com.yandex.ydb.core.Result Maven / Gradle / Ivy

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package com.yandex.ydb.core;

import java.util.Arrays;
import java.util.Objects;
import java.util.Optional;
import java.util.function.Function;

import javax.annotation.Nullable;

import com.google.common.base.Strings;


/**
 * @author Sergey Polovko
 */
public abstract class Result {

    public static  Result success(V value) {
        return new Success<>(value);
    }

    public static  Result fail(Status status) {
        return new Fail<>(status.getCode(), status.getIssues());
    }

    public static  Result fail(StatusCode code) {
        return new Fail<>(code, Issue.EMPTY_ARRAY);
    }

    public static  Result fail(StatusCode code, Issue... issues) {
        return new Fail<>(code, issues);
    }

    public static  Result error(Throwable throwable) {
        return new Error<>("", throwable);
    }

    public static  Result error(String message, Throwable throwable) {
        return new Error<>(message, throwable);
    }

    public boolean isSuccess() {
        return getCode() == StatusCode.SUCCESS;
    }

    public Status toStatus() {
        return Status.of(getCode(), getIssues());
    }

    public  Result cast() {
        @SuppressWarnings("unchecked")
        Result u = (Result) this;
        return u;
    }

    public abstract StatusCode getCode();

    public abstract Issue[] getIssues();

    public abstract T expect(String message);

    public abstract Optional ok();

    public abstract Optional error();

    public abstract  Result map(Function mapper);

    /**
     * SUCCESS
     */
    private static final class Success extends Result {
        @Nullable
        private final V value;

        Success(V value) {
            this.value = value;
        }

        @Override
        public StatusCode getCode() {
            return StatusCode.SUCCESS;
        }

        @Override
        public Issue[] getIssues() {
            return Issue.EMPTY_ARRAY;
        }

        @Override
        public V expect(String message) {
            return value;
        }

        @Override
        public Optional ok() {
            return Optional.ofNullable(value);
        }

        @Override
        public Optional error() {
            return Optional.empty();
        }

        @Override
        public  Result map(Function mapper) {
            return new Success<>(mapper.apply(value));
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Success success = (Success) o;
            return Objects.equals(value, success.value);
        }

        @Override
        public int hashCode() {
            return value != null ? value.hashCode() : 1337;
        }

        @Override
        public String toString() {
            return "Success{" + value + '}';
        }
    }

    /**
     * FAIL
     */
    private static final class Fail extends Result {
        private final StatusCode code;
        private final Issue[] issues;

        Fail(StatusCode code, Issue[] issues) {
            assert code != StatusCode.SUCCESS;
            this.code = Objects.requireNonNull(code, "code");
            this.issues = Objects.requireNonNull(issues, "issues");
        }

        @Override
        public StatusCode getCode() {
            return code;
        }

        @Override
        public Issue[] getIssues() {
            return issues;
        }

        @Override
        public V expect(String message) {
            throw newException(message);
        }

        @Override
        public Optional ok() {
            return Optional.empty();
        }

        @Override
        public Optional error() {
            return Optional.of(newException("error result"));
        }

        @SuppressWarnings("unchecked")
        @Override
        public  Result map(Function mapper) {
            return (Result) this;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Fail fail = (Fail) o;
            if (code != fail.code) return false;
            return Arrays.equals(issues, fail.issues);
        }

        @Override
        public int hashCode() {
            int result = code.hashCode();
            result = 31 * result + Arrays.hashCode(issues);
            return result;
        }

        @Override
        public String toString() {
            return "Fail{code=" + code + ", issues=" + Arrays.toString(issues) + '}';
        }

        private UnexpectedResultException newException(String message) {
            return new UnexpectedResultException(message, code, issues);
        }
    }

    /**
     * ERROR
     */
    private static final class Error extends Result {
        private final String message;
        @Nullable
        private final Throwable cause;

        Error(String message, Throwable cause) {
            this.message = Strings.nullToEmpty(message);
            this.cause = cause;
        }

        @Override
        public StatusCode getCode() {
            return StatusCode.CLIENT_INTERNAL_ERROR;
        }

        @Override
        public Issue[] getIssues() {
            return Issue.EMPTY_ARRAY;
        }

        @Override
        public V expect(String message) {
            if (!this.message.isEmpty()) {
                message += ": " + this.message;
            }
            throw new UnexpectedResultException(message, getCode(), cause);
        }

        @Override
        public Optional ok() {
            return Optional.empty();
        }

        @Override
        public Optional error() {
            return Optional.of(new UnexpectedResultException(message, getCode(), cause));
        }

        @SuppressWarnings("unchecked")
        @Override
        public  Result map(Function mapper) {
            return (Result) this;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Error error = (Error) o;
            if (!message.equals(error.message)) return false;
            return Objects.equals(cause, error.cause);
        }

        @Override
        public int hashCode() {
            return 31 * message.hashCode() + (cause != null ? cause.hashCode() : 0);
        }

        @Override
        public String toString() {
            return "Error{message=" + message + ", cause=" + cause + '}';
        }
    }
}