package OPLUtils;
use base qw(Exporter);

# This file contains the subroutines that build JSON files from the database to help speed up the client side.
#
#  The following files are created:
#		1. $webwork_htdocs/DATA/library-directory-tree.json  (the directory structure of the library)
#		2. $webwork_htdocs/DATA/library-subject-tree.json  (the subject/chapter/section struture of the library)
#		3. $webwork_htdocs/DATA/textbook-tree.json  (the subject/chapter/section struture of the library)

# the above JSON files can be used to load and more quickly lookup OPL information
#

use strict;
use warnings;
use File::Find::Rule;
use File::Basename;
use open qw/:std :utf8/;
use Mojo::JSON qw(encode_json);

our @EXPORT = ();
our @EXPORT_OK =
	qw(build_library_directory_tree build_library_subject_tree build_library_textbook_tree writeJSONtoFile);

### Data for creating the database tables

my %OPLtables = (
	dbsubject      => 'OPL_DBsubject',
	dbchapter      => 'OPL_DBchapter',
	dbsection      => 'OPL_DBsection',
	author         => 'OPL_author',
	path           => 'OPL_path',
	pgfile         => 'OPL_pgfile',
	keyword        => 'OPL_keyword',
	pgfile_keyword => 'OPL_pgfile_keyword',
	textbook       => 'OPL_textbook',
	chapter        => 'OPL_chapter',
	section        => 'OPL_section',
	problem        => 'OPL_problem',
	morelt         => 'OPL_morelt',
	pgfile_problem => 'OPL_pgfile_problem',
);

my %NPLtables = (
	dbsubject      => 'NPL-DBsubject',
	dbchapter      => 'NPL-DBchapter',
	dbsection      => 'NPL-DBsection',
	author         => 'NPL-author',
	path           => 'NPL-path',
	pgfile         => 'NPL-pgfile',
	keyword        => 'NPL-keyword',
	pgfile_keyword => 'NPL-pgfile-keyword',
	textbook       => 'NPL-textbook',
	chapter        => 'NPL-chapter',
	section        => 'NPL-section',
	problem        => 'NPL-problem',
	morelt         => 'NPL-morelt',
	pgfile_problem => 'NPL-pgfile-problem',
);

sub build_library_directory_tree {
	my ($ce, $verbose) = @_;

	print "Creating the Directory Tree\n" if $verbose;
	my $libraryRoot = $ce->{problemLibrary}->{root};
	$libraryRoot =~ s|/+$||;

	my @dirArray = ();
	push(@dirArray, buildTree($libraryRoot));

	my $webwork_htdocs = $ce->{webworkDirs}{htdocs};
	my $file           = "$webwork_htdocs/DATA/library-directory-tree.json";

	writeJSONtoFile(\@dirArray, $file);

	print "Wrote Library Directory Tree to $file\n" if $verbose;
}

sub buildTree {
	my $absoluteDir = shift;
	my $branch      = {};
	my ($name, $dir) = fileparse($absoluteDir);
	$branch->{name} = $name;
	my @dirs = File::Find::Rule->maxdepth(1)->relative(1)->directory->in($absoluteDir);
	if (scalar(@dirs) == 0) {
		return undef;
	}

	my @branches = ();

	for my $dir (@dirs) {
		my $theBranch = buildTree($absoluteDir . "/" . $dir);
		if ($theBranch) {
			my @files = File::Find::Rule->file()->name("*.pg")->in($absoluteDir . "/" . $dir);
			$theBranch->{num_files} = scalar(@files);
			push(@branches, $theBranch);
		} else {
			$b = {};
			$b->{name} = $dir;

			my @files = File::Find::Rule->file()->name("*.pg")->in($absoluteDir . "/" . $dir);

			if (scalar(@files) > 0) {
				$b->{num_files} = scalar(@files);
				push(@branches, $b);
			}
		}
	}

	$branch->{subfields} = \@branches;
	my @files = File::Find::Rule->file()->name("*.pg")->in($absoluteDir);
	$branch->{num_files} = scalar(@files);

	return $branch;
}

sub build_library_subject_tree {
	my ($ce, $dbh, $verbose) = @_;

	my $libraryRoot = $ce->{problemLibrary}->{root};
	$libraryRoot =~ s|/+$||;
	my $libraryVersion = $ce->{problemLibrary}->{version};

	my %tables = ($libraryVersion eq '2.5') ? %OPLtables : %NPLtables;

	# query the database for all of the subject names
	my $cmd           = qq/select name from $tables{dbsubject};/;
	my @subject_names = map { $_->[0] } $dbh->selectall_array($cmd);

	my $tree;    # the library subject tree will be stored as arrays of objects.

	print "Building the subject-tree.  There are " . scalar(@subject_names) . " subjects\n" if $verbose;

	my @subject_tree;    # array to store the individual library tree for each subject

	my $selectClause = "";

	for my $subj_name (@subject_names) {

		my $subj = $subj_name;
		$subj =~ s/'/\'/g;    # escape any single quotes;

		print "subject: $subj_name is being processed.\n" if $verbose;

		my $cmd = qq/SELECT ch.name from $tables{dbchapter} AS ch
			JOIN $tables{dbsubject} AS subj ON ch.DBsubject_id=subj.DBsubject_id
			WHERE subj.name='$subj';/;

		my @chapter_names = map { $_->[0] } $dbh->selectall_array($cmd);

		my @chapter_tree;     # array to store the individual library tree for each chapter

		for my $ch_name (@chapter_names) {

			my $ch = $ch_name;
			$ch =~ s/'/\'/g;    # escape any single quotes;

			my $results =
				$dbh->selectall_arrayref("SELECT sect.name from `$tables{dbsubject}` AS subj "
					. "JOIN `$tables{dbchapter}` AS ch ON subj.DBsubject_id = ch.DBsubject_id "
					. "JOIN `$tables{dbsection}` AS sect ON sect.DBchapter_id = ch.DBchapter_id "
					. "WHERE subj.name='$subj' AND ch.name='$ch';");

			my @section_names = map { $_->[0] } @{$results};

			my @subfields = ();

			for my $sect_name (@section_names) {
				my $section_tree = { name => $sect_name };

				## Determine the number of files that falls into each

				my $sect = $sect_name;
				$sect =~ s/'/\\'/g;    # escape any single quotes

				my $cmd = qq/SELECT COUNT(*) from $tables{dbsection} AS sect
					JOIN $tables{dbchapter} AS ch ON sect.DBchapter_id = ch.DBchapter_id
					JOIN $tables{dbsubject} AS subj ON subj.DBsubject_id = ch.DBsubject_id
					JOIN $tables{pgfile} AS pg ON sect.DBsection_id = pg.DBsection_id
					where subj.name = '$subj' AND ch.name='$ch' AND sect.name='$sect';/;

				$section_tree->{num_files} = $dbh->selectrow_array($cmd);
				my $clone = { %{$section_tree} };    # need to clone it before pushing into the @subfield array.

				push(@subfields, $clone);
			}

			my $chapter_tree = { name => $ch_name, subfields => \@subfields };

			## determine the number of files in each chapter

			my $cmd = qq/select COUNT(*) from $tables{dbsection} AS sect
				JOIN $tables{dbchapter} AS ch ON sect.DBchapter_id = ch.DBchapter_id
				JOIN $tables{dbsubject} AS subj ON subj.DBsubject_id = ch.DBsubject_id
				JOIN $tables{pgfile} AS pg ON sect.DBsection_id = pg.DBsection_id
				JOIN $tables{path} AS path ON pg.path_id = path.path_id
				where ch.name = '$ch' AND subj.name = '$subj_name';/;

			$chapter_tree->{num_files} = $dbh->selectrow_array($cmd);

			my $clone = { %{$chapter_tree} };    # need to clone it before pushing into the @chapter_tree array.
			push(@chapter_tree, $clone);
		}

		my $subject_tree = { name => $subj_name, subfields => \@chapter_tree };

		## find the number of files on the subject level

		$cmd = qq/select COUNT(*) from $tables{dbsection} AS sect
			JOIN $tables{dbchapter} AS ch ON sect.DBchapter_id = ch.DBchapter_id
			JOIN $tables{dbsubject} AS subj ON subj.DBsubject_id = ch.DBsubject_id
			JOIN $tables{pgfile} AS pg ON sect.DBsection_id = pg.DBsection_id
			JOIN $tables{path} AS path ON pg.path_id = path.path_id
			where subj.name = '$subj_name';/;

		$subject_tree->{num_files} = $dbh->selectrow_array($cmd);

		my $clone = { %{$subject_tree} };
		push(@subject_tree, $clone);
	}
	my $webwork_htdocs = $ce->{webworkDirs}{htdocs};
	my $file           = "$webwork_htdocs/DATA/library-subject-tree.json";

	writeJSONtoFile(\@subject_tree, $file);

	print "Wrote Library Subject Tree to $file\n" if $verbose;
}

sub build_library_textbook_tree {

	my ($ce, $dbh, $verbose) = @_;

	my $libraryRoot = $ce->{problemLibrary}->{root};
	$libraryRoot =~ s|/+$||;
	my $libraryVersion = $ce->{problemLibrary}->{version};

	my %tables = ($libraryVersion eq '2.5') ? %OPLtables : %NPLtables;

	my $selectClause =
		"SELECT pg.pgfile_id from $tables{path} as path "
		. "LEFT JOIN $tables{pgfile} AS pg ON pg.path_id=path.path_id "
		. "LEFT JOIN $tables{pgfile_problem} AS pgprob ON pgprob.pgfile_id=pg.pgfile_id "
		. "LEFT JOIN $tables{problem} AS prob ON prob.problem_id=pgprob.problem_id "
		. "LEFT JOIN $tables{section} AS sect ON sect.section_id=prob.section_id "
		. "LEFT JOIN $tables{chapter} AS ch ON ch.chapter_id=sect.chapter_id "
		. "LEFT JOIN $tables{textbook} AS text ON text.textbook_id=ch.textbook_id ";

	my $results = $dbh->selectall_arrayref("select * from `$tables{textbook}` ORDER BY title;");

	my @textbooks = map { {
		textbook_id => $_->[0],
		title       => $_->[1],
		edition     => $_->[2],
		author      => $_->[3],
		publisher   => $_->[4],
		isbn        => $_->[5],
		pubdate     => $_->[6]
	} } @{$results};

	my @output = ();

	my $i = 0;    ## index to alert user the length of the build

	print "Building the Textbook Library Tree\n"                  if $verbose;
	print "There are " . $#textbooks . " textbooks to process.\n" if $verbose;

	for my $textbook (@textbooks) {
		$i++;
		printf("%4d", $i) if $verbose;
		print("\n")       if ($i % 10 == 0 && $verbose);

		my $results =
			$dbh->selectall_arrayref("select ch.chapter_id,ch.name,ch.number "
				. " from `$tables{chapter}` AS ch JOIN `$tables{textbook}` AS text ON ch.textbook_id=text.textbook_id "
				. " WHERE text.textbook_id='"
				. $textbook->{textbook_id}
				. "' ORDER BY ch.number;");

		my @chapters = map { { chapter_id => $_->[0], name => $_->[1], number => $_->[2] } } @{$results};

		my @chs = ();

		for my $chapter (@chapters) {

			my $results =
				$dbh->selectall_arrayref("select sect.section_id,sect.name,sect.number "
					. "FROM `$tables{chapter}` AS ch "
					. "LEFT JOIN `$tables{textbook}` AS text ON ch.textbook_id=text.textbook_id "
					. "LEFT JOIN `$tables{section}` AS sect ON sect.chapter_id = ch.chapter_id "
					. "WHERE text.textbook_id='"
					. $textbook->{textbook_id}
					. "' AND "
					. "ch.chapter_id='"
					. $chapter->{chapter_id}
					. "' ORDER BY sect.number;");

			my @sections = map { { section_id => $_->[0], name => $_->[1], number => $_->[2] } } @{$results};

			for my $section (@sections) {

				my $whereClause =
					"WHERE sect.section_id='"
					. $section->{section_id}
					. "' AND ch.chapter_id='"
					. $chapter->{chapter_id}
					. "' AND "
					. "text.textbook_id='"
					. $textbook->{textbook_id} . "'";

				my $sth = $dbh->prepare($selectClause . $whereClause);
				$sth->execute;
				$section->{num_probs} = scalar @{ $sth->fetchall_arrayref() };
			}
			my $whereClause =
				"WHERE ch.chapter_id='"
				. $chapter->{chapter_id}
				. "' AND "
				. "text.textbook_id='"
				. $textbook->{textbook_id} . "'";

			my $sth = $dbh->prepare($selectClause . $whereClause);
			$sth->execute;
			$chapter->{num_probs} = scalar @{ $sth->fetchall_arrayref() };

			$chapter->{sections} = \@sections;

			my @sects =
				map { { name => $_->{name}, section_id => $_->{section_id}, num_files => $_->{num_probs} } } @sections;

			push(
				@chs,
				{
					name       => $chapter->{name},
					chapter_id => $chapter->{chapter_id},
					num_files  => $chapter->{num_probs},
					subfields  => \@sects
				}
			);

		}
		my $whereClause = "WHERE text.textbook_id='" . $textbook->{textbook_id} . "'";

		my $sth = $dbh->prepare($selectClause . $whereClause);
		$sth->execute;
		$textbook->{num_probs} = scalar @{ $sth->fetchall_arrayref() };

		$textbook->{chapters} = \@chapters;

		push(
			@output,
			{
				name        => $textbook->{title} . " - " . $textbook->{author},
				textbook_id => $textbook->{textbook_id},
				subfields   => \@chs,
				num_files   => $sth->rows
			}
		);
	}

	print "\n";

	my $webwork_htdocs = $ce->{webworkDirs}{htdocs};
	my $file           = "$webwork_htdocs/DATA/textbook-tree.json";

	writeJSONtoFile(\@output, $file);

	print "\n\nWrote Library Textbook Tree to $file\n" if $verbose;

}

# this takes a hash created in the other subroutines and write the result to a file
sub writeJSONtoFile {
	my ($data, $filename) = @_;

	my $json = encode_json($data);
	open my $fh, ">", $filename or die "Cannot open $filename";
	print $fh $json;
	close $fh;
}

1;