// Copyright 2018-2019 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 crate::traits::{AugmentClap, GetLogFilter};

use std::path::PathBuf;
use structopt::{StructOpt, clap::{arg_enum, _clap_count_exprs, App, AppSettings, SubCommand, Arg}};
use client;

/// Auxiliary macro to implement `GetLogFilter` for all types that have the `shared_params` field.
macro_rules! impl_get_log_filter {
	( $type:ident ) => {
		impl $crate::GetLogFilter for $type {
			fn get_log_filter(&self) -> Option<String> {
				self.shared_params.get_log_filter()
			}
		}
	}
}

arg_enum! {
	/// How to execute blocks
	#[derive(Debug, Clone)]
	pub enum ExecutionStrategy {
		Native,
		Wasm,
		Both,
		NativeElseWasm,
		NativeWhenPossible,
	}
}

impl Into<client::ExecutionStrategy> for ExecutionStrategy {
	fn into(self) -> client::ExecutionStrategy {
		match self {
			ExecutionStrategy::Native => client::ExecutionStrategy::NativeWhenPossible,
			ExecutionStrategy::Wasm => client::ExecutionStrategy::AlwaysWasm,
			ExecutionStrategy::Both => client::ExecutionStrategy::Both,
			ExecutionStrategy::NativeElseWasm => client::ExecutionStrategy::NativeElseWasm,
			ExecutionStrategy::NativeWhenPossible => client::ExecutionStrategy::NativeWhenPossible,
		}
	}
}

arg_enum! {
	/// How to execute blocks
	#[derive(Debug, Clone)]
	pub enum OffchainWorkerEnabled {
		Always,
		Never,
		WhenValidating,
	}
}

/// Shared parameters used by all `CoreParams`.
#[derive(Debug, StructOpt, Clone)]
pub struct SharedParams {
	/// Specify the chain specification (one of dev, local or staging)
	#[structopt(long = "chain", value_name = "CHAIN_SPEC")]
	pub chain: Option<String>,

	/// Specify the development chain
	#[structopt(long = "dev")]
	pub dev: bool,

	/// Specify custom base path.
	#[structopt(long = "base-path", short = "d", value_name = "PATH", parse(from_os_str))]
	pub base_path: Option<PathBuf>,

	/// Sets a custom logging filter
	#[structopt(short = "l", long = "log", value_name = "LOG_PATTERN")]
	pub log: Option<String>,
}

impl GetLogFilter for SharedParams {
	fn get_log_filter(&self) -> Option<String> {
		self.log.clone()
	}
}

/// Parameters used to create the network configuration.
#[derive(Debug, StructOpt, Clone)]
pub struct NetworkConfigurationParams {
	/// Specify a list of bootnodes
	#[structopt(long = "bootnodes", value_name = "URL")]
	pub bootnodes: Vec<String>,

	/// Specify a list of reserved node addresses
	#[structopt(long = "reserved-nodes", value_name = "URL")]
	pub reserved_nodes: Vec<String>,

	/// Listen on this multiaddress
	#[structopt(long = "listen-addr", value_name = "LISTEN_ADDR")]
	pub listen_addr: Vec<String>,

	/// Specify p2p protocol TCP port. Only used if --listen-addr is not specified.
	#[structopt(long = "port", value_name = "PORT")]
	pub port: Option<u16>,

	/// Specify the number of outgoing connections we're trying to maintain
	#[structopt(long = "out-peers", value_name = "OUT_PEERS", default_value = "25")]
	pub out_peers: u32,

	/// Specify the maximum number of incoming connections we're accepting
	#[structopt(long = "in-peers", value_name = "IN_PEERS", default_value = "25")]
	pub in_peers: u32,

	/// By default, the network will use mDNS to discover other nodes on the local network. This
	/// disables it. Automatically implied when using --dev.
	#[structopt(long = "no-mdns")]
	pub no_mdns: bool,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub node_key_params: NodeKeyParams
}

arg_enum! {
	#[derive(Debug, Copy, Clone, PartialEq, Eq)]
	pub enum NodeKeyType {
		Secp256k1,
		Ed25519
	}
}

/// Parameters used to create the `NodeKeyConfig`, which determines the keypair
/// used for libp2p networking.
#[derive(Debug, StructOpt, Clone)]
pub struct NodeKeyParams {
	/// The secret key to use for libp2p networking.
	///
	/// The value is a string that is parsed according to the choice of
	/// `--node-key-type` as follows:
	///
	///   `secp256k1`:
	///   The value is parsed as a hex-encoded Secp256k1 32 bytes secret key,
	///   i.e. 64 hex characters.
	///
	///   `ed25519`:
	///   The value is parsed as a hex-encoded Ed25519 32 bytes secret key,
	///   i.e. 64 hex characters.
	///
	/// The value of this option takes precedence over `--node-key-file`.
	///
	/// WARNING: Secrets provided as command-line arguments are easily exposed.
	/// Use of this option should be limited to development and testing. To use
	/// an externally managed secret key, use `--node-key-file` instead.
	#[structopt(long = "node-key", value_name = "KEY")]
	pub node_key: Option<String>,

	/// The type of secret key to use for libp2p networking.
	///
	/// The secret key of the node is obtained as follows:
	///
	///   * If the `--node-key` option is given, the value is parsed as a secret key
	///     according to the type. See the documentation for `--node-key`.
	///
	///   * If the `--node-key-file` option is given, the secret key is read from the
	///     specified file. See the documentation for `--node-key-file`.
	///
	///   * Otherwise, the secret key is read from a file with a predetermined,
	///     type-specific name from the chain-specific network config directory
	///     inside the base directory specified by `--base-dir`. If this file does
	///     not exist, it is created with a newly generated secret key of the
	///     chosen type.
	///
	/// The node's secret key determines the corresponding public key and hence the
	/// node's peer ID in the context of libp2p.
	///
	/// NOTE: The current default key type is `secp256k1` for a transition period only
	/// but will eventually change to `ed25519` in a future release. To continue using
	/// `secp256k1` keys, use `--node-key-type=secp256k1`.
	#[structopt(
		long = "node-key-type",
		value_name = "TYPE",
		raw(
			possible_values = "&NodeKeyType::variants()",
			case_insensitive = "true",
			default_value = r#""Ed25519""#
		)
	)]
	pub node_key_type: NodeKeyType,

	/// The file from which to read the node's secret key to use for libp2p networking.
	///
	/// The contents of the file are parsed according to the choice of `--node-key-type`
	/// as follows:
	///
	///   `secp256k1`:
	///   The file must contain an unencoded 32 bytes Secp256k1 secret key.
	///
	///   `ed25519`:
	///   The file must contain an unencoded 32 bytes Ed25519 secret key.
	///
	/// If the file does not exist, it is created with a newly generated secret key of
	/// the chosen type.
	#[structopt(long = "node-key-file", value_name = "FILE")]
	pub node_key_file: Option<PathBuf>
}

/// Parameters used to create the pool configuration.
#[derive(Debug, StructOpt, Clone)]
pub struct TransactionPoolParams {
	/// Maximum number of transactions in the transaction pool.
	#[structopt(long = "pool-limit", value_name = "COUNT", default_value = "512")]
	pub pool_limit: usize,
	/// Maximum number of kilobytes of all transactions stored in the pool.
	#[structopt(long = "pool-kbytes", value_name = "COUNT", default_value="10240")]
	pub pool_kbytes: usize,
}

/// Execution strategies parameters.
#[derive(Debug, StructOpt, Clone)]
pub struct ExecutionStrategies {
	/// The means of execution used when calling into the runtime while syncing blocks.
	#[structopt(
		long = "syncing-execution",
		value_name = "STRATEGY",
		raw(
			possible_values = "&ExecutionStrategy::variants()",
			case_insensitive = "true",
			default_value = r#""NativeElseWasm""#
		)
	)]
	pub syncing_execution: ExecutionStrategy,

	/// The means of execution used when calling into the runtime while importing blocks.
	#[structopt(
		long = "importing-execution",
		value_name = "STRATEGY",
		raw(
			possible_values = "&ExecutionStrategy::variants()",
			case_insensitive = "true",
			default_value = r#""NativeElseWasm""#
		)
	)]
	pub importing_execution: ExecutionStrategy,

	/// The means of execution used when calling into the runtime while constructing blocks.
	#[structopt(
		long = "block-construction-execution",
		value_name = "STRATEGY",
		raw(
			possible_values = "&ExecutionStrategy::variants()",
			case_insensitive = "true",
			default_value = r#""Wasm""#
		)
	)]
	pub block_construction_execution: ExecutionStrategy,

	/// The means of execution used when calling into the runtime while using an off-chain worker.
	#[structopt(
		long = "offchain-worker-execution",
		value_name = "STRATEGY",
		raw(
			possible_values = "&ExecutionStrategy::variants()",
			case_insensitive = "true",
			default_value = r#""NativeWhenPossible""#
		)
	)]
	pub offchain_worker_execution: ExecutionStrategy,

	/// The means of execution used when calling into the runtime while not syncing, importing or constructing blocks.
	#[structopt(
		long = "other-execution",
		value_name = "STRATEGY",
		raw(
			possible_values = "&ExecutionStrategy::variants()",
			case_insensitive = "true",
			default_value = r#""Wasm""#
		)
	)]
	pub other_execution: ExecutionStrategy,
}

/// The `run` command used to run a node.
#[derive(Debug, StructOpt, Clone)]
pub struct RunCmd {
	/// Specify custom keystore path
	#[structopt(long = "keystore-path", value_name = "PATH", parse(from_os_str))]
	pub keystore_path: Option<PathBuf>,

	/// Specify additional key seed
	#[structopt(long = "key", value_name = "STRING")]
	pub key: Option<String>,

	/// Enable validator mode
	#[structopt(long = "validator")]
	pub validator: bool,

	/// Disable GRANDPA when running in validator mode
	#[structopt(long = "no-grandpa")]
	pub no_grandpa: bool,

	/// Experimental: Run in light client mode
	#[structopt(long = "light")]
	pub light: bool,

	/// Limit the memory the database cache can use
	#[structopt(long = "db-cache", value_name = "MiB")]
	pub database_cache_size: Option<u32>,

	/// Specify the state cache size
	#[structopt(long = "state-cache-size", value_name = "Bytes", default_value = "67108864")]
	pub state_cache_size: usize,

	/// Listen to all RPC interfaces (default is local)
	#[structopt(long = "rpc-external")]
	pub rpc_external: bool,

	/// Listen to all Websocket interfaces (default is local)
	#[structopt(long = "ws-external")]
	pub ws_external: bool,

	/// Specify HTTP RPC server TCP port
	#[structopt(long = "rpc-port", value_name = "PORT")]
	pub rpc_port: Option<u16>,

	/// Specify WebSockets RPC server TCP port
	#[structopt(long = "ws-port", value_name = "PORT")]
	pub ws_port: Option<u16>,

	/// Maximum number of WS RPC server connections.
	#[structopt(long = "ws-max-connections", value_name = "COUNT")]
	pub ws_max_connections: Option<usize>,

	/// Specify browser Origins allowed to access the HTTP & WS RPC servers.
	/// It's a comma-separated list of origins (protocol://domain or special `null` value).
	/// Value of `all` will disable origin validation.
	/// Default is to allow localhost, https://polkadot.js.org and https://substrate-ui.parity.io origins.
	/// When running in --dev mode the default is to allow all origins.
	#[structopt(long = "rpc-cors", value_name = "ORIGINS", parse(try_from_str = "parse_cors"))]
	pub rpc_cors: Option<Option<Vec<String>>>,

	/// Specify the pruning mode, a number of blocks to keep or 'archive'. Default is 256.
	#[structopt(long = "pruning", value_name = "PRUNING_MODE")]
	pub pruning: Option<String>,

	/// The human-readable name for this node, as reported to the telemetry server, if enabled
	#[structopt(long = "name", value_name = "NAME")]
	pub name: Option<String>,

	/// Disable connecting to the Substrate telemetry server (telemetry is on by default on global chains).
	#[structopt(long = "no-telemetry")]
	pub no_telemetry: bool,

	/// The URL of the telemetry server to connect to. This flag can be passed multiple times
	/// as a mean to specify multiple telemetry endpoints. Verbosity levels range from 0-9, with
	/// 0 denoting the least verbosity. If no verbosity level is specified the default is 0.
	#[structopt(long = "telemetry-url", value_name = "URL VERBOSITY", parse(try_from_str = "parse_telemetry_endpoints"))]
	pub telemetry_endpoints: Vec<(String, u8)>,

	/// Should execute offchain workers on every block. By default it's only enabled for nodes that are authoring new
	/// blocks.
	#[structopt(
		long = "offchain-worker",
		value_name = "ENABLED",
		raw(
			possible_values = "&OffchainWorkerEnabled::variants()",
			case_insensitive = "true",
			default_value = r#""WhenValidating""#
		)
	)]
	pub offchain_worker: OffchainWorkerEnabled,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub execution_strategies: ExecutionStrategies,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub shared_params: SharedParams,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub network_config: NetworkConfigurationParams,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub pool_config: TransactionPoolParams,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub keyring: Keyring,

	/// Enable authoring even when offline.
	#[structopt(long = "force-authoring")]
	pub force_authoring: bool,

	/// Interactive password for validator key.
	#[structopt(short = "i")]
	pub interactive_password: bool,
}

/// Stores all required Cli values for a keyring test account.
struct KeyringTestAccountCliValues {
	help: String,
	conflicts_with: Vec<String>,
	name: String,
	variant: keyring::AuthorityKeyring,
}

lazy_static::lazy_static! {
	/// The Cli values for all test accounts.
	static ref TEST_ACCOUNTS_CLI_VALUES: Vec<KeyringTestAccountCliValues> = {
		keyring::AuthorityKeyring::iter().map(|a| {
			let help = format!("Shortcut for `--key //{} --name {}`.", a, a);
			let conflicts_with = keyring::AuthorityKeyring::iter()
				.filter(|b| a != *b)
				.map(|b| b.to_string().to_lowercase())
				.chain(["name", "key"].iter().map(|s| s.to_string()))
				.collect::<Vec<_>>();
			let name = a.to_string().to_lowercase();

			KeyringTestAccountCliValues {
				help,
				conflicts_with,
				name,
				variant: a,
			}
		}).collect()
	};
}

/// Wrapper for exposing the keyring test accounts into the Cli.
#[derive(Debug, Clone)]
pub struct Keyring {
	pub account: Option<keyring::AuthorityKeyring>,
}

impl StructOpt for Keyring {
	fn clap<'a, 'b>() -> App<'a, 'b> {
		unimplemented!("Should not be called for `TestAccounts`.")
	}

	fn from_clap(m: &::structopt::clap::ArgMatches) -> Self {
		Keyring {
			account: TEST_ACCOUNTS_CLI_VALUES.iter().find(|a| m.is_present(&a.name)).map(|a| a.variant),
		}
	}
}

impl AugmentClap for Keyring {
	fn augment_clap<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
		TEST_ACCOUNTS_CLI_VALUES.iter().fold(app, |app, a| {
			let conflicts_with_strs = a.conflicts_with.iter().map(|s| s.as_str()).collect::<Vec<_>>();

			app.arg(
				Arg::with_name(&a.name)
					.long(&a.name)
					.help(&a.help)
					.conflicts_with_all(&conflicts_with_strs)
					.takes_value(false)
			)
		})
	}
}

impl Keyring {
	fn is_subcommand() -> bool {
		false
	}
}

/// Default to verbosity level 0, if none is provided.
fn parse_telemetry_endpoints(s: &str) -> Result<(String, u8), Box<std::error::Error>> {
	let pos = s.find(' ');
	match pos {
		None => {
			Ok((s.to_owned(), 0))
		},
		Some(pos_) => {
			let verbosity = s[pos_ + 1..].parse()?;
			let url = s[..pos_].parse()?;
			Ok((url, verbosity))
		}
	}
}

/// Parse cors origins
fn parse_cors(s: &str) -> Result<Option<Vec<String>>, Box<std::error::Error>> {
	let mut is_all = false;
	let mut origins = Vec::new();
	for part in s.split(',') {
		match part {
			"all" | "*" => {
				is_all = true;
				break;
			},
			other => origins.push(other.to_owned()),
		}
	}

	Ok(if is_all { None } else { Some(origins) })
}

impl_augment_clap!(RunCmd);
impl_get_log_filter!(RunCmd);

/// The `build-spec` command used to build a specification.
#[derive(Debug, StructOpt, Clone)]
pub struct BuildSpecCmd {
	/// Force raw genesis storage output.
	#[structopt(long = "raw")]
	pub raw: bool,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub shared_params: SharedParams,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub node_key_params: NodeKeyParams,
}

impl_get_log_filter!(BuildSpecCmd);

/// The `export-blocks` command used to export blocks.
#[derive(Debug, StructOpt, Clone)]
pub struct ExportBlocksCmd {
	/// Output file name or stdout if unspecified.
	#[structopt(parse(from_os_str))]
	pub output: Option<PathBuf>,

	/// Specify starting block number. 1 by default.
	#[structopt(long = "from", value_name = "BLOCK")]
	pub from: Option<u32>,

	/// Specify last block number. Best block by default.
	#[structopt(long = "to", value_name = "BLOCK")]
	pub to: Option<u32>,

	/// Use JSON output rather than binary.
	#[structopt(long = "json")]
	pub json: bool,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub shared_params: SharedParams,
}

impl_get_log_filter!(ExportBlocksCmd);

/// The `import-blocks` command used to import blocks.
#[derive(Debug, StructOpt, Clone)]
pub struct ImportBlocksCmd {
	/// Input file or stdin if unspecified.
	#[structopt(parse(from_os_str))]
	pub input: Option<PathBuf>,

	/// The default number of 64KB pages to ever allocate for Wasm execution. Don't alter this unless you know what you're doing.
	#[structopt(long = "default-heap-pages", value_name = "COUNT")]
	pub default_heap_pages: Option<u32>,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub shared_params: SharedParams,
}

impl_get_log_filter!(ImportBlocksCmd);

/// The `revert` command used revert the chain to a previous state.
#[derive(Debug, StructOpt, Clone)]
pub struct RevertCmd {
	/// Number of blocks to revert.
	#[structopt(default_value = "256")]
	pub num: u32,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub shared_params: SharedParams,
}

impl_get_log_filter!(RevertCmd);

/// The `purge-chain` command used to remove the whole chain.
#[derive(Debug, StructOpt, Clone)]
pub struct PurgeChainCmd {
	/// Skip interactive prompt by answering yes automatically.
	#[structopt(short = "y")]
	pub yes: bool,

	#[allow(missing_docs)]
	#[structopt(flatten)]
	pub shared_params: SharedParams,
}

impl_get_log_filter!(PurgeChainCmd);

/// All core commands that are provided by default.
///
/// The core commands are split into multiple subcommands and `Run` is the default subcommand. From
/// the CLI user perspective, it is not visible that `Run` is a subcommand. So, all parameters of
/// `Run` are exported as main executable parameters.
#[derive(Debug, Clone)]
pub enum CoreParams<CC, RP> {
	/// Run a node.
	Run(MergeParameters<RunCmd, RP>),

	/// Build a spec.json file, outputing to stdout.
	BuildSpec(BuildSpecCmd),

	/// Export blocks to a file.
	ExportBlocks(ExportBlocksCmd),

	/// Import blocks from file.
	ImportBlocks(ImportBlocksCmd),

	/// Revert chain to the previous state.
	Revert(RevertCmd),

	/// Remove the whole chain data.
	PurgeChain(PurgeChainCmd),

	/// Further custom subcommands.
	Custom(CC),
}

impl<CC, RP> StructOpt for CoreParams<CC, RP> where
	CC: StructOpt + GetLogFilter,
	RP: StructOpt + AugmentClap
{
	fn clap<'a, 'b>() -> App<'a, 'b> {
		RP::augment_clap(
			RunCmd::augment_clap(
				CC::clap().unset_setting(AppSettings::SubcommandRequiredElseHelp)
			)
		).subcommand(
			BuildSpecCmd::augment_clap(SubCommand::with_name("build-spec"))
				.about("Build a spec.json file, outputing to stdout.")
		)
		.subcommand(
			ExportBlocksCmd::augment_clap(SubCommand::with_name("export-blocks"))
				.about("Export blocks to a file.")
		)
		.subcommand(
			ImportBlocksCmd::augment_clap(SubCommand::with_name("import-blocks"))
				.about("Import blocks from file.")
		)
		.subcommand(
			RevertCmd::augment_clap(SubCommand::with_name("revert"))
				.about("Revert chain to the previous state.")
		)
		.subcommand(
			PurgeChainCmd::augment_clap(SubCommand::with_name("purge-chain"))
				.about("Remove the whole chain data.")
		)
	}

	fn from_clap(matches: &::structopt::clap::ArgMatches) -> Self {
		match matches.subcommand() {
			("build-spec", Some(matches)) =>
				CoreParams::BuildSpec(BuildSpecCmd::from_clap(matches)),
			("export-blocks", Some(matches)) =>
				CoreParams::ExportBlocks(ExportBlocksCmd::from_clap(matches)),
			("import-blocks", Some(matches)) =>
				CoreParams::ImportBlocks(ImportBlocksCmd::from_clap(matches)),
			("revert", Some(matches)) => CoreParams::Revert(RevertCmd::from_clap(matches)),
			("purge-chain", Some(matches)) =>
				CoreParams::PurgeChain(PurgeChainCmd::from_clap(matches)),
			(_, None) => CoreParams::Run(MergeParameters::from_clap(matches)),
			_ => CoreParams::Custom(CC::from_clap(matches)),
		}
	}
}

impl<CC, RP> GetLogFilter for CoreParams<CC, RP> where CC: GetLogFilter {
	fn get_log_filter(&self) -> Option<String> {
		match self {
			CoreParams::Run(c) => c.left.get_log_filter(),
			CoreParams::BuildSpec(c) => c.get_log_filter(),
			CoreParams::ExportBlocks(c) => c.get_log_filter(),
			CoreParams::ImportBlocks(c) => c.get_log_filter(),
			CoreParams::PurgeChain(c) => c.get_log_filter(),
			CoreParams::Revert(c) => c.get_log_filter(),
			CoreParams::Custom(c) => c.get_log_filter(),
		}
	}
}

/// A special commandline parameter that expands to nothing.
/// Should be used as custom subcommand/run arguments if no custom values are required.
#[derive(Clone, Debug)]
pub struct NoCustom {}

impl StructOpt for NoCustom {
	fn clap<'a, 'b>() -> App<'a, 'b> {
		App::new("NoCustom")
	}

	fn from_clap(_: &::structopt::clap::ArgMatches) -> Self {
		NoCustom {}
	}
}

impl AugmentClap for NoCustom {
	fn augment_clap<'a, 'b>(app: App<'a, 'b>) -> App<'a, 'b> {
		app
	}
}

impl GetLogFilter for NoCustom {
	fn get_log_filter(&self) -> Option<String> {
		None
	}
}

/// Merge all CLI parameters of `L` and `R` into the same level.
#[derive(Clone, Debug)]
pub struct MergeParameters<L, R> {
	/// The left side parameters.
	pub left: L,
	/// The right side parameters.
	pub right: R,
}

impl<L, R> StructOpt for MergeParameters<L, R> where L: StructOpt + AugmentClap, R: StructOpt {
	fn clap<'a, 'b>() -> App<'a, 'b> {
		L::augment_clap(R::clap())
	}

	fn from_clap(matches: &::structopt::clap::ArgMatches) -> Self {
		MergeParameters {
			left: L::from_clap(matches),
			right: R::from_clap(matches),
		}
	}
}