nym/explorer-nextjs/app/context/delegations.tsx

'use client'

import React, {
  createContext,
  useCallback,
  useContext,
  useMemo,
  useState,
} from 'react'
import {
  Delegation,
  PendingEpochEvent,
  PendingEpochEventKind,
} from '@nymproject/contract-clients/Mixnet.types'
import { ExecuteResult } from '@cosmjs/cosmwasm-stargate'
import { useWalletContext } from './wallet'
import { useMainContext } from './main'

const fee = { gas: '1000000', amount: [{ amount: '1000000', denom: 'unym' }] }

export type PendingEvent = ReturnType<typeof getEventsByAddress>

export type DelegationWithRewards = Delegation & {
  rewards: string
  identityKey: string
  pending: PendingEvent
}

const getEventsByAddress = (kind: PendingEpochEventKind, address: String) => {
  if ('delegate' in kind && kind.delegate.owner === address) {
    return {
      kind: 'delegate' as const,
      mixId: kind.delegate.mix_id,
      amount: kind.delegate.amount,
    }
  }

  if ('undelegate' in kind && kind.undelegate.owner === address) {
    return {
      kind: 'undelegate' as const,
      mixId: kind.undelegate.mix_id,
    }
  }

  return undefined
}

interface DelegationsState {
  delegations?: DelegationWithRewards[]
  handleGetDelegations: () => Promise<void>
  handleDelegate: (
    mixId: number,
    amount: string
  ) => Promise<ExecuteResult | undefined>
  handleUndelegate: (mixId: number) => Promise<ExecuteResult | undefined>
}

export const DelegationsContext = createContext<DelegationsState>({
  delegations: undefined,
  handleGetDelegations: async () => {
    throw new Error('Please connect your wallet')
  },
  handleDelegate: async () => {
    throw new Error('Please connect your wallet')
  },
  handleUndelegate: async () => {
    throw new Error('Please connect your wallet')
  },
})

export const DelegationsProvider = ({
  children,
}: {
  children: React.ReactNode
}) => {
  const [delegations, setDelegations] = useState<DelegationWithRewards[]>()
  const { address, nymQueryClient, nymClient } = useWalletContext()
  const { fetchMixnodes } = useMainContext()

  const handleGetPendingEvents = async () => {
    if (!nymQueryClient) {
      return undefined
    }

    if (!address) {
      return undefined
    }

    const response = await nymQueryClient.getPendingEpochEvents({})
    const pendingEvents: PendingEvent[] = []

    response.events.forEach((e: PendingEpochEvent) => {
      const event = getEventsByAddress(e.event.kind, address)
      if (event) {
        pendingEvents.push(event)
      }
    })

    return pendingEvents
  }

  const handleGetDelegationRewards = async (mixId: number) => {
    if (!nymQueryClient) {
      return undefined
    }

    if (!address) {
      return undefined
    }

    const response = await nymQueryClient.getPendingDelegatorReward({
      address,
      mixId,
    })

    return response
  }

  const handleGetDelegations = useCallback(async () => {
    if (!nymQueryClient) {
      setDelegations(undefined)
      return undefined
    }

    if (!address) {
      setDelegations(undefined)
      return undefined
    }

    // Get all mixnodes - Required to get the identity key for each delegation
    const mixnodes = await fetchMixnodes()

    // Get delegations
    const delegationsResponse = await nymQueryClient.getDelegatorDelegations({
      delegator: address,
    })

    // Get rewards for each delegation
    const rewardsResponse = await Promise.all(
      delegationsResponse.delegations.map((d: Delegation) =>
        handleGetDelegationRewards(d.mix_id)
      )
    )

    // Get all pending events
    const pendingEvents = await handleGetPendingEvents()

    const delegationsWithRewards: DelegationWithRewards[] = []

    // Merge delegations with rewards and pending events
    delegationsResponse.delegations.forEach((d: Delegation, index: number) => {
      delegationsWithRewards.push({
        ...d,
        pending: pendingEvents?.find((e: PendingEvent) =>
          e?.mixId === d.mix_id ? e.kind : undefined
        ),
        identityKey:
          mixnodes?.find((m) => m.mix_id === d.mix_id)?.mix_node.identity_key ||
          '',
        rewards: rewardsResponse[index]?.amount_earned_detailed || '0',
      })
    })

    // Add pending events that are not in the delegations list
    pendingEvents?.forEach((e) => {
      if (
        e &&
        !delegationsWithRewards.find(
          (d: DelegationWithRewards) => d.mix_id === e.mixId
        )
      ) {
        delegationsWithRewards.push({
          mix_id: e.mixId,
          height: 0,
          cumulative_reward_ratio: '0',
          owner: address,
          amount: {
            amount: '0',
            denom: 'unym',
          },
          rewards: '0',
          identityKey:
            mixnodes?.find((m) => m.mix_id === e.mixId)?.mix_node
              .identity_key || '',
          pending: e,
        })
      }
    })

    setDelegations(delegationsWithRewards)

    return undefined
  }, [address, nymQueryClient])

  const handleDelegate = async (mixId: number, amount: string) => {
    if (!address) {
      throw new Error('Please connect your wallet')
    }

    const amountToDelegate = (Number(amount) * 1000000).toString()
    const uNymFunds = [{ amount: amountToDelegate, denom: 'unym' }]
    try {
      const tx = await nymClient?.delegateToMixnode(
        { mixId },
        fee,
        'Delegation from Nym Explorer',
        uNymFunds
      )

      return tx as unknown as ExecuteResult
    } catch (e) {
      console.error('Failed to delegate to mixnode', e)
      throw e
    }
  }

  const handleUndelegate = async (mixId: number) => {
    const tx = await nymClient?.undelegateFromMixnode(
      { mixId },
      fee,
      'Undelegation from Nym Explorer'
    )

    return tx as unknown as ExecuteResult
  }

  const contextValue: DelegationsState = useMemo(
    () => ({
      delegations,
      handleGetDelegations,
      handleDelegate,
      handleUndelegate,
    }),
    [delegations, handleGetDelegations]
  )

  return (
    <DelegationsContext.Provider value={contextValue}>
      {children}
    </DelegationsContext.Provider>
  )
}

export const useDelegationsContext = () => {
  const context = useContext(DelegationsContext)
  if (!context) {
    throw new Error(
      'useDelegationsContext must be used within a DelegationsProvider'
    )
  }
  return context
}