/*
 * Copyright (C) 2006 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject.internal;

import static com.google.inject.internal.MoreTypes.getRawType;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.collect.Ordering;
import com.google.common.primitives.Primitives;
import com.google.inject.Binding;
import com.google.inject.ConfigurationException;
import com.google.inject.CreationException;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.ProvisionException;
import com.google.inject.Scope;
import com.google.inject.TypeLiteral;
import com.google.inject.internal.util.SourceProvider;
import com.google.inject.spi.ElementSource;
import com.google.inject.spi.Message;
import com.google.inject.spi.ScopeBinding;
import com.google.inject.spi.TypeConverterBinding;
import com.google.inject.spi.TypeListenerBinding;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Formatter;
import java.util.List;
import java.util.Map;
import java.util.Set;

A collection of error messages. If this type is passed as a method parameter, the method is
considered to have executed successfully only if new errors were not added to this collection.
Errors can be chained to provide additional context. To add context, call withSource to create a new Errors instance that contains additional context. All messages added to the returned instance will contain full context. 
To avoid messages with redundant context, withSource should be added sparingly. A good rule of thumb is to assume a method's caller has already specified enough context to identify that method. When calling a method that's defined in a different context, call that method with an errors object that includes its context. 
Author:
jessewilson@google.com (Jesse Wilson)/**
 * A collection of error messages. If this type is passed as a method parameter, the method is
 * considered to have executed successfully only if new errors were not added to this collection.
 *
 * <p>Errors can be chained to provide additional context. To add context, call {@link #withSource}
 * to create a new Errors instance that contains additional context. All messages added to the
 * returned instance will contain full context.
 *
 * <p>To avoid messages with redundant context, {@link #withSource} should be added sparingly. A
 * good rule of thumb is to assume a method's caller has already specified enough context to
 * identify that method. When calling a method that's defined in a different context, call that
 * method with an errors object that includes its context.
 *
 * @author jessewilson@google.com (Jesse Wilson)
 */
public final class Errors implements Serializable {

  
When a binding is not found, show at most this many bindings with the same type /** When a binding is not found, show at most this many bindings with the same type */
  private static final int MAX_MATCHING_TYPES_REPORTED = 3;

  
When a binding is not found, show at most this many bindings that have some similarities /** When a binding is not found, show at most this many bindings that have some similarities */
  private static final int MAX_RELATED_TYPES_REPORTED = 3;

  
Throws a ConfigurationException with an NullPointerExceptions as the cause if the given reference is null. /**
   * Throws a ConfigurationException with an NullPointerExceptions as the cause if the given
   * reference is {@code null}.
   */
  static <T> T checkNotNull(T reference, String name) {
    if (reference != null) {
      return reference;
    }

    NullPointerException npe = new NullPointerException(name);
    throw new ConfigurationException(ImmutableSet.of(new Message(npe.toString(), npe)));
  }

  
Throws a ConfigurationException with a formatted Message if this condition is 
false. /**
   * Throws a ConfigurationException with a formatted {@link Message} if this condition is {@code
   * false}.
   */
  static void checkConfiguration(boolean condition, String format, Object... args) {
    if (condition) {
      return;
    }

    throw new ConfigurationException(ImmutableSet.of(new Message(Errors.format(format, args))));
  }

  
If the key is unknown and it is one of these types, it generally means there is a missing
annotation.
/**
   * If the key is unknown and it is one of these types, it generally means there is a missing
   * annotation.
   */
  private static final ImmutableSet<Class<?>> COMMON_AMBIGUOUS_TYPES =
      ImmutableSet.<Class<?>>builder()
          .add(Object.class)
          .add(String.class)
          .addAll(Primitives.allWrapperTypes())
          .build();

  
The root errors object. Used to access the list of error messages. /** The root errors object. Used to access the list of error messages. */
  private final Errors root;

  
The parent errors object. Used to obtain the chain of source objects. /** The parent errors object. Used to obtain the chain of source objects. */
  private final Errors parent;

  
The leaf source for errors added here. /** The leaf source for errors added here. */
  private final Object source;

  
null unless (root == this) and error messages exist. Never an empty list. /** null unless (root == this) and error messages exist. Never an empty list. */
  private List<Message> errors; // lazy, use getErrorsForAdd()

  public Errors() {
    this.root = this;
    this.parent = null;
    this.source = SourceProvider.UNKNOWN_SOURCE;
  }

  public Errors(Object source) {
    this.root = this;
    this.parent = null;
    this.source = source;
  }

  private Errors(Errors parent, Object source) {
    this.root = parent.root;
    this.parent = parent;
    this.source = source;
  }

  
Returns an instance that uses source as a reference point for newly added errors. /** Returns an instance that uses {@code source} as a reference point for newly added errors. */
  public Errors withSource(Object source) {
    return source == this.source || source == SourceProvider.UNKNOWN_SOURCE
        ? this
        : new Errors(this, source);
  }

  
We use a fairly generic error message here. The motivation is to share the same message for
both bind time errors:
Guice.createInjector(new AbstractModule() {
  public void configure() {
    bind(Runnable.class);
  }
}
...and at provide-time errors:
Guice.createInjector().getInstance(Runnable.class);
Otherwise we need to know who's calling when resolving a just-in-time binding, which makes
things unnecessarily complex.
/**
   * We use a fairly generic error message here. The motivation is to share the same message for
   * both bind time errors:
   *
   * <pre><code>Guice.createInjector(new AbstractModule() {
   *   public void configure() {
   *     bind(Runnable.class);
   *   }
   * }</code></pre>
   *
   * ...and at provide-time errors:
   *
   * <pre><code>Guice.createInjector().getInstance(Runnable.class);</code></pre>
   *
   * Otherwise we need to know who's calling when resolving a just-in-time binding, which makes
   * things unnecessarily complex.
   */
  public Errors missingImplementation(Key key) {
    return addMessage("No implementation for %s was bound.", key);
  }

  
Within guice's core, allow for better missing binding messages /** Within guice's core, allow for better missing binding messages */
  <T> Errors missingImplementationWithHint(Key<T> key, Injector injector) {
    StringBuilder sb = new StringBuilder();

    sb.append(format("No implementation for %s was bound.", key));

    // Keys which have similar strings as the desired key
    List<String> possibleMatches = new ArrayList<>();

    // Check for other keys that may have the same type,
    // but not the same annotation
    TypeLiteral<T> type = key.getTypeLiteral();
    List<Binding<T>> sameTypes = injector.findBindingsByType(type);
    if (!sameTypes.isEmpty()) {
      sb.append(format("%n  Did you mean?"));
      int howMany = Math.min(sameTypes.size(), MAX_MATCHING_TYPES_REPORTED);
      for (int i = 0; i < howMany; ++i) {
        // TODO: Look into a better way to prioritize suggestions. For example, possbily
        // use levenshtein distance of the given annotation vs actual annotation.
        sb.append(format("%n    * %s", sameTypes.get(i).getKey()));
      }
      int remaining = sameTypes.size() - MAX_MATCHING_TYPES_REPORTED;
      if (remaining > 0) {
        String plural = (remaining == 1) ? "" : "s";
        sb.append(format("%n    %d more binding%s with other annotations.", remaining, plural));
      }
    } else {
      // For now, do a simple substring search for possibilities. This can help spot
      // issues when there are generics being used (such as a wrapper class) and the
      // user has forgotten they need to bind based on the wrapper, not the underlying
      // class. In the future, consider doing a strict in-depth type search.
      // TODO: Look into a better way to prioritize suggestions. For example, possbily
      // use levenshtein distance of the type literal strings.
      String want = type.toString();
      Map<Key<?>, Binding<?>> bindingMap = injector.getAllBindings();
      for (Key<?> bindingKey : bindingMap.keySet()) {
        String have = bindingKey.getTypeLiteral().toString();
        if (have.contains(want) || want.contains(have)) {
          Formatter fmt = new Formatter();
          Messages.formatSource(fmt, bindingMap.get(bindingKey).getSource());
          String match = String.format("%s bound%s", convert(bindingKey), fmt.toString());
          possibleMatches.add(match);
          // TODO: Consider a check that if there are more than some number of results,
          // don't suggest any.
          if (possibleMatches.size() > MAX_RELATED_TYPES_REPORTED) {
            // Early exit if we have found more than we need.
            break;
          }
        }
      }

      if ((possibleMatches.size() > 0) && (possibleMatches.size() <= MAX_RELATED_TYPES_REPORTED)) {
        sb.append(format("%n  Did you mean?"));
        for (String possibleMatch : possibleMatches) {
          sb.append(format("%n    %s", possibleMatch));
        }
      }
    }

    // If where are no possibilities to suggest, then handle the case of missing
    // annotations on simple types. This is usually a bad idea.
    if (sameTypes.isEmpty()
        && possibleMatches.isEmpty()
        && key.getAnnotationType() == null
        && COMMON_AMBIGUOUS_TYPES.contains(key.getTypeLiteral().getRawType())) {
      // We don't recommend using such simple types without annotations.
      sb.append(format("%nThe key seems very generic, did you forget an annotation?"));
    }

    return addMessage(sb.toString());
  }

  public Errors jitDisabled(Key<?> key) {
    return addMessage("Explicit bindings are required and %s is not explicitly bound.", key);
  }

  public Errors jitDisabledInParent(Key<?> key) {
    return addMessage(
        "Explicit bindings are required and %s would be bound in a parent injector.%n"
            + "Please add an explicit binding for it, either in the child or the parent.",
        key);
  }

  public Errors atInjectRequired(Class clazz) {
    return addMessage(
        "Explicit @Inject annotations are required on constructors,"
            + " but %s has no constructors annotated with @Inject.",
        clazz);
  }

  public Errors converterReturnedNull(
      String stringValue,
      Object source,
      TypeLiteral<?> type,
      TypeConverterBinding typeConverterBinding) {
    return addMessage(
        "Received null converting '%s' (bound at %s) to %s%n using %s.",
        stringValue, convert(source), type, typeConverterBinding);
  }

  public Errors conversionTypeError(
      String stringValue,
      Object source,
      TypeLiteral<?> type,
      TypeConverterBinding typeConverterBinding,
      Object converted) {
    return addMessage(
        "Type mismatch converting '%s' (bound at %s) to %s%n"
            + " using %s.%n"
            + " Converter returned %s.",
        stringValue, convert(source), type, typeConverterBinding, converted);
  }

  public Errors conversionError(
      String stringValue,
      Object source,
      TypeLiteral<?> type,
      TypeConverterBinding typeConverterBinding,
      RuntimeException cause) {
    return errorInUserCode(
        cause,
        "Error converting '%s' (bound at %s) to %s%n using %s.%n Reason: %s",
        stringValue,
        convert(source),
        type,
        typeConverterBinding,
        cause);
  }

  public Errors ambiguousTypeConversion(
      String stringValue,
      Object source,
      TypeLiteral<?> type,
      TypeConverterBinding a,
      TypeConverterBinding b) {
    return addMessage(
        "Multiple converters can convert '%s' (bound at %s) to %s:%n"
            + " %s and%n"
            + " %s.%n"
            + " Please adjust your type converter configuration to avoid overlapping matches.",
        stringValue, convert(source), type, a, b);
  }

  public Errors bindingToProvider() {
    return addMessage("Binding to Provider is not allowed.");
  }

  public Errors notASubtype(Class<?> implementationType, Class<?> type) {
    return addMessage("%s doesn't extend %s.", implementationType, type);
  }

  public Errors recursiveImplementationType() {
    return addMessage("@ImplementedBy points to the same class it annotates.");
  }

  public Errors recursiveProviderType() {
    return addMessage("@ProvidedBy points to the same class it annotates.");
  }

  public Errors missingRuntimeRetention(Class<? extends Annotation> annotation) {
    return addMessage(format("Please annotate %s with @Retention(RUNTIME).", annotation));
  }

  public Errors missingScopeAnnotation(Class<? extends Annotation> annotation) {
    return addMessage(format("Please annotate %s with @ScopeAnnotation.", annotation));
  }

  public Errors optionalConstructor(Constructor constructor) {
    return addMessage(
        "%s is annotated @Inject(optional=true), but constructors cannot be optional.",
        constructor);
  }

  public Errors cannotBindToGuiceType(String simpleName) {
    return addMessage("Binding to core guice framework type is not allowed: %s.", simpleName);
  }

  public Errors scopeNotFound(Class<? extends Annotation> scopeAnnotation) {
    return addMessage("No scope is bound to %s.", scopeAnnotation);
  }

  public Errors scopeAnnotationOnAbstractType(
      Class<? extends Annotation> scopeAnnotation, Class<?> type, Object source) {
    return addMessage(
        "%s is annotated with %s, but scope annotations are not supported "
            + "for abstract types.%n Bound at %s.",
        type, scopeAnnotation, convert(source));
  }

  public Errors misplacedBindingAnnotation(Member member, Annotation bindingAnnotation) {
    return addMessage(
        "%s is annotated with %s, but binding annotations should be applied "
            + "to its parameters instead.",
        member, bindingAnnotation);
  }

  // TODO(diamondm) don't mention zero-arg constructors if requireAtInjectOnConstructors is true
  private static final String CONSTRUCTOR_RULES =
      "Injectable classes must have either one (and only one) constructor annotated with @Inject"
          + " or a zero-argument constructor that is not private.";

  public Errors missingConstructor(TypeLiteral<?> type) {
    // Don't bother including the type in the message twice, unless the type is generic (i.e. the
    // type has generics that the raw class loses)
    String typeString = type.toString();
    String rawTypeString = getRawType(type.getType()).getName();
    return addMessage(
        "No implementation for %s (with no qualifier annotation) was bound, and could not find an"
            + " injectable constructor%s. %s",
        typeString,
        typeString.equals(rawTypeString) ? "" : " in " + rawTypeString,
        CONSTRUCTOR_RULES);
  }

  public Errors tooManyConstructors(Class<?> implementation) {
    return addMessage(
        "%s has more than one constructor annotated with @Inject. %s",
        implementation, CONSTRUCTOR_RULES);
  }

  public Errors constructorNotDefinedByType(Constructor<?> constructor, TypeLiteral<?> type) {
    return addMessage("%s does not define %s", type, constructor);
  }

  public Errors duplicateScopes(
      ScopeBinding existing, Class<? extends Annotation> annotationType, Scope scope) {
    return addMessage(
        "Scope %s is already bound to %s at %s.%n Cannot bind %s.",
        existing.getScope(), annotationType, existing.getSource(), scope);
  }

  public Errors voidProviderMethod() {
    return addMessage("Provider methods must return a value. Do not return void.");
  }

  public Errors missingConstantValues() {
    return addMessage("Missing constant value. Please call to(...).");
  }

  public Errors cannotInjectInnerClass(Class<?> type) {
    return addMessage(
        "Injecting into inner classes is not supported.  "
            + "Please use a 'static' class (top-level or nested) instead of %s.",
        type);
  }

  public Errors duplicateBindingAnnotations(
      Member member, Class<? extends Annotation> a, Class<? extends Annotation> b) {
    return addMessage(
        "%s has more than one annotation annotated with @BindingAnnotation: %s and %s",
        member, a, b);
  }

  public Errors staticInjectionOnInterface(Class<?> clazz) {
    return addMessage("%s is an interface, but interfaces have no static injection points.", clazz);
  }

  public Errors cannotInjectFinalField(Field field) {
    return addMessage("Injected field %s cannot be final.", field);
  }

  public Errors cannotInjectAbstractMethod(Method method) {
    return addMessage("Injected method %s cannot be abstract.", method);
  }

  public Errors cannotInjectNonVoidMethod(Method method) {
    return addMessage("Injected method %s must return void.", method);
  }

  public Errors cannotInjectMethodWithTypeParameters(Method method) {
    return addMessage("Injected method %s cannot declare type parameters of its own.", method);
  }

  public Errors duplicateScopeAnnotations(
      Class<? extends Annotation> a, Class<? extends Annotation> b) {
    return addMessage("More than one scope annotation was found: %s and %s.", a, b);
  }

  public Errors recursiveBinding() {
    return addMessage("Binding points to itself.");
  }

  public Errors bindingAlreadySet(Key<?> key, Object source) {
    return addMessage("A binding to %s was already configured at %s.", key, convert(source));
  }

  public Errors jitBindingAlreadySet(Key<?> key) {
    return addMessage(
        "A just-in-time binding to %s was already configured on a parent injector.", key);
  }

  public Errors childBindingAlreadySet(Key<?> key, Set<Object> sources) {
    Formatter allSources = new Formatter();
    for (Object source : sources) {
      if (source == null) {
        allSources.format("%n    (bound by a just-in-time binding)");
      } else {
        allSources.format("%n    bound at %s", source);
      }
    }
    Errors errors =
        addMessage(
            "Unable to create binding for %s."
                + " It was already configured on one or more child injectors or private modules"
                + "%s%n"
                + "  If it was in a PrivateModule, did you forget to expose the binding?",
            key, allSources.out());
    return errors;
  }

  public Errors errorCheckingDuplicateBinding(Key<?> key, Object source, Throwable t) {
    return addMessage(
        "A binding to %s was already configured at %s and an error was thrown "
            + "while checking duplicate bindings.  Error: %s",
        key, convert(source), t);
  }

  public Errors errorNotifyingTypeListener(
      TypeListenerBinding listener, TypeLiteral<?> type, Throwable cause) {
    return errorInUserCode(
        cause,
        "Error notifying TypeListener %s (bound at %s) of %s.%n Reason: %s",
        listener.getListener(),
        convert(listener.getSource()),
        type,
        cause);
  }

  public Errors exposedButNotBound(Key<?> key) {
    return addMessage("Could not expose() %s, it must be explicitly bound.", key);
  }

  public Errors keyNotFullySpecified(TypeLiteral<?> typeLiteral) {
    return addMessage("%s cannot be used as a key; It is not fully specified.", typeLiteral);
  }

  public Errors errorEnhancingClass(Class<?> clazz, Throwable cause) {
    return errorInUserCode(cause, "Unable to method intercept: %s", clazz);
  }

  public static Collection<Message> getMessagesFromThrowable(Throwable throwable) {
    if (throwable instanceof ProvisionException) {
      return ((ProvisionException) throwable).getErrorMessages();
    } else if (throwable instanceof ConfigurationException) {
      return ((ConfigurationException) throwable).getErrorMessages();
    } else if (throwable instanceof CreationException) {
      return ((CreationException) throwable).getErrorMessages();
    } else {
      return ImmutableSet.of();
    }
  }

  public Errors errorInUserCode(Throwable cause, String messageFormat, Object... arguments) {
    Collection<Message> messages = getMessagesFromThrowable(cause);

    if (!messages.isEmpty()) {
      return merge(messages);
    } else {
      return addMessage(cause, messageFormat, arguments);
    }
  }

  public Errors cannotInjectRawProvider() {
    return addMessage("Cannot inject a Provider that has no type parameter");
  }

  public Errors cannotInjectRawMembersInjector() {
    return addMessage("Cannot inject a MembersInjector that has no type parameter");
  }

  public Errors cannotInjectTypeLiteralOf(Type unsupportedType) {
    return addMessage("Cannot inject a TypeLiteral of %s", unsupportedType);
  }

  public Errors cannotInjectRawTypeLiteral() {
    return addMessage("Cannot inject a TypeLiteral that has no type parameter");
  }

  public void throwCreationExceptionIfErrorsExist() {
    if (!hasErrors()) {
      return;
    }

    throw new CreationException(getMessages());
  }

  public void throwConfigurationExceptionIfErrorsExist() {
    if (!hasErrors()) {
      return;
    }

    throw new ConfigurationException(getMessages());
  }

  // Guice no longer calls this, but external callers do
  public void throwProvisionExceptionIfErrorsExist() {
    if (!hasErrors()) {
      return;
    }

    throw new ProvisionException(getMessages());
  }

  public Errors merge(Collection<Message> messages) {
    List<Object> sources = getSources();
    for (Message message : messages) {
      addMessage(Messages.mergeSources(sources, message));
    }
    return this;
  }

  public Errors merge(Errors moreErrors) {
    if (moreErrors.root == root || moreErrors.root.errors == null) {
      return this;
    }

    merge(moreErrors.root.errors);
    return this;
  }

  public Errors merge(InternalProvisionException ipe) {
    merge(ipe.getErrors());
    return this;
  }

  private List<Object> getSources() {
    List<Object> sources = Lists.newArrayList();
    for (Errors e = this; e != null; e = e.parent) {
      if (e.source != SourceProvider.UNKNOWN_SOURCE) {
        sources.add(0, e.source);
      }
    }
    return sources;
  }

  public void throwIfNewErrors(int expectedSize) throws ErrorsException {
    if (size() == expectedSize) {
      return;
    }

    throw toException();
  }

  public ErrorsException toException() {
    return new ErrorsException(this);
  }

  public boolean hasErrors() {
    return root.errors != null;
  }

  public Errors addMessage(String messageFormat, Object... arguments) {
    return addMessage(null, messageFormat, arguments);
  }

  private Errors addMessage(Throwable cause, String messageFormat, Object... arguments) {
    addMessage(Messages.create(cause, getSources(), messageFormat, arguments));
    return this;
  }

  public Errors addMessage(Message message) {
    if (root.errors == null) {
      root.errors = Lists.newArrayList();
    }
    root.errors.add(message);
    return this;
  }

  // TODO(lukes): inline into callers
  public static String format(String messageFormat, Object... arguments) {
    return Messages.format(messageFormat, arguments);
  }

  public List<Message> getMessages() {
    if (root.errors == null) {
      return ImmutableList.of();
    }

    return new Ordering<Message>() {
      @Override
      public int compare(Message a, Message b) {
        return a.getSource().compareTo(b.getSource());
      }
    }.sortedCopy(root.errors);
  }

  public int size() {
    return root.errors == null ? 0 : root.errors.size();
  }

  // TODO(lukes): inline in callers.  There are some callers outside of guice, so this is difficult
  public static Object convert(Object o) {
    return Messages.convert(o);
  }

  // TODO(lukes): inline in callers.  There are some callers outside of guice, so this is difficult
  public static Object convert(Object o, ElementSource source) {
    return Messages.convert(o, source);
  }

  // TODO(lukes): inline in callers.  There are some callers outside of guice, so this is difficult
  public static void formatSource(Formatter formatter, Object source) {
    Messages.formatSource(formatter, source);
  }

}