[ISSUE-FIX] CASE WHEN ELSE END statement

src/Partial/CaseStatement.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Latitude\QueryBuilder\Partial;
+
+use Latitude\QueryBuilder\EngineInterface;
+use Latitude\QueryBuilder\ExpressionInterface;
+use Latitude\QueryBuilder\StatementInterface;
+
+final class CaseStatement implements StatementInterface
+{
+    private ExpressionInterface $expression;
+    private ?ExpressionInterface $else = null;
+
+    public function __construct(?StatementInterface $expression = null)
+    {
+        $this->expression = new Expression('CASE');
+
+        if ($expression) {
+            $this->expression = $this->expression->append('%s', $expression);
+        }
+    }
+
+    public function when(StatementInterface $when, StatementInterface $then): self
+    {
+        $this->expression = $this->expression->append('WHEN %s THEN %s', $when, $then);
+
+        return $this;
+    }
+
+    public function else(StatementInterface $else): self
+    {
+        $this->else = new Expression('ELSE %s', $else);
+
+        return $this;
+    }
+
+    public function sql(EngineInterface $engine): string
+    {
+        return $this->buildCaseStatement()->append('END')->sql($engine);
+    }
+
+    public function params(EngineInterface $engine): array
+    {
+        return $this->buildCaseStatement()->params($engine);
+    }
+
+    private function buildCaseStatement(): ExpressionInterface
+    {
+        $expression = $this->expression;
+
+        if ($this->else) {
+            $expression = $expression->append('%s', $this->else);
+        }
+
+        return $expression;
+    }
+}

src/functions.php

@@ -4,6 +4,8 @@
 
 namespace Latitude\QueryBuilder;
 
+use Latitude\QueryBuilder\Partial\CaseStatement;
+use Latitude\QueryBuilder\Partial\Criteria;
 use Latitude\QueryBuilder\Partial\Parameter;
 
 use function array_map;
@@ -56,7 +58,7 @@ function on(string $left, string $right): CriteriaInterface
  */
 function order($column, ?string $direction = null): StatementInterface
 {
-    if (! $direction) {
+    if (!$direction) {
         return identify($column);
     }
 
@@ -152,3 +154,8 @@ function listing(array $values, string $separator = ', '): Partial\Listing
 {
     return new Partial\Listing($separator, ...paramAll($values));
 }
+
+function caseStatement(?StatementInterface $expression = null): CaseStatement
+{
+    return new Partial\CaseStatement($expression);
+}

tests/Partial/CaseStatementTest.php

@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Latitude\QueryBuilder\Partial;
+
+use Latitude\QueryBuilder\TestCase;
+
+use function Latitude\QueryBuilder\caseStatement;
+use function Latitude\QueryBuilder\field;
+use function Latitude\QueryBuilder\identify;
+use function Latitude\QueryBuilder\literal;
+use function Latitude\QueryBuilder\param;
+
+class CaseStatementTest extends TestCase
+{
+    public function testAsIfElse(): void
+    {
+        $field = field('role');
+
+        $expr = caseStatement()
+            ->when(
+                $field->eq('admin'),
+                literal(1),
+            )
+            ->when(
+                $field->eq('editor'),
+                literal(2),
+            )
+            ->when(
+                $field->eq('user'),
+                param(3),
+            )
+            ->else(param(4));
+
+        $this->assertSql('CASE WHEN role = ? THEN 1 WHEN role = ? THEN 2 WHEN role = ? THEN ? ELSE ? END', $expr);
+        $this->assertParams(['admin', 'editor', 'user', 3, 4], $expr);
+    }
+
+    public function testAsSwitch(): void
+    {
+        $expr = caseStatement(identify('role'))
+            ->when(
+                param('admin'),
+                literal(1),
+            )
+            ->when(
+                param('editor'),
+                literal(2),
+            )
+            ->when(
+                param('user'),
+                param(3),
+            )
+            ->else(param(4));
+
+        $this->assertSql('CASE role WHEN ? THEN 1 WHEN ? THEN 2 WHEN ? THEN ? ELSE ? END', $expr);
+        $this->assertParams(['admin', 'editor', 'user', 3, 4], $expr);
+    }
+}