                    term.set_value(value);
                    self.modified = true;
                }
            }
            Message::DirectionToggled(key, direction) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    let mut term = TermHelperMut::new(&mut quad.object);
                    term.set_direction(direction);
                    self.modified = true;
                }
            }
            Message::SaveGraph(overwrite) => {
                let client = self.http_client.clone();
                let options = SerializationOptions::from_format(RdfFormat::Turtle)
                    .with_filter(self.ontology.exclude_read_only());
                let request = self
                    .document
                    .to_update(options)
                    .expect("Failed to generate PUT request");
                let url = self.document.origin().clone();
                task = Task::future(async move {
                    match request.send(client, overwrite).await {
                        Ok(RdfSourceUpdateResponse::Success) => Message::FetchDocument(url),
                        Ok(RdfSourceUpdateResponse::DocumentModified(_)) => {
                            Message::ShowOverwriteConfirmationModal
                        }
                        Err(err) => Message::ShowError(format!("Failed to save graph: {err}")),
                    }
                });
            }
            Message::ShowOverwriteConfirmationModal => {
                self.show_overwrite_confirmation = true;
            }
            Message::HideOverwriteConfirmationModal => {
                self.show_overwrite_confirmation = false;
            }
            Message::ConfirmOverwrite => {
                task = Task::done(Message::SaveGraph(true))
                    .chain(Task::done(Message::HideOverwriteConfirmationModal));
            }
            Message::ShowNewDocumentButtons => {
                self.show_new_document_buttons = true;
            }
            Message::HideNewDocumentButtons => {
                self.show_new_document_buttons = false;
            }
            Message::NewDocument(class) => {
                let url = Url::parse(self.url_input.as_str()).expect("Invalid URL");
                let subject = NamedNode::new_unchecked(url.as_str());
                self.document = RdfSource::new(url);

                let template_quads = self
                    .ontology
                    .template_triples(class.as_ref(), subject.as_ref())
                    .map(|triples| {
                        triples
                            .map(|triple| self.document.quad_from_triple(triple))
                            .collect::<Vec<_>>()
                    })
                    .unwrap_or_else(|| {
                        let mut new_quad = self.document.new_quad();
                        new_quad.object = Term::NamedNode(class);
                        vec![new_quad]
                });

                task = Task::done(Message::HideNewDocumentButtons);

                let new_keys = self.document.dataset_mut().extend(template_quads.into_iter());
                let messages = new_keys.map(|triple| Message::AddRow(Some(triple)));
                task = task.chain(Task::batch(messages.map(Task::done)));
            }
            Message::ResetState => {
                self.modified = false;
                self.show_new_document_buttons = false;
                self.show_overwrite_confirmation = false;
            }
            Message::NavigateToPredicate(key) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    let url = Url::parse(quad.predicate.as_str()).expect("Invalid URL");
                    task = Task::done(Message::URLInputChanged(url.to_string()))
                        .chain(Task::done(Message::URLInputSubmitted));
                }
            }
            Message::NavigateToObject(key) => {
                if let Some(quad) = self.document.dataset_mut().quads.get_mut(key) {
                    if let Term::NamedNode(node) = &quad.object {
                        let url = Url::parse(node.as_str()).expect("Invalid URL");
                        task = Task::done(Message::URLInputChanged(url.to_string()))
                            .chain(Task::done(Message::URLInputSubmitted));
                    }
                }
            }
            Message::NavigateBack => {
                let url = self.navigator.back().clone();
                task = Task::done(Message::URLInputChanged(url.to_string()))
                    .chain(Task::done(Message::NavigateTo(url)));
            }
            Message::NavigateForward => {
                let url = self.navigator.forward().clone();
                task = Task::done(Message::URLInputChanged(url.to_string()))
                    .chain(Task::done(Message::NavigateTo(url)));
            }
            _ => {}
        }
        task
    }

    pub(crate) fn title(&self, _window: window::Id) -> String {
        "Graph of Liberty Publisher".to_string()
    }

    pub(crate) fn subscription(&self) -> Subscription<Message> {
        Subscription::batch([
            window::close_events().map(Message::WindowClosed),
        ])
    }

    fn view_row<'a>(
        &'a self,
        key: QuadKey,
        triple: &'a Quad,
        state: &'a RowState,
    ) -> Element<'a, Message> {
        const BUTTON_WIDTH: Length = Length::Fixed(35.0);
        let delete_button = button("\u{274c}")
            .style(|_, _| Style::default().with_background(Background::Color(color!(255, 0, 0))))
            .on_press(Message::DeleteRow(key));

        let button_area = if self.hovered_row == Some(key) && !state.read_only {
            container(delete_button).width(BUTTON_WIDTH)
        } else {
            container(space()).width(BUTTON_WIDTH)
        };

        let base = self.document.origin().as_str();

        let subject = match &triple.subject {
            NamedOrBlankNode::NamedNode(subject) => subject.as_str(),
            _ => "",
        };

        let subject_input_base = iri_input(&self.curie_helper, "Subject", Some(&base), subject);
        let subject_input = if self.ontology.is_read_only(triple.as_ref()) {
            subject_input_base
        } else {
            subject_input_base.on_input(move |value| Message::SubjectUpdated(key, value))
        };

        let predicate_input_base = iri_input(&self.curie_helper, "Predicate", Some(&base), triple.predicate.as_str());
        let predicate_input = if self.ontology.is_read_only(triple.as_ref()) {
            predicate_input_base
        } else {
            predicate_input_base.on_input(move |value| Message::PredicateUpdated(key, value))
                .on_control_click(Message::OpenQueryWindow(SearchResultClickAction::Predicate(key)))
                .on_shift_click(Message::NavigateToPredicate(key))
        };

        let predicate_info = self.ontology.info(&triple.predicate, &*language::ENGLISH_OR_UNTAGGED);
        let predicate_label = container(text(predicate_info.label));

        let term = TermHelper::new(&triple.object);

        let value_label = term.value_as_named_node().and_then(|node| {
            let info = self.ontology.info(&node.into_owned(), &*language::ENGLISH_OR_UNTAGGED);
            Some(container(text(info.label)))
        });

        let value = term
            .value_as_named_node()
            .map(|node| node.as_str().to_string())
            .unwrap_or(term.value().to_string());

        let value_alignment = term
            .direction()
            .map(|direction| match direction {
                BaseDirection::Ltr => Horizontal::Left,
                BaseDirection::Rtl => Horizontal::Right,
            })
            .unwrap_or(Horizontal::Left);

        // If the datatype is something, then it's not a named node, and we should use a plain
        // text_input as opposed to an iri_input.
        let object_input: Element<Message> = if term.datatype().is_some() {
            let base = text_input("Object", value.as_str());
            if self.ontology.is_read_only(triple.as_ref()) {
                base.into()
            } else {
                base.on_input(move |value| Message::ObjectUpdated(key, value)).into()
            }
        } else {
            let base = iri_input(&self.curie_helper, "Object", Some(&base), value.as_str())
                .on_shift_click(Message::NavigateToObject(key));
            if self.ontology.is_read_only(triple.as_ref()) {
                base.into()
            } else {
                base.align_x(value_alignment)
                    .on_input(move |value| Message::ObjectUpdated(key, value))
                    .on_control_click(Message::OpenQueryWindow(SearchResultClickAction::Object(key)))
                    .into()
            }
        };

        let selected_datatype = term.datatype()
            .and_then(|node| self.curie_helper.abbreviate(None, node.as_str()));

        let datatype_selector: Element<Message> = if state.read_only {
            selected_datatype.map(text).into()
        } else {
            combo_box(
                &state.datatype_state,
                "Datatype",
                selected_datatype.as_ref(),
                move |selection| Message::DatatypeUpdated(key, Some(selection)),
            )
            .on_input(move |input| {
                let value = if input.is_empty() { None } else { Some(input) };
                Message::DatatypeUpdated(key, value)
            }).into()
        };

        let language_input = match term.datatype() {
            Some(rdf::LANG_STRING) | Some(rdf::DIR_LANG_STRING) => Some(container(
                text_input("Language", term.language().unwrap_or("en")).on_input(move |input| {
                    let value = if input.is_empty() { None } else { Some(input) };
                    Message::LanguageUpdated(key, value)
                }),
            )),
            _ => None,
        };

        let direction_slider = term
            .direction()
            .map(|direction| match direction {
                BaseDirection::Ltr => toggler(false),
                BaseDirection::Rtl => toggler(true),
            })
            .map(|toggler| {
                container(row![
                    text("LTR"),
                    toggler.on_toggle(move |new_state| {
                        let direction = if new_state {
                            BaseDirection::Rtl
                        } else {
                            BaseDirection::Ltr
                        };
                        Message::DirectionToggled(key, direction)
                    }),
                    text("RTL"),
                ])
            });

        let row = row![
            button_area,
            subject_input,
            predicate_input,
            predicate_label,
            object_input,
            value_label,
            datatype_selector,
            language_input,
            direction_slider,
        ];

        mouse_area(row)
            .on_enter(Message::HoverRow(key))
            .on_exit(Message::UnhoverRow(key))
            .into()
    }

    fn view_new_entity_buttons(
        &self,
        entities: impl IntoIterator<Item = LabeledIri>,
    ) -> Element<'_, Message> {
        let buttons = entities.into_iter().map(|entity| {
            let abbreviation = self.curie_helper.abbreviate(None, entity.iri.as_str())
                .unwrap_or_else(|| entity.iri.as_str().to_string());

            let label = format!("{} ({})", entity.label, abbreviation);
            button(text(label))
                .on_press(Message::NewDocument(entity.iri))
                .into()
        });

        grid(buttons)
            .height(Sizing::EvenlyDistribute(Length::Shrink))
            .into()
    }

    pub(crate) fn view(&self, window: window::Id) -> Element<'_, Message> {
        if let Some(search_state) = &self.search_state
            && search_state.window_id == window
        {
            let search_input =
                text_input("Query", &search_state.query).on_input(Message::QueryUpdated)
                    .id("query");

            let entities = self.ontology
                .searchable_classes(&*language::ENGLISH_OR_UNTAGGED)
                .into_iter()
                .collect::<Vec<_>>();

            let type_selector = pick_list(search_state.entity_selection.as_ref(), entities, ToString::to_string)
                .on_select(|selection| Message::QueryTypeUpdated(selection));

            let mut columns = vec![
                table::column(text("CURIE"), |document: &SearchDocument| {
                    let iri = document.get_first(Schema::iri_field())
                        .and_then(|value| value.as_str())
                        .unwrap_or_default();

                    let abbreviated_iri = self.curie_helper.abbreviate(None, iri)
                        .unwrap_or_else(|| iri.to_string());

                    button(text(abbreviated_iri).wrapping(Wrapping::Word))
                        .on_press(Message::SearchResultClicked(NamedNode::new_unchecked(iri)))
                        .style(button::text)
                })
            ];

            let fields = if let Some(selection) = search_state.entity_selection.as_ref() {
                self.ontology.fields_for_class(&selection.iri, &*language::ENGLISH_OR_UNTAGGED)
                    .expect("Unable to load fields for class")
            } else {
                vec![]
            };

            for field in fields.into_iter() {
                let field_name = field.name.clone();
                columns.push(
                    table::column(text(field.label), move |document: &SearchDocument| {
                        let iri = document.get_first(Schema::iri_field())
                            .and_then(|value| value.as_str())
                            .unwrap_or_default();

                        let value = document.get_first(Schema::field(&field_name, language::ENGLISH_PRIMARY))
                            .and_then(|value| value.as_str())
                            .unwrap_or_default();

                        button(text(value).wrapping(Wrapping::Word))
                            .on_press(Message::SearchResultClicked(NamedNode::new_unchecked(iri)))
                            .style(button::text)
                    }).width(Length::Fixed(256.0))
                );
            }

            let results_table = if columns.is_empty() {
                None
            } else {
                Some(scrollable(table(columns, &search_state.results)))
            };

            return column![
                row![search_input, type_selector],
                results_table
            ].into();
        }

        let back_button = button("\u{1f870}").on_press(Message::NavigateBack);

        let forward_button = button("\u{1f872}").on_press(Message::NavigateForward);

        let add_row_button = button("Add row").on_press(Message::AddRow(None));

        let reindex_ontology_button = button("Rebuild index").on_press(Message::RebuildIndex);

        let address_input = iri_input(&self.curie_helper, "URL", None, &self.url_input)
            .on_input(Message::URLInputChanged)
            .on_submit(Message::URLInputSubmitted)
            .on_control_click(Message::OpenQueryWindow(SearchResultClickAction::URLInput));

        let mut rows: Vec<Element<Message>> = vec![];
        rows = self
            .document
            .dataset()
            .iter_both()
            .map(|(key, quad, state)| self.view_row(key, quad, state))
            .collect();

        let body: Element<Message> = if self.show_new_document_buttons {
            let subclasses = self.ontology.subclasses_of(&rda::ENTITY.into_owned());
            let labeled_subclasses = subclasses.iter().map(|iri| self.ontology.info(iri, &*language::ENGLISH_OR_UNTAGGED));
            column![self.view_new_entity_buttons(labeled_subclasses)].into()
        } else {
            column(rows).into()
        };

        let save_button_base = button(text("\u{1f4be}"));
        let save_button = if self.modified {
            save_button_base.on_press(Message::SaveGraph(false))
        } else {
            save_button_base
        };

        let content = navigation_area(column![
            row![
                reindex_ontology_button,
                add_row_button,
                back_button,
                forward_button,
                address_input,
                save_button,
            ],
            scrollable(body),
            space::vertical(),
        ])
            .on_back_click(Message::NavigateBack)
            .on_forward_click(Message::NavigateForward);

        if self.show_overwrite_confirmation {
            let confirmation_modal = container(column![
                text("The resource has changed since it was fetched. Overwrite?"),
                row![
                    button(text("Yes"))
                        .style(button::danger)
                        .on_press(Message::ConfirmOverwrite),
                    space::horizontal(),
                    button(text("No")).on_press(Message::HideOverwriteConfirmationModal),
                ],
            ])
            .width(Length::Shrink);

            modal(content, confirmation_modal, Message::None)
        } else {
            content.into()
        }
    }
}

fn modal<'a, Message>(
    base: impl Into<Element<'a, Message>>,
    content: impl Into<Element<'a, Message>>,
    on_blur: Message,
) -> Element<'a, Message>
where
    Message: Clone + 'a,
{
    stack![
        base.into(),
        opaque(
            mouse_area(center(opaque(content)).style(|_theme| {
                container::Style {
                    background: Some(
                        Color {
                            a: 0.8,
                            ..Color::BLACK
                        }
                        .into(),
                    ),
                    ..container::Style::default()
                }
            }))
            .on_press(on_blur)
        )
    ]
    .into()
}