<?php

namespace Modules\EcommerceFinance\Services;

use InvalidArgumentException;

class UpstreamSqlDialect
{
    public function __construct(public readonly string $driver)
    {
        if (! in_array($driver, ['sqlsrv', 'pgsql', 'mysql'], true)) {
            throw new InvalidArgumentException('不支持的上游数据库类型。');
        }
    }

    public function quote(string $identifier): string
    {
        if ($identifier === '' || str_contains($identifier, "\0")) throw new InvalidArgumentException('无效的数据库标识符。');
        return match ($this->driver) {
            'pgsql' => '"' . str_replace('"', '""', $identifier) . '"',
            'mysql' => '`' . str_replace('`', '``', $identifier) . '`',
            default => '[' . str_replace(']', ']]', $identifier) . ']',
        };
    }

    public function select(string $columns, string $tail, int $limit): string
    {
        $limit = min(max($limit, 1), 5000);
        return $this->driver === 'sqlsrv'
            ? 'SELECT TOP (' . $limit . ') ' . $columns . ' ' . $tail
            : 'SELECT ' . $columns . ' ' . $tail . ' LIMIT ' . $limit;
    }

    public function catalogSql(): string
    {
        // Same normalized catalog shape for all engines; MySQL never enumerates other databases.
        $schema = $this->driver === 'sqlsrv' ? 'INFORMATION_SCHEMA' : 'information_schema';
        $sql = "SELECT c.table_schema AS schema_name, c.table_name AS object_name,
            CASE WHEN t.table_type = 'VIEW' THEN 'view' ELSE 'table' END AS object_type,
            c.column_name AS column_name, c.ordinal_position AS ordinal_position,
            c.data_type AS data_type, c.character_maximum_length AS max_length,
            c.numeric_precision AS numeric_precision, c.numeric_scale AS numeric_scale,
            c.is_nullable AS is_nullable
            FROM {$schema}." . ($this->driver === 'sqlsrv' ? 'COLUMNS' : 'columns') . " c
            INNER JOIN {$schema}." . ($this->driver === 'sqlsrv' ? 'TABLES' : 'tables') . " t
              ON t.table_schema = c.table_schema AND t.table_name = c.table_name
            WHERE c.table_schema NOT IN ('sys', 'INFORMATION_SCHEMA', 'information_schema', 'pg_catalog', 'mysql', 'performance_schema')";
        if ($this->driver === 'mysql') $sql .= ' AND c.table_schema = DATABASE()';
        $sql .= ' ORDER BY c.table_schema, c.table_name, c.ordinal_position';
        if ($this->driver === 'sqlsrv') {
            $sql = preg_replace_callback('/\b([ct])\.([a-z_]+)\b/', fn ($m) => $m[1] . '.' . strtoupper($m[2]), $sql);
        }
        return $sql;
    }
}