mdinlinedot2mdpng

#!/usr/bin/env ruby

require "pathname"
require "kramdown"

plan = Pathname.new("../plan.md").expand_path(__dir__)
output_dir = Pathname.new("../output").expand_path(__dir__)
output_dir.rmtree if output_dir.exist?
output_dir.mkdir

raw_plan = plan.read

md_output = []
graph = []
graph_counter = 1

raw_plan.split("\n").each do |line|
  if (line =~ /^```dot/) .. (line =~ /```\z/)
    # Don't save markers
    next if line.start_with?("```")

    graph << line
    next
  end

  # Just finished grabbing a graph
  unless graph.empty?
    graph_dot = output_dir.join("graph_#{graph_counter}.dot")
    graph_png = graph_dot.sub_ext(".png")
    graph_dot.open("w+") do |g|
      g.puts graph
    end
    # Generate graph
    %x[dot -Tpng #{graph_dot} > #{graph_png}]
    graph_dot.delete

    # Insert image tag for it into master doc
    md_output << "    ![](#{graph_png.basename})"
    md_output << ""

    # Reset for next graph
    graph_counter += 1
    graph = []
    next
  end

  # Just a normal line
  md_output << line
end

output_dir.join("migration_plan.md").open("w+") do |plan|
  plan.puts md_output
end

puts "Done"