###########################################################################
#
# GreenstoneSQLPlugout.pm -- plugout module for writing all or some the 
# Greenstone document format (metadata and/or fulltext) into a (My)SQL db.
# The rest is then still written out by GreenstoneXMLPlugout as usual.
# 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 GreenstoneSQLPlugout;

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

use GreenstoneXMLPlugout;
use docprint;
use gssql;

use DBI; # the central package for this plugout


# TODO: SIGTERM rollback and disconnect?


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

# NOTTODO: die() statements need to be replaced with premature_termination
# which should ensure the GreenstoneXMLPlugin (group)'s stuff is closed and cleaned up SOMEHOW
# It's fine: the die() stmts all take place before setting up the super class' begin

# 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' => "{GreenstoneSQLPlugout.process_mode.meta_only}" },      
      { 'name' => "text_only",
        'desc' => "{GreenstoneSQLPlugout.process_mode.text_only}" },
      { 'name' => "all",
        'desc' => "{GreenstoneSQLPlugout.process_mode.all}" } ];

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

my $options = { 'name'     => "GreenstoneSQLPlugout",
		'desc'     => "{GreenstoneSQLPlugout.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 "***** GreenstoneSQLPlugout 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";
    $self->{'build_mode'} = "removeold";
    #$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'};
    print STDERR "***** GreenstoneSQLPlugout process mode = \"", $self->{'process_mode'}, "\"\n";

    my $db_params = {
	'collection_name' => $ENV{'GSDLCOLLECTION'},	
	'db_encoding' => $self->{'db_encoding'}
	#'db_name' => $self->{'site_name'},
	#'build_mode' => $self->{'build_mode'},
    };

    my $gs_sql = new gssql($db_params);
    
    # try connecting to the mysql db, if that fails it will die
    # so don't bother preparing GreenstoneXMLPlugout by calling superclass' begin()
    if(!$gs_sql->connect_to_db({
	'db_driver' => $self->{'db_driver'},
	'db_client_user' => $self->{'db_client_user'},
	'db_client_pwd' => $self->{'db_client_pwd'},
	'db_host' => $self->{'db_host'}
			       })
	)
    {
	# 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");
    }
    
    my $db_name = $self->{'site_name'} || "localsite"; # one database per GS3 site
    my $build_mode = $self->{'build_mode'} || "removeold";
    if(!$gs_sql->load_db_and_tables($db_name, $build_mode)) {
	
	# 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'} = $gs_sql->prepare_insert_metadata_row_stmthandle();
    }
    if($proc_mode eq "all" || $proc_mode eq "text_only" ) {
	$self->{'fulltxt_prepared_insert_statement_handle'} = $gs_sql->prepare_insert_fulltxt_row_stmthandle();
    }

    # store the DBI wrapper instance
    $self->{'gs_sql'} = $gs_sql;
    
    print STDERR "#### Meta stmt: " . $self->{'metadata_prepared_insert_statement_handle'}->{'Statement'} . "\n";
    print STDERR "#### Full stmt: " . $self->{'fulltxt_prepared_insert_statement_handle'}->{'Statement'} . "\n";
    
    # 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
    
    $self->SUPER::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
    $self->SUPER::end(@_);    
    
    $self->{'gs_sql'}->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
}
 
# produce files called docsql.xml instead of doc.xml
sub get_short_doc_file {
    my $self = shift (@_);
    my ($doc_dir) = @_;
    return &FileUtils::filenameConcatenate($doc_dir, "docsql.xml");
}

# produce files called docsql.xml instead of doc.xml
sub get_output_file {
    my $self = shift (@_);
    my ($doc_dir) = @_;
    return &FileUtils::filenameConcatenate($self->{'output_dir'}, $doc_dir, "docsql.xml");
}
   
# 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) = @_;

    print STDERR "\n\n@@@ In saveas\n\n";
    
    my $proc_mode = $self->{'process_mode'};
    
    # 1. pre save out and saving debug handle

    # must call superclass (pre/post) saveas methods, as they handle assoc_files too
    my ($docxml_outhandler, $output_file) = $self->SUPER::pre_saveas(@_);

    $self->{'debug_outhandle'} = $docxml_outhandler if ($self->{'debug'}); # STDOUT if debug

    # TODO: also set debugging in begin()? Then stmts creating db and tables also sent to debug out and not executed

    # TODO: remove unused old_unused_saveas from GreenstoneXMLPlugout
    
    
    # 2. overriding saving behaviour to do what the superclass does PLUS saving to sql db    

    #NOTE: if proc_mode == all, then "breadcrumbs" go into both meta and txt elements of doc.xml:
    # statements pointing viewer to the sql db for contents
	
    # write the INVERSE into doc.xml as to what is written to the db    
    my $docxml_output_options = { 'output' => docprint::OUTPUT_NONE };
    if($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
    #$self->SUPER::post_saveas(@_);
    $self->SUPER::post_saveas($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 $doc_oid = $doc_obj->get_OID(); # this method processes a single doc at a time, so it uses the same OID throughout
    my $root_section = $doc_obj->get_top_section();

    # 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, $doc_oid, $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'};
#    print STDERR "#### Meta stmt: " . $metadata_table_sth->{'Statement'} . "\n";
#    print STDERR "#### Full stmt: " . $fulltxt_table_sth->{'Statement'} . "\n";
    
    #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 $escaped_meta_value = &docprint::escape_text($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 $section_text = &docprint::escape_text($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'}}) {
	$self->recursive_write_meta_and_text($doc_obj, $doc_oid, "$section.$subsection", $metadata_table_sth, $fulltxt_table_sth);
    }
}


1;