require "apress/changelogger/version"

module Apress
  class ChangeLogger
    COMMIT_URL = '../../commit/'.freeze
    ISSUE_URL = '../../issues/'.freeze
    JIRA_URL = 'https://jira.railsc.ru/browse/'.freeze

    ISSUE_REGEXP = /[A-Z]+\-[0-9]+/
    JIRA_REGEXP = /(?:\s|^)([A-Z]+-[0-9]+)(?=\s|$)/

    GIT_LOG_CMD = %{git log --date=short --pretty=format:" * %ad [%h](#{COMMIT_URL}%h) - __(%an)__ %s"}.freeze
    EXCLUDE_MERGE = %{grep -v -E "Merge (branch|pull)"}.freeze

    # initialize
    #
    # @param [String] file_name with path
    def initialize(file_name = 'CHANGELOG.md', from = nil, to = nil)
      @file_name = file_name
      @tag_from = from
      @tag_to = to
    end

    def log_changes
      return unless git_repository?

      output = parse_change_log
      write_file output unless output.empty?
    end

    private

    def git_repository?
      initialized = `git rev-parse --is-inside-work-tree`.chomp

      if initialized != 'true'
        initialized = false
        puts 'Exiting. Nothing to create log file.'
      end
      initialized
    end

    def write_file(output)
      File.open(@file_name, 'w') do |file|
        file.puts(output)
      end
    end

    def parse_change_log
      output = []

      tags = `git for-each-ref --sort='*authordate' --format='%(tag)' refs/tags | grep -v '^$'#`

      tags = tags.split
      prev_begin = nil

      if (!@tag_from.nil? && !tags.include?(@tag_from)) || (!@tag_to.nil? && !tags.include?(@tag_to))
        show_not_found_message(tags)
        return output
      end

      if !@tag_from.nil? && !@tag_to.nil?
        from = tags.index(@tag_from)
        to = tags.index(@tag_to)
        tags = tags[from..to]
      elsif !@tag_from.nil?
        from = tags.index @tag_from
        prev_begin = tags[from - 1]
        tags = tags[from..-1]
      elsif !@tag_to.nil?
        to = tags.index @tag_to
        tags = tags[0..to]
      end

      tags.reverse!

      output << "\n#### [Current]" if @tag_to.nil?

      previous_tag = ''
      tags.each do |tag|
        current_tag = tag

        output << "\n#### #{previous_tag}" unless previous_tag.empty?

        if !previous_tag.empty? || @tag_to.nil?
          output << `#{GIT_LOG_CMD} "#{current_tag}".."#{previous_tag}" | #{EXCLUDE_MERGE}`
        end

        previous_tag = current_tag
      end

      output << "\n#### #{previous_tag}"

      if prev_begin.nil?
        output << `#{GIT_LOG_CMD} #{previous_tag} | #{EXCLUDE_MERGE}`
      else
        output << `#{GIT_LOG_CMD} "#{prev_begin}".."#{previous_tag}" | #{EXCLUDE_MERGE}`
      end

      output.each do |line|
        line.encode!('utf-8', 'utf-8', invalid: :replace, undef: :replace, replace: '')

        if line.index(ISSUE_REGEXP)
          line.gsub!(ISSUE_REGEXP) { |s| "[#{s}](#{ISSUE_URL}#{s[-(s.length - 1)..-1]})" }
        end

        if line.index(JIRA_REGEXP)
          line.gsub!(JIRA_REGEXP) { |s| "[#{s}](#{JIRA_URL}#{s[-(s.length - 1)..-1]})" }
        end
      end

      output
    end

    def show_not_found_message(tags)
      puts 'Could not find the given tags. Make sure that given tags exist.'
      puts 'Listing found tags:'
      puts tags
    end
  end
end