import {
  defaultTopicScoreParams,
  PeerScoreParams,
  TopicScoreParams,
  PeerScoreThresholds,
} from "@chainsafe/libp2p-gossipsub/score";
import {computeCommitteeCount} from "@lodestar/state-transition";
import {IBeaconConfig} from "@lodestar/config";
import {ATTESTATION_SUBNET_COUNT, SLOTS_PER_EPOCH, TARGET_AGGREGATORS_PER_COMMITTEE} from "@lodestar/params";
import {Eth2Context} from "../../chain/index.js";
import {getActiveForks} from "../forks.js";
import {Eth2GossipsubModules} from "./gossipsub.js";
import {GossipType} from "./interface.js";
import {stringifyGossipTopic} from "./topic.js";

/* eslint-disable @typescript-eslint/naming-convention */

export const GOSSIP_D = 8;
export const GOSSIP_D_LOW = 6;
export const GOSSIP_D_HIGH = 12;

const MAX_IN_MESH_SCORE = 10.0;
const MAX_FIRST_MESSAGE_DELIVERIES_SCORE = 40.0;
const BEACON_BLOCK_WEIGHT = 0.5;
const BEACON_AGGREGATE_PROOF_WEIGHT = 0.5;
const VOLUNTARY_EXIT_WEIGHT = 0.05;
const PROPOSER_SLASHING_WEIGHT = 0.05;
const ATTESTER_SLASHING_WEIGHT = 0.05;
const BLS_TO_EXECUTION_CHANGE_WEIGHT = 0.05;

const beaconAttestationSubnetWeight = 1 / ATTESTATION_SUBNET_COUNT;
const maxPositiveScore =
  (MAX_IN_MESH_SCORE + MAX_FIRST_MESSAGE_DELIVERIES_SCORE) *
  (BEACON_BLOCK_WEIGHT +
    +BEACON_AGGREGATE_PROOF_WEIGHT +
    beaconAttestationSubnetWeight * ATTESTATION_SUBNET_COUNT +
    VOLUNTARY_EXIT_WEIGHT +
    PROPOSER_SLASHING_WEIGHT +
    ATTESTER_SLASHING_WEIGHT +
    BLS_TO_EXECUTION_CHANGE_WEIGHT);

/**
 * The following params is implemented by Lighthouse at
 * https://github.com/sigp/lighthouse/blob/b0ac3464ca5fb1e9d75060b56c83bfaf990a3d25/beacon_node/eth2_libp2p/src/behaviour/gossipsub_scoring_parameters.rs#L83
 */
export const gossipScoreThresholds: PeerScoreThresholds = {
  gossipThreshold: -4000,
  publishThreshold: -8000,
  graylistThreshold: -16000,
  acceptPXThreshold: 100,
  opportunisticGraftThreshold: 5,
};

/**
 * Peer may sometimes has negative gossipsub score and we give it time to recover, however gossipsub score comes below this we need to take into account.
 * Given gossipsubThresold = -4000, it's comfortable to only ignore negative score gossip peer score > -1000
 */
export const negativeGossipScoreIgnoreThreshold = -1000;

type MeshMessageInfo = {
  decaySlots: number;
  capFactor: number;
  activationWindow: number;
  currentSlot: number;
};

type PreComputedParams = {
  scoreParameterDecayFn: (decayTimeMs: number) => number;
  epochDurationMs: number;
  slotDurationMs: number;
};

type TopicScoreInput = {
  topicWeight: number;
  expectedMessageRate: number;
  firstMessageDecayTime: number;
  meshMessageInfo?: MeshMessageInfo;
};

/**
 * Explanation of each param https://github.com/libp2p/specs/blob/master/pubsub/gossipsub/gossipsub-v1.1.md#peer-scoring
 */
export function computeGossipPeerScoreParams({
  config,
  eth2Context,
}: Pick<Eth2GossipsubModules, "config" | "eth2Context">): Partial<PeerScoreParams> {
  const decayIntervalMs = config.SECONDS_PER_SLOT * 1000;
  const decayToZero = 0.01;
  const epochDurationMs = config.SECONDS_PER_SLOT * SLOTS_PER_EPOCH * 1000;
  const slotDurationMs = config.SECONDS_PER_SLOT * 1000;
  const scoreParameterDecayFn = (decayTimeMs: number): number => {
    return scoreParameterDecayWithBase(decayTimeMs, decayIntervalMs, decayToZero);
  };
  const behaviourPenaltyDecay = scoreParameterDecayFn(epochDurationMs * 10);
  const behaviourPenaltyThreshold = 6;
  const targetValue = decayConvergence(behaviourPenaltyDecay, 10 / SLOTS_PER_EPOCH) - behaviourPenaltyThreshold;
  const topicScoreCap = maxPositiveScore * 0.5;

  const params = {
    topics: getAllTopicsScoreParams(config, eth2Context, {
      epochDurationMs,
      slotDurationMs,
      scoreParameterDecayFn,
    }),
    decayInterval: decayIntervalMs,
    decayToZero,
    // time to remember counters for a disconnected peer, should be in ms
    retainScore: epochDurationMs * 100,
    appSpecificWeight: 1,
    IPColocationFactorThreshold: 3,
    // js-gossipsub doesn't have behaviourPenaltiesThreshold
    behaviourPenaltyDecay,
    behaviourPenaltyWeight: gossipScoreThresholds.gossipThreshold / (targetValue * targetValue),
    behaviourPenaltyThreshold,
    topicScoreCap,
    IPColocationFactorWeight: -1 * topicScoreCap,
  };
  return params;
}

function getAllTopicsScoreParams(
  config: IBeaconConfig,
  eth2Context: Eth2Context,
  precomputedParams: PreComputedParams
): Record<string, TopicScoreParams> {
  const {epochDurationMs, slotDurationMs} = precomputedParams;
  const epoch = eth2Context.currentEpoch;
  const topicsParams: Record<string, TopicScoreParams> = {};
  const forks = getActiveForks(config, epoch);
  const beaconAttestationSubnetWeight = 1 / ATTESTATION_SUBNET_COUNT;
  for (const fork of forks) {
    //first all fixed topics
    topicsParams[
      stringifyGossipTopic(config, {
        type: GossipType.voluntary_exit,
        fork,
      })
    ] = getTopicScoreParams(config, precomputedParams, {
      topicWeight: VOLUNTARY_EXIT_WEIGHT,
      expectedMessageRate: 4 / SLOTS_PER_EPOCH,
      firstMessageDecayTime: epochDurationMs * 100,
    });

    topicsParams[
      stringifyGossipTopic(config, {
        type: GossipType.bls_to_execution_change,
        fork,
      })
    ] = getTopicScoreParams(config, precomputedParams, {
      topicWeight: BLS_TO_EXECUTION_CHANGE_WEIGHT,
      expectedMessageRate: 4 / SLOTS_PER_EPOCH,
      firstMessageDecayTime: epochDurationMs * 100,
    });

    topicsParams[
      stringifyGossipTopic(config, {
        type: GossipType.attester_slashing,
        fork,
      })
    ] = getTopicScoreParams(config, precomputedParams, {
      topicWeight: ATTESTER_SLASHING_WEIGHT,
      expectedMessageRate: 1 / 5 / SLOTS_PER_EPOCH,
      firstMessageDecayTime: epochDurationMs * 100,
    });
    topicsParams[
      stringifyGossipTopic(config, {
        type: GossipType.proposer_slashing,
        fork,
      })
    ] = getTopicScoreParams(config, precomputedParams, {
      topicWeight: PROPOSER_SLASHING_WEIGHT,
      expectedMessageRate: 1 / 5 / SLOTS_PER_EPOCH,
      firstMessageDecayTime: epochDurationMs * 100,
    });

    // other topics
    topicsParams[
      stringifyGossipTopic(config, {
        type: GossipType.beacon_block,
        fork,
      })
    ] = getTopicScoreParams(config, precomputedParams, {
      topicWeight: BEACON_BLOCK_WEIGHT,
      expectedMessageRate: 1,
      firstMessageDecayTime: epochDurationMs * 20,
      meshMessageInfo: {
        decaySlots: SLOTS_PER_EPOCH * 5,
        capFactor: 3,
        activationWindow: epochDurationMs,
        currentSlot: eth2Context.currentSlot,
      },
    });

    const activeValidatorCount = eth2Context.activeValidatorCount;
    const {aggregatorsPerslot, committeesPerSlot} = expectedAggregatorCountPerSlot(activeValidatorCount);

    // Checks to prevent unwanted errors in gossipsub
    // Error: invalid score parameters for topic /eth2/4a26c58b/beacon_attestation_0/ssz_snappy: invalid FirstMessageDeliveriesCap; must be positive
    //   at Object.validatePeerScoreParams (/usr/app/node_modules/libp2p-gossipsub/src/score/peer-score-params.js:62:27)
    if (activeValidatorCount === 0) throw Error("activeValidatorCount === 0");
    if (aggregatorsPerslot === 0) throw Error("aggregatorsPerslot === 0");

    const multipleBurstsPerSubnetPerEpoch = committeesPerSlot >= (2 * ATTESTATION_SUBNET_COUNT) / SLOTS_PER_EPOCH;
    topicsParams[
      stringifyGossipTopic(config, {
        type: GossipType.beacon_aggregate_and_proof,
        fork,
      })
    ] = getTopicScoreParams(config, precomputedParams, {
      topicWeight: BEACON_AGGREGATE_PROOF_WEIGHT,
      expectedMessageRate: aggregatorsPerslot,
      firstMessageDecayTime: epochDurationMs,
      meshMessageInfo: {
        decaySlots: SLOTS_PER_EPOCH * 2,
        capFactor: 4,
        activationWindow: epochDurationMs,
        currentSlot: eth2Context.currentSlot,
      },
    });

    const beaconAttestationParams = getTopicScoreParams(config, precomputedParams, {
      topicWeight: beaconAttestationSubnetWeight,
      expectedMessageRate: activeValidatorCount / ATTESTATION_SUBNET_COUNT / SLOTS_PER_EPOCH,
      firstMessageDecayTime: multipleBurstsPerSubnetPerEpoch ? epochDurationMs : epochDurationMs * 4,
      meshMessageInfo: {
        decaySlots: multipleBurstsPerSubnetPerEpoch ? SLOTS_PER_EPOCH * 4 : SLOTS_PER_EPOCH * 16,
        capFactor: 16,
        activationWindow: multipleBurstsPerSubnetPerEpoch
          ? slotDurationMs * (SLOTS_PER_EPOCH / 2 + 1)
          : epochDurationMs,
        currentSlot: eth2Context.currentSlot,
      },
    });
    for (let subnet = 0; subnet < ATTESTATION_SUBNET_COUNT; subnet++) {
      const topicStr = stringifyGossipTopic(config, {
        type: GossipType.beacon_attestation,
        fork,
        subnet,
      });
      topicsParams[topicStr] = beaconAttestationParams;
    }
  }
  return topicsParams;
}

function getTopicScoreParams(
  config: IBeaconConfig,
  {epochDurationMs, slotDurationMs, scoreParameterDecayFn}: PreComputedParams,
  {topicWeight, expectedMessageRate, firstMessageDecayTime, meshMessageInfo}: TopicScoreInput
): TopicScoreParams {
  const params = {...defaultTopicScoreParams};

  params.topicWeight = topicWeight;

  params.timeInMeshQuantum = slotDurationMs;
  params.timeInMeshCap = 3600 / (params.timeInMeshQuantum / 1000);
  params.timeInMeshWeight = 10 / params.timeInMeshCap;

  params.firstMessageDeliveriesDecay = scoreParameterDecayFn(firstMessageDecayTime);
  params.firstMessageDeliveriesCap = decayConvergence(
    params.firstMessageDeliveriesDecay,
    (2 * expectedMessageRate) / GOSSIP_D
  );
  params.firstMessageDeliveriesWeight = 40 / params.firstMessageDeliveriesCap;

  if (meshMessageInfo) {
    const {decaySlots, capFactor, activationWindow, currentSlot} = meshMessageInfo;
    const decayTimeMs = config.SECONDS_PER_SLOT * decaySlots * 1000;
    params.meshMessageDeliveriesDecay = scoreParameterDecayFn(decayTimeMs);
    params.meshMessageDeliveriesThreshold = threshold(params.meshMessageDeliveriesDecay, expectedMessageRate / 50);
    params.meshMessageDeliveriesCap = Math.max(capFactor * params.meshMessageDeliveriesThreshold, 2);
    params.meshMessageDeliveriesActivation = activationWindow;
    // the default in gossipsub is 2s is not enough since lodestar suffers from I/O lag
    params.meshMessageDeliveriesWindow = 12 * 1000; // 12s
    params.meshFailurePenaltyDecay = params.meshMessageDeliveriesDecay;
    params.meshMessageDeliveriesWeight =
      (-1 * maxPositiveScore) / (params.topicWeight * Math.pow(params.meshMessageDeliveriesThreshold, 2));
    params.meshFailurePenaltyWeight = params.meshMessageDeliveriesWeight;
    if (decaySlots >= currentSlot) {
      params.meshMessageDeliveriesThreshold = 0;
      params.meshMessageDeliveriesWeight = 0;
    }
  } else {
    params.meshMessageDeliveriesWeight = 0;
    params.meshMessageDeliveriesThreshold = 0;
    params.meshMessageDeliveriesDecay = 0;
    params.meshMessageDeliveriesCap = 0;
    params.meshMessageDeliveriesWindow = 0;
    params.meshMessageDeliveriesActivation = 0;
    params.meshFailurePenaltyDecay = 0;
    params.meshFailurePenaltyWeight = 0;
  }
  params.invalidMessageDeliveriesWeight = (-1 * maxPositiveScore) / params.topicWeight;
  params.invalidMessageDeliveriesDecay = scoreParameterDecayFn(epochDurationMs * 50);
  return params;
}

function scoreParameterDecayWithBase(decayTimeMs: number, decayIntervalMs: number, decayToZero: number): number {
  const ticks = decayTimeMs / decayIntervalMs;
  return Math.pow(decayToZero, 1 / ticks);
}

function expectedAggregatorCountPerSlot(
  activeValidatorCount: number
): {
  aggregatorsPerslot: number;
  committeesPerSlot: number;
} {
  const committeesPerSlot = computeCommitteeCount(activeValidatorCount);
  const committeesPerEpoch = committeesPerSlot * SLOTS_PER_EPOCH;
  const smallerCommitteeSize = Math.floor(activeValidatorCount / committeesPerEpoch);
  const largerCommiteeeSize = smallerCommitteeSize + 1;
  const largeCommitteesPerEpoch = activeValidatorCount - smallerCommitteeSize * committeesPerEpoch;
  const smallCommiteesPerEpoch = committeesPerEpoch - largeCommitteesPerEpoch;
  const moduloSmaller = Math.max(1, Math.floor(smallerCommitteeSize / TARGET_AGGREGATORS_PER_COMMITTEE));
  const moduloLarger = Math.max(1, Math.floor((smallerCommitteeSize + 1) / TARGET_AGGREGATORS_PER_COMMITTEE));
  const smallCommitteeAggregatorPerEpoch = Math.floor((smallerCommitteeSize / moduloSmaller) * smallCommiteesPerEpoch);
  const largeCommitteeAggregatorPerEpoch = Math.floor((largerCommiteeeSize / moduloLarger) * largeCommitteesPerEpoch);

  return {
    aggregatorsPerslot: Math.max(
      1,
      Math.floor((smallCommitteeAggregatorPerEpoch + largeCommitteeAggregatorPerEpoch) / SLOTS_PER_EPOCH)
    ),
    committeesPerSlot,
  };
}

function threshold(decay: number, rate: number): number {
  return decayConvergence(decay, rate) * decay;
}

function decayConvergence(decay: number, rate: number): number {
  return rate / (1 - decay);
}