class SyntaxTree::YARV::DataFlowGraph

def to_mermaid
  Mermaid.flowchart do |flowchart|
    disasm = Disassembler::Squished.new
    blocks.each do |block|
      block_flow = block_flows.fetch(block.id)
      graph_name =
        if block_flow.in.any?
          "#{block.id} #{block_flows[block.id].in.join(", ")}"
        else
          block.id
        end
      flowchart.subgraph(graph_name) do
        previous = nil
        block.each_with_length do |insn, length|
          node =
            flowchart.node(
              "node_#{length}",
              "%04d %s" % [length, insn.disasm(disasm)],
              shape: :rounded
            )
          flowchart.link(previous, node, color: :red) if previous
          insn_flows[length].in.each do |input|
            if input.is_a?(LocalArgument)
              from = flowchart.fetch("node_#{input.length}")
              flowchart.link(from, node, color: :green)
            end
          end
          previous = node
        end
      end
    end
    blocks.each do |block|
      block.outgoing_blocks.each do |outgoing|
        offset =
          block.block_start + block.insns.sum(&:length) -
            block.insns.last.length
        from = flowchart.fetch("node_#{offset}")
        to = flowchart.fetch("node_#{outgoing.block_start}")
        flowchart.link(from, to, color: :red)
      end
    end
  end
end