private static Map collectThemeValues()

in android/src/main/java/com/facebook/flipper/plugins/inspector/descriptors/utils/ContextDescriptorUtils.java [42:155]
98 lines of code
22 McCabe index (conditional complexity)

  private static Map<String, FlipperObject.Builder> collectThemeValues(Context context) {
    Map<String, FlipperObject.Builder> builderMap = new HashMap<>(3);
    try {
      Resources.Theme theme = context.getTheme();
      AssetManager assetManager = context.getAssets();
      final Object themeImpl;
      final Object themeKey;

      // Nasty reflection to get a list of theme attributes that apply to this context.
      if (!doneFieldDiscovery) {
        doneFieldDiscovery = true; // even if it fails, we don't want to retry
        try {
          sThemeImplField = theme.getClass().getDeclaredField("mThemeImpl");
          sThemeImplField.setAccessible(true);
        } catch (NoSuchFieldException e) {
          // hardening against #1736
          return builderMap;
        }

        themeImpl = sThemeImplField.get(theme);
        try {
          sThemeImplThemeKeyField = themeImpl.getClass().getDeclaredField("mKey");
          sThemeImplThemeKeyField.setAccessible(true);
        } catch (NoSuchFieldException e) {
          // hardening against #1736
          return builderMap;
        }

        try {
          sThemeImplAssetManagerField = themeImpl.getClass().getDeclaredField("mAssets");
          sThemeImplAssetManagerField.setAccessible(true);
        } catch (NoSuchFieldException e) {
          // hardening against #1736
          return builderMap;
        }

        try {
          sAssetManagerGetStyleAttributesMethod =
              assetManager.getClass().getDeclaredMethod("getStyleAttributes", int.class);
          sAssetManagerGetStyleAttributesMethod.setAccessible(true);
        } catch (NoSuchMethodException e) {
          // hardening against #1736
          return builderMap;
        }

        themeKey = sThemeImplThemeKeyField.get(themeImpl);
        try {
          sThemeKeyResIdField = themeKey.getClass().getDeclaredField("mResId");
          sThemeKeyResIdField.setAccessible(true);
        } catch (NoSuchFieldException e) {
          // hardening against #1736
          return builderMap;
        }
      } else if (sThemeImplField != null && sThemeImplThemeKeyField != null) {
        themeImpl = sThemeImplField.get(theme);
        themeKey = sThemeImplThemeKeyField.get(themeImpl);
      } else {
        themeKey = null;
      }

      if (sThemeKeyResIdField == null
          || sAssetManagerGetStyleAttributesMethod == null
          || themeKey == null) {
        return builderMap;
      }

      int[] appliedThemeResIds = (int[]) sThemeKeyResIdField.get(themeKey);
      TypedValue typedValue = new TypedValue();
      Resources resources = context.getResources();
      for (int themeId : appliedThemeResIds) {
        if (themeId == 0) {
          continue;
        }
        String name = resources.getResourceName(themeId);
        // The res id array can have duplicates
        if (builderMap.containsKey(name)) {
          continue;
        }

        FlipperObject.Builder builder = new FlipperObject.Builder();
        builderMap.put(name, builder);

        int[] attributes =
            (int[]) sAssetManagerGetStyleAttributesMethod.invoke(assetManager, themeId);
        for (int attribute : attributes) {
          if (!theme.resolveAttribute(attribute, typedValue, true)) {
            continue;
          }
          String attributeName = context.getResources().getResourceName(attribute);
          String[] nameParts = attributeName.split(":");
          if (nameParts.length < 2) {
            Log.d(TAG, "Unknown attribute name format " + attributeName);
          } else {
            attributeName = nameParts[1].split("/")[1];
          }
          String strValue = TypedValue.coerceToString(typedValue.type, typedValue.data);
          if (strValue == null) {
            strValue = "null";
          } else if (strValue.startsWith("@")) {
            int resId = Integer.parseInt(strValue.substring(1));
            if (resId == 0) {
              strValue = "null";
            } else {
              strValue = context.getResources().getResourceName(resId);
            }
          }
          builder.put(attributeName, strValue);
        }
      }
    } catch (Throwable ignored) {
      Log.d(TAG, "Failed to generate theme attribute data!", ignored);
    }
    return builderMap;
  }