module GitHubChangelogGenerator
  class Generator
    # A Generator responsible for all logic, related with change log generation from ready-to-parse issues
    #
    # Example:
    #   generator = GitHubChangelogGenerator::Generator.new
    #   content = generator.compound_changelog

    def initialize(options = nil)
      @options = options
    end

    # Parse issue and generate single line formatted issue line.
    #
    # Example output:
    # - Add coveralls integration [\#223](https://github.com/skywinder/github-changelog-generator/pull/223) ([skywinder](https://github.com/skywinder))
    #
    # @param [Hash] issue Fetched issue from GitHub
    # @return [String] Markdown-formatted single issue
    def get_string_for_issue(issue)
      encapsulated_title = encapsulate_string issue[:title]

      title_with_number = "#{encapsulated_title} [\\##{issue[:number]}](#{issue.html_url})"

      unless issue.pull_request.nil?
        if @options[:author]
          if issue.user.nil?
            title_with_number += " ({Null user})"
          else
            title_with_number += " ([#{issue.user.login}](#{issue.user.html_url}))"
          end
        end
      end
      title_with_number
    end

    # Encapsulate characters to make markdown look as expected.
    #
    # @param [String] string
    # @return [String] encapsulated input string
    def encapsulate_string(string)
      string.gsub! '\\', '\\\\'

      encpas_chars = %w(> * _ \( \) [ ] #)
      encpas_chars.each do |char|
        string.gsub! char, "\\#{char}"
      end

      string
    end

    # Main function to start change log generation
    #
    # @return [String] Generated change log file
    def compound_changelog
      log = "# Change Log\n\n"

      if @options[:unreleased_only]
        log += generate_log_between_tags(all_tags[0], nil)
      elsif @options[:tag1] and @options[:tag2]
        tag1 = @options[:tag1]
        tag2 = @options[:tag2]
        tags_strings = []
        all_tags.each { |x| tags_strings.push(x["name"]) }

        if tags_strings.include?(tag1)
          if tags_strings.include?(tag2)
            to_a = tags_strings.map.with_index.to_a
            hash = Hash[to_a]
            index1 = hash[tag1]
            index2 = hash[tag2]
            log += generate_log_between_tags(all_tags[index1], all_tags[index2])
          else
            fail ChangelogGeneratorError, "Can't find tag #{tag2} -> exit".red
          end
        else
          fail ChangelogGeneratorError, "Can't find tag #{tag1} -> exit".red
        end
      else
        log += generate_log_for_all_tags
      end

      log += "\n\n\\* *This Change Log was automatically generated by [github_changelog_generator](https://github.com/skywinder/Github-Changelog-Generator)*"
      @log = log
      @log = log
    end


    # The full cycle of generation for whole project
    # @return [String] The complete change log
    def generate_log_for_all_tags
      fetch_tags_dates

      if @options[:verbose]
        puts "Sorting tags..."
      end

      @all_tags.sort_by! { |x| @fetcher.get_time_of_tag(x) }.reverse!

      if @options[:verbose]
        puts "Generating log..."
      end

      log = ""

      if @options[:unreleased] && @all_tags.count != 0
        unreleased_log = generate_log_between_tags(all_tags[0], nil)
        if unreleased_log
          log += unreleased_log
        end
      end

      (1...all_tags.size).each { |index|
        log += generate_log_between_tags(all_tags[index], all_tags[index - 1])
      }
      if @all_tags.count != 0
        log += generate_log_between_tags(nil, all_tags.last)
      end

      log
    end


  end
end