102 lines
2.4 KiB
Ruby
102 lines
2.4 KiB
Ruby
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# frozen_string_literal: true
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require "json"
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require "net/http"
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require "provider/adapters/adapter"
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class Provider
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module Adapters
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# Hong Kong Monetary Authority. Publishes daily HKD exchange rates for 17
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# currencies via a public JSON API. Rates are expressed as HKD per 1 unit
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# of foreign currency (base = foreign currency, quote = HKD). Data is
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# published monthly with approximately a 1-month lag.
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# Historical data available from 1981-01-02.
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class HKMA < Adapter
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BASE_URL = "https://api.hkma.gov.hk/public/market-data-and-statistics/" \
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"monthly-statistical-bulletin/er-ir/er-eeri-daily"
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PAGE_SIZE = 100
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CURRENCY_FIELDS = [
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"usd",
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"eur",
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"gbp",
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"jpy",
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"cad",
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"aud",
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"sgd",
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"twd",
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"chf",
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"cny",
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"krw",
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"thb",
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"myr",
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"php",
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"inr",
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"idr",
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"zar",
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].freeze
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class << self
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def backfill_range = 365
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end
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def fetch(after: nil, upto: nil)
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end_date = upto || Date.today
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fetch_pages(after, end_date)
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end
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def parse(records)
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records.each_with_object([]) do |record, result|
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date_str = record["end_of_day"]
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next unless date_str
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date = Date.parse(date_str)
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CURRENCY_FIELDS.each do |field|
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rate_value = record[field]
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next unless rate_value.is_a?(Numeric) && rate_value.positive?
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result << { date:, base: field.upcase, quote: "HKD", rate: rate_value.to_f }
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end
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end
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end
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private
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def fetch_pages(start_date, end_date)
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raw_records = []
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offset = 0
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loop do
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page = fetch_page(start_date, end_date, offset)
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break if page.empty?
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raw_records.concat(page)
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break if page.size < PAGE_SIZE
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offset += PAGE_SIZE
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end
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parse(raw_records)
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end
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def fetch_page(start_date, end_date, offset)
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uri = URI(BASE_URL)
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uri.query = URI.encode_www_form(
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"choose" => "end_of_day",
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"from" => start_date.to_s,
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"to" => end_date.to_s,
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"pagesize" => PAGE_SIZE,
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"offset" => offset,
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"sortby" => "end_of_day",
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"sortorder" => "desc",
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)
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response = Net::HTTP.get(uri)
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data = JSON.parse(response)
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data.dig("result", "records") || []
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end
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end
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end
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end
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