discourse/lib/onebox/mixins/git_blob_onebox.rb

# frozen_string_literal: true

module Onebox
  module Mixins
    module GitBlobOnebox
      def self.included(klass)
        klass.include(Onebox::Engine)
        klass.include(Onebox::LayoutSupport)
        klass.matches_regexp(klass.git_regexp)
        klass.always_https
        klass.include(InstanceMethods)
      end

      EXPAND_AFTER = 0b001
      EXPAND_BEFORE = 0b010
      EXPAND_NONE = 0b0

      DEFAULTS = {
        EXPAND_ONE_LINER: EXPAND_AFTER | EXPAND_BEFORE, #set how to expand a one liner. user EXPAND_NONE to disable expand
        LINES_BEFORE: 10,
        LINES_AFTER: 10,
        SHOW_LINE_NUMBER: true,
        MAX_LINES: 20,
        MAX_CHARS: 5000
      }

      module InstanceMethods
        def initialize(url, timeout = nil)
          super url, timeout
          # merge engine options from global Onebox.options interface
          # self.options = Onebox.options["GithubBlobOnebox"] #  self.class.name.split("::").last.to_s
          # self.options = Onebox.options[self.class.name.split("::").last.to_s] #We can use this a more generic approach. extract the engine class name automatically

          self.options = DEFAULTS

          @selected_lines_array = nil
          @selected_one_liner = 0
          @model_file = nil

          # Define constant after merging options set in Onebox.options
          # We can define constant automatically.
          options.each_pair do |constant_name, value|
            constant_name_u = constant_name.to_s.upcase
            if constant_name_u == constant_name.to_s
              #define a constant if not already defined
              unless self.class.const_defined? constant_name_u.to_sym
                Onebox::Mixins::GitBlobOnebox.const_set constant_name_u.to_sym , options[constant_name_u.to_sym]
              end
            end
          end
        end

        private

        def calc_range(m, contents_lines_size)
          truncated = false
          from = /\d+/.match(m[:from])             #get numeric should only match a positive interger
          to   = /\d+/.match(m[:to])               #get numeric should only match a positive interger
          range_provided = !(from.nil? && to.nil?) #true if "from" or "to" provided in URL
          from = from.nil? ?  1 : from[0].to_i     #if from not provided default to 1st line
          to   = to.nil?   ? -1 : to[0].to_i       #if to not provided default to undefiend to be handled later in the logic

          if to === -1 && range_provided   #case "from" exists but no valid "to". aka ONE_LINER
            one_liner = true
            to = from
          else
            one_liner = false
          end

          unless range_provided  #case no range provided default to 1..MAX_LINES
            from = 1
            to   = MAX_LINES
            truncated = true if contents_lines_size > MAX_LINES
            #we can technically return here
          end

          from, to = [from, to].sort                                #enforce valid range.  [from < to]
          from = 1 if from > contents_lines_size                   #if "from" out of TOP bound set to 1st line
          to   = contents_lines_size if to > contents_lines_size   #if "to" is out of TOP bound set to last line.

          if one_liner
            @selected_one_liner = from
            if EXPAND_ONE_LINER != EXPAND_NONE
              if (EXPAND_ONE_LINER & EXPAND_BEFORE != 0) # check if EXPAND_BEFORE flag is on
                from = [1, from - LINES_BEFORE].max      # make sure expand before does not go out of bound
              end

              if (EXPAND_ONE_LINER & EXPAND_AFTER != 0)          # check if EXPAND_FLAG flag is on
                to = [to + LINES_AFTER, contents_lines_size].min # make sure expand after does not go out of bound
              end

              from = contents_lines_size if from > contents_lines_size   #if "from" is out of the content top bound
              # to   = contents_lines_size if to > contents_lines_size   #if "to" is out of  the content top bound
            else
              #no expand show the one liner solely
            end
          end

          if to - from > MAX_LINES && !one_liner  #if exceed the MAX_LINES limit correct unless range was produced by one_liner which it expand setting will allow exceeding the line limit
            truncated = true
           to = from + MAX_LINES - 1
          end

          {
            from: from,                               #calculated from
            from_minus_one: from - 1,                   #used for getting currect ol>li numbering with css used in template
            to: to,                                   #calculated to
            one_liner: one_liner,                     #boolean if a one-liner
            selected_one_liner: @selected_one_liner,  #if a one liner is provided we create a reference for it.
            range_provided: range_provided,           #boolean if range provided
            truncated: truncated
          }
        end

        #minimize/compact leading indentation while preserving overall indentation
        def removeLeadingIndentation(str)
          min_space = 100
          a_lines = str.lines
          a_lines.each do |l|
            l = l.chomp("\n")  # remove new line
            m = l.match(/^[ ]*/) # find leading spaces 0 or more
            unless m.nil? || l.size == m[0].size || l.size == 0 # no match | only spaces in line | empty line
              m_str_length = m[0].size
              if m_str_length <= 1  # minimum space is 1 or nothing we can break we found our minimum
                min_space = m_str_length
                break #stop iteration
              end
              if m_str_length < min_space
                min_space = m_str_length
              end
            else
              next # SKIP no match or line is only spaces
            end
          end
          a_lines.each do |l|
            re = Regexp.new "^[ ]{#{min_space}}"  #match the minimum spaces of the line
            l.gsub!(re, "")
          end
          a_lines.join
        end

        def line_number_helper(lines, start, selected)
          lines = removeLeadingIndentation(lines.join).lines # A little ineffeicent we could modify  removeLeadingIndentation to accept array and return array, but for now it is only working with a string
          hash_builder = []
          output_builder = []
          lines.map.with_index { |line, i|
            lnum = (i.to_i + start)
            hash_builder.push(line_number: lnum, data: line.gsub("\n", ""), selected: (selected == lnum) ? true : false)
            output_builder.push "#{lnum}: #{line}"
          }
          { output: output_builder.join(), array: hash_builder }
        end

        def raw
          return @raw if defined?(@raw)

          m = @url.match(self.raw_regexp)

          if m
            from = /\d+/.match(m[:from])   #get numeric should only match a positive interger
            to   = /\d+/.match(m[:to])     #get numeric should only match a positive interger

            @file = m[:file]
            @lang = Onebox::FileTypeFinder.from_file_name(m[:file])

            if @lang == "stl" && link.match?(/^https?:\/\/(www\.)?github\.com.*\/blob\//)
              @model_file = @lang.dup
              @raw = "https://render.githubusercontent.com/view/solid?url=" + self.raw_template(m)
            else
              contents = URI.parse(self.raw_template(m)).open(read_timeout: timeout).read

              if contents.encoding == Encoding::BINARY || contents.bytes.include?(0)
                @raw = nil
                @binary = true
                return
              end

              contents_lines = contents.lines           #get contents lines
              contents_lines_size = contents_lines.size #get number of lines

              cr = calc_range(m, contents_lines_size)    #calculate the range of lines for output
              selected_one_liner = cr[:selected_one_liner] #if url is a one-liner calc_range will return it
              from = cr[:from]
              to = cr[:to]
              @truncated = cr[:truncated]
              range_provided = cr[:range_provided]
              @cr_results = cr

              if range_provided       #if a range provided (single line or more)
                if SHOW_LINE_NUMBER
                  lines_result = line_number_helper(contents_lines[(from - 1)..(to - 1)], from, selected_one_liner)  #print code with prefix line numbers in case range provided
                  contents = lines_result[:output]
                  @selected_lines_array = lines_result[:array]
                else
                  contents = contents_lines[(from - 1)..(to - 1)].join()
                end

              else
                contents = contents_lines[(from - 1)..(to - 1)].join()
              end

              if contents.length > MAX_CHARS    #truncate content chars to limits
                contents = contents[0..MAX_CHARS]
                @truncated = true
              end

              @raw = contents
            end
          end
        end

        def data
          @data ||= {
            title: title,
            link: link,
            # IMPORTANT NOTE: All of the other class variables are populated
            #     as *side effects* of the `raw` method! They must all appear
            #     AFTER the call to `raw`! Don't get bitten by this like I did!
            content: raw,
            binary: @binary,
            lang: "lang-#{@lang}",
            lines: @selected_lines_array ,
            has_lines: !@selected_lines_array.nil?,
            selected_one_liner: @selected_one_liner,
            cr_results: @cr_results,
            truncated: @truncated,
            model_file: @model_file,
            width: 480,
            height: 360
          }
        end
      end
    end
  end
end