From 27996801eb14510fa3074b78876086d6aa654367 Mon Sep 17 00:00:00 2001
From: Roman <mail@romanh.de>
Date: Sat, 3 Apr 2021 16:23:30 +0200
Subject: [PATCH] Alter Table

---
 core/Driver/SQL/Query/AlterTable.class.php | 62 ++++++++++++++++++++++
 core/Driver/SQL/SQL.class.php              | 48 ++++++++++++++++-
 2 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100644 core/Driver/SQL/Query/AlterTable.class.php

diff --git a/core/Driver/SQL/Query/AlterTable.class.php b/core/Driver/SQL/Query/AlterTable.class.php
new file mode 100644
index 0000000..f7f4bd7
--- /dev/null
+++ b/core/Driver/SQL/Query/AlterTable.class.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace Driver\SQL\Query;
+
+use Driver\SQL\Column\Column;
+use Driver\SQL\Constraint\Constraint;
+use Driver\SQL\SQL;
+
+class AlterTable extends Query {
+
+  private string $table;
+  private string $action;
+
+  private ?Column $column;
+  private ?Constraint $constraint;
+
+  public function __construct(SQL $sql, string $table) {
+    parent::__construct($sql);
+    $this->table = $table;
+  }
+
+  public function add($what): AlterTable {
+    if ($what instanceof Column) {
+      $this->column = $what;
+    } else if ($what instanceof Constraint) {
+      $this->constraint = $what;
+    } else {
+      $this->column = new Column($what);
+    }
+
+    $this->action = "ADD";
+    return $this;
+  }
+
+  public function modify(Column $column): AlterTable {
+    $this->column = $column;
+    $this->action = "MODIFY";
+    return $this;
+  }
+
+  public function drop($what): AlterTable {
+    if ($what instanceof Column) {
+      $this->column = $what;
+    } else if ($what instanceof Constraint) {
+      $this->constraint = $what;
+    } else {
+      $this->column = new Column($what);
+    }
+    $this->action = "DROP";
+    return $this;
+  }
+
+
+  public function execute(): bool {
+    return $this->sql->executeAlter($this);
+  }
+
+  public function getAction(): string { return $this->action; }
+  public function getColumn(): ?Column { return $this->column; }
+  public function getConstraint(): ?Constraint { return $this->constraint; }
+  public function getTable(): string { return $this->table; }
+}
\ No newline at end of file
diff --git a/core/Driver/SQL/SQL.class.php b/core/Driver/SQL/SQL.class.php
index 9187a20..e81f62e 100644
--- a/core/Driver/SQL/SQL.class.php
+++ b/core/Driver/SQL/SQL.class.php
@@ -15,6 +15,7 @@ use Driver\SQL\Constraint\Constraint;
 use \Driver\SQL\Constraint\Unique;
 use \Driver\SQL\Constraint\PrimaryKey;
 use \Driver\SQL\Constraint\ForeignKey;
+use Driver\SQL\Query\AlterTable;
 use Driver\SQL\Query\CreateTable;
 use Driver\SQL\Query\Delete;
 use Driver\SQL\Query\Drop;
@@ -79,6 +80,10 @@ abstract class SQL {
     return new Drop($this, $table);
   }
 
+  public function alterTable($tableName) {
+    return new AlterTable($this, $tableName);
+  }
+
   // ####################
   // ### ABSTRACT METHODS
   // ####################
@@ -246,7 +251,7 @@ abstract class SQL {
 
     $valueStr = array();
     foreach($update->getValues() as $key => $val) {
-      $valueStr[] =  $this->columnName($key) . "=" . $this->addValue($val, $params);
+      $valueStr[] = $this->columnName($key) . "=" . $this->addValue($val, $params);
     }
     $valueStr = implode(",", $valueStr);
 
@@ -262,6 +267,47 @@ abstract class SQL {
     return $this->execute($query);
   }
 
+  public function executeAlter(AlterTable $alter): bool {
+    $tableName = $this->tableName($alter->getTable());
+    $action = $alter->getAction();
+    $column = $alter->getColumn();
+    $constraint = $alter->getConstraint();
+
+    $query = "ALTER TABLE $tableName $action ";
+
+    if ($column) {
+      $query .= "COLUMN ";
+      if ($action === "DROP") {
+        $query .= $this->columnName($column->getName());
+      } else {
+        // ADD or modify
+        $query .= $this->getColumnDefinition($column);
+      }
+    } else if ($constraint) {
+      if ($action === "DROP") {
+        if ($constraint instanceof PrimaryKey) {
+          $query .= "PRIMARY KEY";
+        } else if ($constraint instanceof ForeignKey) {
+          // TODO: how can we pass the constraint name here?
+          $this->lastError = "DROP CONSTRAINT foreign key is not supported yet.";
+          return false;
+        }
+      } else if ($action === "ADD") {
+        $query .= "CONSTRAINT ";
+        $query .= $this->getConstraintDefinition($constraint);
+      } else if ($action === "MODIFY") {
+        $this->lastError = "MODIFY CONSTRAINT foreign key is not supported.";
+        return false;
+      }
+    } else {
+      $this->lastError = "ALTER TABLE requires at least a column or a constraint.";
+      return false;
+    }
+
+    if ($alter->dump) { var_dump($query); }
+    return $this->execute($query);
+  }
+
   protected function getWhereClause($conditions, &$params) {
     if (!$conditions) {
       return "";