// Package driver abstracts the per-database connection details behind a small
// interface so new engines can be added without touching the wait loop.
package driver

import (
	"context"
	"fmt"
	"sort"
	"strings"

	"git.unkin.net/unkin/waitfordb/internal/config"
)

// Pinger is a live handle to a database that can answer a trivial liveness
// query. A successful Ping proves the server is up, auth succeeded, and the
// target database/role exist.
type Pinger interface {
	Ping(ctx context.Context) error
	Close() error
}

// Driver knows how to open a Pinger for one database engine.
type Driver interface {
	Name() string
	Open(cfg config.Config) (Pinger, error)
}

var registry = map[string]Driver{}

func register(d Driver) { registry[d.Name()] = d }

// Get returns the registered driver for name.
func Get(name string) (Driver, error) {
	d, ok := registry[strings.ToLower(name)]
	if !ok {
		return nil, fmt.Errorf("unsupported driver %q (supported: %s)", name, strings.Join(Names(), ", "))
	}
	return d, nil
}

// Names lists the registered driver names, sorted.
func Names() []string {
	out := make([]string, 0, len(registry))
	for n := range registry {
		out = append(out, n)
	}
	sort.Strings(out)
	return out
}