<?php
/**
 * @author Daniel J. Summers <daniel@bitbadger.solutions>
 * @license MIT
 */

declare(strict_types=1);

namespace BitBadger\PDODocument\Query;

use BitBadger\PDODocument\{Configuration, DocumentException, DocumentIndex, Mode};
use Exception;

/**
 * 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 Exception If the database mode has not been set
     */
    public static function ensureTable(string $name): string
    {
        $dataType = match (Configuration::mode('make create table statement')) {
            Mode::PgSQL  => 'JSONB',
            Mode::SQLite => 'TEXT',
        };
        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 string[] $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]));
    }

    /**
     * Create a document-wide index on a table (PostgreSQL only)
     *
     * @param string $tableName The name of the table on which the document index should be created
     * @param DocumentIndex $indexType The type of index to be created
     * @return string The SQL statement to create an index on JSON documents in the specified table
     * @throws Exception|DocumentException If the database mode is not PostgreSQL
     */
    public static function ensureDocumentIndexOn(string $tableName, DocumentIndex $indexType): string
    {
        if (Configuration::mode() <> Mode::PgSQL) {
            throw new DocumentException('Document indexes are only supported on PostgreSQL');
        }
        [, $tbl]  = self::splitSchemaAndTable($tableName);
        $extraOps = match ($indexType) {
            DocumentIndex::Full      => '',
            DocumentIndex::Optimized => ' jsonb_path_ops',
        };
        return "CREATE INDEX IF NOT EXISTS idx_{$tbl}_document ON $tableName USING GIN (data$extraOps)";
    }
}