/*-
 * #%L
 * HAPI FHIR Server - SQL Migration
 * %%
 * Copyright (C) 2014 - 2024 Smile CDR, 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.
 * #L%
 */
package ca.uhn.fhir.jpa.migrate.taskdef;

import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.jpa.migrate.DriverTypeEnum;
import ca.uhn.fhir.jpa.migrate.HapiMigrationException;
import ca.uhn.fhir.system.HapiSystemProperties;
import org.apache.commons.lang3.Validate;
import org.apache.commons.lang3.builder.EqualsBuilder;
import org.apache.commons.lang3.builder.HashCodeBuilder;
import org.flywaydb.core.api.MigrationVersion;
import org.intellij.lang.annotations.Language;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.transaction.support.TransactionTemplate;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public abstract class BaseTask {

        public static final String MIGRATION_VERSION_PATTERN = "\\d{8}\\.\\d+";
        private static final Logger ourLog = LoggerFactory.getLogger(BaseTask.class);
        private static final Pattern versionPattern = Pattern.compile(MIGRATION_VERSION_PATTERN);
        private final String myProductVersion;
        private final String mySchemaVersion;
        private DriverTypeEnum.ConnectionProperties myConnectionProperties;
        private DriverTypeEnum myDriverType;
        private String myDescription;
        private Integer myChangesCount = 0;
        private boolean myDryRun;

        /**
         * Some migrations can not be run in a transaction.
         * When this is true, {@link BaseTask#executeSql} will run without a transaction
         */
        public void setTransactional(boolean theTransactional) {
                myTransactional = theTransactional;
        }

        private boolean myTransactional = true;
        private boolean myDoNothing;
        private List<ExecutedStatement> myExecutedStatements = new ArrayList<>();
        private Set<DriverTypeEnum> myOnlyAppliesToPlatforms = new HashSet<>();
        private boolean myNoColumnShrink;
        private boolean myFailureAllowed;
        private boolean myRunDuringSchemaInitialization;
        /**
         * Whether or not to check for existing tables
         * before generating SQL
         */
        protected boolean myCheckForExistingTables = true;

        /**
         * Whether or not to generate the SQL in a 'readable format'
         */
        protected boolean myPrettyPrint = false;

        protected BaseTask(String theProductVersion, String theSchemaVersion) {
                myProductVersion = theProductVersion;
                mySchemaVersion = theSchemaVersion;
        }

        public boolean isRunDuringSchemaInitialization() {
                return myRunDuringSchemaInitialization;
        }

        public void setPrettyPrint(boolean thePrettyPrint) {
                myPrettyPrint = thePrettyPrint;
        }

        /**
         * Should this task run even if we're doing the very first initialization of an empty schema. By
         * default we skip most tasks during that pass, since they just take up time and the
         * schema should be fully initialized by the {@link InitializeSchemaTask}
         */
        public void setRunDuringSchemaInitialization(boolean theRunDuringSchemaInitialization) {
                myRunDuringSchemaInitialization = theRunDuringSchemaInitialization;
        }

        public void setOnlyAppliesToPlatforms(Set<DriverTypeEnum> theOnlyAppliesToPlatforms) {
                Validate.notNull(theOnlyAppliesToPlatforms);
                myOnlyAppliesToPlatforms = theOnlyAppliesToPlatforms;
        }

        public String getProductVersion() {
                return myProductVersion;
        }

        public String getSchemaVersion() {
                return mySchemaVersion;
        }

        public boolean isNoColumnShrink() {
                return myNoColumnShrink;
        }

        public void setNoColumnShrink(boolean theNoColumnShrink) {
                myNoColumnShrink = theNoColumnShrink;
        }

        public boolean isDryRun() {
                return myDryRun;
        }

        public void setDryRun(boolean theDryRun) {
                myDryRun = theDryRun;
        }

        public String getDescription() {
                if (myDescription == null) {
                        return this.getClass().getSimpleName();
                }
                return myDescription;
        }

        public BaseTask setDescription(String theDescription) {
                myDescription = theDescription;
                return this;
        }

        public List<ExecutedStatement> getExecutedStatements() {
                return myExecutedStatements;
        }

        public int getChangesCount() {
                return myChangesCount;
        }

        /**
         * @param theTableName This is only used for logging currently
         * @param theSql       The SQL statement
         * @param theArguments The SQL statement arguments
         */
        public void executeSql(String theTableName, @Language("SQL") String theSql, Object... theArguments) {
                if (!isDryRun()) {
                        Integer changes;
                        if (myTransactional) {
                                changes = getConnectionProperties().getTxTemplate().execute(t -> doExecuteSql(theSql, theArguments));
                        } else {
                                changes = doExecuteSql(theSql, theArguments);
                        }

                        myChangesCount += changes;
                }

                captureExecutedStatement(theTableName, theSql, theArguments);
        }

        protected void executeSqlListInTransaction(String theTableName, List<String> theSqlStatements) {
                if (!isDryRun()) {
                        Integer changes;
                        changes = getConnectionProperties().getTxTemplate().execute(t -> doExecuteSqlList(theSqlStatements));
                        myChangesCount += changes;
                }

                for (@Language("SQL") String sqlStatement : theSqlStatements) {
                        captureExecutedStatement(theTableName, sqlStatement);
                }
        }

        private Integer doExecuteSqlList(List<String> theSqlStatements) {
                int changesCount = 0;
                for (String nextSql : theSqlStatements) {
                        changesCount += doExecuteSql(nextSql);
                }

                return changesCount;
        }

        private int doExecuteSql(@Language("SQL") String theSql, Object... theArguments) {
                JdbcTemplate jdbcTemplate = getConnectionProperties().newJdbcTemplate();
                // 0 means no timeout -- we use this for index rebuilds that may take time.
                jdbcTemplate.setQueryTimeout(0);
                try {
                        int changesCount = jdbcTemplate.update(theSql, theArguments);
                        if (!HapiSystemProperties.isUnitTestModeEnabled()) {
                                logInfo(ourLog, "SQL \"{}\" returned {}", theSql, changesCount);
                        }
                        return changesCount;
                } catch (DataAccessException e) {
                        if (myFailureAllowed) {
                                ourLog.info("Task {} did not exit successfully, but task is allowed to fail", getMigrationVersion());
                                ourLog.debug("Error was: {}", e.getMessage(), e);
                                return 0;
                        } else {
                                throw new HapiMigrationException(
                                                Msg.code(61) + "Failed during task " + getMigrationVersion() + ": " + e, e);
                        }
                }
        }

        protected void captureExecutedStatement(
                        String theTableName, @Language("SQL") String theSql, Object... theArguments) {
                myExecutedStatements.add(new ExecutedStatement(theTableName, theSql, theArguments));
        }

        public DriverTypeEnum.ConnectionProperties getConnectionProperties() {
                return myConnectionProperties;
        }

        public BaseTask setConnectionProperties(DriverTypeEnum.ConnectionProperties theConnectionProperties) {
                myConnectionProperties = theConnectionProperties;
                return this;
        }

        public DriverTypeEnum getDriverType() {
                return myDriverType;
        }

        public BaseTask setDriverType(DriverTypeEnum theDriverType) {
                myDriverType = theDriverType;
                return this;
        }

        public abstract void validate();

        public TransactionTemplate getTxTemplate() {
                return getConnectionProperties().getTxTemplate();
        }

        public JdbcTemplate newJdbcTemplate() {
                return getConnectionProperties().newJdbcTemplate();
        }

        private final List<ExecuteTaskPrecondition> myPreconditions = new ArrayList<>();

        public void execute() throws SQLException {
                if (myDoNothing) {
                        ourLog.info("Skipping stubbed task: {}", getDescription());
                        return;
                }
                if (!myOnlyAppliesToPlatforms.isEmpty()) {
                        if (!myOnlyAppliesToPlatforms.contains(getDriverType())) {
                                ourLog.info("Skipping task {} as it does not apply to {}", getDescription(), getDriverType());
                                return;
                        }
                }

                for (ExecuteTaskPrecondition precondition : myPreconditions) {
                        ourLog.debug("precondition to evaluate: {}", precondition);
                        if (!precondition.getPreconditionRunner().get()) {
                                ourLog.info(
                                                "Skipping task since one of the preconditions was not met: {}",
                                                precondition.getPreconditionReason());
                                return;
                        }
                }
                doExecute();
        }

        protected abstract void doExecute() throws SQLException;

        protected boolean isFailureAllowed() {
                return myFailureAllowed;
        }

        public void setFailureAllowed(boolean theFailureAllowed) {
                myFailureAllowed = theFailureAllowed;
        }

        public String getMigrationVersion() {
                String releasePart = myProductVersion;
                if (releasePart.startsWith("V")) {
                        releasePart = releasePart.substring(1);
                }
                String version = releasePart + "." + mySchemaVersion;
                MigrationVersion migrationVersion = MigrationVersion.fromVersion(version);
                return migrationVersion.getVersion();
        }

        protected void logInfo(Logger theLog, String theFormattedMessage, Object... theArguments) {
                theLog.info(getMigrationVersion() + ": " + theFormattedMessage, theArguments);
        }

        public void validateVersion() {
                Matcher matcher = versionPattern.matcher(mySchemaVersion);
                if (!matcher.matches()) {
                        throw new IllegalStateException(Msg.code(62) + "The version " + mySchemaVersion
                                        + " does not match the expected pattern " + MIGRATION_VERSION_PATTERN);
                }
        }

        public void doNothing() {
                setDoNothing(true);
        }

        public void failureAllowed() {
                setFailureAllowed(true);
        }

        public boolean isDoNothing() {
                return myDoNothing;
        }

        public BaseTask setDoNothing(boolean theDoNothing) {
                myDoNothing = theDoNothing;
                return this;
        }

        public void addPrecondition(ExecuteTaskPrecondition thePrecondition) {
                myPreconditions.add(thePrecondition);
        }

        @Override
        public final int hashCode() {
                HashCodeBuilder builder = new HashCodeBuilder();
                generateHashCode(builder);
                return builder.hashCode();
        }

        protected abstract void generateHashCode(HashCodeBuilder theBuilder);

        @Override
        public final boolean equals(Object theObject) {
                if (theObject == null || getClass().equals(theObject.getClass()) == false) {
                        return false;
                }
                @SuppressWarnings("unchecked")
                BaseTask otherObject = (BaseTask) theObject;

                EqualsBuilder b = new EqualsBuilder();
                generateEquals(b, otherObject);
                return b.isEquals();
        }

        protected abstract void generateEquals(EqualsBuilder theBuilder, BaseTask theOtherObject);

        public boolean initializedSchema() {
                return false;
        }

        public static class ExecutedStatement {
                private final String mySql;
                private final List<Object> myArguments;
                private final String myTableName;

                public ExecutedStatement(String theDescription, String theSql, Object[] theArguments) {
                        myTableName = theDescription;
                        mySql = theSql;
                        myArguments = theArguments != null ? Arrays.asList(theArguments) : Collections.emptyList();
                }

                public String getTableName() {
                        return myTableName;
                }

                public String getSql() {
                        return mySql;
                }

                public List<Object> getArguments() {
                        return myArguments;
                }
        }
}