From e856ab4abaf0ed862d006065002ac45327731add Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20Vo=C5=99=C3=AD=C5=A1ek?= <mvorisek@mvorisek.cz>
Date: Fri, 23 Feb 2024 19:58:56 +0100
Subject: [PATCH] WIP add parsed colum/select

---
 .../Sql/Optimizer/ParsedColumn.php            | 39 ++++++++++++++++
 .../Sql/Optimizer/ParsedSelect.php            | 45 +++++++++++++++++++
 src/Persistence/Sql/Optimizer/Util.php        | 28 ++++++++++++
 src/Persistence/Sql/Query.php                 | 19 ++++++++
 4 files changed, 131 insertions(+)
 create mode 100644 src/Persistence/Sql/Optimizer/ParsedColumn.php
 create mode 100644 src/Persistence/Sql/Optimizer/ParsedSelect.php

diff --git a/src/Persistence/Sql/Optimizer/ParsedColumn.php b/src/Persistence/Sql/Optimizer/ParsedColumn.php
new file mode 100644
index 000000000..8c9b84adb
--- /dev/null
+++ b/src/Persistence/Sql/Optimizer/ParsedColumn.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Atk4\Data\Persistence\Sql\Optimizer;
+
+use Atk4\Data\Persistence\Sql\Expression;
+
+class ParsedColumn
+{
+    /** @var Expression|string */
+    public $expr;
+    /** @var string|null not-null iff expr is a string */
+    public $exprTableAlias;
+    /** @var string */
+    public $columnAlias;
+
+    public function __construct(Expression $expr, string $columnAlias)
+    {
+        $exprIdentifier = Util::tryParseIdentifier($expr);
+        if ($exprIdentifier !== false) {
+            $this->exprTableAlias = $exprIdentifier[0];
+            $this->expr = $exprIdentifier[1];
+        } else {
+            $this->expr = $expr;
+        }
+
+        $this->columnAlias = Util::parseSingleIdentifier($columnAlias);
+    }
+
+    public function getDsqlExpression(): Expression
+    {
+        if ($this->exprTableAlias !== null) {
+            return new Expression('{}.{} {}', [$this->expr, $this->exprTableAlias, $this->columnAlias]); // @phpstan-ignore-line @TODO not sure what to do here !!!
+        }
+
+        return new Expression('{} {}', [$this->expr, $this->columnAlias]); // @phpstan-ignore-line @TODO not sure what to do here !!!
+    }
+}
diff --git a/src/Persistence/Sql/Optimizer/ParsedSelect.php b/src/Persistence/Sql/Optimizer/ParsedSelect.php
new file mode 100644
index 000000000..ada01d56b
--- /dev/null
+++ b/src/Persistence/Sql/Optimizer/ParsedSelect.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Atk4\Data\Persistence\Sql\Optimizer;
+
+use Atk4\Data\Persistence\Sql\Expression;
+use Atk4\Data\Persistence\Sql\Query;
+
+class ParsedSelect
+{
+    /** @var string */
+    public const TOP_QUERY_ALIAS = '__atk4_top_query__';
+
+    /** @var Query|string */
+    public $expr;
+    /** @var string */
+    public $tableAlias;
+
+    /**
+     * @param Query|string $expr
+     */
+    public function __construct($expr, string $tableAlias)
+    {
+        $exprIdentifier = Util::tryParseIdentifier($expr);
+        if ($exprIdentifier !== false) {
+            $this->expr = Util::parseSingleIdentifier($expr);
+        } else {
+            $this->expr = $expr;
+        }
+
+        $this->tableAlias = Util::parseSingleIdentifier($tableAlias);
+    }
+
+    /*
+    public function getDsqlExpression(): Expression
+    {
+        if ($this->tableAlias === self::TOP_QUERY_ALIAS) {
+            return new Expression('{}', [$this->expr]);
+        }
+
+        return new Expression('{} {}', [$this->expr, $this->tableAlias]);
+    }
+    */
+}
diff --git a/src/Persistence/Sql/Optimizer/Util.php b/src/Persistence/Sql/Optimizer/Util.php
index 32cfbf21d..ed42ece4f 100644
--- a/src/Persistence/Sql/Optimizer/Util.php
+++ b/src/Persistence/Sql/Optimizer/Util.php
@@ -107,4 +107,32 @@ public static function parseSingleIdentifier($expr): string
 
         return $v[1];
     }
+
+    public static function parseSelectQuery(Query $query, string $tableAlias): ParsedSelect
+    {
+        $query->args['is_select_parsed'] = [true];
+        $select = new ParsedSelect($query, $tableAlias);
+        if (is_string($select->expr)) {
+            return $select;
+        }
+
+        // traverse $query and parse everything into ParsedSelect/ParsedColumn
+        foreach ($query->args as $argK => $argV) {
+            // TODO
+        }
+
+        return $select;
+    }
+
+    public static function isSelectQueryParsed(Query $query): bool
+    {
+        return ($query->args['is_select_parsed'] ?? [])[0] ?? false;
+    }
+
+    public static function parseColumn(Expression $expr, string $columnAlias): ParsedColumn
+    {
+        $column = new ParsedColumn($expr, $columnAlias);
+
+        return $column;
+    }
 }
diff --git a/src/Persistence/Sql/Query.php b/src/Persistence/Sql/Query.php
index bdf063040..41276ba5b 100644
--- a/src/Persistence/Sql/Query.php
+++ b/src/Persistence/Sql/Query.php
@@ -954,12 +954,31 @@ public function __debugInfo(): array
 
     // {{{ Miscelanious
 
+    protected function toParsedSelect(): Optimizer\ParsedSelect
+    {
+        return Optimizer\Util::parseSelectQuery($this, Optimizer\ParsedSelect::TOP_QUERY_ALIAS);
+    }
+
+    /**
+     * Deduplicate same subselects, field rereads to produce optimized select query
+     * using CTE/WITH.
+     */
+    protected function transformSelectUsingCte(): Optimizer\ParsedSelect
+    {
+        throw new Exception('Not implemented yet');
+    }
+
     /**
      * @return array{string, array<string, mixed>}
      */
     private function callParentRender(): array
     {
         $firstRender = parent::render();
+        if ($this->mode === 'select' && !Optimizer\Util::isSelectQueryParsed($this)) {
+            $parsedSelect = $this->toParsedSelect();
+            $firstRender = $parsedSelect->expr->render();
+        }
+
         if (($this->args['first_render'] ?? null) === null) {
             $this->args['first_render'] = $firstRender;
             $secondRender = $this->render();