#!/usr/bin/env ruby

require "erb"

TEMPLATE = <<EOF
struct char_desc_t
{
    int start;
    int length;
    float c_x;
    float c_y;
};

immutable float[<%= vertices.size * 2 %>] vertices = [
<% vertices.flatten.each do |coord| -%>
    <%= coord %>,
<% end -%>
];

immutable ushort[<%= indices.size %>] indices = [
<% indices.each do |index| -%>
    <%= index %>,
<% end -%>
];

<% object_ranges.each_pair do |obj_name, obj_ranges| -%>
immutable char_desc_t[] <%= obj_name %> = [
<%   obj_ranges.each do |obj_range| -%>
<%     obj_verts = indices[*obj_range].map {|i| vertices[i]} -%>
<%     c_x = (obj_verts.map {|v| v[0]}.min + obj_verts.map {|v| v[0]}.max) / 2.0 -%>
<%     c_y = (obj_verts.map {|v| v[1]}.min + obj_verts.map {|v| v[1]}.max) / 2.0 -%>
    {<%= obj_range[0] %>, <%= obj_range[1] %>, <%= c_x %>, <%= c_y %>},
<%   end -%>
];
<% end -%>

immutable float width = <%= vertices.map {|v| v[0]}.max - vertices.map {|v| v[0]}.min %>;
immutable float height = <%= vertices.map {|v| v[1]}.max - vertices.map {|v| v[1]}.min %>;
EOF

def main(obj_fname, d_fname)
  objects = {}
  object_ranges = {}
  vertices = []
  indices = []
  cur_obj = nil
  File.read(obj_fname).each_line do |line|
    if line =~ /^v\s+(\S+)\s+(\S+)/
      vertices << [$1.to_f, $2.to_f]
    elsif line =~ /^o\s+(..)-(\d+)/
      obj_class, obj_class_index = $1, $2.to_i
      objects[obj_class] ||= []
      objects[obj_class][obj_class_index] ||= []
      cur_obj = objects[obj_class][obj_class_index]
    elsif line =~ /^o\s+(.*)/
      raise "Do not know how to handle object #{$1.inspect}"
    elsif line =~ /^f\s+(\d+)\s+(\d+)\s+(\d+)/
      cur_obj << [$1, $2, $3].map {|v| v.to_i - 1}
    elsif line =~ /^l\s+(\d+)\s+(\d+)/
      cur_obj << [$1, $2].map {|v| v.to_i - 1}
    end
  end
  objects.each_pair do |obj_name, obj_array|
    object_ranges[obj_name] = obj_array.map do |obj_indices|
      obj_indices.flatten!
      base_index = indices.size
      indices += obj_indices
      [base_index, obj_indices.size]
    end
  end
  File.open(d_fname, "w") do |fh|
    fh.puts ERB.new(TEMPLATE, nil, "<>-").result(binding)
  end
end

main(*ARGV)