// Take a look at the license at the top of the repository in the LICENSE file.

use proc_macro2::{Ident, TokenStream};
use quote::quote;

use crate::utils::{crate_ident_new, parse_nested_meta_items, NestedMetaItem};

fn gen_impl_to_value_optional(name: &Ident, crate_ident: &TokenStream) -> TokenStream {
    let refcounted_type_prefix = refcounted_type_prefix(name, crate_ident);

    quote! {
        impl #crate_ident::value::ToValueOptional for #name {
            #[inline]
            fn to_value_optional(s: ::core::option::Option<&Self>) -> #crate_ident::Value {
                let mut value = #crate_ident::Value::for_value_type::<Self>();
                unsafe {
                    let ptr = match s {
                        ::core::option::Option::Some(s) => #refcounted_type_prefix::into_raw(s.0.clone()),
                        ::core::option::Option::None => ::std::ptr::null(),
                    };

                    #crate_ident::gobject_ffi::g_value_take_boxed(
                        #crate_ident::translate::ToGlibPtrMut::to_glib_none_mut(&mut value).0,
                        ptr as *mut _
                    );
                }

                value
            }
        }

        impl #crate_ident::value::ValueTypeOptional for #name { }
    }
}

fn gen_impl_from_value_optional(name: &Ident, crate_ident: &TokenStream) -> TokenStream {
    let refcounted_type_prefix = refcounted_type_prefix(name, crate_ident);

    quote! {
        unsafe impl<'a> #crate_ident::value::FromValue<'a> for #name {
            type Checker = #crate_ident::value::GenericValueTypeOrNoneChecker<Self>;

            #[inline]
            unsafe fn from_value(value: &'a #crate_ident::Value) -> Self {
                let ptr = #crate_ident::gobject_ffi::g_value_dup_boxed(#crate_ident::translate::ToGlibPtr::to_glib_none(value).0);
                debug_assert!(!ptr.is_null());
                #name(#refcounted_type_prefix::from_raw(ptr as *mut _))
            }
        }
    }
}

fn gen_impl_from_value(name: &Ident, crate_ident: &TokenStream) -> TokenStream {
    let refcounted_type_prefix = refcounted_type_prefix(name, crate_ident);

    quote! {
        unsafe impl<'a> #crate_ident::value::FromValue<'a> for #name {
            type Checker = #crate_ident::value::GenericValueTypeChecker<Self>;

            #[inline]
            unsafe fn from_value(value: &'a #crate_ident::Value) -> Self {
                let ptr = #crate_ident::gobject_ffi::g_value_dup_boxed(#crate_ident::translate::ToGlibPtr::to_glib_none(value).0);
                debug_assert!(!ptr.is_null());
                #name(#refcounted_type_prefix::from_raw(ptr as *mut _))
            }
        }
    }
}

fn refcounted_type(input: &syn::DeriveInput) -> Option<&syn::TypePath> {
    let fields = match &input.data {
        syn::Data::Struct(s) => &s.fields,
        _ => return None,
    };

    let unnamed = match fields {
        syn::Fields::Unnamed(u) if u.unnamed.len() == 1 => &u.unnamed[0],
        _ => return None,
    };

    let refcounted = match &unnamed.ty {
        syn::Type::Path(p) => p,
        _ => return None,
    };

    Some(refcounted)
}

fn refcounted_type_prefix(name: &Ident, crate_ident: &TokenStream) -> proc_macro2::TokenStream {
    quote! {
        <<#name as #crate_ident::subclass::shared::SharedType>::RefCountedType as #crate_ident::subclass::shared::RefCounted>
    }
}

pub fn impl_shared_boxed(input: &syn::DeriveInput) -> syn::Result<proc_macro2::TokenStream> {
    let name = &input.ident;

    let Some(refcounted_type) = refcounted_type(input) else {
        return Err(syn::Error::new_spanned(
            input,
            "#[derive(glib::SharedBoxed)] requires struct MyStruct(T: RefCounted)",
        ));
    };

    let mut gtype_name = NestedMetaItem::<syn::LitStr>::new("name")
        .required()
        .value_required();
    let mut nullable = NestedMetaItem::<syn::LitBool>::new("nullable").value_optional();

    let found = parse_nested_meta_items(
        &input.attrs,
        "shared_boxed_type",
        &mut [&mut gtype_name, &mut nullable],
    )?;

    if found.is_none() {
        return Err(syn::Error::new_spanned(input,
            "#[derive(glib::SharedBoxed)] requires #[shared_boxed_type(name = \"SharedBoxedTypeName\")]"
        ));
    }

    let gtype_name = gtype_name.value.unwrap();
    let nullable = nullable.found || nullable.value.map(|b| b.value()).unwrap_or(false);

    let crate_ident = crate_ident_new();
    let refcounted_type_prefix = refcounted_type_prefix(name, &crate_ident);

    let impl_from_value = if !nullable {
        gen_impl_from_value(name, &crate_ident)
    } else {
        gen_impl_from_value_optional(name, &crate_ident)
    };

    let impl_to_value_optional = if nullable {
        gen_impl_to_value_optional(name, &crate_ident)
    } else {
        quote! {}
    };

    Ok(quote! {
        impl #crate_ident::subclass::shared::SharedType for #name {
            const NAME: &'static ::core::primitive::str = #gtype_name;

            type RefCountedType = #refcounted_type;

            #[inline]
            fn from_refcounted(this: Self::RefCountedType) -> Self {
                Self(this)
            }

            #[inline]
            fn into_refcounted(self) -> Self::RefCountedType {
                self.0
            }
        }

        impl #crate_ident::prelude::StaticType for #name {
            #[inline]
            fn static_type() -> #crate_ident::Type {
                static TYPE: ::std::sync::OnceLock<#crate_ident::Type> = ::std::sync::OnceLock::new();
                *TYPE.get_or_init(|| {
                    #crate_ident::subclass::shared::register_shared_type::<#name>()
                })
            }
        }

        impl #crate_ident::value::ValueType for #name {
            type Type = #name;
        }

        impl #crate_ident::value::ToValue for #name {
            #[inline]
            fn to_value(&self) -> #crate_ident::Value {
                unsafe {
                    let ptr = #refcounted_type_prefix::into_raw(self.0.clone());
                    let mut value = #crate_ident::Value::from_type_unchecked(<#name as #crate_ident::prelude::StaticType>::static_type());
                    #crate_ident::gobject_ffi::g_value_take_boxed(
                        #crate_ident::translate::ToGlibPtrMut::to_glib_none_mut(&mut value).0,
                        ptr as *mut _
                    );
                    value
                }
            }

            #[inline]
            fn value_type(&self) -> #crate_ident::Type {
                <#name as #crate_ident::prelude::StaticType>::static_type()
            }
        }

        impl ::std::convert::From<#name> for #crate_ident::Value {
            #[inline]
            fn from(v: #name) -> Self {
                unsafe {
                    let mut value = #crate_ident::Value::from_type_unchecked(<#name as #crate_ident::prelude::StaticType>::static_type());
                    #crate_ident::gobject_ffi::g_value_take_boxed(
                        #crate_ident::translate::ToGlibPtrMut::to_glib_none_mut(&mut value).0,
                        #crate_ident::translate::IntoGlibPtr::<*mut #refcounted_type_prefix::InnerType>::into_glib_ptr(v) as *mut _,
                    );
                    value
                }
            }
        }

        #impl_to_value_optional

        #impl_from_value

        impl #crate_ident::translate::GlibPtrDefault for #name {
            type GlibType = *mut #refcounted_type_prefix::InnerType;
        }

        impl #crate_ident::translate::FromGlibPtrBorrow<*const #refcounted_type_prefix::InnerType> for #name {
            #[inline]
            unsafe fn from_glib_borrow(ptr: *const #refcounted_type_prefix::InnerType) -> #crate_ident::translate::Borrowed<Self> {
                debug_assert!(!ptr.is_null());

                // from_raw is taking ownership of the raw pointer here, but wrapping its result
                // in Borrowed::new ensures that it won't be deallocated when it will go out of
                // scope, so the pointer will still be valid afterwards
                #crate_ident::translate::Borrowed::new(#name(#refcounted_type_prefix::from_raw(ptr)))
            }
        }

        impl #crate_ident::translate::FromGlibPtrBorrow<*mut #refcounted_type_prefix::InnerType> for #name {
            #[inline]
            unsafe fn from_glib_borrow(ptr: *mut #refcounted_type_prefix::InnerType) -> #crate_ident::translate::Borrowed<Self> {
                #crate_ident::translate::FromGlibPtrBorrow::from_glib_borrow(ptr as *const _)
            }
        }


        impl #crate_ident::translate::FromGlibPtrNone<*const #refcounted_type_prefix::InnerType> for #name {
            #[inline]
            unsafe fn from_glib_none(ptr: *const #refcounted_type_prefix::InnerType) -> Self {
                let ptr = #refcounted_type_prefix::ref_(ptr);
                #name(#refcounted_type_prefix::from_raw(ptr))
            }
        }

        impl #crate_ident::translate::FromGlibPtrNone<*mut #refcounted_type_prefix::InnerType> for #name {
            #[inline]
            unsafe fn from_glib_none(ptr: *mut #refcounted_type_prefix::InnerType) -> Self {
                #crate_ident::translate::FromGlibPtrNone::from_glib_none(ptr as *const _)
            }
        }

        impl #crate_ident::translate::FromGlibPtrFull<*mut #refcounted_type_prefix::InnerType> for #name {
            #[inline]
            unsafe fn from_glib_full(ptr: *mut #refcounted_type_prefix::InnerType) -> Self {
                #name(#refcounted_type_prefix::from_raw(ptr))
            }
        }

        impl #crate_ident::translate::IntoGlibPtr<*mut #refcounted_type_prefix::InnerType> for #name {
            #[inline]
            unsafe fn into_glib_ptr(self) -> *mut #refcounted_type_prefix::InnerType {
                let r = <Self as #crate_ident::subclass::shared::SharedType>::into_refcounted(self);
                #refcounted_type_prefix::into_raw(r) as *mut _
            }
        }

        impl<'a> #crate_ident::translate::ToGlibPtr<'a, *const #refcounted_type_prefix::InnerType> for #name {
            type Storage = std::marker::PhantomData<&'a Self>;

            #[inline]
            fn to_glib_none(&'a self) -> #crate_ident::translate::Stash<'a, *const #refcounted_type_prefix::InnerType, Self> {
                unsafe {
                    #crate_ident::translate::Stash(#refcounted_type_prefix::as_ptr(&self.0), std::marker::PhantomData)
                }
            }

            #[inline]
            fn to_glib_full(&self) -> *const #refcounted_type_prefix::InnerType {
                let r = <#name as #crate_ident::subclass::shared::SharedType>::into_refcounted(self.clone());
                unsafe {
                    #refcounted_type_prefix::into_raw(r)
                }
            }
        }

        impl<'a> #crate_ident::translate::ToGlibPtr<'a, *mut #refcounted_type_prefix::InnerType> for #name {
            type Storage = std::marker::PhantomData<&'a Self>;

            #[inline]
            fn to_glib_none(&'a self) -> #crate_ident::translate::Stash<'a, *mut #refcounted_type_prefix::InnerType, Self> {
                unsafe {
                    #crate_ident::translate::Stash(#refcounted_type_prefix::as_ptr(&self.0) as *mut _, std::marker::PhantomData)
                }
            }

            #[inline]
            fn to_glib_full(&self) -> *mut #refcounted_type_prefix::InnerType {
                let r = <#name as #crate_ident::subclass::shared::SharedType>::into_refcounted(self.clone());
                unsafe {
                    #refcounted_type_prefix::into_raw(r) as *mut _
                }
            }
        }

        impl #crate_ident::HasParamSpec for #name {
            type ParamSpec = #crate_ident::ParamSpecBoxed;
            type SetValue = Self;
            type BuilderFn = fn(&::core::primitive::str) -> #crate_ident::ParamSpecBoxedBuilder<Self>;

            fn param_spec_builder() -> Self::BuilderFn {
                |name| Self::ParamSpec::builder(name)
            }
        }
    })
}