/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

package com.facebook.react.cxxbridge;

import java.util.ArrayList;
import java.util.Arrays;

import org.junit.Before;
import org.junit.Test;

import com.facebook.common.logging.FLog;
import com.facebook.common.logging.FakeLoggingDelegate;
import com.facebook.common.logging.LoggingDelegate;

import static org.fest.assertions.api.Assertions.assertThat;
import static org.fest.assertions.api.Assertions.fail;

import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.never;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

public class FallbackJSBundleLoaderTest {

  private static final String UNRECOVERABLE;
  static {
    String prefix = FallbackJSBundleLoader.RECOVERABLE;
    char first = prefix.charAt(0);

    UNRECOVERABLE = prefix.replace(first, (char) (first + 1));
  }

  private FakeLoggingDelegate mLoggingDelegate;

  @Before
  public void setup() {
    mLoggingDelegate = new FakeLoggingDelegate();
    FLog.setLoggingDelegate(mLoggingDelegate);
  }

  @Test
  public void firstLoaderSucceeds() {
    JSBundleLoader delegates[] = new JSBundleLoader[] {
      successfulLoader("url1"),
      successfulLoader("url2")
    };

    FallbackJSBundleLoader fallbackLoader =
      new FallbackJSBundleLoader(new ArrayList<>(Arrays.asList(delegates)));

    assertThat(fallbackLoader.loadScript(null)).isEqualTo("url1");

    verify(delegates[0], times(1)).loadScript(null);
    verify(delegates[1], never()).loadScript(null);

    assertThat(mLoggingDelegate.logContains(
        FakeLoggingDelegate.WTF,
        FallbackJSBundleLoader.TAG,
        null))
      .isFalse();
  }

  @Test
  public void fallingBackSuccessfully() {
    JSBundleLoader delegates[] = new JSBundleLoader[] {
      recoverableLoader("url1", "error1"),
      successfulLoader("url2"),
      successfulLoader("url3")
    };

    FallbackJSBundleLoader fallbackLoader =
      new FallbackJSBundleLoader(new ArrayList<>(Arrays.asList(delegates)));

    assertThat(fallbackLoader.loadScript(null)).isEqualTo("url2");

    verify(delegates[0], times(1)).loadScript(null);
    verify(delegates[1], times(1)).loadScript(null);
    verify(delegates[2], never()).loadScript(null);

    assertThat(mLoggingDelegate.logContains(
        FakeLoggingDelegate.WTF,
        FallbackJSBundleLoader.TAG,
        recoverableMsg("error1")))
      .isTrue();
  }

  @Test
  public void fallingbackUnsuccessfully() {
    JSBundleLoader delegates[] = new JSBundleLoader[] {
      recoverableLoader("url1", "error1"),
      recoverableLoader("url2", "error2")
    };

    FallbackJSBundleLoader fallbackLoader =
      new FallbackJSBundleLoader(new ArrayList<>(Arrays.asList(delegates)));

    try {
      fallbackLoader.loadScript(null);
      fail("expect throw");
    } catch (Exception e) {
      assertThat(e).isInstanceOf(RuntimeException.class);

      Throwable cause = e.getCause();
      ArrayList<String> msgs = new ArrayList<>();
      while (cause != null) {
        msgs.add(cause.getMessage());
        cause = cause.getCause();
      }

      assertThat(msgs).containsExactly(
        recoverableMsg("error1"),
        recoverableMsg("error2"));
    }

    verify(delegates[0], times(1)).loadScript(null);
    verify(delegates[1], times(1)).loadScript(null);

    assertThat(mLoggingDelegate.logContains(
        FakeLoggingDelegate.WTF,
        FallbackJSBundleLoader.TAG,
        recoverableMsg("error1")))
      .isTrue();

    assertThat(mLoggingDelegate.logContains(
        FakeLoggingDelegate.WTF,
        FallbackJSBundleLoader.TAG,
        recoverableMsg("error2")))
      .isTrue();
  }

  @Test
  public void unrecoverable() {
    JSBundleLoader delegates[] = new JSBundleLoader[] {
      fatalLoader("url1", "error1"),
      recoverableLoader("url2", "error2")
    };

    FallbackJSBundleLoader fallbackLoader =
      new FallbackJSBundleLoader(new ArrayList(Arrays.asList(delegates)));

    try {
      fallbackLoader.loadScript(null);
      fail("expect throw");
    } catch (Exception e) {
      assertThat(e.getMessage()).isEqualTo(fatalMsg("error1"));
    }

    verify(delegates[0], times(1)).loadScript(null);
    verify(delegates[1], never()).loadScript(null);

    assertThat(mLoggingDelegate.logContains(
        FakeLoggingDelegate.WTF,
        FallbackJSBundleLoader.TAG,
        null))
      .isFalse();
  }

  private static JSBundleLoader successfulLoader(String url) {
    JSBundleLoader loader = mock(JSBundleLoader.class);
    when(loader.loadScript(null)).thenReturn(url);

    return loader;
  }

  private static String recoverableMsg(String errMsg) {
    return FallbackJSBundleLoader.RECOVERABLE + errMsg;
  }

  private static JSBundleLoader recoverableLoader(String url, String errMsg) {
    JSBundleLoader loader = mock(JSBundleLoader.class);
    when(loader.loadScript(null))
      .thenThrow(new RuntimeException(FallbackJSBundleLoader.RECOVERABLE + errMsg));

    return loader;
  }

  private static String fatalMsg(String errMsg) {
    return UNRECOVERABLE + errMsg;
  }

  private static JSBundleLoader fatalLoader(String url, String errMsg) {
    JSBundleLoader loader = mock(JSBundleLoader.class);
    when(loader.loadScript(null))
      .thenThrow(new RuntimeException(UNRECOVERABLE + errMsg));

    return loader;
  }
}