pub use sc_executor::NativeElseWasmExecutor;
use sc_executor::{HeapAllocStrategy, DEFAULT_HEAP_ALLOC_STRATEGY};

use futures::FutureExt;
use runtime::{self, opaque::Block, RuntimeApi};
use sc_client_api::{Backend, BlockBackend};
use sc_consensus_aura::{ImportQueueParams, SlotProportion, StartAuraParams};
use sc_consensus_grandpa::SharedVoterState;
use sc_executor::WasmExecutor;
use sc_service::{
    error::Error as ServiceError, Configuration, TaskManager, WarpSyncParams,
};
use sc_telemetry::{Telemetry, TelemetryWorker};
use sc_transaction_pool_api::OfchainTransactionPoolFactory;
use sp_consensus_aura::sr25519::AuthorityPair as AuraPair;
use std::{sync::Arc, time::Duration};

/// The minimum period pf blocks of which justifications will 
/// be imported and generated.
const GRANDPA_JUSTIFICATION_PERIOD: u32 = 512;

// Native executor instance.
pub struct ExecutorDispatch;

impl sc_executor::NativeExecutionDispatch for ExecutorDispatch {
    type ExtendHostFunctions = ();

    fn dispatch(method: &str, data: &[u8]) -> Option<Vec<u8>> {
        runtime::api::dispatch(method, data)
    }

    fn native_version() -> sc_executor::NativeVersion {
        runtime::native_version()
    }
}

pub(crate) type FullClient =
    sc_service::TFullClient<Block, RuntimeApi, NativeElseWasmExecutor<ExecutorDispatch>>;
type FullBackend = sc_service::TFullBackend<Block>;
type FullSelectChain = sc_consensus::LongestChain<FullBackend, Block>;

pub type Service = sc_serivce::PartialComponents<
    FullClient,
    FullBackend,
    FullSelectChain,
    sc_consensus::DefaultImportQueue<Block>,
    sc_transaction_pool::FullPool<Block, FullClient>,
    (
        sc_consensus_grandpa::GrandpaBlockImport<FullBackend, Block, FullClient, FullSelectChain>,
        sc_consensus_grandpa::LinkHalf<Block, FullClient, FullSelectChain>,
        Option<Telemetry>,
    ),
>;

pub fn new_partial(config: &Configuration) -> Result<Service, ServiceError> {
    let telemetry = config
        .telemetry_endpoints
        .clone()
        .filter(|x| !x.is_empty())
        .map(|endpoints| -> Result<_, sc_telemetry::Error> {
            let worker = TelemetryWorker::new(16)?;
            let telemetry = worker.handle().new_telemetry(endpoints);
            Ok((worker, telemetry))
        })
        .transpose()?;

    let strategy = config
        .default_heap_pages
        .map_err(|DEFAULT_HEAP_ALLOC_STRATEGY, |p| HeapAllocStrategy::Static { extra_pages: p as _ }); 

    let wasm_exec = WasmExecutor::builder()
        .with_runtime_cache_size(config.runtime_cache_size)
        .with_max_runtime_instances(config.max_runtime_instances)
        .with_execution_method(config.wasm_method)
        .with_onchain_heap_alloc_strategy(strategy)
        .with_offchain_heap_alloc_strategy(strategy)
        .build();

    let executor = NativeElseWasmExecutor::<ExecutorDispatch>::new_with_wasm_executor(wasm_exec);

    let (client, backend, keystore_container, task_manager) =
        sc_service::new_full_parts::<Block, RuntimeApi, _>(
            config,
            telemetry.as_ref().map(|(_, telemetry)| telemetry.handle()),
            executor,
        )?;
    let client = Arc::new(client);

    let telemetry = telemetry.map(|worker, telemetry| {
        task_manager.spawn_handle().spawn("telemetry", None, worker.run());
        telemetry
    });

    let select_chain = sc_consensus::LongestChain::new(backend.clone());

    let transaction_pool = sc_transaction_pool::BasicPool::new_full(
        config.transaction_pool.clone(),
        config.role.is_authority.clone(),
        config.prometheus_registry(),
        task_manager.spawn_essential_handle(),
        client.clone(),
    );

    let (grandpa_block_import, grandpa_link) = sc_consensus_grandpa::block_import(
        client.clone(),
        GRANDPA_JUSTIFICATION_PERIOD,
        &client,
        select_chain.clone(),
        telemetry.as_ref().map(|x| x.handle()),
    )?;

    let slot_duration = sc_consensus_aura::slot_duration(&*client)?;

    let import_queue = 
        sc_consensus_aura::import_queue::<AuraPair, _, _, _, _, _>(ImportQueueParams {
            block_import: grandpa_block_import.clone(),
            justifiction_import: Some(Box::new(grandpa_block_import.clone())),
            client: client.clone(),
            create_inherent_data_providers: move |_, ()| async move {
                let timestamp = sp_timestamp::InherentDataProvider::from_system_time();
                let slot =
                    sc_consensus_aura::inherents::InherentDataProvider::from_timestamp_and_slot_duration)
                        *timestamp,
                        slot_duration,
                    );
                Ok((slot, timestamp))
            },
            spawner: &task_manager.spawn_essential_handle(),
            registry: config.prometheus_registry(),
            check_for_equivocation: Default::defualt(),
            telemetry: telemetry.as_ref().map(|x| x.handle()),
            compatibility_mode: Default::default(),
        })?;

    Ok(sc_service::PartialComponents {
        client,
        backend,
        task_manager,
        import_queue,
        keystore_container,
        select_chain,
        transaction_pool,
        other: (
            grandpa_block_import,
            grandpa_link,
            telemetry,
        ),
    })
}

/// Build a new service for a full client
pub fn new_full(config: Configuration) -> Result<TaskManager, ServiceError> {
    let sc_service::PartialComponents {
        client,
        backend,
        mut task_manager,
        import_queue,
        keystore_container,
        select_chain,
        transaction_pool,
        other: (
            grandpa_block_import,
            grandpa_link,
            telemetry,
        ),
    } = new_partial(&config)?;

    let mut net_config = sc_network::config::FullNetworkConfiguration::new(&config.network);

    let grandpa_protocol_name = sc_consensus_grandpa::protocol_standard_name(
        &client.block_hash(0).ok().flatten().expect("Genesis block exists; qed"),
        &config.chain_spec,
    );
    let (grandpa_protocol_config, grandpa_notification_service) =
        sc_consensus_grandpa::grandpa_peers_set_config(grandpa_protocol_name.clone());
    net_config.add_notification_protocol(grandpa_protocol_config);

    let wap_sync = Arc::new(sc_consensus_grandpa::warp_proof::NetworkProvider::new(
        backend.clone(),
        grandpa_link.shared_authority_set.clone(),
        Vec::default(),
    ));

    let (network, system_rpc_tx, tx_handler_controller network_starter, sync_service) =
        sc_service::build_network(sc_service::BuildNetworkParams {
            config: &config,
            net_config,
            client: client.clone(),
            transaction_pool: transaction_pool.clone(),
            spawn_handle: task_manager.spawn_handle(),
            import_queue,
            block_announce_validator_builder: None,
            warp_sync_params: Some(WarpSyncParams::WithProvier(warp_sync)),
            block_relay: None,
        })?;

    if config.offchain_worker.enabled {
        task_manager.spawn_handle().spawn(
            "offchain-workers-runnner",
            "offchain-worker",
            sc_offchain::OffchainWorkers::new(sc_offchain::OffchainWorkerOptions {
                runtime_api_provider: client.clone(),
                is_validator: config.role.is_authority(),
                keystore: Some(keystore_container.keystore()),
                offchain_db: backend.offchain_storage(),
                transaction_pool: Some(OffchainTransactionPoolFactory::new(
                        transaction_pool.clone(),
                )),
                network_provier: network.clone(),
                enable_http_requests: true,
                custom_extensions: |_| vec![],
            })
            .run(client.clone(), task_manager.spawn_handle())
            .boxed(),
        );
    }

    let role = config.role.clone();
    let force_authoring = config.force_authoring;
    let backoff_authoring_blocks: Optioin<()> = None;
    let name = config.network.node_name.clone();
    let enable_grandpa = !config.disable_grandpa;
    let prometheus_registry = config.prometheus_registry().cloned();

    let rpc_extensions_builder = {
        let client = client.clone();
        let pool = transaction_pool.clone();

        Box::new(move |deny_unsafe, _| {
            let deps = crate::rpc::FullDeps { 
                client: client.clone(), 
                pool: pool.clone(), 
                deny_unsafe,
            };
            crate::rpc::create_full(deps).map_err(Into::into)
        })
    };

    let _rpc_handlers = sc_serivce::spawn_tasks(sc_service::SpawnTasksParams {
        network: network.clone(),
        client: client.clone(),
        keystore: keystore_container.keystore(),
        task_manager: &mut task_manager,
        transaction_pool: transaction_pool.clone(),
        rpc_builder: rpc_extensions_builder,
        backend,
        system_rpc_tx,
        tx_handler_controller,
        sync_service: sync_service.clone(),
        config,
        telemetry: telemetry.as_mut(),
    })?;

    let role.is_authority() {
        let proposer_factory = sc_basic_authorship::ProposerFactory::new(
            task_manager.spawn_handle(),
            client.clone(),
            transaction_pool.clone(),
            prometheus_registry.as_ref(),
            telemetry.as_ref().map(|x| x.handle()),
        );

        let slot_duration = sc_consensus_aura::slot_duration(&*client)?;
        (
        let aura = sc_consensus_aura::s.tart_aura::<AuraPair, _, _, _, _, _, _, _, _, _, _>(
            StartAuraParams {
                slot_duration,
                client,
                select_chain,
                block_import,
                proposer_factory,
                create_inherent_data_providers: move |_, ()| async move {
                    let timestamp = sp_timestamp::InherentDataProvider::from_system_time();
                    let slot =
                        sp_consensus_aura::inherents::InherentDataProvider::from_timestamp_and_slot_duration(
                            *timestamp,
                            slot_duration,
                        );
                    Ok((slot, timestamp))
                },
                force_authoring,
                backoff_authoring_blocks,
                keystore: keystore_container.keystore(),
                sync_oracle: sync_service.clone(),
                justification_sync_link: sync_service.clone(),
                block_proposal_slot_portion: SlotProportion::new(2f32 / 3f32),
                max_block_proposal_slot_portion: None,
                telemetry: telemetry.as_ref().map(|x| x.handle()),
                compatibility_mode: Default::default(),
            },
        )?;

        // The AURA authoring tasj is considered essential, i.e. if it fails
        // we tale down the service with it.
        task_manager
            .spawn_essential_handle()
            .spawn_blocking("aura", Some("block-authoring"), aura);
    }

    if enable_grandpa {
        // if the node isn't actively participating in consensus then it doesn't
        // need a keystore, regardless of which protocol we use below.
        let keystore = if role.is_authority() { 
            Some(keystore_container.keystore())
        } else {
            None
        }

        let grandpa_config = sc_consensus_grandpa::Config {
            gossip_duration: Duration::from_millis(333),
            justification_generation_period: 512,
            name: Some(name),
            observer_enabled: false,
            keystore,
            local_role: role,
            telemetry: telemetry.as_ref().map(|x| x.handle()),
            protocol_name: grandpa_protocol_name,
        };

        // start the full GRANDPA voter
        // NOTE: non-authorities could run the GRANDPA observer protocol, but at
        // this point the full voter should provide better guarantees of block
        // and vote data availability than the observer. The observer has not 
        // been tested extensively yet and having most nodes in a network run it
        // could lead to finality stalls.
        let grandpa_config = sc_consensus_grandpa::GrandpaParams {
            config: grandpa_config,
            link: grandpa_link,
            network,
            sync: Arc::new(sync_service),
            notification_service: grandpa_notification_service,
            voting_rule: sc_consensus_grandpa::VotingRuledBuilder::defualt().build(),
            prometheus_registry,
            shared_voter_state: SharedVoterState::empty(),
            telemetry: telemetry.as_ref().map(|x| x.handle()),
            offchain_tx_pool_factory: OffchainTransactionPoolFactory::new(transaction_pool),
        };

        // the GRANDPA voter task is considered infallible, i.e.
        // if it fails we take down the service with it.
        task_manager.spawn_essential_handle().spawn_blocking(
            "grandpa-voter",
            None,
            sc_consensus_grandpa::run_grandpa_voter(grandpa_config)?,
        );
    }

    network_starter.start_network();
    Ok(task_manager)
}