# frozen_string_literal: true

require "json"

class HowIs
  BaseReport = Struct.new(:analysis)

  ##
  # Subclasses of BaseReport represent complete reports.
  class BaseReport
    def generate_report_text!
      # title, text, header, horizontal_bar_graph, etc,
      # append to @r, which is returned at the end of the function.

      title "How is #{analysis.repository}?"

      # DateTime#new_offset(0) sets the timezone to UTC. I think it does this
      # without changing anything besides the timezone, but who knows, 'cause
      # new_offset is entirely undocumented! (Even though it's used in the
      # DateTime documentation!)
      #
      # TODO: Stop pretending everyone who runs how_is is in UTC.
      text "Monthly report, ending on #{DateTime.now.new_offset(0).strftime('%B %e, %Y')}."

      text analysis.pulse

      header "Pull Requests"
      issue_or_pr_summary "pull", "pull request"

      header "Issues"
      issue_or_pr_summary "issue", "issue"

      header "Issues Per Label"
      issues_per_label = analysis.issues_with_label.to_a.sort_by { |(_, v)| v["total"].to_i }.reverse
      issues_per_label.map! do |label, hash|
        [label, hash["total"], hash["link"]]
      end
      issues_per_label << ["(No label)", analysis.issues_with_no_label["total"], nil]
      horizontal_bar_graph issues_per_label

      # See comment at beginning of function.
      @r
    end

    # === Methods implemented by subclasses of BaseReport ===

    ##
    # Returns the format of report this class generates.
    #
    # @return [Symbol] A lowercase symbol denoting the report format.
    def format
      raise NotImplementedError
    end

    ##
    # Appends a title to the report.
    def title(_content)
      raise NotImplementedError
    end

    ##
    # Appends a header to the report.
    def header(_content)
      raise NotImplementedError
    end

    ##
    # Appends a line of text to the report.
    def text(_content)
      raise NotImplementedError
    end

    ##
    # Appends a link to the report.
    def link(_content, _url)
      raise NotImplementedError
    end

    ##
    # Appends an unordered list to the report.
    def unordered_list(_arr)
      raise NotImplementedError
    end

    ##
    # Appends a horizontal bar graph to the report.
    def horizontal_bar_graph(_data)
      raise NotImplementedError
    end

    ##
    # Exports the report as a String.
    def export
      raise NotImplementedError
    end

    ##
    # Exports a report to a file.
    #
    # NOTE: May be removed in the future.
    def export_file(_file)
      raise NotImplementedError
    end

    def to_h
      analysis.to_h
    end
    alias_method :to_hash, :to_h

    def to_json
      JSON.pretty_generate(to_h)
    end

    private

    def pluralize(text, number)
      (number == 1) ? text : "#{text}s"
    end

    def are_is(number)
      (number == 1) ? "is" : "are"
    end

    def issue_or_pr_summary(type, type_label)
      date_format = "%b %e, %Y"
      a = analysis

      number_of_type = a.public_send("number_of_#{type}s")

      type_link = a.public_send("#{type}s_url")
      oldest = a.public_send("oldest_#{type}")
      newest = a.public_send("newest_#{type}")

      if number_of_type.zero?
        text "There are #{link("no #{type_label}s open", type_link)}."
      else
        text "There #{are_is(number_of_type)} #{link("#{number_of_type} "\
          "#{pluralize(type_label, number_of_type)} open", type_link)}."

        unordered_list [
          "Average age: #{a.public_send("average_#{type}_age")}.",
          "#{link('Oldest ' + type_label, oldest['html_url'])} was opened on #{oldest['date'].strftime(date_format)}.",
          "#{link('Newest ' + type_label, newest['html_url'])} was opened on #{newest['date'].strftime(date_format)}.",
        ]
      end
    end
  end
end