package main

import (
	"context"
	"fmt"
	"net/http"
	"time"
)

func waitForWireGuard(ctx context.Context, endpoint string, timeout time.Duration) error {
	ctx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()
	transport := &http.Transport{}
	defer transport.CloseIdleConnections()
	client := &http.Client{
		Transport: transport,
		Timeout:   5 * time.Second,
		CheckRedirect: func(_ *http.Request, _ []*http.Request) error {
			return http.ErrUseLastResponse
		},
	}
	ticker := time.NewTicker(2 * time.Second)
	defer ticker.Stop()
	for {
		if err := probeWireGuard(ctx, client, endpoint); err == nil {
			return nil
		} else {
			select {
			case <-ctx.Done():
				return fmt.Errorf("%w: %v", ctx.Err(), err)
			case <-ticker.C:
			}
		}
	}
}

func probeWireGuard(ctx context.Context, client *http.Client, endpoint string) error {
	request, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
	if err != nil {
		return err
	}
	response, err := client.Do(request)
	if err != nil {
		return err
	}
	defer func() { _ = response.Body.Close() }()
	// The relay proxy fetches this response live from the OCI WireGuard address.
	if response.StatusCode != http.StatusOK {
		return fmt.Errorf("WireGuard endpoint returned HTTP %d", response.StatusCode)
	}
	return nil
}