package db

import (
	"context"
	"database/sql"
	"fmt"
	"log/slog"

	_ "github.com/microsoft/go-mssqldb"
)

// Open creates an MSSQL connection pool and validates connectivity.
func Open(ctx context.Context, dsn, name string) (*sql.DB, error) {
	pool, err := sql.Open("sqlserver", dsn)
	if err != nil {
		return nil, fmt.Errorf("open %s: %w", name, err)
	}
	pool.SetMaxOpenConns(15)
	pool.SetMaxIdleConns(5)
	if err := pool.PingContext(ctx); err != nil {
		return nil, fmt.Errorf("ping %s: %w", name, err)
	}
	slog.Info("mssql connected", "db", name)
	return pool, nil
}

// QueryFirst runs each SQL query in order, returning rows from the first one
// that succeeds. Used for schema-fallback queries.
func QueryFirst(ctx context.Context, pool *sql.DB, queries []string) (*sql.Rows, error) {
	var lastErr error
	for _, q := range queries {
		rows, err := pool.QueryContext(ctx, q)
		if err != nil {
			slog.Warn("query variant failed, trying next", "err", err)
			lastErr = err
			continue
		}
		return rows, nil
	}
	return nil, fmt.Errorf("all query variants failed: %w", lastErr)
}