<?php

    /*

    Module: Database stabilization

    File: /modules/stabilize/database.php

    Developers: dionyziz, feedWARd

    */

    

    function CompareFields($field1,$field2) {

        if ( $field1->Name() != $field2->Name() ) return false;

        if ( $field1->Type() != $field2->Type() ) return false;

        if ( $field1->IsNull() != $field2->IsNull() ) return false;

        if ( $field1->GetKey() != $field2->GetKey() ) return false;

        if ( $field1->DefaultValue() != $field2->DefaultValue() ) return false;

        if ( $field1->Extra() != $field2->Extra() ) return false;

        if ( $field1->Type() == "ENUM" ) {

            if ($field1->GetAllEnums() != $field2->GetAllEnums()) return false;

        }

        return true;

    }

    

    function DescribeField($curfield,$showprkey = false,$prinquery = false) {

        $curquery = "    `" . $curfield->Name() . "`";

        $isprimary = false;

        $curquery .= " " . $curfield->Type();

        if ( $curfield->Type() == "ENUM" ) {

            $curquery .= "(";

            while(($curenum = $curfield->GetEnum()) !== false) {

                $curquery .= "'" . $curenum . "',";

            }

            $curquery = substr($curquery,0,-1);

            $curquery .= ")";

        }

        if ( $curfield->IsNull() != "YES" ) $curquery .= " NOT NULL";

        if ( $curfield->DefaultValue() != null ) $curquery .= " default '" . $curfield->DefaultValue() . "'";

        if ( $curfield->Extra() ) $curquery .= " " . $curfield->Extra();

        if ( $curfield->GetKey() == "PRI" ) {

            $isprimary = true;

            if ( $prinquery == true ) $curquery .= " PRIMARY KEY";

        }

        //return values

        if (( $showprkey == true ) && ( $prinquery == false )) {

            return array($curquery,$isprimary);

        }

        else {

            return $curquery;

        }

    }

    

    function CompareTables($table1,$table2) {

        $s = FieldLCS($table1,$table2);

        $i = 0;

        $all = count($s);

        $queries = Array();

        $cur = "";

        $curquery = "";

        while ( $curfield = $table2->GetField() ) {

            if ( $i >= count($s) ) { $queries[] = "ALTER TABLE `" . $table2->Name() . "` DROP `" . $curfield->Name() . "`;"; }

            else if ( CompareFields($curfield,$s[$i]) == true ) {

                $i++;

            }

            else {

                $queries[] = "ALTER TABLE `" . $table2->Name() . "` DROP `" . $curfield->Name() . "`;";

            }

        }

        $i = 0;

        while ( $curfield = $table1->GetField() ) {

            if ( $i >= count($s) ) {

                $curquery = "ALTER TABLE `" . $table2->Name() . "` ADD " . DescribeField($curfield,true,true);

                if ( $cur == "" ) $curquery .= " FIRST;";

                else $curquery .= " AFTER `" . $cur . "`;";

                $queries[] = $curquery;

                $cur = $curfield->Name();

            }

            else if ( CompareFields($curfield,$s[$i]) == true ) {

                $cur = $s[$i]->Name();

                $i++;

            }

            else {

                $curquery = "ALTER TABLE `" . $table2->Name() . "` ADD " . DescribeField($curfield,true,true);

                if ( $cur == "" ) $curquery .= " FIRST;";

                else $curquery .= " AFTER `" . $cur . "`;";

                $queries[] = $curquery;

                $cur = $curfield->Name();

            }

        }

        return $queries;

    }

    

    define('LCS_OK', 0);

    define('LCS_LEFT', 1);

    define('LCS_UP', 2);



    function FieldLCS($table1, $table2) {

        /*

            blame dionyziz

        */

        $x = Array();

        $y = Array();

        while ($curfield = $table1->GetField()) {

            $x[] = $curfield;

        }

        while ($curfield = $table2->GetField()) {

            $y[] = $curfield;

        }

        $m = count($x);

        $n = count($y);

        

        // $c is a two-dimentional array which will store the length of the LCS

        // between the two left-most substrings of $x and $y of length $i and $j

        // so $c[$i][$j] = strlen(LCS(substr($x, 0, $i), substr($y, 0, $j))) if that makes any sense



        // $b is again a two-dimentional array which will store the path we have to

        // follow in order to construct the LCS we are building inside our two strings

        // we are constructing the LCS _backwards_

        // in simple words, LCS_OK means include this character and move backwards in both strings

        // while LCS_LEFT and LCS_UP means move backwards only in one of the two strings and do

        // not any character (since it's not a common character)



        // initialize the arrays, make them two-dimentional

        // in addition, set to zero the length of LCS between zero-length strings (trivially)

        $c = Array();

        $c = array_fill(0, $m + 1, array(0)); // $c[$i][0] = 0; for every $i

        $c[0] = array_fill(0, $n + 1, 0); // $c[0][$j] = 0; for every $j



        // go through the two stings character-by-character to construct the two arrays

        for ($i = 1; $i <= $m; ++$i) {

            for ($j = 1; $j <= $n; ++$j) {

                // if a given character is the same, append it to the LCS

                if (CompareFields($x[$i - 1],$y[$j-1]) == true) {

                    // the new LCS is going to be as long as the previous plus one character

                    $c[$i][$j] = $c[$i - 1][$j - 1] + 1;

                    // this is a character of the LCS

                    $b[$i][$j] = LCS_OK;

                }

                // the character is not the same, we have to compare the lengths of the two possible sub-LCSs

                // and use the greater one (since we want to construct as long a string as possible)

                else if ($c[$i - 1][$j] >= $c[$i][$j - 1]) {

                    // skip one character upwards

                    $c[$i][$j] = $c[$i - 1][$j];

                    $b[$i][$j] = LCS_UP;

                }

                else {

                    // skip one character leftwards

                    $c[$i][$j] = $c[$i][$j - 1];

                    $b[$i][$j] = LCS_LEFT;

                }

            }

        }

        // now all we need is to go through the $b table to make the final string

        $i = $m;

        $j = $n;

        $l = array();

        while ($i != 0 && $j != 0) {

            switch ($b[$i][$j]) {

                case LCS_OK:

                    --$i; // decrementing before using, so we don't need to make it -1 inside the {}

                    $l[] = $x[$i];

                    ++$cnt;

                    //fallthrough

                case LCS_LEFT:

                    --$j;

                    break;

                case LCS_UP:

                    --$i;

                    break;

            }

        }

        $l = array_reverse($l);

        return $l;

    }

    

    function StabilizeDatabase() {

        global $db_access;



        $beta_access = $db_access[ 'unstable_stabilize' ];

        $stable_access = $db_access[ 'stable_stabilize' ];

        $queries = array();

        

        if ( !isset( $beta_access ) || !isset( $stable_access ) ) {

            bc_die( 'Stabilization: Could not read access codes to databases' );

        }



        $beta_database = New BCDatabase(

            'localhost' ,

            $beta_access[ 'username' ] ,

            $beta_access[ 'password' ] ,

            $beta_access[ 'db' ]

        );



        $stable_database = New BCDatabase(

            'localhost' ,

            $stable_access[ 'username' ] ,

            $stable_access[ 'password' ] ,

            $stable_access[ 'db' ]

        );



        if ( !$stable_database->Connect() ) {

            bc_die( 'Stabilization: Connection to Stable failed: ' . $stable_database->Error() );

        }

        if ( !$beta_database->Connect() ) {

            bc_die( 'Stabilization: Connection to Beta failed: ' . $beta_database->Error() );

        }



        $stable_table_list = $stable_database->GetTables();

        $beta_table_list = $beta_database->GetTables();

        

        $stable_table_names = array();

        for($i=0;$i<count($stable_table_list);$i++) {

            $stable_table_names[] = $stable_table_list[$i]->Name();

        }

        $beta_table_names = array();

        for($i=0;$i<count($beta_table_list);$i++) {

            $beta_table_names[] = $beta_table_list[$i]->Name();

        }

        

        //drop tables

        $todrop = array_diff($stable_table_names,$beta_table_names);

        $curquery = "";

        foreach($todrop as $ctablename) {

            if ( $curquery == "" ) $curquery = "DROP TABLE `" . $ctablename . "`";

            else $curquery .= ",`" . $ctablename . "`";

        }

        if ( $curquery != "" ) {

            $curquery .= ";";

            $queries[] = $curquery;

        }

        

        //create tables

        $tocreate = array_diff($beta_table_names,$stable_table_names);

        foreach($tocreate as $ctablename) {

            $curtable = New BCDbTable($ctablename,$beta_database);

            $curquery = "CREATE TABLE `" . $ctablename . "` (";

            $curprkey = "";

            while ($curfield = $curtable->GetField()) {

                $curquery .= "\n";

                $curres = DescribeField($curfield,true);

                $curquery .= $curres[0];

                if ( $curres[1] == true ) $curprkey = $curfield->Name();

                $curquery .= ",";

            }

            if ( $curprkey != "" ) $curquery .= "\n    PRIMARY KEY ( `" . $curprkey . "` ),";

            $curquery = substr($curquery,0,-1);

            $curquery .= "\n);\n";

            $queries[] = $curquery;

        }

        

        //alter tables

        $toalter = array_intersect($beta_table_names,$stable_table_names);

        foreach($toalter as $ctablename) {

            $firsttable = New BCDbTable($ctablename,$beta_database);

            $secondtable = New BCDbTable($ctablename,$stable_database);

            $alterqueries = CompareTables($firsttable,$secondtable);

            $queries = array_merge($queries,$alterqueries);

        }



        return $queries;

    }

?>