Account Issue Model and Resolution Flow + Troubleshooting guides (#1090)

* Rough draft of issue system

* Simplify design

* Remove stale files from merge conflicts

* STI for issues

* Cleanup

* Improve Synth api key flow

* Stub api key for test

app/models/issue/exchange_rate_provider_missing.rb

@@ -0,0 +1,9 @@
+class Issue::ExchangeRateProviderMissing < Issue
+  def default_severity
+    :error
+  end
+
+  def stale?
+    ExchangeRate.provider_healthy?
+  end
+end

app/models/issue/exchange_rates_missing.rb

@@ -0,0 +1,15 @@
+class Issue::ExchangeRatesMissing < Issue
+  store_accessor :data, :from_currency, :to_currency, :dates
+
+  validates :from_currency, :to_currency, :dates, presence: true
+
+  def stale?
+    if dates.length == 1
+      ExchangeRate.find_rate(from: from_currency, to: to_currency, date: dates.first).present?
+    else
+      sorted_dates = dates.sort
+      rates = ExchangeRate.find_rates(from: from_currency, to: to_currency, start_date: sorted_dates.first, end_date: sorted_dates.last)
+      rates.length == dates.length
+    end
+  end
+end

app/models/issue/prices_missing.rb

@@ -0,0 +1,22 @@
+class Issue::PricesMissing < Issue
+  store_accessor :data, :missing_prices
+
+  validates :missing_prices, presence: true
+
+  def append_missing_price(ticker, date)
+    missing_prices[ticker] ||= []
+    missing_prices[ticker] << date
+  end
+
+  def stale?
+    stale = true
+    missing_prices.each do |ticker, dates|
+      oldest_date = dates.min
+      expected_price_count = (oldest_date..Date.current).count
+      prices = Security::Price.find_prices(ticker: ticker, start_date: oldest_date)
+      stale = false if prices.count < expected_price_count
+    end
+
+    stale
+  end
+end

app/models/issue/unknown.rb

@@ -0,0 +1,11 @@
+class Issue::Unknown < Issue
+  def default_severity
+    :warning
+  end
+
+  # Unknown issues are always stale because we only want to show them
+  # to the user once.  If the same error occurs again, we'll create a new instance.
+  def stale?
+    true
+  end
+end