#include <Parsers/ParserCreateUserQuery.h>
#include <Parsers/ASTCreateUserQuery.h>
#include <Parsers/CommonParsers.h>
#include <Parsers/parseUserName.h>
#include <Parsers/parseIdentifierOrStringLiteral.h>
#include <Parsers/ExpressionElementParsers.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTRoleList.h>
#include <ext/range.h>
#include <boost/algorithm/string/predicate.hpp>


namespace DB
{
namespace ErrorCodes
{
    extern const int SYNTAX_ERROR;
}


namespace
{
    bool parseRenameTo(IParserBase::Pos & pos, Expected & expected, String & new_name, String & new_host_pattern)
    {
        return IParserBase::wrapParseImpl(pos, [&]
        {
            if (!new_name.empty())
                return false;

            if (!ParserKeyword{"RENAME TO"}.ignore(pos, expected))
                return false;

            return parseUserName(pos, expected, new_name, new_host_pattern);
        });
    }


    bool parsePassword(IParserBase::Pos & pos, Expected & expected, String & password)
    {
        ASTPtr ast;
        if (!ParserStringLiteral{}.parse(pos, ast, expected))
            return false;

        password = ast->as<const ASTLiteral &>().value.safeGet<String>();
        return true;
    }


    bool parseAuthentication(IParserBase::Pos & pos, Expected & expected, std::optional<Authentication> & authentication)
    {
        return IParserBase::wrapParseImpl(pos, [&]
        {
            if (authentication)
                return false;

            if (!ParserKeyword{"IDENTIFIED"}.ignore(pos, expected))
                return false;

            if (ParserKeyword{"WITH"}.ignore(pos, expected))
            {
                if (ParserKeyword{"NO_PASSWORD"}.ignore(pos, expected))
                {
                    authentication = Authentication{Authentication::NO_PASSWORD};
                }
                else if (ParserKeyword{"PLAINTEXT_PASSWORD"}.ignore(pos, expected))
                {
                    String password;
                    if (!ParserKeyword{"BY"}.ignore(pos, expected) || !parsePassword(pos, expected, password))
                        return false;
                    authentication = Authentication{Authentication::PLAINTEXT_PASSWORD};
                    authentication->setPassword(password);
                }
                else if (ParserKeyword{"SHA256_PASSWORD"}.ignore(pos, expected))
                {
                    String password;
                    if (!ParserKeyword{"BY"}.ignore(pos, expected) || !parsePassword(pos, expected, password))
                        return false;
                    authentication = Authentication{Authentication::SHA256_PASSWORD};
                    authentication->setPassword(password);
                }
                else if (ParserKeyword{"SHA256_HASH"}.ignore(pos, expected))
                {
                    String hash;
                    if (!ParserKeyword{"BY"}.ignore(pos, expected) || !parsePassword(pos, expected, hash))
                        return false;
                    authentication = Authentication{Authentication::SHA256_PASSWORD};
                    authentication->setPasswordHashHex(hash);
                }
                else if (ParserKeyword{"DOUBLE_SHA1_PASSWORD"}.ignore(pos, expected))
                {
                    String password;
                    if (!ParserKeyword{"BY"}.ignore(pos, expected) || !parsePassword(pos, expected, password))
                        return false;
                    authentication = Authentication{Authentication::DOUBLE_SHA1_PASSWORD};
                    authentication->setPassword(password);
                }
                else if (ParserKeyword{"DOUBLE_SHA1_HASH"}.ignore(pos, expected))
                {
                    String hash;
                    if (!ParserKeyword{"BY"}.ignore(pos, expected) || !parsePassword(pos, expected, hash))
                        return false;
                    authentication = Authentication{Authentication::DOUBLE_SHA1_PASSWORD};
                    authentication->setPasswordHashHex(hash);
                }
                else
                    return false;
            }
            else
            {
                String password;
                if (!ParserKeyword{"BY"}.ignore(pos, expected) || !parsePassword(pos, expected, password))
                    return false;
                authentication = Authentication{Authentication::SHA256_PASSWORD};
                authentication->setPassword(password);
            }

            return true;
        });
    }


    bool parseHosts(IParserBase::Pos & pos, Expected & expected, const char * prefix, std::optional<AllowedClientHosts> & hosts)
    {
        return IParserBase::wrapParseImpl(pos, [&]
        {
            if (prefix && !ParserKeyword{prefix}.ignore(pos, expected))
                return false;

            if (!ParserKeyword{"HOST"}.ignore(pos, expected))
                return false;

            if (ParserKeyword{"ANY"}.ignore(pos, expected))
            {
                if (!hosts)
                    hosts.emplace();
                hosts->addAnyHost();
                return true;
            }

            if (ParserKeyword{"NONE"}.ignore(pos, expected))
            {
                if (!hosts)
                    hosts.emplace();
                return true;
            }

            do
            {
                if (ParserKeyword{"LOCAL"}.ignore(pos, expected))
                {
                    if (!hosts)
                        hosts.emplace();
                    hosts->addLocalHost();
                }
                else if (ParserKeyword{"NAME REGEXP"}.ignore(pos, expected))
                {
                    ASTPtr ast;
                    if (!ParserStringLiteral{}.parse(pos, ast, expected))
                        return false;

                    if (!hosts)
                        hosts.emplace();
                    hosts->addNameRegexp(ast->as<const ASTLiteral &>().value.safeGet<String>());
                }
                else if (ParserKeyword{"NAME"}.ignore(pos, expected))
                {
                    ASTPtr ast;
                    if (!ParserStringLiteral{}.parse(pos, ast, expected))
                        return false;

                    if (!hosts)
                        hosts.emplace();
                    hosts->addName(ast->as<const ASTLiteral &>().value.safeGet<String>());
                }
                else if (ParserKeyword{"IP"}.ignore(pos, expected))
                {
                    ASTPtr ast;
                    if (!ParserStringLiteral{}.parse(pos, ast, expected))
                        return false;

                    if (!hosts)
                        hosts.emplace();
                    hosts->addSubnet(ast->as<const ASTLiteral &>().value.safeGet<String>());
                }
                else if (ParserKeyword{"LIKE"}.ignore(pos, expected))
                {
                    ASTPtr ast;
                    if (!ParserStringLiteral{}.parse(pos, ast, expected))
                        return false;

                    if (!hosts)
                        hosts.emplace();
                    hosts->addLikePattern(ast->as<const ASTLiteral &>().value.safeGet<String>());
                }
                else
                    return false;
            }
            while (ParserToken{TokenType::Comma}.ignore(pos, expected));
            return true;
        });
    }


    bool parseProfileName(IParserBase::Pos & pos, Expected & expected, std::optional<String> & profile)
    {
        return IParserBase::wrapParseImpl(pos, [&]
        {
            if (profile)
                return false;

            if (!ParserKeyword{"PROFILE"}.ignore(pos, expected))
                return false;

            ASTPtr ast;
            if (!ParserStringLiteral{}.parse(pos, ast, expected))
                return false;

            profile = ast->as<const ASTLiteral &>().value.safeGet<String>();
            return true;
        });
    }
}


bool ParserCreateUserQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
{
    bool alter;
    if (ParserKeyword{"CREATE USER"}.ignore(pos, expected))
        alter = false;
    else if (ParserKeyword{"ALTER USER"}.ignore(pos, expected))
        alter = true;
    else
        return false;

    bool if_exists = false;
    bool if_not_exists = false;
    bool or_replace = false;
    if (alter)
    {
        if (ParserKeyword{"IF EXISTS"}.ignore(pos, expected))
            if_exists = true;
    }
    else
    {
        if (ParserKeyword{"IF NOT EXISTS"}.ignore(pos, expected))
            if_not_exists = true;
        else if (ParserKeyword{"OR REPLACE"}.ignore(pos, expected))
            or_replace = true;
    }

    String name;
    String host_pattern;
    if (!parseUserName(pos, expected, name, host_pattern))
        return false;

    String new_name;
    String new_host_pattern;
    std::optional<Authentication> authentication;
    std::optional<AllowedClientHosts> hosts;
    std::optional<AllowedClientHosts> add_hosts;
    std::optional<AllowedClientHosts> remove_hosts;
    std::optional<String> profile;

    while (parseAuthentication(pos, expected, authentication)
           || parseHosts(pos, expected, nullptr, hosts)
           || parseProfileName(pos, expected, profile)
           || (alter && parseRenameTo(pos, expected, new_name, new_host_pattern))
           || (alter && parseHosts(pos, expected, "ADD", add_hosts))
           || (alter && parseHosts(pos, expected, "REMOVE", remove_hosts)))
        ;

    if (!hosts)
    {
        if (!alter)
            hosts.emplace().addLikePattern(host_pattern);
        else if (alter && !new_name.empty())
            hosts.emplace().addLikePattern(new_host_pattern);
    }

    auto query = std::make_shared<ASTCreateUserQuery>();
    node = query;

    query->alter = alter;
    query->if_exists = if_exists;
    query->if_not_exists = if_not_exists;
    query->or_replace = or_replace;
    query->name = std::move(name);
    query->new_name = std::move(new_name);
    query->authentication = std::move(authentication);
    query->hosts = std::move(hosts);
    query->add_hosts = std::move(add_hosts);
    query->remove_hosts = std::move(remove_hosts);
    query->profile = std::move(profile);

    return true;
}
}