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/*
 * 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.opentable.metrics.ready;

import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Objects;

/**
 * The result of a {@link ReadyCheck} being run. It can be ready (with an optional message and optional details)
 * or unready (with either an error message or a thrown exception and optional details).
 */
public class Result {

    private final boolean ready;
    private final String message;
    private final Throwable error;
    private final String timestamp =
            DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSXXX").format(ZonedDateTime.now());

    public Result(boolean isReady, String message, Throwable error) {
        this.ready = isReady;
        this.message = message;
        this.error = error;
    }


    /**
     * Returns a ready {@link Result} with no additional message.
     *
     * @return a ready {@link Result} with no additional message
     */
    public static Result ready() {
        return new Result(true, null, null);
    }

    /**
     * Returns a ready {@link Result} with an additional message.
     *
     * @param message an informative message
     * @return a ready {@link Result} with an additional message
     */
    public static Result ready(String message) {
        return new Result(true, message, null);
    }

    /**
     * Returns a ready {@link Result} with a formatted message.
     * 
     * Message formatting follows the same rules as {@link String#format(String, Object...)}.
     *
     * @param message a message format
     * @param args    the arguments apply to the message format
     * @return a ready {@link Result} with an additional message
     * @see String#format(String, Object...)
     */
    public static Result ready(String message, Object... args) {
        return ready(String.format(message, args));
    }

    /**
     * Returns an unready {@link Result} with the given message.
     *
     * @param message an informative message describing how the ready check failed
     * @return an unready {@link Result} with the given message
     */
    public static Result unready(String message) {
        return new Result(false, message, null);
    }

    /**
     * Returns an unready {@link Result} with a formatted message.
     * 
     * Message formatting follows the same rules as {@link String#format(String, Object...)}.
     *
     * @param message a message format
     * @param args    the arguments apply to the message format
     * @return an unready {@link Result} with an additional message
     * @see String#format(String, Object...)
     */
    public static Result unready(String message, Object... args) {
        return unready(String.format(message, args));
    }

    /**
     * Returns an unready {@link Result} with the given error.
     *
     * @param error an exception thrown during the ready check
     * @return an unready {@link Result} with the given {@code error}
     */
    public static Result unready(Throwable error) {
        return new Result(false, error.getMessage(), error);
    }

    /**
     * Returns {@code true} if the result indicates the component is ready; {@code false}
     * otherwise.
     *
     * @return {@code true} if the result indicates the component is ready
     */
    public boolean isReady() {
        return ready;
    }

    /**
     * Returns any additional message for the result, or {@code null} if the result has no
     * message.
     *
     * @return any additional message for the result, or {@code null}
     */
    public String getMessage() {
        return message;
    }

    /**
     * Returns any exception for the result, or {@code null} if the result has no exception.
     *
     * @return any exception for the result, or {@code null}
     */
    public Throwable getError() {
        return error;
    }

    /**
     * Returns the timestamp when the result was created.
     *
     * @return a formatted timestamp
     */
    public String getTimestamp() {
        return timestamp;
    }

    @Override
    public boolean equals(final Object o) {
        if (this == o)  {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        final Result result = (Result) o;
        return ready == result.ready &&
                Objects.equals(message, result.message) &&
                Objects.equals(error, result.error) &&
                Objects.equals(timestamp, result.timestamp);
    }

    @Override
    public int hashCode() {
        return Objects.hash(ready, message, error, timestamp);
    }

    @Override
    public String toString() {
        final StringBuilder builder = new StringBuilder("Result{isReady=");
        builder.append(ready);
        if (message != null) {
            builder.append(", message=").append(message);
        }
        if (error != null) {
            builder.append(", error=").append(error);
        }
        builder.append(", timestamp=").append(timestamp);
        builder.append('}');
        return builder.toString();
    }
}