module HtmlToc

# File lib/html_toc.rb, line 6
    def self.process(source:, h_tags: Range.new(2, 6), show_toggle: false, use_numbers: false)

            #Search regex for {{toc}}
token = /<toc\s*\/>|\[\[toc\]\]/i #Allow for a token of either <toc/> or [[toc]]

            #If there is no token, just return the source
            if source !~ token then 
                    return source
            end
            
            #Initialize here for later
            toc = ""
            refnum = ""
            d1 = 0
            d2 = 0
            d3 = 0
            d4 = 0
            d5 = 0
            d6 = 0        

#Make a copy of the source, in case we need to
            #preserve the original string
            result = source       

            #Loop through the tags range to get the header tags
            tags_hash = Hash.new

            depth = 0
            h_tags.each do |x|
                    #Get the depth
                    depth += 1

                    #Regex for indexed header tags
                    test = /<h#{x}(?: .*?)?>(.*?)<\/h#{x}>/i
            
                    #Scan, and use the resulting MatchData objects
                    #to populate the hash
                    result.scan(test) do
                            m=Regexp.last_match
                            tags_hash[m.begin(0)] = Hx.new(m, depth)
                    end #result.scan(test) do
            end #tags.each do

            #Execute this block only if we have indexed headers
            if tags_hash.length > 0 then
                    #Sort the hash. tags becomes an array with each element consisting
                    #of an array with two objects: the integer key and the Hx value
                    tags = tags_hash.sort_by { |k, v| k }

                    #Start with the last tag and work towards the front: this way,
                    #the begin index of subsequent headers will not be moved.
                    tags.reverse.each do |elem|
                            #Replace the section in the text with the corresponding d_anchor
                            result[elem[1].start_index..elem[1].end_index]=elem[1].text
                    end #tags.reverse.each do

                    #Now move forward through the array and build the toc itself
                    toc = "<div id='__toc'>\n"
                    toc += "<div id='__toc_header'>Contents"
                    if show_toggle then
                            toc+=" [<span id='__toc_toggle' onclick='ShowHideToc();'>Hide</span>]"
                    end
                    toc+="</div>\n"
                    toc+="<div id='__toc_content' style='display:block'>\n"
                    tags.each do |elem|
                            if use_numbers
                                    case elem[1].depth
                                            when 1 
                                                    d1+=1
                                                    d2 = 0
                                                    d3 = 0
                                                    d4 = 0
                                                    d5 = 0
                                                    d6 = 0           
                                                    refnum = "#{d1} "
                                            when 2
                                                    d2+=1
                                                    d3 = 0
                                                    d4 = 0
                                                    d5 = 0
                                                    d6 = 0           
                                                    refnum = "#{d1}.#{d2} "
                                            when 3
                                                    d3+=1
                                                    d4 = 0
                                                    d5 = 0
                                                    d6 = 0           
                                                    refnum = "#{d1}.#{d2}.#{d3} "
                                            when 4
                                                    d4+=1
                                                    d5 = 0
                                                    d6 = 0           
                                                    refnum = "#{d1}.#{d2}.#{d3}.#{d4} "
                                            when 5
                                                    d5+=1
                                                    d6 = 0           
                                                    refnum = "#{d1}.#{d2}.#{d3}.#{d4}.#{d5} "
                                            when 6
                                                    d6+=1
                                                    refnum = "#{d1}.#{d2}.#{d3}.#{d4}.#{d5}.#{d6} "
                                    end #case elem[1].depth
                            end #if use_numbers

                            toc+=elem[1].l_anchor refnum
                    end
                    toc+="</div>\n" #end __toc_content
                    toc+="</div>\n" #end __toc
                    
            end #if tags_hash.length > 0

            #The location of the toc token may have changed, so get its location
            toc_md = result.match(token)
            result[toc_md.begin(0)..toc_md.end(0)] = toc
            
            result
    end