/*
 * QQQ - Low-code Application Framework for Engineers.
 * Copyright (C) 2021-2025.  Kingsrook, LLC
 * 651 N Broad St Ste 205 # 6917 | Middletown DE 19709 | United States
 * contact@kingsrook.com
 * https://github.com/Kingsrook/
 *
 * 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 com.kingsrook.qbits.documentgeneration;


import java.sql.Connection;
import java.sql.DriverManager;
import java.util.UUID;
import com.kingsrook.qqq.backend.module.postgres.model.metadata.PostgreSQLBackendMetaData;
import com.kingsrook.qqq.backend.module.rdbms.jdbc.ConnectionManager;
import com.kingsrook.qqq.backend.module.rdbms.model.metadata.RDBMSBackendMetaData;
import org.testcontainers.containers.GenericContainer;
import org.testcontainers.containers.wait.strategy.Wait;


/*******************************************************************************
 ** Disposable synthetic PostgreSQL 17 engine on a dynamic loopback port. The
 ** superuser is fixture-only migration authority; native QQQ connections use a
 ** separate DML-only role with bounded lock_timeout. No shared volume or data.
 *******************************************************************************/
final class PostgresGenerationDatabase implements AutoCloseable
{
   private static final String IMAGE = "postgres:17";
   private static final String OPTIONS = "?connectTimeout=5&socketTimeout=20&options=-c%20TimeZone%3DUTC";
   private final String rootPassword = UUID.randomUUID().toString();
   private final String appPassword = UUID.randomUUID().toString();
   private final GenericContainer<?> container;
   private String schema;
   private String server;
   private RDBMSBackendMetaData backend;
   private final java.util.TimeZone previousZone;

   /***************************************************************************
    ** Starts only this suite's loopback container with durable settings.
    ***************************************************************************/
   PostgresGenerationDatabase()
   {
      this(true);
   }

   /***************************************************************************
    ** Pinned durability settings come from the server command line, which no
    ** ALTER SYSTEM can override. An unpinned engine starts with the same values
    ** (the PostgreSQL defaults) and lets a test weaken them through system().
    ***************************************************************************/
   PostgresGenerationDatabase(boolean pinned)
   {
      // pgjdbc announces the JVM zone as the session TimeZone; qualification requires UTC.
      previousZone = java.util.TimeZone.getDefault();
      java.util.TimeZone.setDefault(java.util.TimeZone.getTimeZone("UTC"));
      container = new GenericContainer<>(IMAGE)
         .withEnv("POSTGRES_PASSWORD", rootPassword).withEnv("POSTGRES_DB", "bootstrap")
         .withCommand(pinned ? new String[] { "postgres", "-c", "fsync=on", "-c", "synchronous_commit=on", "-c", "full_page_writes=on", "-c", "max_connections=60" }
            : new String[] { "postgres", "-c", "max_connections=60" })
         .withExposedPorts(5432)
         .withCreateContainerCmdModifier(command -> command.getHostConfig().withMemory(768L * 1024 * 1024).withNanoCPUs(2_000_000_000L)
            .withPortBindings(FixtureEndpoint.publishedBinding(5432)))
         .waitingFor(Wait.forLogMessage(".*database system is ready to accept connections.*\\s", 2).withStartupTimeout(java.time.Duration.ofMinutes(2)));
      try
      {
         container.start();
         refreshEndpoint();
         try(var connection = DriverManager.getConnection(server + "bootstrap" + OPTIONS, "postgres", rootPassword); var statement = connection.createStatement())
         {
            statement.execute("CREATE ROLE generation_app LOGIN PASSWORD '" + appPassword + "' NOSUPERUSER NOCREATEDB NOCREATEROLE");
            statement.execute("ALTER ROLE generation_app SET lock_timeout='5s'");
         }
      }
      catch(Exception failure)
      {
         try
         {
            close();
         }
         catch(RuntimeException cleanup)
         {
            failure.addSuppressed(cleanup);
         }
         throw new IllegalStateException("PostgreSQL fixture failed to start", failure);
      }
   }

   /***************************************************************************
    ** Every inherited test receives a fresh database and the DML-only identity.
    ***************************************************************************/
   RDBMSBackendMetaData database(String name) throws Exception
   {
      schema = "generation_" + UUID.randomUUID().toString().replace("-", "");
      try(var connection = DriverManager.getConnection(server + "bootstrap" + OPTIONS, "postgres", rootPassword); var statement = connection.createStatement())
      {
         statement.execute("CREATE DATABASE " + schema);
         statement.execute("REVOKE ALL ON DATABASE " + schema + " FROM PUBLIC");
         statement.execute("GRANT CONNECT ON DATABASE " + schema + " TO generation_app");
      }
      try(var connection = connection(); var statement = connection.createStatement())
      {
         statement.execute("GRANT USAGE ON SCHEMA public TO generation_app");
         statement.execute("ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT, INSERT, UPDATE, DELETE ON TABLES TO generation_app");
         statement.execute("ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT USAGE, SELECT ON SEQUENCES TO generation_app");
      }
      backend = new PostgreSQLBackendMetaData();
      backend.setName(name);
      backend.setDatabaseName(schema);
      backend.setUsername("generation_app");
      backend.setPassword(appPassword);
      backend.setJdbcUrl(server + schema + OPTIONS);
      return (backend);
   }

   /***************************************************************************
    ** Separate owned fixture connection for migrations/assertions/fault injection.
    ***************************************************************************/
   Connection connection() throws Exception
   {
      return (DriverManager.getConnection(server + schema + OPTIONS, "postgres", rootPassword));
   }

   /***************************************************************************
    ** Translate only the known fixture-specific H2 statements, never application SQL.
    ***************************************************************************/
   void sql(String source) throws Exception
   {
      if(source.equals("INSERT INTO document_generation_item (state) SELECT 'QUEUED' FROM SYSTEM_RANGE(1,10000)"))
      {
         source = "INSERT INTO document_generation_item (state) SELECT 'QUEUED' FROM generate_series(1,10000)";
      }
      try(var connection = connection(); var statement = connection.createStatement())
      {
         for(String sql : source.split(";"))
         {
            if(!sql.isBlank())
            {
               statement.execute(sql);
            }
         }
      }
   }

   /***************************************************************************
    ** Change one reloadable server setting of an unpinned engine (ALTER SYSTEM and
    ** a configuration reload), then wait until a new session actually reports it.
    ** Fixed fixture names and values only, never application input.
    ***************************************************************************/
   void system(String name, String value) throws Exception
   {
      ConnectionManager.closeConnectionProviders();
      try(var connection = DriverManager.getConnection(server + "bootstrap" + OPTIONS, "postgres", rootPassword); var statement = connection.createStatement())
      {
         statement.execute("ALTER SYSTEM SET " + name + " = '" + value + "'");
         statement.execute("SELECT pg_reload_conf()");
      }
      long deadline = System.nanoTime() + java.time.Duration.ofSeconds(30).toNanos();
      while(true)
      {
         try(var connection = DriverManager.getConnection(server + "bootstrap" + OPTIONS, "postgres", rootPassword); var statement = connection.createStatement();
            var row = statement.executeQuery("SELECT current_setting('" + name + "')"))
         {
            if(row.next() && value.equals(row.getString(1)))
            {
               return;
            }
         }
         if(System.nanoTime() >= deadline)
         {
            throw new IllegalStateException("PostgreSQL fixture did not apply " + name);
         }
         Thread.sleep(100);
      }
   }

   /***************************************************************************
    ** Cold server restart retains only this container's data layer (committed
    ** data must survive; Docker may publish a different loopback port).
    ***************************************************************************/
   void restart() throws Exception
   {
      ConnectionManager.closeConnectionProviders();
      container.getDockerClient().stopContainerCmd(container.getContainerId()).withTimeout(10).exec();
      container.getDockerClient().startContainerCmd(container.getContainerId()).exec();
      refreshEndpoint();
      backend.setJdbcUrl(server + schema + OPTIONS);
      long deadline = System.nanoTime() + java.time.Duration.ofSeconds(60).toNanos();
      while(true)
      {
         try(var connection = connection())
         {
            if(connection.isValid(2))
            {
               return;
            }
         }
         catch(java.sql.SQLException unavailable)
         {
            if(System.nanoTime() >= deadline)
            {
               throw unavailable;
            }
         }
         Thread.sleep(200);
      }
   }

   /***************************************************************************
    ** Native inspect avoids Testcontainers' stale mapped-port cache after restart.
    ***************************************************************************/
   private void refreshEndpoint()
   {
      var address = FixtureEndpoint.of(container, 5432);
      server = "jdbc:postgresql://" + address.host() + ":" + address.port() + "/";
   }

   /***************************************************************************
    ** Removes only this exact disposable test container and its anonymous volumes.
    ***************************************************************************/
   @Override
   public void close()
   {
      try
      {
         container.close();
      }
      finally
      {
         java.util.TimeZone.setDefault(previousZone);
      }
   }
}