/*
 * 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 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.
 *
 * <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 */
  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 */
  private static final int MAX_RELATED_TYPES_REPORTED = 3;

  /**
   * 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 {@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.
   */
  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. */
  private final Errors root;

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

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

  /** 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 {@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:
   *
   * <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 */
  <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.getAnnotation() == 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);
  }

  private static final String CONSTRUCTOR_RULES =
      "Classes must have either one (and only one) constructor "
          + "annotated with @Inject or a zero-argument constructor that is not private.";

  public Errors missingConstructor(Class<?> implementation) {
    return addMessage(
        "Could not find a suitable constructor in %s. " + CONSTRUCTOR_RULES, implementation);
  }

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

  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);
  }

}