// Copyright 2024 Moonbeam foundation

// This file is part of Moonbeam.

// Moonbeam 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.

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

//! # WASM Local Blob-Override

//!

//! WASM Local blob override provides tools to replace on-chain WASM with custom WASM.

//! These customized WASM blobs may include functionality that is not included in the

//! on-chain WASM, such as tracing or debugging information. This extra information is especially

//! useful in external scenarios, like exchanges or archive nodes.

//!

//! ## Usage

//!

//! WASM overrides may be enabled with the `--wasm-runtime-overrides` argument. The argument

//! expects a path to a directory that holds custom WASM.

//!

//! Any file ending in '.wasm' will be scraped and instantiated as a WASM blob. WASM can be built by

//! compiling the required runtime with the changes needed. For example, compiling a runtime with

//! tracing enabled would produce a WASM blob that can used.

//!

//! A custom WASM blob will override on-chain WASM if the spec version matches. If it is

//! required to overrides multiple runtimes, multiple WASM blobs matching each of the spec versions

//! needed must be provided in the given directory.

use sc_executor::RuntimeVersionOf;

use sp_blockchain::Result;

use sp_core::traits::{FetchRuntimeCode, RuntimeCode, WrappedRuntimeCode};

use sp_state_machine::BasicExternalities;

use sp_version::RuntimeVersion;

use std::{

	collections::{hash_map::DefaultHasher, HashMap},

	fs,

	hash::Hasher as _,

	path::{Path, PathBuf},

	time::{Duration, Instant},

};

/// The interval in that we will print a warning when a wasm blob `spec_name`

/// doesn't match with the on-chain `spec_name`.

const WARN_INTERVAL: Duration = Duration::from_secs(30);

/// Auxiliary structure that holds a wasm blob and its hash.

#[derive(Debug)]

struct WasmBlob {

	/// The actual wasm blob, aka the code.

	code: Vec<u8>,

	/// The hash of [`Self::code`].

	hash: Vec<u8>,

	/// The path where this blob was found.

	path: PathBuf,

	/// The runtime version of this blob.

	version: RuntimeVersion,

	/// When was the last time we have warned about the wasm blob having

	/// a wrong `spec_name`?

	last_warn: parking_lot::Mutex<Option<Instant>>,

}

impl WasmBlob {

}

/// Make a hash out of a byte string using the default rust hasher

impl FetchRuntimeCode for WasmBlob {

}

#[allow(missing_docs)]

pub enum WasmOverrideError {

	#[error("Failed to get runtime version: {0}")]

	VersionInvalid(String),

	#[error("WASM override IO error")]

	Io(PathBuf, #[source] std::io::Error),

	#[error("Overwriting WASM requires a directory where local \

	WASM is stored. {} is not a directory", .0.display())]

	NotADirectory(PathBuf),

	#[error("Duplicate WASM Runtimes found: \n{}\n", .0.join("\n") )]

	DuplicateRuntime(Vec<String>),

}

impl From<WasmOverrideError> for sp_blockchain::Error {

}

/// Scrapes WASM from a folder and returns WASM from that folder

/// if the runtime spec version matches.

#[derive(Debug)]

pub struct WasmOverride {

	// Map of runtime spec version -> Wasm Blob

	overrides: HashMap<u32, WasmBlob>,

}

impl WasmOverride {

	/// Gets an override by it's runtime spec version.

	///

	/// Returns `None` if an override for a spec version does not exist.

			} else {

			}

	/// Scrapes a folder for WASM runtimes.

	/// Returns a hashmap of the runtime version and wasm runtime code.

		}

}