# Attention: expects @query to be set (with a Chiliproject Query Object)
module IssueListSumsHelper

  # Duplicate code from IssueController#index action, retrieves all issues for a query
  def all_issues
    @all_issues ||= @query.issues(:include => [:assigned_to, :tracker, :priority, :category, :fixed_version],
                                  :order   => sort_clause)
  end

  def next_in_same_group?(issue = cached_issue)
    caching_issue issue do |issue|
      !last_issue? && @query.group_by_column.value(issue) == @query.group_by_column.value(all_issues[issue_index + 1])
    end
  end

  def last_issue?(issue = cached_issue)
    caching_issue issue do |issue|
      issue_index == all_issues.size - 1
    end
  end

  def issue_index(issue = cached_issue)
    caching_issue issue do |issue|
      all_issues.find_index(issue)
    end
  end

  def grouped_sum_of(column, issue = cached_issue)
    sum_of(column, group_for_issue(issue))
  end

  def total_sum_of(column)
    sum_of(column, all_issues)
  end

  def sum_of(column, collection)
    return unless should_be_summed_up?(column)

    # This is a workaround to be able to sum up currency with the redmine_costs plugin
    values = collection.map { |issue| column.respond_to?(:real_value) ? column.real_value(issue) : column.value(issue) }.select do |value|
      begin
        next if value.respond_to? :today? or value.is_a? String
        true if Float(value)
      rescue ArgumentError, TypeError
        false
      end
    end
    crunch(values.reduce :+)
  end

  def caching_issue(issue)
    @cached_issue = issue unless @cached_issue == issue
    block_given? ? yield(issue) : issue
  end

  def cached_issue
    @cached_issue
  end

  def mapping_for(column)
    if column.respond_to? :real_value
      method(:number_to_currency)
    else
      # respond_to? :call, but do nothing
      @nilproc ||= Proc.new { |val| val }
    end
  end

  def crunch(num)
    return num if num.nil? or num.integer?
    Float(format "%.2f", num.to_f)
  end

  def group_for_issue(issue = @current_issue)
    caching_issue issue do |issue|
      all_issues.select do |is|
        @query.group_by_column.value(issue) == @query.group_by_column.value(is)
      end
    end
  end

  def display_sums?
    @query.display_sums? && any_summable_columns?
  end

  def should_be_summed_up?(column)
    Setting.issue_list_summable_columns.include?(column.name.to_s)
  end

  def any_summable_columns?
    Setting.issue_list_summable_columns.any?
  end
end