// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.

// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity.  If not, see <http://www.gnu.org/licenses/>.

use aster;

use syntax::ast::{
	MetaItem,
	Item,
	ImplItemKind,
	ImplItem,
	MethodSig,
	Arg,
	PatKind,
	FunctionRetTy,
};

use syntax::ast;
use syntax::codemap::Span;
use syntax::ext::base::{Annotatable, ExtCtxt};
use syntax::ext::build::AstBuilder;
use syntax::ptr::P;

pub struct Error;

pub fn expand_ipc_implementation(
	cx: &mut ExtCtxt,
	span: Span,
	meta_item: &MetaItem,
	annotatable: &Annotatable,
	push: &mut FnMut(Annotatable)
) {
	let item = match *annotatable {
		Annotatable::Item(ref item) => item,
		_ => {
			cx.span_err(meta_item.span, "`#[derive(Ipc)]` may only be applied to struct implementations");
			return;
		}
	};

	let builder = aster::AstBuilder::new().span(span);

	let impl_item = match implement_interface(cx, &builder, &item, push) {
		Ok(item) => item,
		Err(Error) => { return; }
	};

	push_proxy(cx, &builder, &item, push);

	push(Annotatable::Item(impl_item))
}

fn field_name(builder: &aster::AstBuilder, arg: &Arg) -> ast::Ident {
	match arg.pat.node {
		PatKind::Ident(_, ref ident, _) => builder.id(ident.node),
		_ => { panic!("unexpected param in interface: {:?}", arg.pat.node) }
	}
}

fn push_invoke_signature_aster(
	builder: &aster::AstBuilder,
	implement: &ImplItem,
	signature: &MethodSig,
	push: &mut FnMut(Annotatable),
) -> Dispatch {

	let inputs = &signature.decl.inputs;
	let (input_type_name, input_arg_names) = if inputs.len() > 0 {
		let first_field_name = field_name(builder, &inputs[0]).name.as_str();
		if first_field_name == "self" && inputs.len() == 1 { (None, vec![]) }
		else {
			let skip = if first_field_name == "self" { 2 } else { 1 };
			let name_str = format!("{}_input", implement.ident.name.as_str());

			let mut arg_names = Vec::new();
			let arg_name = format!("{}", field_name(builder, &inputs[skip-1]).name);
			let mut tree = builder.item()
				.attr().word("derive(Serialize, Deserialize)")
				.attr().word("allow(non_camel_case_types)")
				.struct_(name_str.as_str())
				.field(arg_name.as_str()).ty().build(inputs[skip-1].ty.clone());
			arg_names.push(arg_name);
			for arg in inputs.iter().skip(skip) {
				let arg_name = format!("{}", field_name(builder, &arg));
				tree = tree.field(arg_name.as_str()).ty().build(arg.ty.clone());
				arg_names.push(arg_name);
			}

			push(Annotatable::Item(tree.build()));
			(Some(name_str.to_owned()), arg_names)
		}
	}
	else {
		(None, vec![])
	};

	let return_type_name = match signature.decl.output {
		FunctionRetTy::Ty(ref ty) => {
			let name_str = format!("{}_output", implement.ident.name.as_str());
			let tree = builder.item()
				.attr().word("derive(Serialize, Deserialize)")
				.attr().word("allow(non_camel_case_types)")
				.struct_(name_str.as_str())
				.field(format!("payload")).ty().build(ty.clone());
			push(Annotatable::Item(tree.build()));
			Some(name_str.to_owned())
		}
		_ => None
	};

	Dispatch {
		function_name: format!("{}", implement.ident.name.as_str()),
		input_type_name: input_type_name,
		input_arg_names: input_arg_names,
		return_type_name: return_type_name,
	}
}

struct Dispatch {
	function_name: String,
	input_type_name: Option<String>,
	input_arg_names: Vec<String>,
	return_type_name: Option<String>,
}

fn implement_dispatch_arm_invoke(
	cx: &ExtCtxt,
	builder: &aster::AstBuilder,
	dispatch: &Dispatch,
) -> P<ast::Expr>
{
	let deserialize_expr = quote_expr!(cx, ::bincode::serde::deserialize_from(r, ::bincode::SizeLimit::Infinite).expect("ipc deserialization error, aborting"));
	let input_type_id = builder.id(dispatch.input_type_name.clone().unwrap().as_str());
	let function_name = builder.id(dispatch.function_name.as_str());
	let output_type_id = builder.id(dispatch.return_type_name.clone().unwrap().as_str());

	let input_args_exprs = dispatch.input_arg_names.iter().map(|ref arg_name| {
		let arg_ident = builder.id(arg_name);
		quote_expr!(cx, input. $arg_ident)
	}).collect::<Vec<P<ast::Expr>>>();

	//	This is the expanded version of this:
	//
	//	let invoke_serialize_stmt = quote_stmt!(cx, {
	//		::bincode::serde::serialize(& $output_type_id { payload: self. $function_name ($hand_param_a, $hand_param_b) }, ::bincode::SizeLimit::Infinite).unwrap()
	//  });
	//
	// But the above does not allow comma-separated expressions for arbitrary number
	// of parameters ...$hand_param_a, $hand_param_b, ... $hand_param_n
	let invoke_serialize_stmt = {
		let ext_cx = &*cx;
		::quasi::parse_stmt_panic(&mut ::syntax::parse::new_parser_from_tts(
			ext_cx.parse_sess(),
			ext_cx.cfg(),
			{
				let _sp = ext_cx.call_site();
				let mut tt = ::std::vec::Vec::new();
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::OpenDelim(::syntax::parse::token::Brace)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::ModSep));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("bincode"), ::syntax::parse::token::ModName)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::ModSep));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("serde"), ::syntax::parse::token::ModName)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::ModSep));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("serialize"), ::syntax::parse::token::Plain)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::OpenDelim(::syntax::parse::token::Paren)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::BinOp(::syntax::parse::token::And)));
				tt.extend(::quasi::ToTokens::to_tokens(&output_type_id, ext_cx).into_iter());
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::OpenDelim(::syntax::parse::token::Brace)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("payload"), ::syntax::parse::token::Plain)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Colon));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("self"), ::syntax::parse::token::Plain)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Dot));
				tt.extend(::quasi::ToTokens::to_tokens(&function_name, ext_cx).into_iter());
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::OpenDelim(::syntax::parse::token::Paren)));

				for arg_expr in input_args_exprs {
					tt.extend(::quasi::ToTokens::to_tokens(&arg_expr, ext_cx).into_iter());
					tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Comma));
				}

				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::CloseDelim(::syntax::parse::token::Paren)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::CloseDelim(::syntax::parse::token::Brace)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Comma));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::ModSep));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("bincode"), ::syntax::parse::token::ModName)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::ModSep));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("SizeLimit"), ::syntax::parse::token::ModName)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::ModSep));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("Infinite"), ::syntax::parse::token::Plain)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::CloseDelim(::syntax::parse::token::Paren)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Dot));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::Ident(ext_cx.ident_of("unwrap"), ::syntax::parse::token::Plain)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::OpenDelim(::syntax::parse::token::Paren)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::CloseDelim(::syntax::parse::token::Paren)));
				tt.push(::syntax::ast::TokenTree::Token(_sp, ::syntax::parse::token::CloseDelim(::syntax::parse::token::Brace)));
				tt
			}))
	};
	quote_expr!(cx, {
		let input: $input_type_id = $deserialize_expr;
		$invoke_serialize_stmt
	})
}

fn implement_dispatch_arm(cx: &ExtCtxt, builder: &aster::AstBuilder, index: u32, dispatch: &Dispatch)
	-> ast::Arm
{
	let index_ident = builder.id(format!("{}", index).as_str());
	let invoke_expr = implement_dispatch_arm_invoke(cx, builder, dispatch);
	quote_arm!(cx, $index_ident => { $invoke_expr } )
}

fn push_proxy_struct(cx: &ExtCtxt, builder: &aster::AstBuilder, item: &Item, push: &mut FnMut(Annotatable)) {
	let proxy_ident = builder.id(format!("{}Proxy", item.ident.name.as_str()));

	let proxy_struct_item = quote_item!(cx,
		pub struct $proxy_ident <S: ::ipc::IpcSocket> {
			socket: ::std::cell::RefCell<S>,
			phantom: ::std::marker::PhantomData<S>,
		});

	push(Annotatable::Item(proxy_struct_item.expect(&format!("could not generate proxy struct for {:?}", proxy_ident.name))));
}

fn push_proxy(cx: &ExtCtxt, builder: &aster::AstBuilder, item: &Item, push: &mut FnMut(Annotatable)) {
	push_proxy_struct(cx, builder, item, push)
}

fn implement_interface(
	cx: &ExtCtxt,
	builder: &aster::AstBuilder,
	item: &Item,
	push: &mut FnMut(Annotatable),
) -> Result<P<ast::Item>, Error> {
	let (generics, impl_items) = match item.node {
		ast::ItemKind::Impl(_, _, ref generics, _, _, ref impl_items) => (generics, impl_items),
		_ => {
			cx.span_err(
				item.span,
				"`#[derive(Ipc)]` may only be applied to item implementations");
			return Err(Error);
		}
	};

	let impl_generics = builder.from_generics(generics.clone())
		.add_ty_param_bound(
			builder.path().global().ids(&["ethcore_ipc"]).build()
		)
		.build();

	let ty = builder.ty().path()
		.segment(item.ident).with_generics(impl_generics.clone()).build()
		.build();

	let where_clause = &impl_generics.where_clause;

	let mut dispatch_table = Vec::new();
	for impl_item in impl_items {
		if let ImplItemKind::Method(ref signature, _) = impl_item.node {
			dispatch_table.push(push_invoke_signature_aster(builder, &impl_item, signature, push));
		}
	}
	let mut index = -1;
	let dispatch_arms: Vec<_> = dispatch_table.iter()
		.map(|dispatch| { index = index + 1; implement_dispatch_arm(cx, builder, index as u32, dispatch) }).collect();

	Ok(quote_item!(cx,
		impl $impl_generics ::ipc::IpcInterface<$ty> for $ty $where_clause {
			fn dispatch<R>(&self, r: &mut R) -> Vec<u8>
				where R: ::std::io::Read
			{
				let mut method_num = vec![0u8;2];
				match r.read(&mut method_num) {
					Ok(size) if size == 0 => { panic!("method id not supplied" ); }
					Err(e) => { panic!("ipc read error: {:?}, aborting", e); }
					_ => { }
				}
				match method_num[0] as u16 + (method_num[1] as u16)*256 {
					$dispatch_arms
					_ => vec![]
				}
			}
		}
	).unwrap())
}