module Churn
  class HgAnalyzer < SourceControl
    def get_logs
      `hg log -v#{date_range}`.split("\n").reject{|line| line !~ /^files:/}.map{|l| l.split(" ")[1..-1]}.flatten
    end

    def get_revisions
      `hg log#{date_range}`.split("\n").reject{|line| line !~ /^changeset:/}.map{|l| l[/:(\S+)$/, 1] }
    end

    def get_updated_files_from_log(revision, revisions)
      current_index = revisions.index(revision)
      previous_index = current_index+1
      previous_revision = revisions[previous_index] unless revisions.length < previous_index
      if revision && previous_revision
        `hg diff -r #{revision}:#{previous_revision} -U 0`.split(/\n/).select{|line| line.match(/^@@/) || line.match(/^---/) || line.match(/^\+\+\+/) }
      else
        []
      end
    end

    def get_updated_files_change_info(revision, revisions)
      updated     = {}
      logs        = get_updated_files_from_log(revision, revisions)
      recent_file = nil
      logs.each do |line|
        if line.match(/^---/) || line.match(/^\+\+\+/)
          # Remove the --- a/ and +++ b/ if present
          recent_file = get_recent_file(line)
          updated[recent_file] = [] unless updated.include?(recent_file)
        elsif line.match(/^@@/)
          # Now add the added/removed ranges for the line
          removed_range = get_changed_range(line, '-')
          added_range   = get_changed_range(line, '\+')
          updated[recent_file] << removed_range
          updated[recent_file] << added_range
        else
          puts line.match(/^---/)
          raise "hg diff lines that don't match the two patterns aren't expected: '#{line}'"
        end
      end
      updated
    end

  private
    def date_range
      if @start_date
        date = Chronic.parse(@start_date)
        " -d \"> #{date.strftime('%Y-%m-%d')}\""
      end
    end

    def get_recent_file(line)
      line = line.gsub(/^--- /,'').gsub(/^\+\+\+ /,'').gsub(/^a\//,'').gsub(/^b\//,'').split("\t")[0]
    end

    def get_changed_range(line, matcher)
      change_start = line.match(/#{matcher}[0-9]+/)
      change_end   = line.match(/#{matcher}[0-9]+,[0-9]+/)
      change_start = change_start.to_s.gsub(/#{matcher}/,'')
      change_end   = change_end.to_s.gsub(/.*,/,'')

      range  = if change_end && change_end!=''
                 (change_start.to_i..(change_start.to_i+change_end.to_i))
               else
                 (change_start.to_i..change_start.to_i)
               end
      range
    end
  end
end