# Selima Website Content Management System
# Guestbook.pm: The guestbook-related subroutines.

#  Copyright (c) 2004-2018 imacat.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

# Author: imacat <imacat@mail.imacat.idv.tw>
# First written: 2004-10-23

package Selima::Guestbook;
use 5.008;
use strict;
use warnings;
use base qw(Exporter);
use vars qw(@EXPORT @EXPORT_OK);
BEGIN {
@EXPORT = qw(update_pageno);
@EXPORT_OK = @EXPORT;
# Prototype declaration
sub update_pageno($$$;$);
sub split_page(\@\%$;$);
sub update_old_gbpageno($$;$);
}

use Selima::DataVars qw($DBH);
use Selima::Format;

# update_pageno: Update the guestbook page number
sub update_pageno($$$;$) {
    local ($_, %_);
    my ($table, $page_size, $cols, $from, $sql, $sth, $count, $row, $len, $where);
    my (@ents, %sizes, %orig, %pagenos, $startno, $startat, $commit);
    ($table, $page_size, $cols, $from) = @_;
    
    # If we should begin and commit here
    $commit = $DBH->{"AutoCommit"};
    $DBH->begin_work if $commit;
    
    # Update the current page number
    # Check the page to start from
    undef $startno;
    undef $startat;
    $from = fmttime $from if defined $from;
    if (defined $from) {
        $sql = "SELECT pageno FROM $table WHERE NOT hid AND created<'$from'"
            . " ORDER BY created DESC LIMIT 1;\n";
        $sth = $DBH->prepare($sql);
        $sth->execute;
        undef $from if $sth->rows != 1;
    }
    if (defined $from) {
        $startno = ${$sth->fetch}[0];
        undef $sth;
        $sql = "SELECT created FROM $table WHERE NOT hid AND pageno=$startno"
            . " ORDER BY created LIMIT 1;\n";
        $sth = $DBH->prepare($sql);
        $sth->execute;
        $startat = ${$sth->fetch}[0];
    }
    @_ = qw();
    push @_, "created>='" . fmttime($startat) . "'" if defined $startat;
    $where = (@_ > 0)? " WHERE " . join(" AND ", @_): "";
    # Ge the size of everyhing
    $len = join " + ", map "CASE WHEN $_ IS NULL THEN 0 ELSE char_length($_) END", @$cols;
    $len = "CASE WHEN hid THEN 0 ELSE $len END AS len";
    $sql = "SELECT sn, $len, pageno FROM $table $where ORDER BY created;\n";
    $sth = $DBH->prepare($sql);
    $sth->execute;
    $count = $sth->rows;
    for ($_ = 0, @ents = qw(), %sizes = qw(), %orig = qw(); $_ < $count; $_++) {
        $row = $sth->fetchrow_hashref;
        push @ents, $$row{"sn"};
        $sizes{$$row{"sn"}} = $$row{"len"};
        $orig{$$row{"sn"}} = $$row{"pageno"};
    }
    # Split page
    %pagenos = split_page @ents, %sizes, $page_size, $startno;
    # Update it
    foreach (@ents) {
        next if $orig{$_} == $pagenos{$_};
        $sql = "UPDATE $table SET pageno=$pagenos{$_} WHERE sn=$_;\n";
        $DBH->gdo($sql);
    }
    
    # Update the old page number
    # No need to update it anymore.  Let it go.
    $DBH->commit if $commit;
    return;
}

# split_page: Split page according to the entry sizes
sub split_page(\@\%$;$) {
    local ($_, %_);
    my ($ents, $sizes, $page_size, $startno, $cursize, %pagenos);
    ($ents, $sizes, $page_size, $startno) = @_;
    $startno = 1 if !defined $startno;
    
    # Bounce for nothing
    return if scalar @$ents == 0;
    
    # Split pages
    %pagenos = qw();
    $pagenos{$$ents[0]} = $startno;
    $cursize = $$sizes{$$ents[0]};
    for ($_ = 1; $_ < scalar(@$ents); $_++) {
        my ($hi_gap, $lo_gap);
        # We need at least one record
        if ($cursize == 0) {
            $pagenos{$$ents[$_]} = $pagenos{$$ents[$_-1]};
            $cursize += $$sizes{$$ents[$_]};
            next;
        # Not oversized yet
        } elsif ($cursize + $$sizes{$$ents[$_]} < $page_size) {
            $pagenos{$$ents[$_]} = $pagenos{$$ents[$_-1]};
            $cursize += $$sizes{$$ents[$_]};
            next;
        }
        $hi_gap = $cursize + $$sizes{$$ents[$_]} - $page_size;
        $lo_gap = $page_size - $cursize;
        # The upper boundary is closer, and the page is not too oversized
        if ($hi_gap < $lo_gap && $hi_gap <= $page_size / 4) {
            $pagenos{$$ents[$_]} = $pagenos{$$ents[$_-1]};
            $cursize += $$sizes{$$ents[$_]};
        # Or, we prefer the lower, since the page is not oversized
        } else {
            $pagenos{$$ents[$_]} = $pagenos{$$ents[$_-1]} + 1;
            $cursize = $$sizes{$$ents[$_]};
        }
    }
    
    return %pagenos;
}

# update_old_gbpageno: Update the old guestbook page number
sub update_old_gbpageno($$;$) {
    local ($_, %_);
    my ($table, $page_size, $from, $sql, $sth, $count, $row, $len, $cond);
    my (@ents, %sizes, %orig, %pagenos, $startno, $startat, $commit);
    ($table, $page_size, $from) = @_;
    
    # If we should begin and commit here
    $commit = $DBH->{"AutoCommit"};
    $DBH->begin_work if $commit;
    
    # Update the old page number
    undef $startno;
    undef $startat;
    if (defined $from) {
        $sql = "SELECT oldpageno FROM $table WHERE NOT hid AND created<'$from'"
            . " ORDER BY created DESC LIMIT 1;\n";
        $sth = $DBH->prepare($sql);
        $sth->execute;
        $startno = ${$sth->fetch}[0];
        undef $sth;
        $sql = "SELECT created FROM $table WHERE NOT hid AND oldpageno=$startno"
            . " ORDER BY created LIMIT 1;\n";
        $sth = $DBH->prepare($sql);
        $sth->execute;
        $startat = ${$sth->fetch}[0];
    }
    @_ = qw();
    push @_, "NOT hid";
    push @_, "created>='$startat'" if defined $startat;
    $cond = join " AND ", @_;
    # Ge the size of everyhing
    $len = "${table}_oldlen(created, ip, host, name, identity, location, email, url, message, updated, updatedby) AS len";
    # Tavern Backalley has a special table structure
    $len = "garbage_oldlen(created, ip, host, message, updated, updatedby) AS len"
        if $table eq "garbage";
    $sql = "SELECT sn, $len, oldpageno FROM $table WHERE $cond ORDER BY created;\n";
    $sth = $DBH->prepare($sql);
    $sth->execute;
    $count = $sth->rows;
    for ($_ = 0, @ents = qw(), %sizes = qw(), %orig = qw(); $_ < $count; $_++) {
        $row = $sth->fetchrow_hashref;
        push @ents, $$row{"sn"};
        $sizes{$$row{"sn"}} = $$row{"len"};
        $orig{$$row{"sn"}} = $$row{"oldpageno"};
    }
    # Split page
    # Old page size is always 10240
    %pagenos = split_page @ents, %sizes, 10240, $startno;
    # Update it
    foreach (@ents) {
        next if $orig{$_} == $pagenos{$_};
        $sql = "UPDATE $table SET oldpageno=$pagenos{$_} WHERE sn=$_;\n";
        $DBH->gdo($sql);
    }
    
    $DBH->commit if $commit;
    
    return;
}

return 1;