// This file is part of Substrate.

// Copyright (C) 2020-2022 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::{pallet::Def, COUNTER};
use quote::ToTokens;
use syn::spanned::Spanned;

///
/// * Generate enum call and implement various trait on it.
/// * Implement Callable and call_function on `Pallet`
pub fn expand_call(def: &mut Def) -> proc_macro2::TokenStream {
	let (span, where_clause, methods, docs) = match def.call.as_ref() {
		Some(call) => {
			let span = call.attr_span;
			let where_clause = call.where_clause.clone();
			let methods = call.methods.clone();
			let docs = call.docs.clone();

			(span, where_clause, methods, docs)
		},
		None => (def.item.span(), def.config.where_clause.clone(), Vec::new(), Vec::new()),
	};
	let frame_support = &def.frame_support;
	let frame_system = &def.frame_system;
	let type_impl_gen = &def.type_impl_generics(span);
	let type_decl_bounded_gen = &def.type_decl_bounded_generics(span);
	let type_use_gen = &def.type_use_generics(span);
	let call_ident = syn::Ident::new("Call", span);
	let pallet_ident = &def.pallet_struct.pallet;

	let fn_name = methods.iter().map(|method| &method.name).collect::<Vec<_>>();
	let call_index = methods.iter().map(|method| method.call_index).collect::<Vec<_>>();
	let new_call_variant_fn_name = fn_name
		.iter()
		.map(|fn_name| quote::format_ident!("new_call_variant_{}", fn_name))
		.collect::<Vec<_>>();

	let new_call_variant_doc = fn_name
		.iter()
		.map(|fn_name| format!("Create a call with the variant `{}`.", fn_name))
		.collect::<Vec<_>>();

	let mut warning_structs = Vec::new();
	let mut warning_names = Vec::new();
	// Emit a warning for each call that is missing `call_index` when not in dev-mode.
	for method in &methods {
		if method.explicit_call_index || def.dev_mode {
			continue
		}

		let name = syn::Ident::new(&format!("{}", method.name), method.name.span());
		let warning: syn::ItemStruct = syn::parse_quote!(
			#[deprecated(note = r"
			Implicit call indices are deprecated in favour of explicit ones.
			Please ensure that all calls have the `pallet::call_index` attribute or that the
			`dev-mode` of the pallet is enabled. For more info see:
			<https://github.com/paritytech/substrate/pull/12891> and
			<https://github.com/paritytech/substrate/pull/11381>.")]
			#[allow(non_camel_case_types)]
			struct #name;
		);
		warning_names.push(name);
		warning_structs.push(warning);
	}

	let fn_weight = methods.iter().map(|method| &method.weight);

	let fn_doc = methods.iter().map(|method| &method.docs).collect::<Vec<_>>();

	let args_name = methods
		.iter()
		.map(|method| method.args.iter().map(|(_, name, _)| name.clone()).collect::<Vec<_>>())
		.collect::<Vec<_>>();

	let args_name_stripped = methods
		.iter()
		.map(|method| {
			method
				.args
				.iter()
				.map(|(_, name, _)| {
					syn::Ident::new(name.to_string().trim_start_matches('_'), name.span())
				})
				.collect::<Vec<_>>()
		})
		.collect::<Vec<_>>();

	let make_args_name_pattern = |ref_tok| {
		args_name
			.iter()
			.zip(args_name_stripped.iter())
			.map(|(args_name, args_name_stripped)| {
				args_name
					.iter()
					.zip(args_name_stripped)
					.map(|(args_name, args_name_stripped)| {
						if args_name == args_name_stripped {
							quote::quote!( #ref_tok #args_name )
						} else {
							quote::quote!( #args_name_stripped: #ref_tok #args_name )
						}
					})
					.collect::<Vec<_>>()
			})
			.collect::<Vec<_>>()
	};

	let args_name_pattern = make_args_name_pattern(None);
	let args_name_pattern_ref = make_args_name_pattern(Some(quote::quote!(ref)));

	let args_type = methods
		.iter()
		.map(|method| method.args.iter().map(|(_, _, type_)| type_.clone()).collect::<Vec<_>>())
		.collect::<Vec<_>>();

	let args_compact_attr = methods.iter().map(|method| {
		method
			.args
			.iter()
			.map(|(is_compact, _, type_)| {
				if *is_compact {
					quote::quote_spanned!(type_.span() => #[codec(compact)] )
				} else {
					quote::quote!()
				}
			})
			.collect::<Vec<_>>()
	});

	let default_docs = [syn::parse_quote!(
		r"Contains one variant per dispatchable that can be called by an extrinsic."
	)];
	let docs = if docs.is_empty() { &default_docs[..] } else { &docs[..] };

	let maybe_compile_error = if def.call.is_none() {
		quote::quote! {
			compile_error!(concat!(
				"`",
				stringify!($pallet_name),
				"` does not have #[pallet::call] defined, perhaps you should remove `Call` from \
				construct_runtime?",
			));
		}
	} else {
		proc_macro2::TokenStream::new()
	};

	let count = COUNTER.with(|counter| counter.borrow_mut().inc());
	let macro_ident = syn::Ident::new(&format!("__is_call_part_defined_{}", count), span);

	let capture_docs = if cfg!(feature = "no-metadata-docs") { "never" } else { "always" };

	// Wrap all calls inside of storage layers
	if let Some(syn::Item::Impl(item_impl)) = def
		.call
		.as_ref()
		.map(|c| &mut def.item.content.as_mut().expect("Checked by def parser").1[c.index])
	{
		item_impl.items.iter_mut().for_each(|i| {
			if let syn::ImplItem::Method(method) = i {
				let block = &method.block;
				method.block = syn::parse_quote! {{
					// We execute all dispatchable in a new storage layer, allowing them
					// to return an error at any point, and undoing any storage changes.
					#frame_support::storage::with_storage_layer(|| #block)
				}};
			}
		});
	}

	// Extracts #[allow] attributes, necessary so that we don't run into compiler warnings
	let maybe_allow_attrs = methods
		.iter()
		.map(|method| {
			method
				.attrs
				.iter()
				.find(|attr| {
					if let Ok(syn::Meta::List(syn::MetaList { path, .. })) = attr.parse_meta() {
						path.segments.last().map(|seg| seg.ident == "allow").unwrap_or(false)
					} else {
						false
					}
				})
				.map_or(proc_macro2::TokenStream::new(), |attr| attr.to_token_stream())
		})
		.collect::<Vec<_>>();

	quote::quote_spanned!(span =>
		mod warnings {
			#(
				#warning_structs
				// This triggers each deprecated warning once.
				const _: Option<#warning_names> = None;
			)*
		}

		#[doc(hidden)]
		pub mod __substrate_call_check {
			#[macro_export]
			#[doc(hidden)]
			macro_rules! #macro_ident {
				($pallet_name:ident) => {
					#maybe_compile_error
				};
			}

			#[doc(hidden)]
			pub use #macro_ident as is_call_part_defined;
		}

		#( #[doc = #docs] )*
		#[derive(
			#frame_support::RuntimeDebugNoBound,
			#frame_support::CloneNoBound,
			#frame_support::EqNoBound,
			#frame_support::PartialEqNoBound,
			#frame_support::codec::Encode,
			#frame_support::codec::Decode,
			#frame_support::scale_info::TypeInfo,
		)]
		#[codec(encode_bound())]
		#[codec(decode_bound())]
		#[scale_info(skip_type_params(#type_use_gen), capture_docs = #capture_docs)]
		#[allow(non_camel_case_types)]
		pub enum #call_ident<#type_decl_bounded_gen> #where_clause {
			#[doc(hidden)]
			#[codec(skip)]
			__Ignore(
				#frame_support::sp_std::marker::PhantomData<(#type_use_gen,)>,
				#frame_support::Never,
			),
			#(
				#( #[doc = #fn_doc] )*
				#[codec(index = #call_index)]
				#fn_name {
					#(
						#[allow(missing_docs)]
						#args_compact_attr #args_name_stripped: #args_type
					),*
				},
			)*
		}

		impl<#type_impl_gen> #call_ident<#type_use_gen> #where_clause {
			#(
				#[doc = #new_call_variant_doc]
				pub fn #new_call_variant_fn_name(
					#( #args_name_stripped: #args_type ),*
				) -> Self {
					Self::#fn_name {
						#( #args_name_stripped ),*
					}
				}
			)*
		}

		impl<#type_impl_gen> #frame_support::dispatch::GetDispatchInfo
			for #call_ident<#type_use_gen>
			#where_clause
		{
			fn get_dispatch_info(&self) -> #frame_support::dispatch::DispatchInfo {
				match *self {
					#(
						Self::#fn_name { #( #args_name_pattern_ref, )* } => {
							let __pallet_base_weight = #fn_weight;

							let __pallet_weight = <
								dyn #frame_support::dispatch::WeighData<( #( & #args_type, )* )>
							>::weigh_data(&__pallet_base_weight, ( #( #args_name, )* ));

							let __pallet_class = <
								dyn #frame_support::dispatch::ClassifyDispatch<
									( #( & #args_type, )* )
								>
							>::classify_dispatch(&__pallet_base_weight, ( #( #args_name, )* ));

							let __pallet_pays_fee = <
								dyn #frame_support::dispatch::PaysFee<( #( & #args_type, )* )>
							>::pays_fee(&__pallet_base_weight, ( #( #args_name, )* ));

							#frame_support::dispatch::DispatchInfo {
								weight: __pallet_weight,
								class: __pallet_class,
								pays_fee: __pallet_pays_fee,
							}
						},
					)*
					Self::__Ignore(_, _) => unreachable!("__Ignore cannot be used"),
				}
			}
		}

		// Deprecated, but will warn when used
		#[allow(deprecated)]
		impl<#type_impl_gen> #frame_support::weights::GetDispatchInfo for #call_ident<#type_use_gen> #where_clause {}

		impl<#type_impl_gen> #frame_support::dispatch::GetCallName for #call_ident<#type_use_gen>
			#where_clause
		{
			fn get_call_name(&self) -> &'static str {
				match *self {
					#( Self::#fn_name { .. } => stringify!(#fn_name), )*
					Self::__Ignore(_, _) => unreachable!("__PhantomItem cannot be used."),
				}
			}

			fn get_call_names() -> &'static [&'static str] {
				&[ #( stringify!(#fn_name), )* ]
			}
		}

		impl<#type_impl_gen> #frame_support::traits::UnfilteredDispatchable
			for #call_ident<#type_use_gen>
			#where_clause
		{
			type RuntimeOrigin = #frame_system::pallet_prelude::OriginFor<T>;
			fn dispatch_bypass_filter(
				self,
				origin: Self::RuntimeOrigin
			) -> #frame_support::dispatch::DispatchResultWithPostInfo {
				match self {
					#(
						Self::#fn_name { #( #args_name_pattern, )* } => {
							#frame_support::sp_tracing::enter_span!(
								#frame_support::sp_tracing::trace_span!(stringify!(#fn_name))
							);
							#maybe_allow_attrs
							<#pallet_ident<#type_use_gen>>::#fn_name(origin, #( #args_name, )* )
								.map(Into::into).map_err(Into::into)
						},
					)*
					Self::__Ignore(_, _) => {
						let _ = origin; // Use origin for empty Call enum
						unreachable!("__PhantomItem cannot be used.");
					},
				}
			}
		}

		impl<#type_impl_gen> #frame_support::dispatch::Callable<T> for #pallet_ident<#type_use_gen>
			#where_clause
		{
			type RuntimeCall = #call_ident<#type_use_gen>;
		}

		impl<#type_impl_gen> #pallet_ident<#type_use_gen> #where_clause {
			#[doc(hidden)]
			pub fn call_functions() -> #frame_support::metadata::PalletCallMetadata {
				#frame_support::scale_info::meta_type::<#call_ident<#type_use_gen>>().into()
			}
		}
	)
}