#!/usr/bin/python3

# Copyright (C) 2018 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.

import argparse
import os.path
import sys
import time

from abc import ABC, abstractmethod
from sqlalchemy import create_engine
from sqlalchemy.exc import SQLAlchemyError

from git_config_parser import GitConfigParser
from log import get_logger

LOG = get_logger("validate-db")


class DatabaseConfig:
    def __init__(self, name, host, port, user, pwd):
        self.name = name
        self.host = host
        self.port = port
        self.user = user
        self.pwd = pwd


class AbstractGerritDB(ABC):
    def __init__(self, config, secure_config):
        self._read_config(config, secure_config)

    @abstractmethod
    def _read_config(self, config, secure_config):
        """
    Read all required configuration values.
    """

    @abstractmethod
    def _create_db_url(self):
        """
    Create a URL with which the database can be reached.
    """

    @abstractmethod
    def wait_for_db_server(self):
        """
    Wait until a connection with the database server is achieved.
    """

    @abstractmethod
    def wait_for_db(self):
        """
    Check whether a database with the name configured for the ReviewDB
    exists on the database server and wait for its creation.
    """

    @abstractmethod
    def wait_for_schema(self):
        """
    Check whether the schema of the ReviewDBwas created and wait for its
    creation.
    """


class H2GerritDB(AbstractGerritDB):
    def __init__(self, config, secure_config, site):
        super().__init__(config, secure_config)
        self.site = site
        self.url = self._create_db_url()

    def _read_config(self, config, secure_config):
        name = config.get("database.database", default="ReviewDB")
        self.db_config = DatabaseConfig(name, None, None, None, None)

    def _create_db_url(self):
        suffix = ".h2.db"
        if os.path.isabs(self.db_config.name):
            if self.db_config.name.endswith(suffix):
                return self.db_config.name
            return self.db_config.name + suffix
        return os.path.join(self.site, "db", self.db_config.name) + suffix

    def wait_for_db_server(self):
        # Not required. H2 is an embedded database.
        pass

    def wait_for_db(self):
        LOG.info("Waiting for database to be available...")
        while not os.path.exists(self.url):
            time.sleep(3)
            LOG.info("Still waiting...")
        LOG.info("Found it!")

    def wait_for_schema(self):
        # Since no replication of a H2 databas is implemented yet, this test is not
        # needed, because the schema is created by Gerrit.
        pass


class MysqlGerritDB(AbstractGerritDB):
    def __init__(self, config, secure_config):
        super().__init__(config, secure_config)

        # tables expected in Gerrit 2.12 - 2.16
        self.tables = ["changes", "patch_sets"]
        self.server_url, self.reviewdb_url = self._create_db_url()

        self.engine = None
        self.connection = None

    def _read_config(self, config, secure_config):
        name = config.get("database.database", default="reviewdb")
        host = config.get("database.hostname", default="localhost")
        port = config.get("database.port", default="3306")
        user = secure_config.get("database.username", default="")
        pwd = secure_config.get("database.password", default="")
        self.db_config = DatabaseConfig(name, host, port, user, pwd)

    def _create_db_url(self):
        server_url = "mysql+pymysql://%s:%s@%s:%s" % (
            self.db_config.user,
            self.db_config.pwd,
            self.db_config.host,
            self.db_config.port,
        )
        reviewdb_url = "%s/%s" % (server_url, self.db_config.name)
        return (server_url, reviewdb_url)

    def _connect_to_db(self, url):
        self.engine = create_engine(url)
        self.connection = self.engine.connect()

    def wait_for_db_server(self):
        LOG.info("Waiting for database server connection...")
        while not self.connection or self.connection.closed:
            try:
                self._connect_to_db(self.server_url)
                continue
            except SQLAlchemyError:
                LOG.info("Still waiting...")
                time.sleep(3)
        self.connection.close()
        LOG.info("Connection successful!")

    def wait_for_db(self):
        LOG.info("Waiting for database to be available...")
        self.connection.close()
        while not self.connection or self.connection.closed:
            try:
                self._connect_to_db(self.reviewdb_url)
                continue
            except SQLAlchemyError:
                LOG.info("Still waiting...")
                time.sleep(3)
        self.connection.close()
        LOG.info("Found it!")

    def wait_for_schema(self):
        LOG.info("Waiting for database schema to be created...")
        for table in self.tables:
            while not self.engine.dialect.has_table(self.engine, table):
                LOG.info("Still waiting for table %s...", table)
                time.sleep(3)
        LOG.info("Schema appears to have been created!")


def select_db(gerrit_site_path):
    gerrit_config_path = os.path.join(gerrit_site_path, "etc/gerrit.config")
    config = GitConfigParser(gerrit_config_path)

    gerrit_secure_config_path = os.path.join(gerrit_site_path, "etc/secure.config")
    secure_config = GitConfigParser(gerrit_secure_config_path)

    db_type = config.get("database.type")

    if db_type.upper() == "H2":
        gerrit_db = H2GerritDB(config, secure_config, gerrit_site_path)
    elif db_type.upper() == "MYSQL":
        gerrit_db = MysqlGerritDB(config, secure_config)
    else:
        LOG.error("Unknown database type.")
        sys.exit(1)

    return gerrit_db


def validate_db(gerrit_site_path):
    gerrit_db = select_db(gerrit_site_path)

    gerrit_db.wait_for_db_server()
    gerrit_db.wait_for_db()
    gerrit_db.wait_for_schema()


# pylint: disable=C0103
if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "-s",
        "--site",
        help="Path to Gerrit site",
        dest="site",
        action="store",
        default="/var/gerrit",
        required=True,
    )
    args = parser.parse_args()

    validate_db(args.site)