feat: add estimated_apc to dao contract

app/models/dao_contract.rb

@@ -1,6 +1,13 @@
 class DaoContract < ApplicationRecord
   validates :total_deposit, :interest_granted, :deposit_transactions_count, :withdraw_transactions_count, :depositors_count, :total_depositors_count, presence: true, numericality: { greater_than_or_equal_to: 0 }
   CONTRACT_NAME = "nervos_dao".freeze
+  GENESIS_ISSUANCE = 336 * 10**8
+  ANNUAL_PRIMARY_ISSUANCE_BASE = GENESIS_ISSUANCE / 8
+  PRIMARY_ISSUANCE_PER_YEAR_BASE = BigDecimal(42 * 10**8)
+  EPOCHS_IN_ONE_NATURAL_YEAR = 2190
+  YEARS_IN_PERIOD = 4
+  EPOCHS_IN_PERIOD = BigDecimal(EPOCHS_IN_ONE_NATURAL_YEAR * YEARS_IN_PERIOD)
+  SECONDARY_ISSUANCE_PER_EPOCH = BigDecimal(1344 * 10**6) / 2190
 
   def self.default_contract
     find_or_create_by(id: 1)
@@ -10,6 +17,57 @@ def ckb_transactions
     ckb_transaction_ids = CellOutput.nervos_dao_deposit.pluck("generated_by_id") + CellOutput.nervos_dao_withdrawing.pluck("generated_by_id") + CellOutput.nervos_dao_withdrawing.pluck("consumed_by_id").compact
     CkbTransaction.where(id: ckb_transaction_ids.uniq)
   end
+
+  def estimated_apc(deposit_epoch, deposited_epochs = EPOCHS_IN_ONE_NATURAL_YEAR)
+    start_epoch_number = deposit_epoch.number
+    end_epoch_number = start_epoch_number + deposited_epochs - 1
+    checkpoint_start =(start_epoch_number / EPOCHS_IN_PERIOD).ceil * EPOCHS_IN_PERIOD
+    checkpoint_end = (end_epoch_number / EPOCHS_IN_PERIOD).floor * EPOCHS_IN_PERIOD
+    checkpoints_size = (checkpoint_end - checkpoint_start) / EPOCHS_IN_PERIOD + 1
+    checkpoints = checkpoints_size.to_i.times.map { |index| (index * EPOCHS_IN_PERIOD + checkpoint_start - 1).to_i }
+
+    checkpoints.unshift(start_epoch_number.to_i) if checkpoints.empty? || checkpoints[0] > start_epoch_number
+    checkpoints.push(end_epoch_number.to_i) if checkpoints.last < end_epoch_number
+    end_epoch_numbers = checkpoints[1..-1]
+    rates = end_epoch_numbers.each_with_index.map do |inner_end_epoch_number, index|
+      epoch_index = deposit_epoch.index * 1800 / deposit_epoch.length
+      start_epoch = OpenStruct.new(number: checkpoints[index], index: epoch_index, length: 1800)
+      end_epoch = OpenStruct.new(number: inner_end_epoch_number, index: epoch_index, length: 1800)
+      rate(start_epoch, end_epoch)
+    end
+
+    rates.reduce(1) { |memo, rate| memo * (1 + rate) } - 1
+  end
+
+  private
+
+  def alpha(start_epoch_number)
+    i = ((start_epoch_number + 1) / EPOCHS_IN_PERIOD).floor
+    p = PRIMARY_ISSUANCE_PER_YEAR_BASE / 2 ** i / 2190
+    p / SECONDARY_ISSUANCE_PER_EPOCH
+  end
+
+  def rate(start_epoch, end_epoch)
+    alpha = alpha(start_epoch.number)
+    sn = SECONDARY_ISSUANCE_PER_EPOCH * ((end_epoch.number + end_epoch.index / end_epoch.length) - (start_epoch.number + start_epoch.index / start_epoch.length))
+    Math.log(1 + (alpha + 1) * sn / total_issuance(start_epoch)) / (alpha + 1)
+  end
+
+  def total_issuance(start_epoch)
+    primary_issuance(start_epoch) + secondary_issuance(start_epoch)
+  end
+
+  def primary_issuance(start_epoch)
+    epochs = (start_epoch.number / EPOCHS_IN_PERIOD).floor
+    epochs.times.reduce(GENESIS_ISSUANCE) { |memo, item| memo + (ANNUAL_PRIMARY_ISSUANCE_BASE * YEARS_IN_PERIOD) / 2 ** item } \
+      + (ANNUAL_PRIMARY_ISSUANCE_BASE * ((start_epoch.number + 1 - epochs * EPOCHS_IN_PERIOD) / EPOCHS_IN_ONE_NATURAL_YEAR)) / 2 ** epochs
+  end
+
+  def secondary_issuance(start_epoch)
+    deposit_fraction = start_epoch.number + (start_epoch.index / start_epoch.length)
+    epochs = deposit_fraction > 0 ? (deposit_fraction + 1) : deposit_fraction
+    epochs * SECONDARY_ISSUANCE_PER_EPOCH
+  end
 end
 
 # == Schema Information

app/workers/charts/daily_statistic.rb

@@ -5,7 +5,7 @@ class DailyStatistic
     sidekiq_options retry: false
     sidekiq_options queue: "critical"
 
-    MILLISECONDS_IN_DAY = BigDecimal.new(24 * 60 * 60 * 1000)
+    MILLISECONDS_IN_DAY = BigDecimal(24 * 60 * 60 * 1000)
 
     def perform(datetime = nil)
       to_be_counted_date = datetime.presence || DateTime.now - 1.day