leptos_macro 0.7.0-preview

use super::{event_to_tokens, fragment_to_tokens, TagType};
use proc_macro2::{Ident, TokenStream, TokenTree};
use quote::{format_ident, quote, quote_spanned};
use rstml::node::{NodeAttribute, NodeElement, NodeName};
use std::collections::HashMap;
use syn::spanned::Spanned;

pub(crate) fn component_to_tokens(
    node: &NodeElement,
    global_class: Option<&TokenTree>,
) -> TokenStream {
    let name = node.name();
    #[cfg(debug_assertions)]
    let component_name = ident_from_tag_name(node.name());

    let attrs = node.attributes().iter().filter_map(|node| {
        if let NodeAttribute::Attribute(node) = node {
            Some(node)
        } else {
            None
        }
    });

    let props = attrs
        .clone()
        .filter(|attr| {
            !attr.key.to_string().starts_with("let:")
                && !attr.key.to_string().starts_with("clone:")
                && !attr.key.to_string().starts_with("on:")
                && !attr.key.to_string().starts_with("attr:")
                && !attr.key.to_string().starts_with("use:")
        })
        .map(|attr| {
            let name = &attr.key;

            let value = attr
                .value()
                .map(|v| {
                    quote! { #v }
                })
                .unwrap_or_else(|| quote! { #name });

            let value = quote_spanned! {value.span()=>
                #[allow(unused_braces)] {#value}
            };

            quote_spanned! {attr.span()=>
                .#name(#value)
            }
        });

    let items_to_bind = attrs
        .clone()
        .filter_map(|attr| {
            attr.key
                .to_string()
                .strip_prefix("let:")
                .map(|ident| format_ident!("{ident}", span = attr.key.span()))
        })
        .collect::<Vec<_>>();

    let items_to_clone = attrs
        .clone()
        .filter_map(|attr| {
            attr.key
                .to_string()
                .strip_prefix("clone:")
                .map(|ident| format_ident!("{ident}", span = attr.key.span()))
        })
        .collect::<Vec<_>>();

    // TODO events and directives
    let events = attrs
        .clone()
        .filter(|attr| attr.key.to_string().starts_with("on:"))
        .map(|attr| {
            let name = attr.key.to_string();
            let name = name.strip_prefix("on:").unwrap_or_default();
            event_to_tokens(&name, attr)
        })
        .collect::<Vec<_>>();

    /*let directives = attrs
        .clone()
        .filter_map(|attr| {
            attr.key
                .to_string()
                .strip_prefix("use:")
                .map(|ident| directive_call_from_attribute_node(attr, ident))
        })
        .collect::<Vec<_>>();

    let events_and_directives =
        events.into_iter().chain(directives).collect::<Vec<_>>(); */
    let events_and_directives = events;

    let dyn_attrs = attrs
        .filter(|attr| attr.key.to_string().starts_with("attr:"))
        .filter_map(|attr| {
            let name = &attr.key.to_string();
            let name = name.strip_prefix("attr:");
            let value = attr.value().map(|v| {
                quote! { #v }
            })?;
            Some(quote! { (#name, #value.into_attribute()) })
        })
        .collect::<Vec<_>>();

    let dyn_attrs = if dyn_attrs.is_empty() {
        quote! {}
    } else {
        quote! { .dyn_attrs(vec![#(#dyn_attrs),*]) }
    };

    let mut slots = HashMap::new();
    let children = if node.children.is_empty() {
        quote! {}
    } else {
        let children = fragment_to_tokens(
            &node.children,
            TagType::Unknown,
            Some(&mut slots),
            global_class,
            None,
        );

        cfg_if::cfg_if! {
            if #[cfg(debug_assertions)] {
                let marker = format!("<{component_name}/>-children");
                // For some reason spanning for `.children` breaks, unless `#view_marker`
                // is also covered by `children.span()`.
                let view_marker = quote_spanned!(children.span()=> .with_view_marker(#marker));
            } else {
                let view_marker = quote! {};
            }
        }

        if let Some(children) = children {
            let bindables =
                items_to_bind.iter().map(|ident| quote! { #ident, });

            let clonables = items_to_clone.iter().map(|ident| {
                let ident_ref = quote_spanned!(ident.span()=> &#ident);
                quote! { let #ident = ::core::clone::Clone::clone(#ident_ref); }
            });

            if bindables.len() > 0 {
                quote_spanned! {children.span()=>
                    .children({
                        #(#clonables)*

                        move |#(#bindables)*| #children
                    })
                }
            } else {
                quote_spanned! {children.span()=>
                    .children({
                        #(#clonables)*

                        ::leptos::children::ToChildren::to_children(move || #children)
                    })
                }
            }
        } else {
            quote! {}
        }
    };

    let slots = slots.drain().map(|(slot, mut values)| {
        let span = values
            .last()
            .expect("List of slots must not be empty")
            .span();
        let slot = Ident::new(&slot, span);
        let value = if values.len() > 1 {
            quote_spanned! {span=>
                ::std::vec![
                    #(#values)*
                ]
            }
        } else {
            values.remove(0)
        };

        quote! { .#slot(#value) }
    });

    let generics = &node.open_tag.generics;
    let generics = if generics.lt_token.is_some() {
        quote! { ::#generics }
    } else {
        quote! {}
    };

    let name_ref = quote_spanned! {name.span()=>
        &#name
    };

    let build = quote_spanned! {name.span()=>
        .build()
    };

    let component_props_builder = quote_spanned! {name.span()=>
        ::leptos::component::component_props_builder(#name_ref #generics)
    };

    #[allow(unused_mut)] // used in debug
    let mut component = quote_spanned! {node.span()=>
        {
            let props = #component_props_builder
                #(#props)*
                #(#slots)*
                #children;

            #[allow(clippy::let_unit_value, clippy::unit_arg)]
            let props = props
                #build
                #dyn_attrs;

            #[allow(unreachable_code)]
            ::leptos::component::component_view(
                #[allow(clippy::needless_borrows_for_generic_args)]
                #name_ref,
                props
            )
        }
    };

    // (Temporarily?) removed
    // See note on the function itself below.
    /* #[cfg(debug_assertions)]
    IdeTagHelper::add_component_completion(&mut component, node); */

    // TODO events and directives
    if events_and_directives.is_empty() {
        component
    } else {
        quote_spanned! {node.span()=>
            #component.into_view()
            #(#events_and_directives)*
        }
    }
}

#[cfg(debug_assertions)]
fn ident_from_tag_name(tag_name: &NodeName) -> Ident {
    match tag_name {
        NodeName::Path(path) => path
            .path
            .segments
            .iter()
            .last()
            .map(|segment| segment.ident.clone())
            .expect("element needs to have a name"),
        NodeName::Block(_) => {
            let span = tag_name.span();
            proc_macro_error::emit_error!(
                span,
                "blocks not allowed in tag-name position"
            );
            Ident::new("", span)
        }
        _ => Ident::new(
            &tag_name.to_string().replace(['-', ':'], "_"),
            tag_name.span(),
        ),
    }
}