1 files changed, 219 insertions, 0 deletions
diff --git a/library/main/src/com/android/setupwizardlib/util/ThemeResolver.java b/library/main/src/com/android/setupwizardlib/util/ThemeResolver.java
new file mode 100644
index 0000000..14fdc85
--- /dev/null
+++ b/library/main/src/com/android/setupwizardlib/util/ThemeResolver.java
@@ -0,0 +1,219 @@
+package com.android.setupwizardlib.util;
+
+import android.app.Activity;
+import android.content.Intent;
+import androidx.annotation.Nullable;
+import androidx.annotation.StyleRes;
+import com.android.setupwizardlib.R;
+
+/**
+ * A resolver to resolve the theme from a string or an activity intent, setting options like the
+ * default theme and the oldest supported theme. Apps can share the resolver across the entire
+ * process by calling {@link #setDefault(ThemeResolver)} in {@link
+ * android.app.Application#onCreate()}. If an app needs more granular sharing of the theme default
+ * values, additional instances of {@link ThemeResolver} can be created using the builder.
+ */
+public class ThemeResolver {
+  @StyleRes private final int defaultTheme;
+  @Nullable private final String oldestSupportedTheme;
+  private final boolean useDayNight;
+
+  @Nullable private static ThemeResolver defaultResolver;
+
+  /**
+   * Sets the default instance used for the whole process. Can be null to reset the default to the
+   * preset one.
+   */
+  public static void setDefault(@Nullable ThemeResolver resolver) {
+    defaultResolver = resolver;
+  }
+
+  /**
+   * Returns the default instance, which can be changed using {@link #setDefault(ThemeResolver)}.
+   */
+  public static ThemeResolver getDefault() {
+    if (defaultResolver == null) {
+      defaultResolver =
+          new ThemeResolver.Builder()
+              .setDefaultTheme(R.style.SuwThemeGlif_DayNight)
+              .setUseDayNight(true)
+              .build();
+    }
+    return defaultResolver;
+  }
+
+  private ThemeResolver(
+      int defaultTheme, @Nullable String oldestSupportedTheme, boolean useDayNight) {
+    this.defaultTheme = defaultTheme;
+    this.oldestSupportedTheme = oldestSupportedTheme;
+    this.useDayNight = useDayNight;
+  }
+
+  /**
+   * Returns the style for the theme specified in the intent extra. If the specified string theme is
+   * older than the oldest supported theme, the default will be returned instead. Note that the
+   * default theme is returned without processing -- it may not be a DayNight theme even if {@link
+   * #useDayNight} is true.
+   */
+  @StyleRes
+  public int resolve(Intent intent) {
+    return resolve(
+        intent.getStringExtra(WizardManagerHelper.EXTRA_THEME),
+        /* suppressDayNight= */ WizardManagerHelper.isSetupWizardIntent(intent));
+  }
+
+  /**
+   * Returns the style for the given string theme. If the specified string theme is older than the
+   * oldest supported theme, the default will be returned instead. Note that the default theme is
+   * returned without processing -- it may not be a DayNight theme even if {@link #useDayNight} is
+   * true.
+   */
+  @StyleRes
+  public int resolve(@Nullable String theme) {
+    return resolve(theme, /* suppressDayNight= */ false);
+  }
+
+  @StyleRes
+  private int resolve(@Nullable String theme, boolean suppressDayNight) {
+    int themeResource =
+        useDayNight && !suppressDayNight ? getDayNightThemeRes(theme) : getThemeRes(theme);
+    if (themeResource == 0) {
+      return defaultTheme;
+    }
+
+    if (oldestSupportedTheme != null && compareThemes(theme, oldestSupportedTheme) < 0) {
+      return defaultTheme;
+    }
+    return themeResource;
+  }
+
+  /** Reads the theme from the intent, and applies the resolved theme to the activity. */
+  public void applyTheme(Activity activity) {
+    activity.setTheme(resolve(activity.getIntent()));
+  }
+
+  /**
+   * Returns the corresponding DayNight theme resource ID for the given string theme. DayNight
+   * themes are themes that will be either light or dark depending on the system setting. For
+   * example, the string {@link WizardManagerHelper#THEME_GLIF_LIGHT} will return
+   * {@code @style/SuwThemeGlif.DayNight}.
+   */
+  @StyleRes
+  private static int getDayNightThemeRes(@Nullable String theme) {
+    if (theme != null) {
+      switch (theme) {
+        case WizardManagerHelper.THEME_GLIF_V3_LIGHT:
+        case WizardManagerHelper.THEME_GLIF_V3:
+          return R.style.SuwThemeGlifV3_DayNight;
+        case WizardManagerHelper.THEME_GLIF_V2_LIGHT:
+        case WizardManagerHelper.THEME_GLIF_V2:
+          return R.style.SuwThemeGlifV2_DayNight;
+        case WizardManagerHelper.THEME_GLIF_LIGHT:
+        case WizardManagerHelper.THEME_GLIF:
+          return R.style.SuwThemeGlif_DayNight;
+        case WizardManagerHelper.THEME_MATERIAL_LIGHT:
+        case WizardManagerHelper.THEME_MATERIAL:
+          return R.style.SuwThemeMaterial_DayNight;
+        default:
+          // fall through
+      }
+    }
+    return 0;
+  }
+
+  /**
+   * Returns the theme resource ID for the given string theme. For example, the string {@link
+   * WizardManagerHelper#THEME_GLIF_LIGHT} will return {@code @style/SuwThemeGlif.Light}.
+   */
+  @StyleRes
+  private static int getThemeRes(@Nullable String theme) {
+    if (theme != null) {
+      switch (theme) {
+        case WizardManagerHelper.THEME_GLIF_V3_LIGHT:
+          return R.style.SuwThemeGlifV3_Light;
+        case WizardManagerHelper.THEME_GLIF_V3:
+          return R.style.SuwThemeGlifV3;
+        case WizardManagerHelper.THEME_GLIF_V2_LIGHT:
+          return R.style.SuwThemeGlifV2_Light;
+        case WizardManagerHelper.THEME_GLIF_V2:
+          return R.style.SuwThemeGlifV2;
+        case WizardManagerHelper.THEME_GLIF_LIGHT:
+          return R.style.SuwThemeGlif_Light;
+        case WizardManagerHelper.THEME_GLIF:
+          return R.style.SuwThemeGlif;
+        case WizardManagerHelper.THEME_MATERIAL_LIGHT:
+          return R.style.SuwThemeMaterial_Light;
+        case WizardManagerHelper.THEME_MATERIAL:
+          return R.style.SuwThemeMaterial;
+        default:
+          // fall through
+      }
+    }
+    return 0;
+  }
+
+  /** Compares whether the versions of {@code theme1} and {@code theme2} to check which is newer. */
+  private static int compareThemes(String theme1, String theme2) {
+    return Integer.valueOf(getThemeVersion(theme1)).compareTo(getThemeVersion(theme2));
+  }
+
+  /**
+   * Returns the version of the theme. The absolute number of the theme version is not defined, but
+   * a larger number in the version indicates a newer theme.
+   */
+  private static int getThemeVersion(String theme) {
+    if (theme != null) {
+      switch (theme) {
+        case WizardManagerHelper.THEME_GLIF_V3_LIGHT:
+        case WizardManagerHelper.THEME_GLIF_V3:
+          return 4;
+        case WizardManagerHelper.THEME_GLIF_V2_LIGHT:
+        case WizardManagerHelper.THEME_GLIF_V2:
+          return 3;
+        case WizardManagerHelper.THEME_GLIF_LIGHT:
+        case WizardManagerHelper.THEME_GLIF:
+          return 2;
+        case WizardManagerHelper.THEME_MATERIAL_LIGHT:
+        case WizardManagerHelper.THEME_MATERIAL:
+          return 1;
+        default:
+          // fall through
+      }
+    }
+    return -1;
+  }
+
+  /** Builder class for {@link ThemeResolver}. */
+  public static class Builder {
+    @StyleRes private int defaultTheme = R.style.SuwThemeGlif_DayNight;
+    @Nullable private String oldestSupportedTheme = null;
+    private boolean useDayNight = true;
+
+    public Builder() {}
+
+    public Builder(ThemeResolver themeResolver) {
+      this.defaultTheme = themeResolver.defaultTheme;
+      this.oldestSupportedTheme = themeResolver.oldestSupportedTheme;
+      this.useDayNight = themeResolver.useDayNight;
+    }
+
+    public Builder setDefaultTheme(@StyleRes int defaultTheme) {
+      this.defaultTheme = defaultTheme;
+      return this;
+    }
+
+    public Builder setOldestSupportedTheme(String oldestSupportedTheme) {
+      this.oldestSupportedTheme = oldestSupportedTheme;
+      return this;
+    }
+
+    public Builder setUseDayNight(boolean useDayNight) {
+      this.useDayNight = useDayNight;
+      return this;
+    }
+
+    public ThemeResolver build() {
+      return new ThemeResolver(defaultTheme, oldestSupportedTheme, useDayNight);
+    }
+  }
+}