rust_browser/tests/js_events.rs

use shared::NodeId;
use web_api::WebApiFacade;

/// Helper: build a WebApiFacade with a DOM:  html > body > div#target("original")
/// Returns (facade, body_id, div_id).
fn setup_facade() -> (WebApiFacade, NodeId, NodeId) {
    let mut facade = WebApiFacade::new();

    let doc = facade.document_mut();
    let root = doc.root().unwrap();
    let html = doc.create_element("html");
    doc.append_child(root, html);
    let body = doc.create_element("body");
    doc.append_child(html, body);
    let div = doc.create_element("div");
    doc.set_attribute(div, "id", "target");
    doc.append_child(body, div);
    let text = doc.create_text("original");
    doc.append_child(div, text);

    facade.bootstrap().unwrap();
    (facade, body, div)
}

// --- Basic click handler registration and dispatch ---

#[test]
fn click_handler_mutates_dom() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function(event) {
            el.textContent = "clicked";
        });
    "#,
        )
        .unwrap();

    let result = facade.dispatch_click(div).unwrap();
    assert!(!result.default_prevented);
    assert_eq!(facade.document().text_content(div), "clicked");
}

// --- Multiple handlers on same element fire in insertion order ---

#[test]
fn multiple_handlers_fire_in_order() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function() {
            el.textContent = "first";
        });
        el.addEventListener("click", function() {
            el.textContent = el.textContent + "_second";
        });
    "#,
        )
        .unwrap();

    facade.dispatch_click(div).unwrap();
    assert_eq!(facade.document().text_content(div), "first_second");
}

// --- preventDefault sets result flag ---

#[test]
fn prevent_default_sets_result() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function(event) {
            event.preventDefault();
        });
    "#,
        )
        .unwrap();

    let result = facade.dispatch_click(div).unwrap();
    assert!(result.default_prevented);
}

// --- removeEventListener prevents handler from firing ---

#[test]
fn remove_event_listener_prevents_fire() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        var handler = function() {
            el.textContent = "should not happen";
        };
        el.addEventListener("click", handler);
        el.removeEventListener("click", handler);
    "#,
        )
        .unwrap();

    facade.dispatch_click(div).unwrap();
    // Text should remain "original" since handler was removed
    assert_eq!(facade.document().text_content(div), "original");
}

// --- Bubbling: child click reaches parent handler ---

#[test]
fn event_bubbles_to_parent() {
    let mut facade = WebApiFacade::new();
    let doc = facade.document_mut();
    let root = doc.root().unwrap();
    let html = doc.create_element("html");
    doc.append_child(root, html);
    let body = doc.create_element("body");
    doc.set_attribute(body, "id", "body");
    doc.append_child(html, body);
    let outer = doc.create_element("div");
    doc.set_attribute(outer, "id", "outer");
    doc.append_child(body, outer);
    let inner = doc.create_element("span");
    doc.set_attribute(inner, "id", "inner");
    doc.append_child(outer, inner);
    let text = doc.create_text("hello");
    doc.append_child(inner, text);

    facade.bootstrap().unwrap();

    // Register handler on outer (parent of inner)
    facade
        .execute_script(
            r#"
        var outer = document.getElementById("outer");
        outer.addEventListener("click", function() {
            outer.textContent = "bubbled";
        });
    "#,
        )
        .unwrap();

    // Dispatch click on inner — should bubble to outer
    facade.dispatch_click(inner).unwrap();
    assert_eq!(facade.document().text_content(outer), "bubbled");
}

// --- stopPropagation halts bubbling ---

#[test]
fn stop_propagation_halts_bubbling() {
    let mut facade = WebApiFacade::new();
    let doc = facade.document_mut();
    let root = doc.root().unwrap();
    let html = doc.create_element("html");
    doc.append_child(root, html);
    let body = doc.create_element("body");
    doc.set_attribute(body, "id", "body");
    doc.append_child(html, body);
    let child = doc.create_element("div");
    doc.set_attribute(child, "id", "child");
    doc.append_child(body, child);
    let text = doc.create_text("init");
    doc.append_child(child, text);

    facade.bootstrap().unwrap();

    facade
        .execute_script(
            r#"
        var child = document.getElementById("child");
        var body = document.getElementById("body");
        child.addEventListener("click", function(event) {
            event.stopPropagation();
            child.textContent = "child_handled";
        });
        body.addEventListener("click", function() {
            body.textContent = "body_should_not_fire";
        });
    "#,
        )
        .unwrap();

    facade.dispatch_click(child).unwrap();
    assert_eq!(facade.document().text_content(child), "child_handled");
    // body listener should NOT have fired due to stopPropagation
    assert_ne!(facade.document().text_content(body), "body_should_not_fire");
}

// --- Handler throws exception — runtime recovers, other handlers still fire ---

#[test]
fn handler_exception_does_not_block_others() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function() {
            undeclaredVariable;
        });
        el.addEventListener("click", function() {
            el.textContent = "recovered";
        });
    "#,
        )
        .unwrap();

    facade.dispatch_click(div).unwrap();
    // Second handler should fire despite the first one throwing
    assert_eq!(facade.document().text_content(div), "recovered");
}

// --- No listeners = no error ---

#[test]
fn no_listeners_dispatch_succeeds() {
    let (mut facade, _, div) = setup_facade();
    let result = facade.dispatch_click(div).unwrap();
    assert!(!result.default_prevented);
}

// --- Re-entrant dispatch is blocked ---

#[test]
fn dispatch_with_no_crash() {
    // Basic test that dispatch doesn't crash with various scenarios
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function(event) {
            el.textContent = "ok";
        });
    "#,
        )
        .unwrap();

    // Multiple sequential dispatches work fine
    facade.dispatch_click(div).unwrap();
    assert_eq!(facade.document().text_content(div), "ok");

    // Can dispatch again
    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function() {
            el.textContent = "second_click";
        });
    "#,
        )
        .unwrap();
    facade.dispatch_click(div).unwrap();
    assert_eq!(facade.document().text_content(div), "second_click");
}

// --- Document listener fires during bubbling ---

#[test]
fn document_listener_fires_on_bubble() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        document.addEventListener("click", function() {
            el.textContent = "doc_heard";
        });
    "#,
        )
        .unwrap();

    facade.dispatch_click(div).unwrap();
    assert_eq!(facade.document().text_content(div), "doc_heard");
}

// --- Event properties are accessible from handler ---

#[test]
fn event_properties_accessible() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function(event) {
            el.textContent = event.type;
        });
    "#,
        )
        .unwrap();

    facade.dispatch_click(div).unwrap();
    assert_eq!(facade.document().text_content(div), "click");
}

// --- Handler does createElement + appendChild + reads textContent ---

#[test]
fn handler_creates_and_appends_element() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function() {
            var span = document.createElement("span");
            span.textContent = "dynamic";
            el.appendChild(span);
        });
    "#,
        )
        .unwrap();

    facade.dispatch_click(div).unwrap();
    // After appendChild, textContent includes both the original text and the appended span's text
    assert_eq!(facade.document().text_content(div), "originaldynamic");
}

// --- Second handler sees DOM changes from first handler ---

#[test]
fn second_handler_sees_first_handlers_dom_changes() {
    let (mut facade, _, div) = setup_facade();

    facade
        .execute_script(
            r#"
        var el = document.getElementById("target");
        el.addEventListener("click", function() {
            el.textContent = "modified_by_first";
        });
        el.addEventListener("click", function() {
            el.textContent = el.textContent + "_seen_by_second";
        });
    "#,
        )
        .unwrap();

    facade.dispatch_click(div).unwrap();
    assert_eq!(
        facade.document().text_content(div),
        "modified_by_first_seen_by_second"
    );
}

// --- Dispatching on an element without an id attribute does not panic ---

#[test]
fn dispatch_click_on_element_without_id_is_noop() {
    let mut facade = WebApiFacade::new();
    let doc = facade.document_mut();
    let root = doc.root().unwrap();
    let html = doc.create_element("html");
    doc.append_child(root, html);
    let body = doc.create_element("body");
    doc.append_child(html, body);
    // No id attribute set on this div
    let div = doc.create_element("div");
    doc.append_child(body, div);
    let text = doc.create_text("no_id");
    doc.append_child(div, text);

    facade.bootstrap().unwrap();

    // dispatch_click on a node with no listeners and no id must not panic
    let result = facade.dispatch_click(div).unwrap();
    assert!(!result.default_prevented);
    assert_eq!(facade.document().text_content(div), "no_id");
}