source: main/trunk/greenstone2/perllib/plugouts/MySQLPlugout.pm@ 32521

###########################################################################
#
# GreenstoneXMLPlugout.pm -- the plugout module for Greenstone Archives
# A component of the Greenstone digital library software
# from the New Zealand Digital Library Project at the 
# University of Waikato, New Zealand.
#
# Copyright (C) 2006 New Zealand Digital Library Project
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#
###########################################################################

package MySQLPlugout;

use strict;
no strict 'refs';
no strict 'subs';

use util;
use FileUtils;
use GreenstoneXMLPlugout;
use docprint;

use IPC::Open2;
use POSIX ":sys_wait_h"; # for waitpid, http://perldoc.perl.org/functions/waitpid.html

# TODO: SIGTERM rollback and disconnect?


# this plugout does not output xml to a file, but outputs rows into a mysql table
sub BEGIN {
    @MySQLPlugout::ISA = ('GreenstoneXMLPlugout');
}


# TODO: deal with -removeold and everything? Or type out instructions for user

# TODO Q: what is "group" in GreenstoneXMLPlugout?
# TODO Q: site_name only exists for GS3. What about GS2?

my $process_mode_list =
    [ { 'name' => "meta_only",
        'desc' => "{MySQLPlugout.process_mode.meta_only}" },      
      { 'name' => "text_only",
        'desc' => "{MySQLPlugout.process_mode.text_only}" },
      { 'name' => "all",
        'desc' => "{MySQLPlugout.process_mode.all}" } ];

my $arguments = [ 
       { 'name' => "process_mode", 
     'desc' => "{MySQLPlugout.process_mode}",
     'type' => "enum",
     'list' => $process_mode_list,
     'deft' => "all",
     'reqd' => "no",
     'hiddengli' => "no"} ];

my $options = { 'name'     => "MySQLPlugout",
        'desc'     => "{MySQLPlugout.desc}",
        'abstract' => "no",
        'inherits' => "yes",
        'args'     => $arguments };

sub new {
    my ($class) = shift (@_);
    my ($plugoutlist, $inputargs,$hashArgOptLists) = @_;
    push(@$plugoutlist, $class);

    push(@{$hashArgOptLists->{"ArgList"}},@{$arguments});
    push(@{$hashArgOptLists->{"OptList"}},$options);

    my $self = new GreenstoneXMLPlugout($plugoutlist,$inputargs,$hashArgOptLists);
    
    if ($self->{'info_only'}) { 
        # don't worry about any options etc
        return bless $self, $class;
    }
    print STDERR "***** MySQLPlugout process mode = \"", $self->{'process_mode'}, "\"\n";
    
    return bless $self, $class;
}

# connect here and ensure all tables and databases exist
sub begin {

    my $self= shift (@_);

    ########### TODO: these should be set from cmdline/GLI options to plugout #########
    $self->{'db_driver'} = "mysql";
    $self->{'site_name'} = "localsite";    
    $self->{'db_client_user'} = "root";
    $self->{'db_client_pwd'} = "6reenstone3";
    #$self->{'db_host'} = "127.0.0.1";
    #$self->{'db_encoding'} = "utf8";
    #TODO: proc_mode is also a saveas option
    
    ############ LOAD NECESSARY OPTIONS ###########
    print STDERR "########## COLLECTION: ". $ENV{'GSDLCOLLECTION'}."\n";
    $self->{'collection_name'} = $ENV{'GSDLCOLLECTION'};
    
    if(!$self->connect_to_db()) {
    # This is fatal for the plugout, let's terminate here
    # PrintError would already have displayed the warning message on connection fail    
    die("Could not connect to db. Can't proceed.\n");
    }
    if(!$self->load_db_and_tables()) {
    # This is fatal for the plugout, let's terminate here
    # PrintError would already have displayed the warning message on connection fail    
    die("Could not use db or prepare its tables. Can't proceed.\n");
    }

    # prepare the shared/common HANDLES to SQL insert statements that contain placeholders
    # and which we will reuse repeatedly when actually executing the insert statements
    my $proc_mode = $self->{'process_mode'};
    if($proc_mode eq "all" || $proc_mode eq "meta_only" ) {
    $self->{'metadata_prepared_insert_statement_handle'} = $self->prepare_insert_metadata_row_stmthandle();
    }
    if($proc_mode eq "all" || $proc_mode eq "text_only" ) {
    $self->{'fulltxt_prepared_insert_statement_handle'} = $self->prepare_insert_fulltxt_row_stmthandle();
    }

    # if setting up to work with sql db failed, we'd have terminated and wouldn't come up to here:
    # won't bother preparing GreenstoneXMLPlugout by calling superclass' begin()
    # finally, can call begin on super - important as doc.xml is opened as a group etc

    if($proc_mode ne "all") { # TODO Q
    $self->GreenstoneXMLPlugout::begin(@_);
    }
}

# disconnect from database here, see inexport.pm
sub end
{
    my $self = shift(@_);

    # do the superclass stuff first, as any sql db failures should not prevent superclass cleanup
    
    if($self->{'process_mode'} ne "all") {# TODO Q
    $self->GreenstoneXMLPlugout::end(@_);
    }
    
    $self->disconnect_from_db() || warn("Unable to disconnect from database " . $self->{'site_name'} . "\n"); # disconnect_from_db() will also issue a warning, but this may be clearer
}
 
sub close_group_output {
    my $self = shift (@_);
    
    if($proc_mode ne "all") { # TODO Q
    $self->GreenstoneXMLPlugout::close_group_output();
    }
}
   
# TODO: check arc-inf.db for whether each entry is to be deleted/indexed/reindexed/been indexed
sub saveas {
    my $self = shift (@_);
    my ($doc_obj, $doc_dir) = @_;

    # 1. pre save out and saving debug handle
    if($proc_mode ne "all") { # TODO Q
    my ($docxml_outhandler, $output_file) = $self->GreenstoneXMLPlugout::pre_saveas(@_);

    $self->{'debug_outhandle'} = $docxml_outhandler if ($self->{'debug'}); # STDOUT if debug
    }
    elsif ($self->{'debug'}) { # if we didn't call superclass::pre_saveas, then set debug handle
    $self->{'debug_outhandle'} = STDOUT; # superclass also debugs to STDOUT
    # TODO: also set debugging in begin()? Then stmts creating db and tables also sent to debug out and not executed
    }
    
    
    # 2. overriding saving behaviour to do what the superclass does PLUS saving to sql db    

    if($proc_mode ne "all" ) { # if all, then nothing to go into doc.xml
    # write the INVERSE into doc.xml as to what is written to the db
    my $proc_mode = $self->{'process_mode'};
    
    my $docxml_output_options = { 'output' => docprint::OUTPUT_NONE }; # TODO Q
    
    if($proc_mode eq "meta_only" ) { # since only meta to go into MySQL db, text will go into docxml
        $docxml_output_options->{'output'} = docprint::OUTPUT_TEXT_ONLY;
    } elsif($proc_mode eq "text_only" ) { # since only full text to go into MySQL db, meta will go into docxml
        $docxml_output_options->{'output'} = docprint::OUTPUT_META_ONLY;
    }

    # now we've prepared to write out whatever is meant to go into docxml
    # and can do actual the steps superclass GreenstoneXMLPlugout carries out to write out docxml
    # So: write out the doc xml file for the current document
    my $section_text = &docprint::get_section_xml($doc_obj, $docxml_output_options);
    print $docxml_outhandler $section_text;    
    }
    
    # We also write out whatever needs to go into the MySQL database
    $self->write_meta_and_text($doc_obj);

    
    # 3. post save out
    if($proc_mode ne "all" ) { # TODO Q
    #$self->GreenstoneXMLPlugout::post_saveas(@_);
    $self->GreenstoneXMLPlugout::post_saveas($doc_obj, $doc_dir, $docxml_outhandler, $output_file);
    }
    
    # database connection is closed in end() method
    # so we don't open and close over and over for each doc during a single build
}


# write meta and/or text PER DOC out to DB
sub write_meta_and_text {
    my $self = shift (@_);
    my ($doc_obj) = @_;
    my $root_section = $doc_obj->get_top_section();
    my $doc_oid = $doc_obj->get_OID(); # we're processing a single doc at a time, so single OID

    # load the prepared INSERT statement handles for both tables (can be undef for any table depending on whether meta_only or txt_only are set)
    my $metadata_table_sth = $self->{'metadata_prepared_insert_statement_handle'};
    my $fulltxt_table_sth = $self->{'fulltxt_prepared_insert_statement_handle'};
    
    $self->recursive_write_meta_and_text($doc_obj, $root_section, $metadata_table_sth, $fulltxt_table_sth);
}

# Perl: Reading or Writing to Another Program
# https://nnc3.com/mags/Perl3/cookbook/ch16_05.htm
sub recursive_write_meta_and_text {
    my $self = shift (@_);
    my ($doc_obj, $doc_oid, $section, $metadata_table_sth, $fulltxt_table_sth) = @_;    

    # If section=ROOT, write "root" as section name into table
    # doc->get_top_section() is the name of the doc root section, which is ""
    my $section_name = ($section eq "") ? "root" : $section;
    
    my $section_ptr = $doc_obj->_lookup_section ($section);
    return "" unless defined $section_ptr;

    my $debug_out = $self->{'debug_outhandle'};
    
    #my $proc_mode = $self->{'process_mode'};
    #if($proc_mode eq "all" || $proc_mode eq "meta_only" ) {
    if($metadata_table_sth) { # meta insert statement handle will be undef if not writing meta
    
    foreach my $data (@{$section_ptr->{'metadata'}}) {
        my $meta_name = $data->[0];
        my $escaped_meta_value = &escape_text($data->[1]);

        # Write out the current section's meta to collection db's METADATA table        
        
        # for each set of values to write to meta table, execute the prepared statement, filling in the values

        if($self->{'debug'}) {
        # just print the statement we were going to execute

        print $debug_out $metadata_table_sth->Statement . "($doc_oid, $section_name, $meta_name, $escaped_meta_value)\n";
        }
        else {
        
        $metadata_table_sth->execute($doc_oid, $section_name, $meta_name, $escaped_meta_value); 
        #|| warn ("Unable to write metadata row to db:\n\tOID $doc_oid, section $section_name,\n\tmeta name: $meta_name, val: $escaped_meta_value");
        # Execution failure will print out info anyway: since db connection sets PrintError
        }
    }
    }
    
    #if($proc_mode eq "all" || $proc_mode eq "text_only" ) {
    if($fulltxt_table_sth) { # fulltxt insert statement handle will be undef if not writing fulltxt

    if($self->{'debug'}) {
        # just print the statement we were going to execute, minus the fulltxt value
        my $txt_repr = $section_ptr->{'text'} ? "<TXT>" : "NULL";
        print $debug_out $fulltxt_table_sth->Statement . "($doc_oid, $section_name, $txt_repr)\n";
    } else {
        my $section_text = &escape_text($section_ptr->{'text'});
        
        # fulltxt column can be SQL NULL. undef value gets written out as NULL:
        # https://stackoverflow.com/questions/12708633/which-one-represents-null-undef-or-empty-string
        
        # Write out the current section's text to collection db's FULLTeXT table
        $fulltxt_table_sth->execute($doc_oid, $section_name, $section_text);
        #|| warn ("Unable to write fulltxt row to db for row:\n\tOID $doc_oid, section $section_name");
        # Execution failure will print out info anyway: since db connection sets PrintError
    }
    }
    
    # output all subsections: RECURSIVE CALL
    foreach my $subsection (@{$section_ptr->{'subsection_order'}}) {
    &recursive_write_meta_and_text($doc_obj, $doc_oid, "$section.$subsection", $metadata_table_sth, $fulltxt_table_sth);
    }
}

#################################

# Database access related functions
# http://g2pc1.bu.edu/~qzpeng/manual/MySQL%20Commands.htm
# https://www.guru99.com/insert-into.html

# TODO Q: What on cancelling a build: delete table? But what if it was a rebuild and the rebuild is cancelled (not the original build)?
# Do we create a copy of the orig database as backup, then start populating current db, and if cancelled, delete current db and RENAME backup table to current? 
# https://stackoverflow.com/questions/3280006/duplicating-a-mysql-table-indexes-and-data
# BUT what if the table is HUGE? (Think of a collection with millions of docs.) Huge overhead in copying?
# The alternative is we just quit on cancel, but then: cancel could leave the table in a partial committed state, with no way of rolling back.
# Unless they do a full rebuild, which will recreate the table from scratch?
# SOLUTION-> rollback transaction on error, see https://www.effectiveperlprogramming.com/2010/07/set-custom-dbi-error-handlers/
# But then should set AutoCommit to off on connection, and remember to commit every time

#################
# Database functions that use the perl DBI module (with the DBD driver module for mysql)
#################

# THE NEW DB FUNCTIONS
# NOTE: FULLTEXT is a reserved keyword in (My)SQL. So we can't name a table or any of its columns "fulltext".
# https://dev.mysql.com/doc/refman/5.5/en/keywords.html

# TODO: Consider AutoCommit status (and Autocommit off allowing commit or rollback for GS coll build cancel) later

sub connect_to_db {
    my $self= shift (@_);
    
    my $db_driver = $self->{'db_driver'};
    my $db_user = $self->{'db_client_user'} || "root";
    my $db_pwd = $self->{'db_client_pwd'};
    my $db_host = $self->{'db_host'} || "127.0.0.1";
    my $db_enc = $self->{'db_encoding'} || "utf8";
    
    #my $db_name = $self->{'site_name'};
    
    # try connecting to the mysql db, if that fails it will die
    # so don't bother preparing GreenstoneXMLPlugout by calling superclass' begin()

    # localhost doesn't work for us, but 127.0.0.1 works
    # https://metacpan.org/pod/DBD::mysql
    # "The hostname, if not specified or specified as '' or 'localhost', will default to a MySQL server
    # running on the local machine using the default for the UNIX socket. To connect to a MySQL server
    # on the local machine via TCP, you must specify the loopback IP address (127.0.0.1) as the host."
    #my $connect_str = "dbi:$db_driver:database=$db_name;host=$db_host";
    my $connect_str = "dbi:$db_driver:host=$db_host"; # don't provide db, so we can check the db is there
    my $dbh = DBI->connect("$connect_str", $db_user, $db_pwd,
               {
                   ShowErrorStatement => 1, # more informative as DBI will append failed SQL stmt to error message
                   PrintError => 1, # on by default, but being explicit
                   RaiseError => 0, # off by default, but being explicit
                   AutoCommit => 1, # on by default, but being explicit
               });

    if(!$dbh) {
    # NOTE, despite handle dbh being undefined, error code will be in DBI->err
    return 0;   
    }

    # set encoding https://metacpan.org/pod/DBD::mysql
    # https://dev.mysql.com/doc/refman/5.7/en/charset.html
    # https://dev.mysql.com/doc/refman/5.7/en/charset-conversion.html
    # Setting the encoding at db server level.
    # Not sure if this command is mysql specific:
    my $stmt = "set NAMES '" . $db_enc . "'";
    $dbh->do($stmt) || warn("Unable to set charset encoding at db server level to: " . $db_enc . "\n");
    
    # if we're here, then connection succeeded, store handle
    $self->{'db_handle'} = $dbh;
    return 1;
}

sub load_db_and_tables {
    my $self= shift (@_);
    my $db_name = $self->{'site_name'}; # one database per GS3 site
    my $dbh = $self->{'db_handle'};
    
    # perl DBI switch database: https://www.perlmonks.org/?node_id=995434
    # do() returns undef on error.
    # connection succeeded, try to load our database. If that didn't work, attempt to create db
    my $success = $dbh->do("use $db_name");
    
    if(!$success && $dbh->err == 1049) { # "Unknown database" error has code 1049 (mysql only?) meaning db doesn't exist yet
    # attempt to create the db and its tables
    $self->create_db($db_name) || return 0;

    # once more attempt to use db, now that it exists
    $dbh->do("use $db_name") || return 0;
    #$dbh->do("use localsite") or die "Error (code" . $dbh->err ."): " . $dbh->errstr . "\n";

    # attempt to create tables in current db
    $self->create_metadata_table() || return 0;
    $self->create_fulltext_table() || return 0; 

    $success = 1;
    }
    elsif($success) { # database existed and loaded successfully, but
    # before proceeding check that the current collection's tables exist
    
    # attempt to create tables in current db
    if(!$self->table_exists($self->{'collection_name'} . "metadata")) {
        $self->create_metadata_table() || return 0;
    }
    if(!$self->table_exists($self->{'collection_name'} .  "fulltxt")) {
        $self->create_fulltext_table() || return 0;
    }
    }
    
    return $success; # could still return 0, if database failed to load with an error code != 1049
}

# disconnect from db - https://metacpan.org/pod/DBI#disconnect
# TODO: make sure to have committed or rolled back before disconnect
# and that you've call finish() on statement handles if any fetch remnants remain
sub disconnect_from_db {
    my $self= shift (@_);    
    my $dbh = $self->{'db_handle'};

    # make sure any active stmt handles are finished
    # NO: "When all the data has been fetched from a SELECT statement, the driver will automatically call finish for you. So you should not call it explicitly except when you know that you've not fetched all the data from a statement handle and the handle won't be destroyed soon."
    
    #$meta_sth = $self->{'metadata_prepared_insert_statement_handle'};
    #$txt_sth = $self->{'fulltxt_prepared_insert_statement_handle'};
    #$meta_sth->finish() if($meta_sth);
    #$txt_sth->finish() if($txt_sth);
    
    my $rc = $dbh->disconnect or warn $dbh->errstr; # The handle is of little use after disconnecting. Possibly PrintError already prints a warning and this duplicates it?
    return $rc;
}

sub create_db {
    my $self= shift (@_);
    my $db_name = $self->{'site_name'};
    my $dbh = $self->{'db_handle'};
    
    # https://stackoverflow.com/questions/5025768/how-can-i-create-a-mysql-database-from-a-perl-script
    return $dbh->do("create database $db_name"); # do() will return undef on fail, https://metacpan.org/pod/DBI#do
}

sub create_metadata_table {
    my $self= shift (@_);
    my $dbh = $self->{'db_handle'};
    
    my $table_name = $self->{'collection_name'} . "metadata";

    # If using an auto incremented primary key:
    my $stmt = "CREATE TABLE $table_name (id INT NOT NULL AUTO_INCREMENT, did VARCHAR(63) NOT NULL, sid VARCHAR(63) NOT NULL, metaname VARCHAR(127) NOT NULL, metavalue VARCHAR(1023) NOT NULL, PRIMARY KEY(id));";
    return $dbh->do($stmt);
}

# TODO: Investigate: https://dev.mysql.com/doc/search/?d=10&p=1&q=FULLTEXT
# 12.9.1 Natural Language Full-Text Searches
# to see whether we have to index the 'fulltxt' column of the 'fulltext' tables
# or let user edit this file, or add it as another option
sub create_fulltext_table {
    my $self= shift (@_);
    my $dbh = $self->{'db_handle'};
    
    my $table_name = $self->{'collection_name'} . "fulltxt";

    # If using an auto incremented primary key:
    my $stmt = "CREATE TABLE $table_name (id INT NOT NULL AUTO_INCREMENT, did VARCHAR(63) NOT NULL, sid VARCHAR(63) NOT NULL, fulltxt LONGTEXT, PRIMARY KEY(id));";
    return $dbh->do($stmt);

}


# USEFUL: https://metacpan.org/pod/DBI
# "Many methods have an optional \%attr parameter which can be used to pass information to the driver implementing the method. Except where specifically documented, the \%attr parameter can only be used to pass driver specific hints. In general, you can ignore \%attr parameters or pass it as undef."


# https://www.guru99.com/insert-into.html
# and https://dev.mysql.com/doc/refman/8.0/en/example-auto-increment.html
#     for inserting multiple rows at once
# https://www.perlmonks.org/bare/?node_id=316183
# https://metacpan.org/pod/DBI#do
# https://www.quora.com/What-is-the-difference-between-prepare-and-do-statements-in-Perl-while-we-make-a-connection-to-the-database-for-executing-the-query
# https://docstore.mik.ua/orelly/linux/dbi/ch05_05.htm

# https://metacpan.org/pod/DBI#performance
# 'The q{...} style quoting used in this example avoids clashing with quotes that may be used in the SQL statement. Use the double-quote like qq{...} operator if you want to interpolate variables into the string. See "Quote and Quote-like Operators" in perlop for more details.'
sub prepare_insert_metadata_row_stmthandle {
    my $self = shift (@_);    
    my ($did, $sid, $metaname, $metavalue) = @_;
    my $dbh = $self->{'db_handle'};
    
    my $tablename = $self->{'colname'}."_metadata";

    #my $stmt = "INSERT INTO $tablename (did, sid, metaname, metavalue) VALUES ('$did', '$sid', '$metaname', '$metavalue');"; # ?, ?, ?, ?

    # using qq{} since we want $tablename placeholder to be filled in
    # returns Statement Handle object!
    my $sth = $dbh->prepare(qq{INSERT INTO $tablename (did, sid, metaname, metavalue) VALUES (?, ?, ?, ?)"}) || warn("Could not prepare insert statement for metadata table\n");
    
    return $sth;
}

sub prepare_insert_fulltxt_row_stmthandle {
    my $self = shift (@_);
    my ($did, $sid, $fulltext) = @_;
    my $dbh = $self->{'db_handle'};
    
    my $tablename = $self->{'colname'}."_fulltxt";

    #my $stmt = "INSERT INTO $tablename (did, sid, fulltxt) VALUES ('$did', '$sid', '$fulltext');"; ?, ?, ?

    # using qq{} since we want $tablename placeholder to be filled in
    # returns Statement Handle object!
    my $sth = $dbh->prepare(qq{INSERT INTO $tablename (did, sid, fulltxt) VALUES (?, ?, ?)"}) || warn("Could not prepare insert statement for fulltxt table\n");
    
    return $sth;
}

# I can get my version of table_exists to work, but it's not so ideal
# Interesting that MySQL has non-standard command to CREATE TABLE IF NOT EXISTS and DROP TABLE IF EXISTS, 
# see https://www.perlmonks.org/bare/?node=DBI%20Recipes
#    The page further has a table_exists function that could work with proper comparison
# Couldn't get the first solution at https://www.perlmonks.org/bare/?node_id=500050 to work though
sub table_exists {
    my ($dbh,$table_name) = @_;

    my @table_list = $dbh->tables;
    #my $tables_str = @table_list[0];
    foreach my $table (@table_list) {
    return 1 if ($table =~ m/$table_name/);
    }
    return 0;
}

1;