use sp_core::{Pair, Public, sr25519};
use sp_consensus_babe::{AuthorityId as BabeId};
use sp_finality_grandpa::{AuthorityId as GrandpaId};
use sc_service;
use sp_runtime::traits::{Verify, IdentifyAccount};
use runtime::{AccountId, GenesisConfig, Signature};
use runtime_genesis::testnet_genesis;

// Note this is the URL for the telemetry server
//const STAGING_TELEMETRY_URL: &str = "wss://telemetry.polkadot.io/submit/";

/// Specialized `ChainSpec`. This is a specialization of the general Substrate ChainSpec type.
pub type ChainSpec = sc_service::ChainSpec<GenesisConfig>;

/// The chain specification option. This is expected to come in from the CLI and
/// is little more than one of a number of alternatives which can easily be converted
/// from a string (`--chain=...`) into a `ChainSpec`.
#[derive(Clone, Debug)]
pub enum Alternative {
	/// Whatever the current runtime is, with just Alice as an auth.
	Development,
	/// Whatever the current runtime is, with simple Alice/Bob auths.
	LocalTestnet,
}

/// Helper function to generate a crypto pair from seed
pub fn get_from_seed<TPublic: Public>(seed: &str) -> <TPublic::Pair as Pair>::Public {
	TPublic::Pair::from_string(&format!("//{}", seed), None)
		.expect("static values are valid; qed")
		.public()
}

type AccountPublic = <Signature as Verify>::Signer;

/// Helper function to generate an account ID from seed
pub fn get_account_id_from_seed<TPublic: Public>(seed: &str) -> AccountId where
	AccountPublic: From<<TPublic::Pair as Pair>::Public>
{
	AccountPublic::from(get_from_seed::<TPublic>(seed)).into_account()
}

/// Helper function to generate session key from seed
pub fn get_authority_keys_from_seed(seed: &str) -> (BabeId, GrandpaId) {
	(
		get_from_seed::<BabeId>(seed),
		get_from_seed::<GrandpaId>(seed),
	)
}

impl Alternative {
	/// Get an actual chain config from one of the alternatives.
	pub(crate) fn load(self) -> Result<ChainSpec, String> {
		Ok(match self {
			Alternative::Development => ChainSpec::from_genesis(
				"Development",
				"dev",
				|| testnet_genesis(vec![
					get_authority_keys_from_seed("Alice"),
				],
				get_account_id_from_seed::<sr25519::Public>("Alice"),
				vec![
					get_account_id_from_seed::<sr25519::Public>("Alice"),
					get_account_id_from_seed::<sr25519::Public>("Bob"),
					get_account_id_from_seed::<sr25519::Public>("Alice//stash"),
					get_account_id_from_seed::<sr25519::Public>("Bob//stash"),
				],
				true),
				vec![],
				None,
				None,
				None,
				None
			),
			Alternative::LocalTestnet => ChainSpec::from_genesis(
				"Local Testnet",
				"local_testnet",
				|| testnet_genesis(vec![
					get_authority_keys_from_seed("Alice"),
					get_authority_keys_from_seed("Bob"),
				],
				get_account_id_from_seed::<sr25519::Public>("Alice"),
				vec![
					get_account_id_from_seed::<sr25519::Public>("Alice"),
					get_account_id_from_seed::<sr25519::Public>("Bob"),
					get_account_id_from_seed::<sr25519::Public>("Charlie"),
					get_account_id_from_seed::<sr25519::Public>("Dave"),
					get_account_id_from_seed::<sr25519::Public>("Eve"),
					get_account_id_from_seed::<sr25519::Public>("Ferdie"),
					get_account_id_from_seed::<sr25519::Public>("Alice//stash"),
					get_account_id_from_seed::<sr25519::Public>("Bob//stash"),
					get_account_id_from_seed::<sr25519::Public>("Charlie//stash"),
					get_account_id_from_seed::<sr25519::Public>("Dave//stash"),
					get_account_id_from_seed::<sr25519::Public>("Eve//stash"),
					get_account_id_from_seed::<sr25519::Public>("Ferdie//stash"),
				],
				true),
				vec![],
				None,
				None,
				None,
				None
			),
		})
	}

	pub(crate) fn from(s: &str) -> Option<Self> {
		match s {
			"dev" => Some(Alternative::Development),
			"" | "local" => Some(Alternative::LocalTestnet),
			_ => None,
		}
	}
}

pub fn load_spec(id: &str) -> Result<Option<ChainSpec>, String> {
	Ok(match Alternative::from(id) {
		Some(spec) => Some(spec.load()?),
		None => None,
	})
}
