#include "args.hpp"

#include <charconv>
#include <format>
#include <stdexcept>

namespace rog::cli {

args parse(int argc, char **argv) {
  args result{};
  result.extent = {512, 512};
  result.samples_per_pixel = 256;

  if (argc < 2) {
    throw std::runtime_error("no scene provided");
  }

  std::vector<std::string_view> args_view(argv + 1,
                                          argv + argc); // skip program name

  for (size_t i = 0; i < args_view.size(); ++i) {
    std::string_view arg = args_view[i];

    if (arg == "--help" || arg == "-h" || arg == "-?") {
      result.help = true;
      return result;
    }

    if (arg[0] != '-' && result.scene_path.empty()) {
      result.scene_path = std::filesystem::path(arg);
      continue;
    }

    if (arg == "--width" || arg == "-w") {
      if (i + 1 >= args_view.size()) {
        throw std::runtime_error("error: --width requires a value");
      }
      const auto val = args_view[++i];
      uint32_t w = 0;
      std::from_chars(val.data(), val.data() + val.size(), w);
      result.extent.x = w;
      continue;
    }

    if (arg == "--height" || (arg == "-h" && i + 1 < args_view.size() &&
                              args_view[i + 1][0] != '-')) {
      if (i + 1 >= args_view.size()) {
        throw std::runtime_error("error: --height requires a value");
      }
      const auto val = args_view[++i];
      uint32_t h = 0;
      std::from_chars(val.data(), val.data() + val.size(), h);
      result.extent.y = h;
      continue;
    }

    if (arg == "--spp") {
      if (i + 1 >= args_view.size()) {
        throw std::runtime_error("error: --spp requires a value");
      }
      const auto val = args_view[++i];
      uint32_t spp = 0;
      std::from_chars(val.data(), val.data() + val.size(), spp);
      result.samples_per_pixel = spp;
      continue;
    }

    if (arg == "--blender") {
      if (i + 1 >= args_view.size()) {
        throw std::runtime_error("error: --blender requires a path");
      }
      result.blender_path = std::filesystem::path(args_view[++i]);
      continue;
    }

    if (arg[0] == '-') {
      throw std::runtime_error(std::format("error: unknown option '{}'", arg));
    }
  }

  return result;
}

std::string_view help_message() noexcept {
  return R"(Usage: rogue [OPTIONS] <scene>

positional:
  <scene>                  Path to .glb or .blend file (required)

options:
  -w, --width <uint>       Render width (default: 512)
  -h, --height <uint>      Render height (default: 512)
  --spp <uint>             Samples per pixel (default: 256)
  --blender <path>         Custom path to Blender executable
  --help                   Show this help message

examples:
  rogue scene.glb
  rogue my_scene.blend --interactive
  rogue scene.blend -w 1920 -h 1080 --spp 1024
)";
}
} // namespace rog::cli