/*
    *    Copyright 2010-2023 the original author or authors.
    *
    *    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
    *
    *       https://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 org.apache.ibatis.migration.operations;
  
  import java.io.PrintStream;
  import java.io.Reader;
  import java.sql.Connection;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.ibatis.migration.Change;
  import org.apache.ibatis.migration.ConnectionProvider;
  import org.apache.ibatis.migration.MigrationException;
  import org.apache.ibatis.migration.MigrationLoader;
  import org.apache.ibatis.migration.hook.HookContext;
  import org.apache.ibatis.migration.hook.MigrationHook;
  import org.apache.ibatis.migration.options.DatabaseOperationOption;
  import org.apache.ibatis.migration.utils.Util;
  
  public final class PendingOperation extends DatabaseOperation {
  
    public PendingOperation operate(ConnectionProvider connectionProvider, MigrationLoader migrationsLoader,
        DatabaseOperationOption option, PrintStream printStream) {
      return operate(connectionProvider, migrationsLoader, option, printStream, null);
    }
  
    public PendingOperation operate(ConnectionProvider connectionProvider, MigrationLoader migrationsLoader,
        DatabaseOperationOption option, PrintStream printStream, MigrationHook hook) {
      try (Connection con = connectionProvider.getConnection()) {
        if (option == null) {
          option = new DatabaseOperationOption();
        }
        if (!changelogExists(con, option)) {
          throw new MigrationException("Change log doesn't exist, no migrations applied.  Try running 'up' instead.");
        }
        List<Change> pending = getPendingChanges(con, migrationsLoader, option);
        int stepCount = 0;
        Map<String, Object> hookBindings = new HashMap<>();
        println(printStream, "WARNING: Running pending migrations out of order can create unexpected results.");
        try {
          ScriptRunner runner = getScriptRunner(con, option, printStream);
          for (Change change : pending) {
            if (stepCount == 0 && hook != null) {
              hookBindings.put(MigrationHook.HOOK_CONTEXT, new HookContext(connectionProvider, runner, null));
              hook.before(hookBindings);
            }
            if (hook != null) {
              hookBindings.put(MigrationHook.HOOK_CONTEXT,
                  new HookContext(connectionProvider, runner, new Change(change)));
              hook.beforeEach(hookBindings);
            }
            println(printStream, Util.horizontalLine("Applying: " + change.getFilename(), 80));
            try (Reader scriptReader = migrationsLoader.getScriptReader(change, false)) {
              runner.runScript(scriptReader);
            }
            insertChangelog(change, con, option);
            println(printStream);
            if (hook != null) {
              hookBindings.put(MigrationHook.HOOK_CONTEXT,
                  new HookContext(connectionProvider, runner, new Change(change)));
              hook.afterEach(hookBindings);
            }
            stepCount++;
          }
          if (stepCount > 0 && hook != null) {
            hookBindings.put(MigrationHook.HOOK_CONTEXT, new HookContext(connectionProvider, runner, null));
            hook.after(hookBindings);
          }
          return this;
        } catch (Exception e) {
          throw new MigrationException("Error executing command.  Cause: " + e, e);
        }
      } catch (Throwable e) {
        while (e instanceof MigrationException && e.getCause() != null) {
          e = e.getCause();
        }
        throw new MigrationException("Error executing command.  Cause: " + e, e);
      }
    }
  
    private List<Change> getPendingChanges(Connection con, MigrationLoader migrationsLoader,
        DatabaseOperationOption option) {
      List<Change> pending = new ArrayList<>();
     List<Change> migrations = migrationsLoader.getMigrations();
     List<Change> changelog = getChangelog(con, option);
     for (Change change : migrations) {
       int index = changelog.indexOf(change);
       if (index < 0) {
         pending.add(change);
       }
     }
     Collections.sort(pending);
     return pending;
   }
 }