// This file is part of Substrate.

// Copyright (C) 2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program 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.

// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.

use codec::{Decode as _, Encode as _};
use sc_executor_common::{runtime_blob::RuntimeBlob, wasm_runtime::WasmModule};
use sc_runtime_test::wasm_binary_unwrap;
use std::sync::Arc;

type HostFunctions = sp_io::SubstrateHostFunctions;

struct RuntimeBuilder {
	code: Option<&'static str>,
	fast_instance_reuse: bool,
	canonicalize_nans: bool,
	deterministic_stack: bool,
	heap_pages: u32,
	max_memory_pages: Option<u32>,
}

impl RuntimeBuilder {
	/// Returns a new builder that won't use the fast instance reuse mechanism, but instead will
	/// create a new runtime instance each time.
	fn new_on_demand() -> Self {
		Self {
			code: None,
			fast_instance_reuse: false,
			canonicalize_nans: false,
			deterministic_stack: false,
			heap_pages: 1024,
			max_memory_pages: None,
		}
	}

	fn use_wat(&mut self, code: &'static str) {
		self.code = Some(code);
	}

	fn canonicalize_nans(&mut self, canonicalize_nans: bool) {
		self.canonicalize_nans = canonicalize_nans;
	}

	fn deterministic_stack(&mut self, deterministic_stack: bool) {
		self.deterministic_stack = deterministic_stack;
	}

	fn max_memory_pages(&mut self, max_memory_pages: Option<u32>) {
		self.max_memory_pages = max_memory_pages;
	}

	fn build(self) -> Arc<dyn WasmModule> {
		let blob = {
			let wasm: Vec<u8>;

			let wasm = match self.code {
				None => wasm_binary_unwrap(),
				Some(wat) => {
					wasm = wat::parse_str(wat).expect("wat parsing failed");
					&wasm
				},
			};

			RuntimeBlob::uncompress_if_needed(&wasm)
				.expect("failed to create a runtime blob out of test runtime")
		};

		let rt = crate::create_runtime(
			blob,
			crate::Config {
				heap_pages: self.heap_pages,
				max_memory_pages: self.max_memory_pages,
				allow_missing_func_imports: true,
				cache_path: None,
				semantics: crate::Semantics {
					fast_instance_reuse: self.fast_instance_reuse,
					deterministic_stack_limit: match self.deterministic_stack {
						true => Some(crate::DeterministicStackLimit {
							logical_max: 65536,
							native_stack_max: 256 * 1024 * 1024,
						}),
						false => None,
					},
					canonicalize_nans: self.canonicalize_nans,
				},
			},
			{
				use sp_wasm_interface::HostFunctions as _;
				HostFunctions::host_functions()
			},
		)
		.expect("cannot create runtime");

		Arc::new(rt) as Arc<dyn WasmModule>
	}
}

#[test]
fn test_nan_canonicalization() {
	let runtime = {
		let mut builder = RuntimeBuilder::new_on_demand();
		builder.canonicalize_nans(true);
		builder.build()
	};

	let mut instance = runtime.new_instance().expect("failed to instantiate a runtime");

	/// A NaN with canonical payload bits.
	const CANONICAL_NAN_BITS: u32 = 0x7fc00000;
	/// A NaN value with an abitrary payload.
	const ARBITRARY_NAN_BITS: u32 = 0x7f812345;

	// This test works like this: we essentially do
	//
	//     a + b
	//
	// where
	//
	//     * a is a nan with arbitrary bits in its payload
	//     * b is 1.
	//
	// according to the wasm spec, if one of the inputs to the operation is a non-canonical NaN
	// then the value be a NaN with non-deterministic payload bits.
	//
	// However, with the `canonicalize_nans` option turned on above, we expect that the output will
	// be a canonical NaN.
	//
	// We exterpolate the results of this tests so that we assume that all intermediate computations
	// that involve floats are sanitized and cannot produce a non-deterministic NaN.

	let params = (u32::to_le_bytes(ARBITRARY_NAN_BITS), u32::to_le_bytes(1)).encode();
	let res = {
		let raw_result = instance.call_export("test_fp_f32add", &params).unwrap();
		u32::from_le_bytes(<[u8; 4]>::decode(&mut &raw_result[..]).unwrap())
	};
	assert_eq!(res, CANONICAL_NAN_BITS);
}

#[test]
fn test_stack_depth_reaching() {
	const TEST_GUARD_PAGE_SKIP: &str = include_str!("test-guard-page-skip.wat");

	let runtime = {
		let mut builder = RuntimeBuilder::new_on_demand();
		builder.use_wat(TEST_GUARD_PAGE_SKIP);
		builder.deterministic_stack(true);
		builder.build()
	};
	let mut instance = runtime.new_instance().expect("failed to instantiate a runtime");

	let err = instance.call_export("test-many-locals", &[]).unwrap_err();

	assert!(
		format!("{:?}", err).starts_with("Other(\"Wasm execution trapped: wasm trap: unreachable")
	);
}

#[test]
fn test_max_memory_pages() {
	fn try_instantiate(
		max_memory_pages: Option<u32>,
		wat: &'static str,
	) -> Result<(), Box<dyn std::error::Error>> {
		let runtime = {
			let mut builder = RuntimeBuilder::new_on_demand();
			builder.use_wat(wat);
			builder.max_memory_pages(max_memory_pages);
			builder.build()
		};
		let mut instance = runtime.new_instance()?;
		let _ = instance.call_export("main", &[])?;
		Ok(())
	}

	// check the old behavior if preserved. That is, if no limit is set we allow 4 GiB of memory.
	try_instantiate(
		None,
		r#"
		(module
			;; we want to allocate the maximum number of pages supported in wasm for this test.
			;;
			;; However, due to a bug in wasmtime (I think wasmi is also affected) it is only possible
			;; to allocate 65536 - 1 pages.
			;;
			;; Then, during creation of the Substrate Runtime instance, 1024 (heap_pages) pages are
			;; mounted.
			;;
			;; Thus 65535 = 64511 + 1024
			(import "env" "memory" (memory 64511))

			(global (export "__heap_base") i32 (i32.const 0))
			(func (export "main")
				(param i32 i32) (result i64)
				(i64.const 0)
			)
		)
		"#,
	)
	.unwrap();

	// max is not specified, therefore it's implied to be 65536 pages (4 GiB).
	//
	// max_memory_pages = 1 (initial) + 1024 (heap_pages)
	try_instantiate(
		Some(1 + 1024),
		r#"
		(module

			(import "env" "memory" (memory 1)) ;; <- 1 initial, max is not specified

			(global (export "__heap_base") i32 (i32.const 0))
			(func (export "main")
				(param i32 i32) (result i64)
				(i64.const 0)
			)
		)
		"#,
	)
	.unwrap();

	// max is specified explicitly to 2048 pages.
	try_instantiate(
		Some(1 + 1024),
		r#"
		(module

			(import "env" "memory" (memory 1 2048)) ;; <- max is 2048

			(global (export "__heap_base") i32 (i32.const 0))
			(func (export "main")
				(param i32 i32) (result i64)
				(i64.const 0)
			)
		)
		"#,
	)
	.unwrap();

	// memory grow should work as long as it doesn't exceed 1025 pages in total.
	try_instantiate(
		Some(0 + 1024 + 25),
		r#"
		(module
			(import "env" "memory" (memory 0)) ;; <- zero starting pages.

			(global (export "__heap_base") i32 (i32.const 0))
			(func (export "main")
				(param i32 i32) (result i64)

				;; assert(memory.grow returns != -1)
				(if
					(i32.eq
						(memory.grow
							(i32.const 25)
						)
						(i32.const -1)
					)
					(unreachable)
				)

				(i64.const 0)
			)
		)
		"#,
	)
	.unwrap();

	// We start with 1025 pages and try to grow at least one.
	try_instantiate(
		Some(1 + 1024),
		r#"
		(module
			(import "env" "memory" (memory 1))  ;; <- initial=1, meaning after heap pages mount the
												;; total will be already 1025
			(global (export "__heap_base") i32 (i32.const 0))
			(func (export "main")
				(param i32 i32) (result i64)

				;; assert(memory.grow returns == -1)
				(if
					(i32.ne
						(memory.grow
							(i32.const 1)
						)
						(i32.const -1)
					)
					(unreachable)
				)

				(i64.const 0)
			)
		)
		"#,
	)
	.unwrap();
}