#include <filesystem>
#include <fstream>
#include <iostream>
#include <list>
#include <utility>

#include "heading.h"
#include "scene.h"
#include "script.h"

struct EmbeddedScript {
  Script script;
  bool internal = false;  // true if referred from within another script
  int id = -1;            // if internal is false, ExtResource id
  std::string path;       // if internal is true
};

void show_usage() {
  std::cout << "godot3_tscn_compactor [path to root tscn] [file prefix]"
            << std::endl;
}

int main(int argc, char** argv) {
  if (argc != 3) {
    show_usage();
    return 0;
  }

  std::filesystem::path root_tscn_path(argv[1]);
  std::string file_prefix(argv[2]);

  Scene root_tscn(root_tscn_path);

  std::vector<EmbeddedScript> sub_scripts;

  for (const auto& [id, heading] : root_tscn.ext_resources()) {
    std::string resource_filename =
        std::get<std::string>(heading.GetKeyval("path"));
    if (resource_filename.substr(0, file_prefix.size()) == file_prefix) {
      std::filesystem::path relative_filename =
          resource_filename.substr(file_prefix.size());
      std::filesystem::path resource_path =
          root_tscn_path.parent_path() / relative_filename;

      EmbeddedScript embedded_script;
      embedded_script.script = Script(resource_path, file_prefix);
      embedded_script.id = id;

      sub_scripts.push_back(std::move(embedded_script));
    }
  }

  std::list<EmbeddedScript> all_scripts;
  std::vector<EmbeddedScript> scripts_to_check = sub_scripts;
  while (!scripts_to_check.empty()) {
    std::vector<EmbeddedScript> cur_scripts;
    cur_scripts.swap(scripts_to_check);

    for (const EmbeddedScript& embedded_script : cur_scripts) {
      all_scripts.push_front(embedded_script);

      for (const std::string& loaded_script_path :
           embedded_script.script.loaded_scripts()) {
        std::filesystem::path resource_path =
            root_tscn_path.parent_path() / loaded_script_path;

        EmbeddedScript embedded_script;
        embedded_script.script = Script(resource_path, file_prefix);
        embedded_script.internal = true;
        embedded_script.path = loaded_script_path;

        scripts_to_check.push_back(std::move(embedded_script));
      }
    }
  }

  std::map<std::string, int> new_sub_scripts;
  for (EmbeddedScript embedded_script : all_scripts) {
    embedded_script.script.ReplaceScriptReferences(new_sub_scripts);
    int sub_resource_id = root_tscn.AddSubResource(embedded_script.script);

    if (embedded_script.internal) {
      new_sub_scripts[embedded_script.path] = sub_resource_id;
    } else {
      root_tscn.RemoveExtResource(embedded_script.id);
      root_tscn.ReplaceScriptReferences(embedded_script.id, sub_resource_id);
    }
  }

  std::filesystem::path output_name = root_tscn_path;
  output_name.replace_filename(std::string(output_name.stem()) +
                               "_compiled.tscn");

  std::ofstream output_stream(output_name);
  output_stream << root_tscn.ToString();

  return 0;
}