/* LICENSE BEGIN
    This file is part of the SixtyFPS Project -- https://sixtyfps.io
    Copyright (c) 2020 Olivier Goffart <olivier.goffart@sixtyfps.io>
    Copyright (c) 2020 Simon Hausmann <simon.hausmann@sixtyfps.io>

    SPDX-License-Identifier: GPL-3.0-only
    This file is also available under commercial licensing terms.
    Please contact info@sixtyfps.io for more information.
LICENSE END */
//! Inline each object_tree::Component within the main Component

use crate::{expression_tree::NamedReference, object_tree::*, typeregister::Type};
use by_address::ByAddress;
use std::cell::RefCell;
use std::collections::HashMap;
use std::rc::Rc;

pub fn inline(doc: &Document) {
    fn inline_components_recursively(component: &Rc<Component>) {
        recurse_elem(&component.root_element, &(), &mut |elem, _| {
            let base = elem.borrow().base_type.clone();
            if let Type::Component(c) = base {
                // First, make sure that the component itself is properly inlined
                inline_components_recursively(&c);
                // Inline this component.
                inline_element(elem, &c, component);
            }
        })
    }
    inline_components_recursively(&doc.root_component)
}

fn clone_tuple<U: Clone, V: Clone>((u, v): (&U, &V)) -> (U, V) {
    (u.clone(), v.clone())
}

fn element_key(e: ElementRc) -> ByAddress<ElementRc> {
    ByAddress(e)
}

fn inline_element(
    elem: &ElementRc,
    inlined_component: &Rc<Component>,
    root_component: &Rc<Component>,
) {
    // inlined_component must be the base type of this element
    debug_assert_eq!(
        format!("{:?}", elem.borrow().base_type),
        format!("{:?}", Type::Component(inlined_component.clone()))
    );
    debug_assert!(
        inlined_component.root_element.borrow().repeated.is_none(),
        "root element of a component cannot be repeated"
    );

    let mut elem_mut = elem.borrow_mut();
    elem_mut.base_type = inlined_component.root_element.borrow().base_type.clone();
    elem_mut.property_declarations.extend(
        inlined_component.root_element.borrow().property_declarations.iter().map(clone_tuple),
    );
    elem_mut.property_animations.extend(
        inlined_component.root_element.borrow().property_animations.iter().map(clone_tuple),
    );

    // Map the old element to the new
    let mut mapping = HashMap::new();
    mapping.insert(element_key(inlined_component.root_element.clone()), elem.clone());

    let mut new_children = vec![];
    new_children
        .reserve(elem_mut.children.len() + inlined_component.root_element.borrow().children.len());
    new_children.extend(
        inlined_component
            .root_element
            .borrow()
            .children
            .iter()
            .map(|x| duplicate_element_with_mapping(x, &mut mapping, root_component)),
    );

    match inlined_component
        .child_insertion_point
        .borrow()
        .as_ref()
        .and_then(|elem| mapping.get(&element_key(elem.clone())))
    {
        Some(insertion_element) if !Rc::ptr_eq(elem, insertion_element) => {
            insertion_element.borrow_mut().children.append(&mut elem_mut.children);
            root_component.child_insertion_point.borrow_mut().as_mut().map(|cip| {
                if Rc::ptr_eq(cip, elem) {
                    *cip = insertion_element.clone();
                }
            });
        }
        _ => {
            new_children.append(&mut elem_mut.children);
        }
    }

    elem_mut.children = new_children;

    elem_mut.bindings.extend(
        inlined_component
            .root_element
            .borrow()
            .bindings
            .iter()
            .map(|(k, val)| (k.clone(), val.clone())),
    );

    core::mem::drop(elem_mut);

    // Now fixup all binding and reference
    for (_, e) in &mapping {
        visit_all_named_references(e, |nr| fixup_reference(nr, &mapping));
    }
}

// Duplicate the element elem and all its children. And fill the mapping to point from the old to the new
fn duplicate_element_with_mapping(
    element: &ElementRc,
    mapping: &mut HashMap<ByAddress<ElementRc>, ElementRc>,
    root_component: &Rc<Component>,
) -> ElementRc {
    let elem = element.borrow();
    let new = Rc::new(RefCell::new(Element {
        base_type: elem.base_type.clone(),
        id: elem.id.clone(),
        property_declarations: elem.property_declarations.clone(),
        property_animations: elem
            .property_animations
            .iter()
            .map(|(k, v)| (k.clone(), duplicate_element_with_mapping(v, mapping, root_component)))
            .collect(),
        // We will do the fixup of the bindings later
        bindings: elem.bindings.clone(),
        children: elem
            .children
            .iter()
            .map(|x| duplicate_element_with_mapping(x, mapping, root_component))
            .collect(),
        repeated: elem.repeated.clone(),
        node: elem.node.clone(),
        enclosing_component: Rc::downgrade(root_component),
        states: elem.states.clone(),
        transitions: elem
            .transitions
            .iter()
            .map(|t| duplicate_transition(t, mapping, root_component))
            .collect(),
        child_of_layout: elem.child_of_layout,
    }));
    mapping.insert(element_key(element.clone()), new.clone());
    new
}

fn fixup_reference(
    NamedReference { element, .. }: &mut NamedReference,
    mapping: &HashMap<ByAddress<ElementRc>, ElementRc>,
) {
    if let Some(e) = element.upgrade().and_then(|e| mapping.get(&element_key(e.clone()))) {
        *element = Rc::downgrade(e);
    }
}

fn duplicate_transition(
    t: &Transition,
    mapping: &mut HashMap<ByAddress<ElementRc>, Rc<RefCell<Element>>>,
    root_component: &Rc<Component>,
) -> Transition {
    Transition {
        is_out: t.is_out,
        state_id: t.state_id.clone(),
        property_animations: t
            .property_animations
            .iter()
            .map(|(r, anim)| {
                (r.clone(), duplicate_element_with_mapping(anim, mapping, root_component))
            })
            .collect(),
    }
}