// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0

//! Passe that transform the PopupWindow element into a component

use crate::diagnostics::BuildDiagnostics;
use crate::expression_tree::{Expression, NamedReference};
use crate::langtype::{ElementType, EnumerationValue, Type};
use crate::object_tree::*;
use crate::typeregister::TypeRegister;
use smol_str::format_smolstr;
use std::rc::{Rc, Weak};

pub fn lower_popups(
    component: &Rc<Component>,
    type_register: &TypeRegister,
    diag: &mut BuildDiagnostics,
) {
    let window_type = type_register.lookup_builtin_element("Window").unwrap();

    recurse_elem_including_sub_components_no_borrow(
        component,
        &None,
        &mut |elem, parent_element: &Option<ElementRc>| {
            let is_popup = match &elem.borrow().base_type {
                ElementType::Builtin(base_type) => base_type.name == "PopupWindow",
                ElementType::Component(base_type) => base_type.inherits_popup_window.get(),
                _ => false,
            };

            if is_popup {
                lower_popup_window(elem, parent_element.as_ref(), &window_type, diag);
            }
            Some(elem.clone())
        },
    )
}

fn lower_popup_window(
    popup_window_element: &ElementRc,
    parent_element: Option<&ElementRc>,
    window_type: &ElementType,
    diag: &mut BuildDiagnostics,
) {
    let parent_component = popup_window_element.borrow().enclosing_component.upgrade().unwrap();
    let parent_element = match parent_element {
        None => {
            if matches!(popup_window_element.borrow().base_type, ElementType::Builtin(_)) {
                popup_window_element.borrow_mut().base_type = window_type.clone();
            }
            parent_component.inherits_popup_window.set(true);
            return;
        }
        Some(parent_element) => parent_element,
    };

    if Rc::ptr_eq(&parent_component.root_element, popup_window_element) {
        diag.push_error(
            "PopupWindow cannot be directly repeated or conditional".into(),
            &*popup_window_element.borrow(),
        );
        return;
    }

    // Remove the popup_window_element from its parent
    let old_size = parent_element.borrow().children.len();
    parent_element.borrow_mut().children.retain(|child| !Rc::ptr_eq(child, popup_window_element));
    debug_assert_eq!(
        parent_element.borrow().children.len() + 1,
        old_size,
        "Exactly one child must be removed (the popup itself)"
    );
    parent_element.borrow_mut().has_popup_child = true;

    if matches!(popup_window_element.borrow().base_type, ElementType::Builtin(_)) {
        popup_window_element.borrow_mut().base_type = window_type.clone();
    }

    const CLOSE_ON_CLICK: &str = "close-on-click";
    let close_on_click = popup_window_element.borrow_mut().bindings.remove(CLOSE_ON_CLICK);

    // Take a reference to the close on click
    let close_on_click = close_on_click
        .map(|b| {
            diag.push_property_deprecation_warning(
                "close-on-click",
                "close-policy",
                &b.borrow().span,
            );
            let b = b.into_inner();
            (b.expression, b.span)
        })
        .or_else(|| {
            let mut base = popup_window_element.borrow().base_type.clone();
            while let ElementType::Component(b) = base {
                base = b.root_element.borrow().base_type.clone();
                if let Some(binding) = b.root_element.borrow().bindings.get(CLOSE_ON_CLICK) {
                    let b = binding.borrow();
                    return Some((b.expression.clone(), b.span.clone()));
                }
            }
            None
        });

    const CLOSE_POLICY: &str = "close-policy";
    let close_policy = popup_window_element.borrow_mut().bindings.remove(CLOSE_POLICY);

    // Take a reference to the close policy
    let close_policy = close_policy
        .map(|b| {
            let b = b.into_inner();
            (b.expression, b.span)
        })
        .or_else(|| {
            let mut base = popup_window_element.borrow().base_type.clone();
            while let ElementType::Component(b) = base {
                base = b.root_element.borrow().base_type.clone();
                if let Some(binding) = b.root_element.borrow().bindings.get(CLOSE_POLICY) {
                    let b = binding.borrow();
                    return Some((b.expression.clone(), b.span.clone()));
                }
            }
            None
        });

    if close_policy.is_some() && close_on_click.is_some() {
        diag.push_error(
            "close-policy and close-on-click cannot be set at the same time".into(),
            &close_on_click.unwrap().1,
        );
        return;
    }

    let close_on_click = match close_on_click {
        Some((expr, location)) => match expr {
            Expression::BoolLiteral(value) => Some(value),
            _ => {
                diag.push_error(
                    "The close-on-click property only supports constants at the moment".into(),
                    &location,
                );
                return;
            }
        },
        None => None,
    };

    let close_policy = match close_policy {
        Some((expr, location)) => match expr {
            Expression::EnumerationValue(value) => value,
            _ => {
                diag.push_error(
                    "The close-policy property only supports constants at the moment".into(),
                    &location,
                );
                return;
            }
        },
        None => {
            let enum_ty = crate::typeregister::BUILTIN_ENUMS.with(|e| e.PopupClosePolicy.clone());

            let mut value = String::from("close-on-click");

            if let Some(close_on_click) = close_on_click {
                if !close_on_click {
                    value = "no-auto-close".into()
                }
            }
            EnumerationValue {
                value: enum_ty.values.iter().position(|v| v == value.as_str()).unwrap(),
                enumeration: enum_ty,
            }
        }
    };

    let popup_comp = Rc::new(Component {
        root_element: popup_window_element.clone(),
        parent_element: Rc::downgrade(parent_element),
        ..Component::default()
    });

    let weak = Rc::downgrade(&popup_comp);
    recurse_elem(&popup_comp.root_element, &(), &mut |e, _| {
        e.borrow_mut().enclosing_component = weak.clone()
    });

    // Take a reference to the x/y coordinates, to be read when calling show_popup(), and
    // converted to absolute coordinates in the run-time library.
    let coord_x = NamedReference::new(&popup_comp.root_element, "x");
    let coord_y = NamedReference::new(&popup_comp.root_element, "y");

    // Meanwhile, set the geometry x/y to zero, because we'll be shown as a top-level and
    // children should be rendered starting with a (0, 0) offset.
    {
        let mut popup_mut = popup_comp.root_element.borrow_mut();
        let name = format_smolstr!("popup-{}-dummy", popup_mut.id);
        popup_mut.property_declarations.insert(name.clone(), Type::LogicalLength.into());
        drop(popup_mut);
        let dummy1 = NamedReference::new(&popup_comp.root_element, &name);
        let dummy2 = NamedReference::new(&popup_comp.root_element, &name);
        let mut popup_mut = popup_comp.root_element.borrow_mut();
        popup_mut.geometry_props.as_mut().unwrap().x = dummy1;
        popup_mut.geometry_props.as_mut().unwrap().y = dummy2;
    }

    // Throw error when accessing the popup from outside
    // FIXME:
    // - the span is the span of the PopupWindow, that's wrong, we should have the span of the reference
    // - There are other object reference than in the NamedReference
    // - Maybe this should actually be allowed
    visit_all_named_references(&parent_component, &mut |nr| {
        let element = &nr.element();
        if check_element(element, &weak, diag, popup_window_element) {
            // just set it to whatever is a valid NamedReference, otherwise we'll panic later
            *nr = coord_x.clone();
        }
    });
    visit_all_expressions(&parent_component, |exp, _| {
        exp.visit_recursive_mut(&mut |exp| {
            if let Expression::ElementReference(ref element) = exp {
                let elem = element.upgrade().unwrap();
                if !Rc::ptr_eq(&elem, popup_window_element) {
                    check_element(&elem, &weak, diag, popup_window_element);
                }
            }
        });
    });

    parent_component.popup_windows.borrow_mut().push(PopupWindow {
        component: popup_comp,
        x: coord_x,
        y: coord_y,
        close_policy,
        parent_element: parent_element.clone(),
    });
}

fn check_element(
    element: &ElementRc,
    popup_comp: &Weak<Component>,
    diag: &mut BuildDiagnostics,
    popup_window_element: &ElementRc,
) -> bool {
    if Weak::ptr_eq(&element.borrow().enclosing_component, popup_comp) {
        diag.push_error(
            "Cannot access the inside of a PopupWindow from enclosing component".into(),
            &*popup_window_element.borrow(),
        );
        true
    } else {
        false
    }
}