#include "platform.hpp"

#include "config.hpp"

#include <cstdlib>
#include <filesystem>

namespace connector {
namespace {

std::string environment(const char* name) {
  const char* value = std::getenv(name);
  return value ? value : "";
}

void append_path_candidates(std::vector<std::filesystem::path>& candidates) {
  const std::string value = environment("PATH");
#ifdef _WIN32
  constexpr char delimiter = ';';
  constexpr const char* name = "Spine.com";
#else
  constexpr char delimiter = ':';
  constexpr const char* name = "Spine";
#endif
  std::size_t start = 0;
  while (start <= value.size()) {
    const auto end = value.find(delimiter, start);
    std::string item = value.substr(start, end - start);
    if (item.size() >= 2 && item.front() == '"' && item.back() == '"') item = item.substr(1, item.size() - 2);
    if (!item.empty()) {
      const auto path = to_path(item);
      if (!path.empty()) candidates.push_back(path / name);
    }
    if (end == std::string::npos) break;
    start = end + 1;
  }
}

}  // namespace

std::filesystem::path to_path(const std::string& value) {
  try {
    return std::filesystem::u8path(value);
  } catch (...) {
    // 输入不是合法 UTF-8 时回退到本地代码页构造。
    try {
      return std::filesystem::path(value);
    } catch (...) {
      // 本地代码页也无法转换时返回空路径，由调用方跳过。
      return std::filesystem::path();
    }
  }
}

std::string platform_name() {
#ifdef _WIN32
  return "win32";
#elif defined(__APPLE__)
  return "darwin";
#else
  return "linux";
#endif
}

bool valid_spine_executable(const std::string& path) {
  if (path.empty()) return false;
  std::error_code error;
  const auto status = std::filesystem::status(to_path(path), error);
  return !error && std::filesystem::is_regular_file(status);
}

std::string find_spine_executable() {
  try {
    std::vector<std::filesystem::path> candidates;
    const std::string environment_path = environment("SPINE_EXECUTABLE");
    if (!environment_path.empty()) {
      const auto path = to_path(environment_path);
      if (!path.empty()) candidates.push_back(path);
    }
    const ConnectorConfig config = load_config();
    if (!config.spine_executable.empty()) {
      const auto path = to_path(config.spine_executable);
      if (!path.empty()) candidates.push_back(path);
    }
#ifdef _WIN32
    for (const char* variable : {"ProgramFiles", "ProgramFiles(x86)", "LOCALAPPDATA"}) {
      const std::string root = environment(variable);
      if (root.empty()) continue;
      const auto root_path = to_path(root);
      if (root_path.empty()) continue;
      candidates.push_back(root_path / "Spine" / "Spine.com");
      candidates.push_back(root_path / "Esoteric Software" / "Spine" / "Spine.com");
      candidates.push_back(root_path / "Programs" / "Spine" / "Spine.com");
    }
#elif defined(__APPLE__)
    candidates.emplace_back("/Applications/Spine.app/Contents/MacOS/Spine");
    const std::string home = environment("HOME");
    if (!home.empty()) {
      const auto path = to_path(home);
      if (!path.empty()) candidates.push_back(path / "Applications" / "Spine.app" / "Contents" / "MacOS" / "Spine");
    }
#else
    candidates.emplace_back("/opt/Spine/Spine.sh");
    candidates.emplace_back("/usr/local/bin/Spine");
    candidates.emplace_back("/usr/bin/Spine");
#endif
    append_path_candidates(candidates);
    for (const auto& candidate : candidates) {
      const std::string path = candidate.u8string();
      if (valid_spine_executable(path)) return path;
    }
    return "";
  } catch (...) {
    // 任何异常都不应导致程序崩溃，返回未找到。
    return "";
  }
}

}  // namespace connector