// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-1.1 OR LicenseRef-Slint-commercial

//! Pass that lowers synthetic `visible` properties to Clip element

use std::cell::RefCell;
use std::rc::Rc;

use crate::diagnostics::BuildDiagnostics;
use crate::expression_tree::{Expression, NamedReference};
use crate::langtype::{ElementType, NativeClass, Type};
use crate::object_tree::{self, Component, Element, ElementRc};
use crate::typeregister::TypeRegister;

pub fn handle_visible(
    component: &Rc<Component>,
    type_register: &TypeRegister,
    diag: &mut BuildDiagnostics,
) {
    if let Some(b) = component.root_element.borrow().bindings.get("visible") {
        diag.push_warning(
            "The visible property cannot be used on the root element, it will not be applied"
                .into(),
            &*b.borrow(),
        );
    }

    let native_clip =
        type_register.lookup_builtin_element("Clip").unwrap().as_builtin().native_class.clone();

    crate::object_tree::recurse_elem_including_sub_components(
        component,
        &(),
        &mut |elem: &ElementRc, _| {
            let is_lowered_from_visible_property =
                elem.borrow().native_class().map_or(false, |n| {
                    Rc::ptr_eq(&n, &native_clip) && elem.borrow().id.ends_with("-visibility")
                });
            if is_lowered_from_visible_property {
                // This is the element we just created. Skip it.
                return;
            }

            let old_children = {
                let mut elem = elem.borrow_mut();
                let new_children = Vec::with_capacity(elem.children.len());
                std::mem::replace(&mut elem.children, new_children)
            };

            let has_visible_binding = |e: &ElementRc| {
                e.borrow().base_type.lookup_property("visible").property_type != Type::Invalid
                    && (e.borrow().bindings.contains_key("visible")
                        || e.borrow()
                            .property_analysis
                            .borrow()
                            .get("visible")
                            .map_or(false, |a| a.is_set || a.is_linked))
            };

            for mut child in old_children {
                if child.borrow().repeated.is_some() {
                    let root_elem = child.borrow().base_type.as_component().root_element.clone();
                    if has_visible_binding(&root_elem) {
                        let clip_elem = create_visibility_element(&root_elem, &native_clip);
                        object_tree::inject_element_as_repeated_element(&child, clip_elem.clone());
                        // The width and the height must be null
                        let d = NamedReference::new(&clip_elem, "dummy");
                        clip_elem.borrow_mut().geometry_props.as_mut().unwrap().width = d.clone();
                        clip_elem.borrow_mut().geometry_props.as_mut().unwrap().height = d;
                    }
                } else if has_visible_binding(&child) {
                    let new_child = create_visibility_element(&child, &native_clip);
                    new_child.borrow_mut().children.push(child);
                    child = new_child;
                }

                elem.borrow_mut().children.push(child);
            }
        },
    );
}

fn create_visibility_element(child: &ElementRc, native_clip: &Rc<NativeClass>) -> ElementRc {
    let element = Element {
        id: format!("{}-visibility", child.borrow().id),
        base_type: ElementType::Native(native_clip.clone()),
        enclosing_component: child.borrow().enclosing_component.clone(),
        bindings: std::iter::once((
            "clip".to_owned(),
            RefCell::new(
                Expression::UnaryOp {
                    sub: Box::new(Expression::PropertyReference(NamedReference::new(
                        child, "visible",
                    ))),
                    op: '!',
                }
                .into(),
            ),
        ))
        .collect(),
        ..Default::default()
    };
    Element::make_rc(element)
}