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package RT::SQL;

use strict;
use warnings;


# States
use constant VALUE       => 1;
use constant AGGREG      => 2;
use constant OP          => 4;
use constant OPEN_PAREN  => 8;
use constant CLOSE_PAREN => 16;
use constant KEYWORD     => 32;
my @tokens = qw[VALUE AGGREGATOR OPERATOR OPEN_PAREN CLOSE_PAREN KEYWORD];

use Regexp::Common qw /delimited/;
my $re_aggreg      = qr[(?i:AND|OR)];
my $re_delim       = qr[$RE{delimited}{-delim=>qq{\'\"}}];

# We need to support bare(not quoted) strings like CF.{Beta Date} to use the
# content of related custom field as the value to compare, e.g.
#
#       Due < CF.{Beta Date}
#
# Support it in keyword part is mainly for consistency.

my $re_value       = qr[(?i:CF)\.\{.+?\}(?:\.(?i:Content|LargeContent))?|[\w\.]+|[+-]?\d+|(?i:NULL)|$re_delim];
my $re_keyword     = qr[(?i:CF)\.\{.+?\}(?:\.(?i:Content|LargeContent))?|[{}\w\.]+|$re_delim];
my $re_op          = qr[(?i:SHALLOW )?(?:=|!=|>=|<=|>|<|(?i:IS NOT)|(?i:IS)|(?i:NOT LIKE)|(?i:LIKE)|(?i:NOT STARTSWITH)|(?i:STARTSWITH)|(?i:NOT ENDSWITH)|(?i:ENDSWITH))]; # long to short
my $re_open_paren  = qr[\(];
my $re_close_paren = qr[\)];

sub ParseToArray {
    my ($string) = shift;

    my ($tree, $node, @pnodes);
    $node = $tree = [];

    my %callback;
    $callback{'OpenParen'} = sub { push @pnodes, $node; $node = []; push @{ $pnodes[-1] }, $node };
    $callback{'CloseParen'} = sub { $node = pop @pnodes };
    $callback{'EntryAggregator'} = sub { push @$node, $_[0] };
    $callback{'Condition'} = sub { push @$node, { key => $_[0], op => $_[1], value => $_[2] } };

    Parse($string, \%callback);
    return $tree;
}

sub Parse {
    my ($string, $cb) = @_;
    my $loc = sub {HTML::Mason::Commands::loc(@_)};
    $string = '' unless defined $string;

    my $want = KEYWORD | OPEN_PAREN;
    my $last = 0;

    my $depth = 0;
    my ($key,$op,$value) = ("","","");

    # order of matches in the RE is important.. op should come early,
    # because it has spaces in it.    otherwise "NOT LIKE" might be parsed
    # as a keyword or value.

    while ($string =~ /(
                        $re_aggreg
                        |$re_op
                        |$re_keyword
                        |$re_value
                        |$re_open_paren
                        |$re_close_paren
                       )/iogx )
    {
        my $match = $1;

        # Highest priority is last
        my $current = 0;
        $current = OP          if ($want & OP)          && $match =~ /^$re_op$/io;
        $current = VALUE       if ($want & VALUE)       && $match =~ /^$re_value$/io;
        $current = KEYWORD     if ($want & KEYWORD)     && $match =~ /^$re_keyword$/io;
        $current = AGGREG      if ($want & AGGREG)      && $match =~ /^$re_aggreg$/io;
        $current = OPEN_PAREN  if ($want & OPEN_PAREN)  && $match =~ /^$re_open_paren$/io;
        $current = CLOSE_PAREN if ($want & CLOSE_PAREN) && $match =~ /^$re_close_paren$/io;


        unless ($current && $want & $current) {
            my $tmp = substr($string, 0, pos($string)- length($match));
            $tmp .= '>'. $match .'<--here'. substr($string, pos($string));
            my $msg = $loc->("Wrong query, expecting a [_1] in '[_2]'", _BitmaskToString($want), $tmp);
            return $cb->{'Error'}->( $msg ) if $cb->{'Error'};
            die $msg;
        }

        # State Machine:

        # Parens are highest priority
        if ( $current & OPEN_PAREN ) {
            $cb->{'OpenParen'}->();
            $depth++;
            $want = KEYWORD | OPEN_PAREN;
        }
        elsif ( $current & CLOSE_PAREN ) {
            $cb->{'CloseParen'}->();
            $depth--;
            $want = AGGREG;
            $want |= CLOSE_PAREN if $depth;
        }
        elsif ( $current & AGGREG ) {
            $cb->{'EntryAggregator'}->( $match );
            $want = KEYWORD | OPEN_PAREN;
        }
        elsif ( $current & KEYWORD ) {
            $key = $match;
            $want = OP;
        }
        elsif ( $current & OP ) {
            $op = $match;
            $want = VALUE;
        }
        elsif ( $current & VALUE ) {
            $value = $match;

            # Remove surrounding quotes and unescape escaped
            # characters from $key, $match
            for ( $key, $value ) {
                if ( /$re_delim/o ) {
                    substr($_,0,1) = "";
                    substr($_,-1,1) = "";
                }
                s!\\(.)!$1!g;
            }

            my $quote_value;
            if ( $match =~ /$re_delim/o ) {
                $quote_value = 1;

                # It's really rare to search strings like "CF.foo", to DWIM,
                # automatically convert to columns
                if ( $value =~ /^CF\.(?:\{(.*)\}|(.*?))(?:\.(Content|LargeContent))?$/i ) {
                    RT->Logger->debug("Unquote value($match) to search custom field instead");
                    $quote_value = 0;
                }
            }
            elsif ( $match =~ /^[a-z]/i ) {
                # Value is a column
                $quote_value = 0;
            }
            else {
                # Not setting value here to fallback to default behavior
            }

            $cb->{'Condition'}->( $key, $op, $value, $quote_value );

            ($key,$op,$value) = ("","","");
            $want = AGGREG;
            $want |= CLOSE_PAREN if $depth;
        } else {
            my $msg = $loc->("Query parser is lost");
            return $cb->{'Error'}->( $msg ) if $cb->{'Error'};
            die $msg;
        }

        $last = $current;
    } # while

    unless( !$last || $last & (CLOSE_PAREN | VALUE) ) {
        my $msg = $loc->("Incomplete query, last element ([_1]) is not close paren or value in '[_2]'",
                         _BitmaskToString($last),
                         $string);
        return $cb->{'Error'}->( $msg ) if $cb->{'Error'};
        die $msg;
    }

    if( $depth ) {
        my $msg = $loc->("Incomplete query, [quant,_1,unclosed paren,unclosed parens] in '[_2]'", $depth, $string);
        return $cb->{'Error'}->( $msg ) if $cb->{'Error'};
        die $msg;
    }
}

sub _BitmaskToString {
    my $mask = shift;

    my @res;
    for( my $i = 0; $i<@tokens; $i++ ) {
        next unless $mask & (1<<$i);
        push @res, $tokens[$i];
    }

    my $tmp = join ', ', splice @res, 0, -1;
    unshift @res, $tmp if $tmp;
    return join ' or ', @res;
}

sub _Optimize {
    my $tree = shift;

    # Convert simple OR'd clauses to IN for better performance, e.g.
    #     (Status = 'new' OR Status = 'open' OR Status = 'stalled')
    # to
    #     Status IN ('new', 'open', 'stalled')

    $tree->traverse(
        sub {
            my $node   = shift;
            my $parent = $node->getParent;
            return if $parent eq 'root';    # Skip root's root

            # For simple searches like "Status = 'new' OR Status = 'open'",
            # the OR node is also the root node, go up one level.
            $node = $parent if $node->isLeaf && $parent->isRoot;

            return if $node->isLeaf;

            if ( ( $node->getNodeValue // '' ) =~ /^or$/i && $node->getChildCount > 1 ) {
                my @children = $node->getAllChildren;
                my %info;
                for my $child (@children) {

                    # Only handle innermost ORs
                    return unless $child->isLeaf;
                    my $entry = $child->getNodeValue;
                    return unless $entry->{Op} =~ /^!?=$/;

                    # Handle String/Int/Id/Enum/Queue/Lifecycle only for
                    # now. Others have more complicated logic inside, which
                    # can't be easily converted.

                    # TICKETQUEUEFIELD only supports Lifecycle right now, which is fine
                    return
                        unless ( $entry->{Meta}[0] // '' )
                        =~ /^(?:STRING|INT|ID|ENUM|QUEUE|LIFECYCLE|TICKETFIELD|TICKETQUEUEFIELD)$/;

                    # TICKETFIELD contains more than what we want, need to filter a bit more deeply.
                    if ( $entry->{Meta}[0] eq 'TICKETFIELD' ) {
                        my ($field) = $entry->{Key} =~ /Ticket(\w+)/;
                        require RT::Tickets;
                        return
                            unless $RT::Tickets::FIELD_METADATA{$field}[0]
                            =~ /^(?:STRING|INT|ID|ENUM|QUEUE|LIFECYCLE)$/;
                    }

                    for my $field (qw/Key SubKey Op Value/) {
                        $info{$field}{ $entry->{$field} // '' } ||= 1;

                        if ( $field eq 'Value' ) {

                            # In case it's meta value like __Bookmarked__
                            return if $entry->{Meta}[0] eq 'ID' && $entry->{$field} !~ /^\d+$/;
                        }
                        elsif ( keys %{ $info{$field} } > 1 ) {
                            return;    # Skip if Key/SubKey/Op are different
                        }
                    }
                }

                my $first_child = shift @children;
                my $entry       = $first_child->getNodeValue;
                $entry->{Op} = $info{Op}{'='} ? 'IN' : 'NOT IN';
                $entry->{Value} = [ sort keys %{ $info{Value} } ];
                if ( $node->isRoot ) {
                    $parent->removeChild($_) for @children;
                }
                else {
                    $parent->removeChild($node);
                    $parent->addChild($first_child);
                }
            }
        }
    );
    return $tree;
}

RT::Base->_ImportOverlays();

1;
