Initial SQLite development (#1)

Reviewed-on: #1

src/Query/Definition.php

@@ -0,0 +1,71 @@
+<?php declare(strict_types=1);
+
+namespace BitBadger\PDODocument\Query;
+
+use BitBadger\PDODocument\{Configuration, DocumentException, Mode};
+
+/**
+ * Queries to define tables and indexes
+ */
+class Definition
+{
+    /**
+     * SQL statement to create a document table
+     *
+     * @param string $name The name of the table (including schema, if applicable)
+     * @return string The CREATE TABLE statement for the document table
+     * @throws DocumentException If the database mode has not been set
+     */
+    public static function ensureTable(string $name): string
+    {
+        $dataType = match (Configuration::$mode) {
+            Mode::PgSQL  => 'JSONB',
+            Mode::SQLite => 'TEXT',
+            default      => throw new DocumentException('Database mode not set; cannot make create table statement')
+        };
+        return "CREATE TABLE IF NOT EXISTS $name (data $dataType NOT NULL)";
+    }
+
+    /**
+     * Split a schema and table name
+     *
+     * @param string $tableName The name of the table, possibly including the schema
+     * @return array|string[] An array with the schema at index 0 and the table name at index 1
+     */
+    private static function splitSchemaAndTable(string $tableName): array
+    {
+        $parts = explode('.', $tableName);
+        return sizeof($parts) == 1 ? ["", $tableName] : [$parts[0], $parts[1]];
+    }
+
+    /**
+     * SQL statement to create an index on one or more fields in a JSON document
+     *
+     * @param string $tableName The name of the table which should be indexed
+     * @param string $indexName The name of the index to create
+     * @param array $fields An array of fields to be indexed; may contain direction (ex. 'salary DESC')
+     * @return string The CREATE INDEX statement to ensure the index exists
+     */
+    public static function ensureIndexOn(string $tableName, string $indexName, array $fields): string
+    {
+        [, $tbl] = self::splitSchemaAndTable($tableName);
+        $jsonFields = implode(', ', array_map(function (string $field) {
+            $parts     = explode(' ', $field);
+            $fieldName = sizeof($parts) == 1 ? $field : $parts[0];
+            $direction = sizeof($parts) < 2 ? "" : " $parts[1]";
+            return "(data->>'$fieldName')$direction";
+        }, $fields));
+        return "CREATE INDEX IF NOT EXISTS idx_{$tbl}_$indexName ON $tableName ($jsonFields)";
+    }
+
+    /**
+     * SQL statement to create a key index for a document table
+     *
+     * @param string $tableName The name of the table whose key should be ensured
+     * @return string The CREATE INDEX statement to ensure the key index exists
+     */
+    public static function ensureKey(string $tableName): string
+    {
+        return str_replace('INDEX', 'UNIQUE INDEX', self::ensureIndexOn($tableName, 'key', [Configuration::$idField]));
+    }
+}