// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum 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.

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

//! Tests for the on-demand service.

use cache::Cache;
use common_types::header::Header;
use ethereum_types::H256;
use futures::Future;
use net::*;
use network::{NodeId, PeerId};
use parking_lot::Mutex;
use request::{self as basic_request, Response};

use std::{
    sync::Arc,
    thread,
    time::{Duration, Instant},
};

use super::{request, HeaderRef, OnDemand, OnDemandRequester, Peer};

// useful contexts to give the service.
enum Context {
    NoOp,
    WithPeer(PeerId),
    RequestFrom(PeerId, ReqId),
    Punish(PeerId),
    FaultyRequest,
}

impl EventContext for Context {
    fn peer(&self) -> PeerId {
        match *self {
            Context::WithPeer(id) | Context::RequestFrom(id, _) | Context::Punish(id) => id,
            Context::FaultyRequest => 0,
            _ => panic!("didn't expect to have peer queried."),
        }
    }

    fn as_basic(&self) -> &dyn BasicContext {
        self
    }
}

impl BasicContext for Context {
    /// Returns the relevant's peer persistent Id (aka NodeId).
    fn persistent_peer_id(&self, _: PeerId) -> Option<NodeId> {
        panic!("didn't expect to provide persistent ID")
    }

    fn request_from(&self, peer_id: PeerId, _: ::request::NetworkRequests) -> Result<ReqId, Error> {
        match *self {
            Context::RequestFrom(id, req_id) => {
                if peer_id == id {
                    Ok(req_id)
                } else {
                    Err(Error::NoCredits)
                }
            }
            Context::FaultyRequest => Err(Error::NoCredits),
            _ => panic!("didn't expect to have requests dispatched."),
        }
    }

    fn make_announcement(&self, _: Announcement) {
        panic!("didn't expect to make announcement")
    }

    fn disconnect_peer(&self, id: PeerId) {
        self.disable_peer(id)
    }

    fn disable_peer(&self, peer_id: PeerId) {
        match *self {
            Context::Punish(id) if id == peer_id => {}
            _ => panic!("Unexpectedly punished peer."),
        }
    }
}

// test harness.
struct Harness {
    service: OnDemand,
}

impl Harness {
    fn create() -> Self {
        let cache = Arc::new(Mutex::new(Cache::new(
            Default::default(),
            Duration::from_secs(60),
        )));
        Harness {
            service: OnDemand::new_test(
                cache,
                // Response `time_to_live`
                Duration::from_secs(5),
                // Request start backoff
                Duration::from_secs(1),
                // Request max backoff
                Duration::from_secs(20),
                super::DEFAULT_MAX_REQUEST_BACKOFF_ROUNDS,
                super::DEFAULT_NUM_CONSECUTIVE_FAILED_REQUESTS,
            ),
        }
    }

    fn inject_peer(&self, id: PeerId, peer: Peer) {
        self.service.peers.write().insert(id, peer);
    }
}

fn dummy_status() -> Status {
    Status {
        protocol_version: 1,
        network_id: 999,
        head_td: 1.into(),
        head_hash: H256::default(),
        head_num: 1359,
        genesis_hash: H256::default(),
        last_head: None,
    }
}

fn dummy_capabilities() -> Capabilities {
    Capabilities {
        serve_headers: true,
        serve_chain_since: Some(1),
        serve_state_since: Some(1),
        tx_relay: true,
    }
}

#[test]
fn detects_hangup() {
    let on_demand = Harness::create().service;
    let result = on_demand.request_raw(
        &Context::NoOp,
        vec![request::HeaderByHash(H256::default().into()).into()],
    );

    assert_eq!(on_demand.pending.read().len(), 1);
    drop(result);

    on_demand.dispatch_pending(&Context::NoOp);
    assert!(on_demand.pending.read().is_empty());
}

#[test]
fn single_request() {
    let harness = Harness::create();

    let peer_id = 10101;
    let req_id = ReqId(14426);

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let header = Header::default();
    let encoded = header.encoded();

    let recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![request::HeaderByHash(header.hash().into()).into()],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_id));

    assert_eq!(harness.service.pending.read().len(), 0);

    harness.service.on_responses(
        &Context::WithPeer(peer_id),
        req_id,
        &[Response::Headers(basic_request::HeadersResponse {
            headers: vec![encoded],
        })],
    );

    assert!(recv.wait().is_ok());
}

#[test]
fn no_capabilities() {
    let harness = Harness::create();

    let peer_id = 10101;

    let mut capabilities = dummy_capabilities();
    capabilities.serve_headers = false;

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: capabilities,
        },
    );

    let _recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![request::HeaderByHash(H256::default().into()).into()],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness.service.dispatch_pending(&Context::NoOp);

    assert_eq!(harness.service.pending.read().len(), 1);
}

#[test]
fn reassign() {
    let harness = Harness::create();

    let peer_ids = (10101, 12345);
    let req_ids = (ReqId(14426), ReqId(555));

    harness.inject_peer(
        peer_ids.0,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let header = Header::default();
    let encoded = header.encoded();

    let recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![request::HeaderByHash(header.hash().into()).into()],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_ids.0, req_ids.0));
    assert_eq!(harness.service.pending.read().len(), 0);

    harness
        .service
        .on_disconnect(&Context::WithPeer(peer_ids.0), &[req_ids.0]);
    assert_eq!(harness.service.pending.read().len(), 1);

    harness.inject_peer(
        peer_ids.1,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_ids.1, req_ids.1));
    assert_eq!(harness.service.pending.read().len(), 0);

    harness.service.on_responses(
        &Context::WithPeer(peer_ids.1),
        req_ids.1,
        &[Response::Headers(basic_request::HeadersResponse {
            headers: vec![encoded],
        })],
    );

    assert!(recv.wait().is_ok());
}

#[test]
fn partial_response() {
    let harness = Harness::create();

    let peer_id = 111;
    let req_ids = (ReqId(14426), ReqId(555));

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let make = |num| {
        let mut hdr = Header::default();
        hdr.set_number(num);

        let encoded = hdr.encoded();
        (hdr, encoded)
    };

    let (header1, encoded1) = make(5);
    let (header2, encoded2) = make(23452);

    // request two headers.
    let recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![
                request::HeaderByHash(header1.hash().into()).into(),
                request::HeaderByHash(header2.hash().into()).into(),
            ],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_ids.0));
    assert_eq!(harness.service.pending.read().len(), 0);

    // supply only the first one.
    harness.service.on_responses(
        &Context::WithPeer(peer_id),
        req_ids.0,
        &[Response::Headers(basic_request::HeadersResponse {
            headers: vec![encoded1],
        })],
    );

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_ids.1));
    assert_eq!(harness.service.pending.read().len(), 0);

    // supply the next one.
    harness.service.on_responses(
        &Context::WithPeer(peer_id),
        req_ids.1,
        &[Response::Headers(basic_request::HeadersResponse {
            headers: vec![encoded2],
        })],
    );

    assert!(recv.wait().is_ok());
}

#[test]
fn part_bad_part_good() {
    let harness = Harness::create();

    let peer_id = 111;
    let req_ids = (ReqId(14426), ReqId(555));

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let make = |num| {
        let mut hdr = Header::default();
        hdr.set_number(num);

        let encoded = hdr.encoded();
        (hdr, encoded)
    };

    let (header1, encoded1) = make(5);
    let (header2, encoded2) = make(23452);

    // request two headers.
    let recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![
                request::HeaderByHash(header1.hash().into()).into(),
                request::HeaderByHash(header2.hash().into()).into(),
            ],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_ids.0));
    assert_eq!(harness.service.pending.read().len(), 0);

    // supply only the first one, but followed by the wrong kind of response.
    // the first header should be processed.
    harness.service.on_responses(
        &Context::Punish(peer_id),
        req_ids.0,
        &[
            Response::Headers(basic_request::HeadersResponse {
                headers: vec![encoded1],
            }),
            Response::Receipts(basic_request::ReceiptsResponse { receipts: vec![] }),
        ],
    );

    assert_eq!(harness.service.pending.read().len(), 1);

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_ids.1));
    assert_eq!(harness.service.pending.read().len(), 0);

    // supply the next one.
    harness.service.on_responses(
        &Context::WithPeer(peer_id),
        req_ids.1,
        &[Response::Headers(basic_request::HeadersResponse {
            headers: vec![encoded2],
        })],
    );

    assert!(recv.wait().is_ok());
}

#[test]
fn wrong_kind() {
    let harness = Harness::create();

    let peer_id = 10101;
    let req_id = ReqId(14426);

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let _recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![request::HeaderByHash(H256::default().into()).into()],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_id));

    assert_eq!(harness.service.pending.read().len(), 0);

    harness.service.on_responses(
        &Context::Punish(peer_id),
        req_id,
        &[Response::Receipts(basic_request::ReceiptsResponse {
            receipts: vec![],
        })],
    );

    assert_eq!(harness.service.pending.read().len(), 1);
}

#[test]
fn back_references() {
    let harness = Harness::create();

    let peer_id = 10101;
    let req_id = ReqId(14426);

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let header = Header::default();
    let encoded = header.encoded();

    let recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![
                request::HeaderByHash(header.hash().into()).into(),
                request::BlockReceipts(HeaderRef::Unresolved(0, header.hash().into())).into(),
            ],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_id));

    assert_eq!(harness.service.pending.read().len(), 0);

    harness.service.on_responses(
        &Context::WithPeer(peer_id),
        req_id,
        &[
            Response::Headers(basic_request::HeadersResponse {
                headers: vec![encoded],
            }),
            Response::Receipts(basic_request::ReceiptsResponse { receipts: vec![] }),
        ],
    );

    assert!(recv.wait().is_ok());
}

#[test]
#[should_panic]
fn bad_back_reference() {
    let harness = Harness::create();

    let header = Header::default();

    let _ = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![
                request::HeaderByHash(header.hash().into()).into(),
                request::BlockReceipts(HeaderRef::Unresolved(1, header.hash().into())).into(),
            ],
        )
        .unwrap();
}

#[test]
fn fill_from_cache() {
    let harness = Harness::create();

    let peer_id = 10101;
    let req_id = ReqId(14426);

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let header = Header::default();
    let encoded = header.encoded();

    let recv = harness
        .service
        .request_raw(
            &Context::NoOp,
            vec![
                request::HeaderByHash(header.hash().into()).into(),
                request::BlockReceipts(HeaderRef::Unresolved(0, header.hash().into())).into(),
            ],
        )
        .unwrap();

    assert_eq!(harness.service.pending.read().len(), 1);

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_id));

    assert_eq!(harness.service.pending.read().len(), 0);

    harness.service.on_responses(
        &Context::WithPeer(peer_id),
        req_id,
        &[Response::Headers(basic_request::HeadersResponse {
            headers: vec![encoded],
        })],
    );

    assert!(recv.wait().is_ok());
}

#[test]
fn request_without_response_should_backoff_and_then_be_dropped() {
    let harness = Harness::create();
    let peer_id = 0;
    let req_id = ReqId(13);

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let binary_exp_backoff: Vec<u64> = vec![1, 2, 4, 8, 16, 20, 20, 20, 20, 20];

    let _recv = harness
        .service
        .request_raw(
            &Context::RequestFrom(peer_id, req_id),
            vec![request::HeaderByHash(Header::default().encoded().hash().into()).into()],
        )
        .unwrap();
    assert_eq!(harness.service.pending.read().len(), 1);

    for backoff in &binary_exp_backoff {
        harness.service.dispatch_pending(&Context::FaultyRequest);
        assert_eq!(
            harness.service.pending.read().len(),
            1,
            "Request should not be dropped"
        );
        let now = Instant::now();
        while now.elapsed() < Duration::from_secs(*backoff) {}
    }

    harness.service.dispatch_pending(&Context::FaultyRequest);
    assert_eq!(
        harness.service.pending.read().len(),
        0,
        "Request exceeded the 10 backoff rounds should be dropped"
    );
}

#[test]
fn empty_responses_exceeds_limit_should_be_dropped() {
    let harness = Harness::create();
    let peer_id = 0;
    let req_id = ReqId(13);

    harness.inject_peer(
        peer_id,
        Peer {
            status: dummy_status(),
            capabilities: dummy_capabilities(),
        },
    );

    let _recv = harness
        .service
        .request_raw(
            &Context::RequestFrom(peer_id, req_id),
            vec![request::HeaderByHash(Header::default().encoded().hash().into()).into()],
        )
        .unwrap();

    harness
        .service
        .dispatch_pending(&Context::RequestFrom(peer_id, req_id));

    assert_eq!(harness.service.pending.read().len(), 0);
    assert_eq!(harness.service.in_transit.read().len(), 1);

    let now = Instant::now();

    // Send `empty responses` in the current time window
    // Use only half of the `time_window` because we can't be sure exactly
    // when the window started and the clock accurancy
    while now.elapsed() < harness.service.response_time_window / 2 {
        harness
            .service
            .on_responses(&Context::RequestFrom(13, req_id), req_id, &[]);
        assert!(harness.service.pending.read().len() != 0);
        let pending = harness.service.pending.write().remove(0);
        harness.service.in_transit.write().insert(req_id, pending);
    }

    // Make sure we passed the first `time window`
    thread::sleep(Duration::from_secs(5));

    // Now, response is in failure state but need another response to be `polled`
    harness
        .service
        .on_responses(&Context::RequestFrom(13, req_id), req_id, &[]);

    assert!(harness.service.in_transit.read().is_empty());
    assert!(harness.service.pending.read().is_empty());
}