/*
 * Copyright 2015-2022 Transmogrify LLC, 2022-2024 Revetware LLC.
 *
 * 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.pyranid;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.NotThreadSafe;
import javax.annotation.concurrent.ThreadSafe;
import java.time.Duration;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.stream.Collectors;

import static java.lang.String.format;
import static java.util.Objects.requireNonNull;

/**
 * A collection of SQL statement execution diagnostics.
 *
 * @author <a href="https://www.revetkn.com">Mark Allen</a>
 * @since 1.0.0
 */
@ThreadSafe
public class StatementLog<T> {
        @Nonnull
        private final StatementContext<T> statementContext;
        @Nonnull
        private final Duration totalDuration;
        @Nullable
        private final Duration connectionAcquisitionDuration;
        @Nullable
        private final Duration preparationDuration;
        @Nullable
        private final Duration executionDuration;
        @Nullable
        private final Duration resultSetMappingDuration;
        @Nullable
        private final Integer batchSize;
        @Nullable
        private final Exception exception;

        /**
         * Creates a {@code StatementLog} for the given {@code builder}.
         *
         * @param builder the builder used to construct this {@code StatementLog}
         */
        private StatementLog(@Nonnull Builder builder) {
                requireNonNull(builder);

                this.statementContext = requireNonNull(builder.statementContext);
                this.connectionAcquisitionDuration = builder.connectionAcquisitionDuration;
                this.preparationDuration = builder.preparationDuration;
                this.executionDuration = builder.executionDuration;
                this.resultSetMappingDuration = builder.resultSetMappingDuration;
                this.batchSize = builder.batchSize;
                this.exception = builder.exception;

                Duration totalDuration = Duration.ZERO;

                if (this.connectionAcquisitionDuration != null)
                        totalDuration = totalDuration.plus(this.connectionAcquisitionDuration);

                if (this.preparationDuration != null)
                        totalDuration = totalDuration.plus(this.preparationDuration);

                if (this.executionDuration != null)
                        totalDuration = totalDuration.plus(this.executionDuration);

                if (this.resultSetMappingDuration != null)
                        totalDuration = totalDuration.plus(this.resultSetMappingDuration);

                this.totalDuration = totalDuration;
        }

        /**
         * Creates a {@link StatementLog} builder for the given {@code statementContext}.
         *
         * @param statementContext current SQL context
         * @return a {@link StatementLog} builder
         */
        @Nonnull
        public static <T> Builder forStatementContext(@Nonnull StatementContext<T> statementContext) {
                requireNonNull(statementContext);
                return new Builder(statementContext);
        }

        @Override
        public String toString() {
                List<String> components = new ArrayList<>(8);

                components.add(format("statementContext=%s", getStatementContext()));
                components.add(format("totalDuration=%s", getTotalDuration()));

                Duration connectionAcquisitionDuration = getConnectionAcquisitionDuration().orElse(null);

                if (connectionAcquisitionDuration != null)
                        components.add(format("connectionAcquisitionDuration=%s", connectionAcquisitionDuration));

                Duration preparationDuration = getPreparationDuration().orElse(null);

                if (preparationDuration != null)
                        components.add(format("preparationDuration=%s", preparationDuration));

                Duration executionDuration = getExecutionDuration().orElse(null);

                if (executionDuration != null)
                        components.add(format("executionDuration=%s", executionDuration));

                Duration resultSetMappingDuration = getResultSetMappingDuration().orElse(null);

                if (resultSetMappingDuration != null)
                        components.add(format("resultSetMappingDuration=%s", resultSetMappingDuration));

                Integer batchSize = getBatchSize().orElse(null);

                if (batchSize != null)
                        components.add(format("batchSize=%s", batchSize));

                Exception exception = getException().orElse(null);

                if (exception != null)
                        components.add(format("exception=%s", exception));

                return format("%s{%s}", getClass().getSimpleName(), components.stream().collect(Collectors.joining(", ")));
        }

        @Override
        public boolean equals(Object object) {
                if (this == object)
                        return true;

                if (!(object instanceof StatementLog))
                        return false;

                StatementLog statementLog = (StatementLog) object;

                return Objects.equals(getStatementContext(), statementLog.getStatementContext())
                                && Objects.equals(getConnectionAcquisitionDuration(), statementLog.getConnectionAcquisitionDuration())
                                && Objects.equals(getPreparationDuration(), statementLog.getPreparationDuration())
                                && Objects.equals(getExecutionDuration(), statementLog.getExecutionDuration())
                                && Objects.equals(getResultSetMappingDuration(), statementLog.getResultSetMappingDuration())
                                && Objects.equals(getBatchSize(), statementLog.getBatchSize())
                                && Objects.equals(getException(), statementLog.getException());
        }

        @Override
        public int hashCode() {
                return Objects.hash(getStatementContext(), getConnectionAcquisitionDuration(), getPreparationDuration(),
                                getExecutionDuration(), getResultSetMappingDuration(), getBatchSize(), getException());
        }

        /**
         * How long did it take to acquire a {@link java.sql.Connection} from the {@link javax.sql.DataSource}?
         *
         * @return how long it took to acquire a {@link java.sql.Connection}, if available
         */
        @Nonnull
        public Optional<Duration> getConnectionAcquisitionDuration() {
                return Optional.ofNullable(this.connectionAcquisitionDuration);
        }

        /**
         * How long did it take to bind data to the {@link java.sql.PreparedStatement}?
         *
         * @return how long it took to bind data to the {@link java.sql.PreparedStatement}, if available
         */
        @Nonnull
        public Optional<Duration> getPreparationDuration() {
                return Optional.ofNullable(this.preparationDuration);
        }

        /**
         * How long did it take to execute the SQL statement?
         *
         * @return how long it took to execute the SQL statement, if available
         */
        public Optional<Duration> getExecutionDuration() {
                return Optional.ofNullable(this.executionDuration);
        }

        /**
         * How long did it take to extract data from the {@link java.sql.ResultSet}?
         *
         * @return how long it took to extract data from the {@link java.sql.ResultSet}, if available
         */
        public Optional<Duration> getResultSetMappingDuration() {
                return Optional.ofNullable(this.resultSetMappingDuration);
        }

        /**
         * How long did it take to perform the database operation in total?
         * <p>
         * This is the sum of {@link #getConnectionAcquisitionDuration()} + {@link #getPreparationDuration()} +
         * {@link #getExecutionDuration()} + {@link #getResultSetMappingDuration()}.
         *
         * @return how long the database operation took in total
         */
        @Nonnull
        public Duration getTotalDuration() {
                return this.totalDuration;
        }

        /**
         * The SQL statement that was executed.
         *
         * @return the SQL statement that was executed.
         */
        @Nonnull
        public StatementContext<T> getStatementContext() {
                return this.statementContext;
        }

        /**
         * The size of the batch operation.
         *
         * @return how many records were processed as part of the batch operation, if available
         */
        @Nonnull
        public Optional<Integer> getBatchSize() {
                return Optional.ofNullable(this.batchSize);
        }

        /**
         * The exception that occurred during SQL statement execution.
         *
         * @return the exception that occurred during SQL statement execution, if available
         */
        @Nonnull
        public Optional<Exception> getException() {
                return Optional.ofNullable(this.exception);
        }

        /**
         * Builder used to construct instances of {@link StatementLog}.
         * <p>
         * This class is intended for use by a single thread.
         *
         * @author <a href="https://www.revetkn.com">Mark Allen</a>
         * @since 1.0.0
         */
        @NotThreadSafe
        public static class Builder<T> {
                @Nonnull
                private final StatementContext<T> statementContext;
                @Nullable
                private Duration connectionAcquisitionDuration;
                @Nullable
                private Duration preparationDuration;
                @Nullable
                private Duration executionDuration;
                @Nullable
                private Duration resultSetMappingDuration;
                @Nullable
                private Integer batchSize;
                @Nullable
                private Exception exception;

                /**
                 * Creates a {@code Builder} for the given {@code statementContext}.
                 *
                 * @param statementContext current SQL context
                 */
                private Builder(@Nonnull StatementContext<T> statementContext) {
                        requireNonNull(statementContext);
                        this.statementContext = statementContext;
                }

                /**
                 * Specifies how long it took to acquire a {@link java.sql.Connection} from the {@link javax.sql.DataSource}.
                 *
                 * @param connectionAcquisitionDuration how long it took to acquire a {@link java.sql.Connection}, if available
                 * @return this {@code Builder}, for chaining
                 */
                @Nonnull
                public Builder connectionAcquisitionDuration(@Nullable Duration connectionAcquisitionDuration) {
                        this.connectionAcquisitionDuration = connectionAcquisitionDuration;
                        return this;
                }

                /**
                 * Specifies how long it took to bind data to a {@link java.sql.PreparedStatement}.
                 *
                 * @param preparationDuration how long it took to bind data to a {@link java.sql.PreparedStatement}, if available
                 * @return this {@code Builder}, for chaining
                 */
                public Builder preparationDuration(@Nullable Duration preparationDuration) {
                        this.preparationDuration = preparationDuration;
                        return this;
                }

                /**
                 * Specifies how long it took to execute a SQL statement.
                 *
                 * @param executionDuration how long it took to execute a SQL statement, if available
                 * @return this {@code Builder}, for chaining
                 */
                public Builder executionDuration(@Nullable Duration executionDuration) {
                        this.executionDuration = executionDuration;
                        return this;
                }

                /**
                 * Specifies how long it took to extract data from a {@link java.sql.ResultSet}.
                 *
                 * @param resultSetMappingDuration how long it took to extract data from a {@link java.sql.ResultSet}, if available
                 * @return this {@code Builder}, for chaining
                 */
                public Builder resultSetMappingDuration(@Nullable Duration resultSetMappingDuration) {
                        this.resultSetMappingDuration = resultSetMappingDuration;
                        return this;
                }

                /**
                 * Specifies the size of the batch operation.
                 *
                 * @param batchSize how many records were processed as part of the batch operation, if available
                 * @return this {@code Builder}, for chaining
                 */
                public Builder batchSize(@Nullable Integer batchSize) {
                        this.batchSize = batchSize;
                        return this;
                }

                /**
                 * Specifies the exception that occurred during SQL statement execution.
                 *
                 * @param exception the exception that occurred during SQL statement execution, if available
                 * @return this {@code Builder}, for chaining
                 */
                public Builder exception(@Nullable Exception exception) {
                        this.exception = exception;
                        return this;
                }

                /**
                 * Constructs a {@code StatementLog} instance.
                 *
                 * @return a {@code StatementLog} instance
                 */
                @Nonnull
                public StatementLog build() {
                        return new StatementLog(this);
                }
        }
}