/*-
 * #%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;

import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.jpa.migrate.dao.HapiMigrationDao;
import ca.uhn.fhir.jpa.migrate.taskdef.BaseTask;
import ca.uhn.fhir.jpa.migrate.taskdef.InitializeSchemaTask;
import ca.uhn.fhir.jpa.migrate.tasks.api.TaskFlagEnum;
import ca.uhn.fhir.system.HapiSystemProperties;
import ca.uhn.fhir.util.StopWatch;
import com.google.common.annotations.VisibleForTesting;
import jakarta.annotation.Nonnull;
import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.SQLException;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import javax.sql.DataSource;

import static org.apache.commons.lang3.StringUtils.isBlank;

public class HapiMigrator {

        private static final Logger ourLog = LoggerFactory.getLogger(HapiMigrator.class);
        private final MigrationTaskList myTaskList = new MigrationTaskList();
        private boolean myDryRun;
        private boolean myRunHeavyweightSkippableTasks;
        private boolean myNoColumnShrink;
        private final DriverTypeEnum myDriverType;
        private final DataSource myDataSource;
        private final HapiMigrationStorageSvc myHapiMigrationStorageSvc;
        private List<IHapiMigrationCallback> myCallbacks = Collections.emptyList();

        public HapiMigrator(String theMigrationTableName, DataSource theDataSource, DriverTypeEnum theDriverType) {
                myDriverType = theDriverType;
                myDataSource = theDataSource;
                myHapiMigrationStorageSvc =
                                new HapiMigrationStorageSvc(new HapiMigrationDao(theDataSource, theDriverType, theMigrationTableName));
        }

        public DataSource getDataSource() {
                return myDataSource;
        }

        /**
         * If set to true, instead of executing migrations, will instead simply print the SQL that would be executed against the connection.
         * @return A boolean indicating whether or not the migration should be a dry run
         */
        public boolean isDryRun() {
                return myDryRun;
        }

        /**
         * If set to true, instead of executing migrations, will instead simply print the SQL that would be executed against the connection.
         */
        public void setDryRun(boolean theDryRun) {
                myDryRun = theDryRun;
        }

        /**
         * Should we run the tasks marked with {@link ca.uhn.fhir.jpa.migrate.tasks.api.TaskFlagEnum#HEAVYWEIGHT_SKIP_BY_DEFAULT}
         *
         * @since 7.4.0
         */
        public boolean isRunHeavyweightSkippableTasks() {
                return myRunHeavyweightSkippableTasks;
        }

        /**
         * Should we run the tasks marked with {@link ca.uhn.fhir.jpa.migrate.tasks.api.TaskFlagEnum#HEAVYWEIGHT_SKIP_BY_DEFAULT}
         *
         * @since 7.4.0
         */
        public void setRunHeavyweightSkippableTasks(boolean theRunHeavyweightSkippableTasks) {
                myRunHeavyweightSkippableTasks = theRunHeavyweightSkippableTasks;
        }

        public boolean isNoColumnShrink() {
                return myNoColumnShrink;
        }

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

        public DriverTypeEnum getDriverType() {
                return myDriverType;
        }

        protected StringBuilder buildExecutedStatementsString(MigrationResult theMigrationResult) {
                StringBuilder statementBuilder = new StringBuilder();
                String lastTable = null;
                for (BaseTask.ExecutedStatement next : theMigrationResult.executedStatements) {
                        if (!Objects.equals(lastTable, next.getTableName())) {
                                statementBuilder
                                                .append("\n\n-- Table: ")
                                                .append(next.getTableName())
                                                .append("\n");
                                lastTable = next.getTableName();
                        }

                        statementBuilder.append(next.getSql()).append(";\n");

                        for (Object nextArg : next.getArguments()) {
                                statementBuilder.append("  -- Arg: ").append(nextArg).append("\n");
                        }
                }
                return statementBuilder;
        }

        /**
         * Helper method to clear a lock with a given UUID.
         * @param theUUID the
         */
        public void clearMigrationLockWithUUID(String theUUID) {
                ourLog.info("Attempting to remove lock entry. [uuid={}]", theUUID);
                boolean success = myHapiMigrationStorageSvc.deleteLockRecord(theUUID);
                if (success) {
                        ourLog.info("Successfully removed lock entry. [uuid={}]", theUUID);
                } else {
                        ourLog.error("Did not successfully remove lock entry. [uuid={}]", theUUID);
                }
        }

        public MigrationResult migrate() {
                ourLog.info("Loaded {} migration tasks", myTaskList.size());
                MigrationResult retval = new MigrationResult();

                // Lock the migration table so only one server migrates the database at once
                try (HapiMigrationLock ignored = new HapiMigrationLock(myHapiMigrationStorageSvc)) {
                        MigrationTaskList newTaskList = myHapiMigrationStorageSvc.diff(myTaskList);
                        ourLog.info(
                                        "{} of these {} migration tasks are new.  Executing them now.",
                                        newTaskList.size(),
                                        myTaskList.size());

                        try (DriverTypeEnum.ConnectionProperties connectionProperties =
                                        getDriverType().newConnectionProperties(getDataSource())) {

                                if (!isRunHeavyweightSkippableTasks()) {
                                        newTaskList.removeIf(BaseTask::isHeavyweightSkippableTask);
                                }

                                boolean initializedSchema = false;
                                for (BaseTask next : newTaskList) {
                                        if (initializedSchema && !next.hasFlag(TaskFlagEnum.RUN_DURING_SCHEMA_INITIALIZATION)) {
                                                ourLog.info("Skipping task {} because schema is being initialized", next.getMigrationVersion());
                                                recordTaskAsCompletedIfNotDryRun(next, 0L, true);
                                                continue;
                                        }

                                        next.setDriverType(getDriverType());
                                        next.setDryRun(isDryRun());
                                        next.setNoColumnShrink(isNoColumnShrink());
                                        next.setConnectionProperties(connectionProperties);

                                        executeTask(next, retval);

                                        initializedSchema |= next.initializedSchema();
                                }
                        }
                } catch (Exception e) {
                        ourLog.error("Migration failed", e);
                        throw e;
                }

                ourLog.info(retval.summary());

                if (isDryRun()) {
                        StringBuilder statementBuilder = buildExecutedStatementsString(retval);
                        ourLog.info(
                                        "SQL that would be executed:\n\n***********************************\n{}***********************************",
                                        statementBuilder);
                }

                return retval;
        }

        private void executeTask(BaseTask theTask, MigrationResult theMigrationResult) {
                StopWatch sw = new StopWatch();
                try {
                        if (isDryRun()) {
                                ourLog.info("Dry run {} {}", theTask.getMigrationVersion(), theTask.getDescription());
                        } else {
                                ourLog.info("Executing {} {}", theTask.getMigrationVersion(), theTask.getDescription());
                        }
                        preExecute(theTask);
                        theTask.execute();
                        recordTaskAsCompletedIfNotDryRun(theTask, sw.getMillis(), true);
                        theMigrationResult.changes += theTask.getChangesCount();
                        theMigrationResult.executedStatements.addAll(theTask.getExecutedStatements());
                        theMigrationResult.succeededTasks.add(theTask);
                } catch (SQLException | HapiMigrationException e) {
                        theMigrationResult.failedTasks.add(theTask);
                        recordTaskAsCompletedIfNotDryRun(theTask, sw.getMillis(), false);
                        String description = theTask.getDescription();
                        if (isBlank(description)) {
                                description = theTask.getClass().getSimpleName();
                        }
                        String prefix = String.format(
                                        "Failure executing task '%s', for driver: %s, aborting! Cause: ", description, getDriverType());
                        throw new HapiMigrationException(Msg.code(47) + prefix + e, theMigrationResult, e);
                }
        }

        private void preExecute(BaseTask theTask) {
                myCallbacks.forEach(action -> action.preExecution(theTask));
        }

        private void recordTaskAsCompletedIfNotDryRun(BaseTask theNext, long theExecutionMillis, boolean theSuccess) {
                if (!theNext.isDryRun()) {
                        myHapiMigrationStorageSvc.saveTask(theNext, Math.toIntExact(theExecutionMillis), theSuccess);
                }
        }

        public void addTasks(Iterable<BaseTask> theMigrationTasks) {
                if (HapiSystemProperties.isUnitTestModeEnabled()) {
                        // Tests only need to initialize the schemas. No need to run all the migrations for every test.
                        for (BaseTask task : theMigrationTasks) {
                                if (task instanceof InitializeSchemaTask) {
                                        addTask(task);
                                }
                        }
                } else {
                        myTaskList.append(theMigrationTasks);
                }
        }

        public void addTask(BaseTask theTask) {
                myTaskList.add(theTask);
        }

        public void setCallbacks(@Nonnull List<IHapiMigrationCallback> theCallbacks) {
                Validate.notNull(theCallbacks, "theCallbacks must not be null");
                myCallbacks = theCallbacks;
        }

        @VisibleForTesting
        public void removeAllTasksForUnitTest() {
                myTaskList.clear();
        }

        public void createMigrationTableIfRequired() {
                if (!myDryRun) {
                        myHapiMigrationStorageSvc.createMigrationTableIfRequired();
                }
        }
}