<?php
/**
 * our standard code relies on links.ini files for the relationships in mysql.
 *
 * as we use 'loose' relationships - eg. we allow '0' as a missing link mysql FORIEGN KEYS do not really work.
 *
 * There are a couple of ideas behind this code.
 *
 * a) put the relationships in the table comments FK(col=table:col,col=table:col)
 *  -- we can not put it in the column comments as there is no clean way to update column comments.
 *  -- This can be used by external programs to extract the Relationships.
 *
 * b) generate triggers? to protect against updates to the database..
 *
 *  -- stored procedures are named
 *     {tablename}_before_{insert|delete|update}
 *     
 *  
 *   initial code will auto generate triggers
 *   -- how to add User defined modifications to triggers?
 *   -- we can CALL a stored procedure..?
 *   -- {tablename}_trigger_before_delete_{column_name}(NEW.column)
 *   -- {tablename}_trigger_before_delete_{column_name}(OLD.column, NEW.column}
 *   -- {tablename}_trigger_before_delete_{column_name}(OLD.column}
 *
 *  
 *
 */

class Pman_Core_UpdateDatabase_MysqlLinks {
    
    var $dburl;
    var $schema;
    var $links;
    
    function __construct()
    {
          
        $this->loadIniFiles();
        $this->updateTableComments();
        $ff = HTML_FlexyFramework::get();
        if (!empty($ff->Pman['enable_trigger_tests'])) {
            
            // note we may want to override some of these... - to do special triggers..
            // as you can only have one trigger per table for each action.
            
            $this->createDeleteTriggers();
            $this->createInsertTriggers();
            $this->createUpdateTriggers();
        }
        
        
    }
    
    function loadIniFiles()
    {
        // will create the combined ini cache file for the running user.
        
        $ff = HTML_FlexyFramework::get();
        $ff->generateDataobjectsCache(true);
        $this->dburl = parse_url($ff->database);
        
        $dbini = 'ini_'. basename($this->dburl['path']);
        
        
        $iniCache = $ff->DB_DataObject[$dbini];
        
        $this->schema = parse_ini_file($iniCache, true);
        $this->links = parse_ini_file(preg_replace('/\.ini$/', '.links.ini', $iniCache), true);
        

        
    }
    function updateTableComments()
    {
        foreach($this->links as $tbl =>$map) {
            $this->updateTableComment($tbl, $map);
            
        }
        
        
    }
    
    function updateTableComment($tbl, $map)
    {
         
        
        if (!isset($this->schema[$tbl])) {
            echo "Skip $tbl\n";
            return;
        }
        
        
        $q = DB_DAtaObject::factory('core_enum');
        $q->query("SELECT
                     TABLE_COMMENT
                    FROM
                        information_schema.TABLES
                    WHERE
                        TABLE_SCHEMA = '{$q->escape($q->database())}'
                        AND
                        TABLE_NAME = '{$q->escape($tbl)}'
        ");
        $q->fetch();
        $tc = $q->TABLE_COMMENT;
        //echo "$tbl: $tc\n\n";
        if (!empty($q->TABLE_COMMENT)) {
            //var_dump($tc);
            $tc = trim(preg_replace('/FK\([^)]+\)/', '' , $q->TABLE_COMMENT));
            //var_dump($tc);exit;
            // strip out the old FC(....) 
                        
        }
        $fks = array();
        foreach($map as $k=>$v) {
            $fks[] = "$k=$v";
        }
        $fkstr = $tc . ' FK(' . implode("\n", $fks) .')';
        if ($q->TABLE_COMMENT == $fkstr) {
            return;
        }
        
        $q = DB_DAtaObject::factory('core_enum');
        $q->query("ALTER TABLE $tbl COMMENT = '{$q->escape($fkstr)}'");
        
        
        
    }
    
    function createDeleteTriggers()
    {
        
        // this should only be enabled if the project settings are configured..
        
       
        
        // delete triggers on targets -
        // if you delete a company, and a person points to it, then it should fire an error...
        
        
        
        
        // create a list of source/targets from $this->links
        
        $revmap = array();
        foreach($this->links as $tbl => $map) {
            if (!isset($this->schema[$tbl])) {
                continue;
            }
            foreach($map as $k =>$v) {
                list ($tname, $tcol) = explode(':', $v);
                
                
                if (!isset($revmap[$tname])) {
                    $revmap[$tname] = array();
                }
                $revmap[$tname]["$tbl:$k"] = "$tname:$tcol";
            }
        }
        
        
        foreach($revmap as $target_table => $sources) {
            
            
            // throw example.. UPDATE `Error: invalid_id_test` SET x=1;
            
            $q = DB_DataObject::factory('core_enum');
            $q->query("
                DROP TRIGGER IF EXISTS `{$target_table}_before_delete` ;
            ");
            
            $trigger = "
             
            CREATE TRIGGER `{$target_table}_before_delete`
                BEFORE DELETE ON `{$target_table}`
            FOR EACH ROW
            BEGIN
               DECLARE mid INT(11);
             
               
            ";
            foreach($sources as $source=>$target) {
                list($source_table , $source_col) = explode(':', $source);
                list($target_table , $target_col) = explode(':', $target);
                $err = substr("Failed Delete {$target_table} refs {$source_table}:{$source_col}", 0, 64);
                $trigger .="
                    SET mid = 0;
                    SELECT count(*) into mid FROM {$source_table} WHERE {$source_col} = OLD.{$target_col};
                    IF mid > 0 THEN
                       
                       UPDATE `$err` SET x = 1;
                       
                    END IF;
                ";
            }
            $trigger .= "
            END 
           
            ";
            
            //DB_DAtaObject::debugLevel(1);
            $q = DB_DataObject::factory('core_enum');
            $q->query($trigger);
             
        }
        
        
        // inserting - row should not point to a reference that does not exist...
        
        
        
        
    }
    function createInsertTriggers()
    {
        foreach($this->links as $tbl => $map) {
            if (!isset($this->schema[$tbl])) {
                continue;
            }
            
            $q = DB_DataObject::factory('core_enum');
            $q->query("
                DROP TRIGGER IF EXISTS `{$tbl}_before_insert` ;
            ");
            
            $trigger = "
             
            CREATE TRIGGER `{$tbl}_before_insert`
                BEFORE INSERT ON `{$tbl}`
            FOR EACH ROW
            BEGIN
               DECLARE mid INT(11);
               
               
            ";
            foreach($map as $source_col=>$target) {
                // check that source_col exists in schema.
                if (!isset($this->schema[$tbl][$source_col])) {
                    continue;
                }
                
                
                $source_tbl = $tbl;
                list($target_table , $target_col) = explode(':', $target);
                $err = substr("Fail: INSERT referenced {$tbl}:{$source_col}", 0, 64);
                $trigger .="
                    SET mid = 0;
                    if NEW.{$source_col} > 0 THEN
                        SELECT {$target_col} into mid FROM {$target_table} WHERE {$target_col} = NEW.{$source_col};
                        IF mid < 1 THEN
                            UPDATE `$err` SET x = 1;
                        END IF;
                       
                    END IF;
                ";
            }
            $trigger .= "
            END 
           
            ";
            //echo $trigger; exit;
            //DB_DAtaObject::debugLevel(1);
            $q = DB_DataObject::factory('core_enum');
            $q->query($trigger);
             
            
            
            
            
            
            
            
        }
        
        
        
    }
     function createUpdateTriggers()
    {
        foreach($this->links as $tbl => $map) {
            if (!isset($this->schema[$tbl])) {
                continue;
            }
            
            $q = DB_DataObject::factory('core_enum');
            $q->query("
                DROP TRIGGER IF EXISTS `{$tbl}_before_update` ;
            ");
            
            $trigger = "
             
            CREATE TRIGGER `{$tbl}_before_update`
                BEFORE UPDATE ON `{$tbl}`
            FOR EACH ROW
            BEGIN
               DECLARE mid INT(11);
               
               
            ";
            foreach($map as $source_col=>$target) {
                // check that source_col exists in schema.
                if (!isset($this->schema[$tbl][$source_col])) {
                    continue;
                }
                
                
                $source_tbl = $tbl;
                list($target_table , $target_col) = explode(':', $target);
                $err = substr("Fail: UPDATE referenced {$tbl}:$source_col", 0, 64);
                $trigger .="
                    SET mid = 0;
                    if NEW.{$source_col} > 0 THEN
                        SELECT {$target_col} into mid FROM {$target_table} WHERE {$target_col} = NEW.{$source_col};
                        IF mid < 1 THEN
                            UPDATE `$err` SET x = 1;
                        END IF;
                       
                    END IF;
                ";
            }
            $trigger .= "
            END 
           
            ";
            //echo $trigger; exit;
            //DB_DAtaObject::debugLevel(1);
            $q = DB_DataObject::factory('core_enum');
            $q->query($trigger);
             
            
            
            
            
            
            
            
        }
        
        
        
    }
    
    
}