// Copyright (C) 2017 The Android Open Source Project
//
// 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.google.gerrit.server.schema;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.SECONDS;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableSet;
import com.google.common.flogger.FluentLogger;
import com.google.common.primitives.Ints;
import com.google.gerrit.entities.Account;
import com.google.gerrit.entities.Change;
import com.google.gerrit.entities.PatchSet;
import com.google.gerrit.exceptions.DuplicateKeyException;
import com.google.gerrit.exceptions.StorageException;
import com.google.gerrit.extensions.events.LifecycleListener;
import com.google.gerrit.extensions.registration.DynamicItem;
import com.google.gerrit.lifecycle.LifecycleModule;
import com.google.gerrit.server.change.AccountPatchReviewStore;
import com.google.gerrit.server.config.ConfigUtil;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.server.config.ThreadSettingsConfig;
import com.google.gerrit.server.logging.Metadata;
import com.google.gerrit.server.logging.TraceContext;
import com.google.gerrit.server.logging.TraceContext.TraceTimer;
import java.nio.file.Path;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Collection;
import java.util.Optional;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
import org.eclipse.jgit.lib.Config;

public abstract class JdbcAccountPatchReviewStore
    implements AccountPatchReviewStore, LifecycleListener {
  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  // DB_CLOSE_DELAY=-1: By default the content of an in-memory H2 database is lost at the moment the
  // last connection is closed. This option keeps the content as long as the VM lives.
  @VisibleForTesting
  public static final String TEST_IN_MEMORY_URL =
      "jdbc:h2:mem:account_patch_reviews;DB_CLOSE_DELAY=-1";

  private static final String ACCOUNT_PATCH_REVIEW_DB = "accountPatchReviewDb";
  private static final String H2_DB = "h2";
  private static final String MARIADB = "mariadb";
  private static final String MYSQL = "mysql";
  private static final String POSTGRESQL = "postgresql";
  private static final String URL = "url";

  public static class Module extends LifecycleModule {
    private final Config cfg;

    public Module(Config cfg) {
      this.cfg = cfg;
    }

    @Override
    protected void configure() {
      Class<? extends JdbcAccountPatchReviewStore> impl;
      String url = cfg.getString(ACCOUNT_PATCH_REVIEW_DB, null, URL);
      if (url == null || url.contains(H2_DB)) {
        impl = H2AccountPatchReviewStore.class;
      } else if (url.contains(POSTGRESQL)) {
        impl = PostgresqlAccountPatchReviewStore.class;
      } else if (url.contains(MYSQL)) {
        impl = MysqlAccountPatchReviewStore.class;
      } else if (url.contains(MARIADB)) {
        impl = MariaDBAccountPatchReviewStore.class;
      } else {
        throw new IllegalArgumentException(
            "unsupported driver type for account patch reviews db: " + url);
      }
      DynamicItem.bind(binder(), AccountPatchReviewStore.class).to(impl);
      listener().to(impl);
    }
  }

  private DataSource ds;

  public static JdbcAccountPatchReviewStore createAccountPatchReviewStore(
      Config cfg, SitePaths sitePaths, ThreadSettingsConfig threadSettingsConfig) {
    String url = cfg.getString(ACCOUNT_PATCH_REVIEW_DB, null, URL);
    if (url == null || url.contains(H2_DB)) {
      return new H2AccountPatchReviewStore(cfg, sitePaths, threadSettingsConfig);
    }
    if (url.contains(POSTGRESQL)) {
      return new PostgresqlAccountPatchReviewStore(cfg, sitePaths, threadSettingsConfig);
    }
    if (url.contains(MYSQL)) {
      return new MysqlAccountPatchReviewStore(cfg, sitePaths, threadSettingsConfig);
    }
    if (url.contains(MARIADB)) {
      return new MariaDBAccountPatchReviewStore(cfg, sitePaths, threadSettingsConfig);
    }
    throw new IllegalArgumentException(
        "unsupported driver type for account patch reviews db: " + url);
  }

  protected JdbcAccountPatchReviewStore(
      Config cfg, SitePaths sitePaths, ThreadSettingsConfig threadSettingsConfig) {
    this.ds = createDataSource(cfg, sitePaths, threadSettingsConfig);
  }

  private static String getUrl(@GerritServerConfig Config cfg, SitePaths sitePaths) {
    String url = cfg.getString(ACCOUNT_PATCH_REVIEW_DB, null, URL);
    if (url == null) {
      return createH2Url(sitePaths.db_dir.resolve("account_patch_reviews"));
    }
    return url;
  }

  private static DataSource createDataSource(
      Config cfg, SitePaths sitePaths, ThreadSettingsConfig threadSettingsConfig) {
    BasicDataSource datasource = new BasicDataSource();
    String url = getUrl(cfg, sitePaths);
    int poolLimit = threadSettingsConfig.getDatabasePoolLimit();
    datasource.setUrl(url);
    datasource.setDriverClassName(getDriverFromUrl(url));
    datasource.setMaxActive(cfg.getInt(ACCOUNT_PATCH_REVIEW_DB, "poolLimit", poolLimit));
    datasource.setMinIdle(cfg.getInt(ACCOUNT_PATCH_REVIEW_DB, "poolminidle", 4));
    datasource.setMaxIdle(
        cfg.getInt(ACCOUNT_PATCH_REVIEW_DB, "poolmaxidle", Math.min(poolLimit, 16)));
    datasource.setInitialSize(datasource.getMinIdle());
    datasource.setMaxWait(
        ConfigUtil.getTimeUnit(
            cfg,
            ACCOUNT_PATCH_REVIEW_DB,
            null,
            "poolmaxwait",
            MILLISECONDS.convert(30, SECONDS),
            MILLISECONDS));
    long evictIdleTimeMs = 1000L * 60;
    datasource.setMinEvictableIdleTimeMillis(evictIdleTimeMs);
    datasource.setTimeBetweenEvictionRunsMillis(evictIdleTimeMs / 2);
    return datasource;
  }

  private static String getDriverFromUrl(String url) {
    if (url.contains(POSTGRESQL)) {
      return "org.postgresql.Driver";
    }
    if (url.contains(MYSQL)) {
      return "com.mysql.jdbc.Driver";
    }
    if (url.contains(MARIADB)) {
      return "org.mariadb.jdbc.Driver";
    }
    return "org.h2.Driver";
  }

  @Override
  public void start() {
    try {
      createTableIfNotExists();
    } catch (StorageException e) {
      logger.atSevere().withCause(e).log("Failed to create table to store account patch reviews");
    }
  }

  public Connection getConnection() throws SQLException {
    return ds.getConnection();
  }

  public void createTableIfNotExists() {
    try (Connection con = ds.getConnection();
        Statement stmt = con.createStatement()) {
      doCreateTable(stmt);
    } catch (SQLException e) {
      throw convertError("create", e);
    }
  }

  protected void doCreateTable(Statement stmt) throws SQLException {
    stmt.executeUpdate(
        "CREATE TABLE IF NOT EXISTS account_patch_reviews ("
            + "account_id INTEGER DEFAULT 0 NOT NULL, "
            + "change_id INTEGER DEFAULT 0 NOT NULL, "
            + "patch_set_id INTEGER DEFAULT 0 NOT NULL, "
            + "file_name VARCHAR(4096) DEFAULT '' NOT NULL, "
            + "CONSTRAINT primary_key_account_patch_reviews "
            + "PRIMARY KEY (change_id, patch_set_id, account_id, file_name)"
            + ")");
  }

  public void dropTableIfExists() {
    try (Connection con = ds.getConnection();
        Statement stmt = con.createStatement()) {
      stmt.executeUpdate("DROP TABLE IF EXISTS account_patch_reviews");
    } catch (SQLException e) {
      throw convertError("create", e);
    }
  }

  @Override
  public void stop() {}

  @Override
  public boolean markReviewed(PatchSet.Id psId, Account.Id accountId, String path) {
    try (TraceTimer ignored =
            TraceContext.newTimer(
                "Mark file as reviewed",
                Metadata.builder()
                    .patchSetId(psId.get())
                    .accountId(accountId.get())
                    .filePath(path)
                    .build());
        Connection con = ds.getConnection();
        PreparedStatement stmt =
            con.prepareStatement(
                "INSERT INTO account_patch_reviews "
                    + "(account_id, change_id, patch_set_id, file_name) VALUES "
                    + "(?, ?, ?, ?)")) {
      stmt.setInt(1, accountId.get());
      stmt.setInt(2, psId.changeId().get());
      stmt.setInt(3, psId.get());
      stmt.setString(4, path);
      stmt.executeUpdate();
      return true;
    } catch (SQLException e) {
      StorageException ormException = convertError("insert", e);
      if (ormException instanceof DuplicateKeyException) {
        return false;
      }
      throw ormException;
    }
  }

  @Override
  public void markReviewed(PatchSet.Id psId, Account.Id accountId, Collection<String> paths) {
    if (paths == null || paths.isEmpty()) {
      return;
    }

    try (TraceTimer ignored =
            TraceContext.newTimer(
                "Mark files as reviewed",
                Metadata.builder()
                    .patchSetId(psId.get())
                    .accountId(accountId.get())
                    .resourceCount(paths.size())
                    .build());
        Connection con = ds.getConnection();
        PreparedStatement stmt =
            con.prepareStatement(
                "INSERT INTO account_patch_reviews "
                    + "(account_id, change_id, patch_set_id, file_name) VALUES "
                    + "(?, ?, ?, ?)")) {
      for (String path : paths) {
        stmt.setInt(1, accountId.get());
        stmt.setInt(2, psId.changeId().get());
        stmt.setInt(3, psId.get());
        stmt.setString(4, path);
        stmt.addBatch();
      }
      stmt.executeBatch();
    } catch (SQLException e) {
      StorageException ormException = convertError("insert", e);
      if (ormException instanceof DuplicateKeyException) {
        return;
      }
      throw ormException;
    }
  }

  @Override
  public void clearReviewed(PatchSet.Id psId, Account.Id accountId, String path) {
    try (TraceTimer ignored =
            TraceContext.newTimer(
                "Clear reviewed flag",
                Metadata.builder()
                    .patchSetId(psId.get())
                    .accountId(accountId.get())
                    .filePath(path)
                    .build());
        Connection con = ds.getConnection();
        PreparedStatement stmt =
            con.prepareStatement(
                "DELETE FROM account_patch_reviews "
                    + "WHERE account_id = ? AND change_id = ? AND "
                    + "patch_set_id = ? AND file_name = ?")) {
      stmt.setInt(1, accountId.get());
      stmt.setInt(2, psId.changeId().get());
      stmt.setInt(3, psId.get());
      stmt.setString(4, path);
      stmt.executeUpdate();
    } catch (SQLException e) {
      throw convertError("delete", e);
    }
  }

  @Override
  public void clearReviewed(PatchSet.Id psId) {
    try (TraceTimer ignored =
            TraceContext.newTimer(
                "Clear all reviewed flags of patch set",
                Metadata.builder().patchSetId(psId.get()).build());
        Connection con = ds.getConnection();
        PreparedStatement stmt =
            con.prepareStatement(
                "DELETE FROM account_patch_reviews "
                    + "WHERE change_id = ? AND patch_set_id = ?")) {
      stmt.setInt(1, psId.changeId().get());
      stmt.setInt(2, psId.get());
      stmt.executeUpdate();
    } catch (SQLException e) {
      throw convertError("delete", e);
    }
  }

  @Override
  public void clearReviewed(Change.Id changeId) {
    try (TraceTimer ignored =
            TraceContext.newTimer(
                "Clear all reviewed flags of change",
                Metadata.builder().changeId(changeId.get()).build());
        Connection con = ds.getConnection();
        PreparedStatement stmt =
            con.prepareStatement("DELETE FROM account_patch_reviews WHERE change_id = ?")) {
      stmt.setInt(1, changeId.get());
      stmt.executeUpdate();
    } catch (SQLException e) {
      throw convertError("delete", e);
    }
  }

  @Override
  public Optional<PatchSetWithReviewedFiles> findReviewed(PatchSet.Id psId, Account.Id accountId) {
    try (TraceTimer ignored =
            TraceContext.newTimer(
                "Find reviewed flags",
                Metadata.builder().patchSetId(psId.get()).accountId(accountId.get()).build());
        Connection con = ds.getConnection();
        PreparedStatement stmt =
            con.prepareStatement(
                "SELECT patch_set_id, file_name FROM account_patch_reviews APR1 "
                    + "WHERE account_id = ? AND change_id = ? AND patch_set_id = "
                    + "(SELECT MAX(patch_set_id) FROM account_patch_reviews APR2 WHERE "
                    + "APR1.account_id = APR2.account_id "
                    + "AND APR1.change_id = APR2.change_id "
                    + "AND patch_set_id <= ?)")) {
      stmt.setInt(1, accountId.get());
      stmt.setInt(2, psId.changeId().get());
      stmt.setInt(3, psId.get());
      try (ResultSet rs = stmt.executeQuery()) {
        if (rs.next()) {
          PatchSet.Id id = PatchSet.id(psId.changeId(), rs.getInt("patch_set_id"));
          ImmutableSet.Builder<String> builder = ImmutableSet.builder();
          do {
            builder.add(rs.getString("file_name"));
          } while (rs.next());

          return Optional.of(
              AccountPatchReviewStore.PatchSetWithReviewedFiles.create(id, builder.build()));
        }

        return Optional.empty();
      }
    } catch (SQLException e) {
      throw convertError("select", e);
    }
  }

  public StorageException convertError(String op, SQLException err) {
    if (err.getCause() == null && err.getNextException() != null) {
      err.initCause(err.getNextException());
    }
    return new StorageException(op + " failure on account_patch_reviews", err);
  }

  private static String getSQLState(SQLException err) {
    String ec;
    SQLException next = err;
    do {
      ec = next.getSQLState();
      next = next.getNextException();
    } while (ec == null && next != null);
    return ec;
  }

  protected static int getSQLStateInt(SQLException err) {
    String s = getSQLState(err);
    if (s != null) {
      Integer i = Ints.tryParse(s);
      return i != null ? i : -1;
    }
    return 0;
  }

  private static String createH2Url(Path path) {
    return new StringBuilder().append("jdbc:h2:").append(path.toUri().toString()).toString();
  }
}