// Copyright 2018-2020 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate 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.

// Substrate 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.

use codec::{Encode, Decode};
use frame_support::Hashable;
use sp_state_machine::TestExternalities as CoreTestExternalities;
use sp_core::{
	Blake2Hasher, NeverNativeValue, NativeOrEncoded, traits::{CodeExecutor, RuntimeCode},
};
use sp_runtime::{ApplyExtrinsicResult, traits::Header as HeaderT};
use sc_executor::{NativeExecutor, WasmExecutionMethod};
use sc_executor::error::Result;

use node_executor::Executor;
use node_runtime::{
	Header, Block, UncheckedExtrinsic, CheckedExtrinsic, Runtime, BuildStorage,
	constants::currency::*,
};
use node_primitives::{Hash, BlockNumber};
use node_testing::keyring::*;

/// The wasm runtime code.
///
/// `compact` since it is after post-processing with wasm-gc which performs tree-shaking thus
/// making the binary slimmer. There is a convention to use compact version of the runtime
/// as canonical. This is why `native_executor_instance` also uses the compact version of the
/// runtime.
pub const COMPACT_CODE: &[u8] = node_runtime::WASM_BINARY;

pub const GENESIS_HASH: [u8; 32] = [69u8; 32];

pub const VERSION: u32 = node_runtime::VERSION.spec_version;

pub type TestExternalities<H> = CoreTestExternalities<H, u64>;

pub fn sign(xt: CheckedExtrinsic) -> UncheckedExtrinsic {
	node_testing::keyring::sign(xt, VERSION, GENESIS_HASH)
}

pub fn default_transfer_call() -> pallet_balances::Call<Runtime> {
	pallet_balances::Call::transfer::<Runtime>(bob().into(), 69 * DOLLARS)
}

pub fn from_block_number(n: u32) -> Header {
	Header::new(n, Default::default(), Default::default(), [69; 32].into(), Default::default())
}

pub fn executor() -> NativeExecutor<Executor> {
	NativeExecutor::new(WasmExecutionMethod::Interpreted, None)
}

pub fn executor_call<
	R:Decode + Encode + PartialEq,
	NC: FnOnce() -> std::result::Result<R, String> + std::panic::UnwindSafe
>(
	t: &mut TestExternalities<Blake2Hasher>,
	method: &str,
	data: &[u8],
	use_native: bool,
	native_call: Option<NC>,
) -> (Result<NativeOrEncoded<R>>, bool) {
	let mut t = t.ext();
	let runtime_code = RuntimeCode::from_externalities(&t)
		.expect("Code should be part of the externalities");
	executor().call::<_, R, NC>(
		&mut t,
		&runtime_code,
		method,
		data,
		use_native,
		native_call,
	)
}

pub fn new_test_ext(code: &[u8], support_changes_trie: bool) -> TestExternalities<Blake2Hasher> {
	let mut ext = TestExternalities::new_with_code(
		code,
		node_testing::genesis::config(support_changes_trie, Some(code)).build_storage().unwrap(),
	);
	ext.changes_trie_storage().insert(0, GENESIS_HASH.into(), Default::default());
	ext
}

/// Construct a fake block.
///
/// `extrinsics` must be a list of valid extrinsics, i.e. none of the extrinsics for example
/// can report `ExhaustResources`. Otherwise, this function panics.
pub fn construct_block(
	env: &mut TestExternalities<Blake2Hasher>,
	number: BlockNumber,
	parent_hash: Hash,
	extrinsics: Vec<CheckedExtrinsic>,
) -> (Vec<u8>, Hash) {
	use sp_trie::{TrieConfiguration, trie_types::Layout};

	// sign extrinsics.
	let extrinsics = extrinsics.into_iter().map(sign).collect::<Vec<_>>();

	// calculate the header fields that we can.
	let extrinsics_root =
		Layout::<Blake2Hasher>::ordered_trie_root(extrinsics.iter().map(Encode::encode))
			.to_fixed_bytes()
			.into();

	let header = Header {
		parent_hash,
		number,
		extrinsics_root,
		state_root: Default::default(),
		digest: Default::default(),
	};

	// execute the block to get the real header.
	executor_call::<NeverNativeValue, fn() -> _>(
		env,
		"Core_initialize_block",
		&header.encode(),
		true,
		None,
	).0.unwrap();

	for extrinsic in extrinsics.iter() {
		// Try to apply the `extrinsic`. It should be valid, in the sense that it passes
		// all pre-inclusion checks.
		let r = executor_call::<NeverNativeValue, fn() -> _>(
			env,
			"BlockBuilder_apply_extrinsic",
			&extrinsic.encode(),
			true,
			None,
		).0.expect("application of an extrinsic failed").into_encoded();
		match ApplyExtrinsicResult::decode(&mut &r[..]).expect("apply result deserialization failed") {
			Ok(_) => {},
			Err(e) => panic!("Applying extrinsic failed: {:?}", e),
		}
	}

	let header = match executor_call::<NeverNativeValue, fn() -> _>(
		env,
		"BlockBuilder_finalize_block",
		&[0u8;0],
		true,
		None,
	).0.unwrap() {
		NativeOrEncoded::Native(_) => unreachable!(),
		NativeOrEncoded::Encoded(h) => Header::decode(&mut &h[..]).unwrap(),
	};

	let hash = header.blake2_256();
	(Block { header, extrinsics }.encode(), hash.into())
}