// Copyright (C) 2021 The Android Open Source Project
//
// 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.gerrit.entities;

import com.google.auto.value.AutoValue;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.gson.Gson;
import com.google.gson.TypeAdapter;
import java.util.Optional;

/** Result of evaluating a submit requirement expression on a given Change. */
@AutoValue
public abstract class SubmitRequirementExpressionResult {

  /** Submit requirement expression for which this result is evaluated. */
  public abstract SubmitRequirementExpression expression();

  /** Status of evaluation. */
  public abstract Status status();

  /**
   * Optional error message. Populated if the evaluator fails to evaluate the expression for a
   * certain change.
   */
  public abstract Optional<String> errorMessage();

  /**
   * List leaf predicates that are fulfilled, for example the expression
   *
   * <p><i>label:Code-Review=+2 and branch:refs/heads/master</i>
   *
   * <p>has two leaf predicates:
   *
   * <ul>
   *   <li>label:Code-Review=+2
   *   <li>branch:refs/heads/master
   * </ul>
   *
   * This method will return the leaf predicates that were fulfilled, for example if only the first
   * predicate was fulfilled, the returned list will be equal to ["label:Code-Review=+2"].
   */
  public abstract ImmutableList<String> passingAtoms();

  /**
   * List of leaf predicates that are not fulfilled. See {@link #passingAtoms()} for more details.
   */
  public abstract ImmutableList<String> failingAtoms();

  /**
   * Map of leaf predicates to their explanations.
   *
   * <p>This is used to provide more information about complex atoms, which may otherwise be opaque
   * and hard to debug.
   *
   * <p>This will only be populated/implemented for some atoms.
   */
  public abstract Optional<ImmutableMap<String, String>> atomExplanations();

  public static SubmitRequirementExpressionResult create(
      SubmitRequirementExpression expression, PredicateResult predicateResult) {
    return create(
        expression,
        predicateResult.status() ? Status.PASS : Status.FAIL,
        predicateResult.getPassingAtoms(),
        predicateResult.getFailingAtoms(),
        Optional.of(predicateResult.getAtomExplanations()));
  }

  public static SubmitRequirementExpressionResult create(
      SubmitRequirementExpression expression,
      Status status,
      ImmutableList<String> passingAtoms,
      ImmutableList<String> failingAtoms) {
    return create(expression, status, passingAtoms, failingAtoms, Optional.empty());
  }

  public static SubmitRequirementExpressionResult create(
      SubmitRequirementExpression expression,
      Status status,
      ImmutableList<String> passingAtoms,
      ImmutableList<String> failingAtoms,
      Optional<ImmutableMap<String, String>> atomExplanations) {
    return create(
        expression, status, passingAtoms, failingAtoms, atomExplanations, Optional.empty());
  }

  public static SubmitRequirementExpressionResult create(
      SubmitRequirementExpression expression,
      Status status,
      ImmutableList<String> passingAtoms,
      ImmutableList<String> failingAtoms,
      Optional<ImmutableMap<String, String>> atomExplanations,
      Optional<String> errorMessage) {
    return new AutoValue_SubmitRequirementExpressionResult(
        expression, status, errorMessage, passingAtoms, failingAtoms, atomExplanations);
  }

  public static SubmitRequirementExpressionResult error(
      SubmitRequirementExpression expression, String errorMessage) {
    return new AutoValue_SubmitRequirementExpressionResult(
        expression,
        Status.ERROR,
        Optional.of(errorMessage),
        ImmutableList.of(),
        ImmutableList.of(),
        Optional.empty());
  }

  public static SubmitRequirementExpressionResult notEvaluated(SubmitRequirementExpression expr) {
    return SubmitRequirementExpressionResult.create(
        expr, Status.NOT_EVALUATED, ImmutableList.of(), ImmutableList.of());
  }

  public static TypeAdapter<SubmitRequirementExpressionResult> typeAdapter(Gson gson) {
    return new AutoValue_SubmitRequirementExpressionResult.GsonTypeAdapter(gson);
  }

  public abstract Builder toBuilder();

  @AutoValue.Builder
  public abstract static class Builder {
    public abstract Builder expression(SubmitRequirementExpression expression);

    public abstract Builder status(Status status);

    public abstract Builder errorMessage(Optional<String> errorMessage);

    public abstract Builder passingAtoms(ImmutableList<String> passingAtoms);

    public abstract Builder failingAtoms(ImmutableList<String> failingAtoms);

    public abstract Builder atomExplanations(
        Optional<ImmutableMap<String, String>> atomExplanations);

    public abstract SubmitRequirementExpressionResult build();
  }

  public enum Status {
    /** Submit requirement expression is fulfilled for a given change. */
    PASS,

    /** Submit requirement expression is failing for a given change. */
    FAIL,

    /** Submit requirement expression contains invalid syntax and is not parsable. */
    ERROR,

    /** Submit requirement expression was not evaluated. */
    NOT_EVALUATED
  }
}