com.example.mortar.mortarscreen.ScreenScoper Maven / Gradle / Ivy

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package com.example.mortar.mortarscreen;

import android.content.Context;
import android.content.res.Resources;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.LinkedHashMap;
import java.util.Map;
import mortar.MortarScope;
import mortar.dagger1support.ObjectGraphService;

import static java.lang.String.format;

/**
 * Creates {@link MortarScope}s for screens that may be annotated with {@link WithModuleFactory},
 * {@link WithModule}.
 */
public class ScreenScoper {
  private static final ModuleFactory NO_FACTORY = new ModuleFactory() {
    @Override protected Object createDaggerModule(Resources resources, Object screen) {
      throw new UnsupportedOperationException();
    }
  };

  private final Map moduleFactoryCache = new LinkedHashMap<>();

  public MortarScope getScreenScope(Context context, String name, Object screen) {
    MortarScope parentScope = MortarScope.getScope(context);
    return getScreenScope(context.getResources(), parentScope, name, screen);
  }

  /**
   * Finds or creates the scope for the given screen, honoring its optional {@link
   * WithModuleFactory} or {@link WithModule} annotation. Note that scopes are also created
   * for unannotated screens.
   */
  public MortarScope getScreenScope(Resources resources, MortarScope parentScope, final String name,
      final Object screen) {
    ModuleFactory moduleFactory = getModuleFactory(screen);
    Object childModule;
    if (moduleFactory != NO_FACTORY) {
      childModule = moduleFactory.createDaggerModule(resources, screen);
    } else {
      // We need every screen to have a scope, so that anything it injects is scoped.  We need
      // this even if the screen doesn't declare a module, because Dagger allows injection of
      // objects that are annotated even if they don't appear in a module.
      childModule = null;
    }

    MortarScope childScope = parentScope.findChild(name);
    if (childScope == null) {
      childScope = parentScope.buildChild()
          .withService(ObjectGraphService.SERVICE_NAME,
              ObjectGraphService.create(parentScope, childModule))
          .build(name);
    }

    return childScope;
  }

  private ModuleFactory getModuleFactory(Object screen) {
    Class screenType = screen.getClass();
    ModuleFactory moduleFactory = moduleFactoryCache.get(screenType);

    if (moduleFactory != null) return moduleFactory;

    WithModule withModule = screenType.getAnnotation(WithModule.class);
    if (withModule != null) {
      Class moduleClass = withModule.value();

      Constructor[] constructors = moduleClass.getDeclaredConstructors();

      if (constructors.length != 1) {
        throw new IllegalArgumentException(
            format("Module %s for screen %s should have exactly one public constructor",
                moduleClass.getName(), screen));
      }

      Constructor constructor = constructors[0];

      Class[] parameters = constructor.getParameterTypes();

      if (parameters.length > 1) {
        throw new IllegalArgumentException(
            format("Module %s for screen %s should have 0 or 1 parameter", moduleClass.getName(),
                screen));
      }

      Class screenParameter;
      if (parameters.length == 1) {
        screenParameter = parameters[0];
        if (!screenParameter.isInstance(screen)) {
          throw new IllegalArgumentException(format("Module %s for screen %s should have a "
                  + "constructor parameter that is a super class of %s", moduleClass.getName(),
              screen, screen.getClass().getName()));
        }
      } else {
        screenParameter = null;
      }

      try {
        if (screenParameter == null) {
          moduleFactory = new NoArgsFactory(constructor);
        } else {
          moduleFactory = new SingleArgFactory(constructor);
        }
      } catch (Exception e) {
        throw new RuntimeException(
            format("Failed to instantiate module %s for screen %s", moduleClass.getName(), screen),
            e);
      }
    }

    if (moduleFactory == null) {
      WithModuleFactory withModuleFactory = screenType.getAnnotation(WithModuleFactory.class);
      if (withModuleFactory != null) {
        Class mfClass = withModuleFactory.value();

        try {
          moduleFactory = mfClass.newInstance();
        } catch (Exception e) {
          throw new RuntimeException(format("Failed to instantiate module factory %s for screen %s",
              withModuleFactory.value().getName(), screen), e);
        }
      }
    }

    if (moduleFactory == null) moduleFactory = NO_FACTORY;

    moduleFactoryCache.put(screenType, moduleFactory);

    return moduleFactory;
  }

  private static class NoArgsFactory extends ModuleFactory