class RSpec::Rails::Matchers::SendEmail

def define_matched_emails(block)
  before = deliveries.dup
  block.call
  after = deliveries
  @diff = after - before
  @matched_emails = @diff.select(&method(:matched_email?))
end

def deliveries
  ActionMailer::Base.deliveries
end

def diffable?
  true
end

def failure_message
  result =
    if multiple_match?
      "More than 1 matching emails were sent."
    else
      "No matching emails were sent."
    end
  "#{result}#{sent_emails_message}"
end

def failure_message_when_negated
  "Expected not to send an email but it was sent."
end

def initialize(criteria)
  @criteria = criteria
end

def matched_email?(email)
  @criteria.all? do |attr, value|
    expected =
      case attr
      when :to, :from, :cc, :bcc then Array(value)
      else
        value
      end
    values_match?(expected, email.public_send(attr))
  end
end

def matches?(block)
  define_matched_emails(block)
  @matched_emails.one?
end

def multiple_match?
  @matched_emails.many?
end

def sent_emails_message
  if @diff.empty?
    "\n\nThere were no any emails sent inside the expectation block."
  else
    sent_emails =
      @diff.map do |email|
        inspected = INSPECT_EMAIL_ATTRIBUTES.map { |attr| "#{attr}: #{email.public_send(attr)}" }.join(", ")
        "- #{inspected}"
      end.join("\n")
    "\n\nThe following emails were sent:\n#{sent_emails}"
  end
end

def supports_block_expectations?
  true
end

def supports_value_expectations?
  false
end