bouncer/internal/proxy/director/context.go

package director

import (
	"context"
	"net/http"
	"net/url"

	"forge.cadoles.com/cadoles/bouncer/internal/store"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

type contextKey string

const (
	contextKeyProxy       contextKey = "proxy"
	contextKeyLayers      contextKey = "layers"
	contextKeyOriginalURL contextKey = "originalURL"
	contextKeyHandleError contextKey = "handleError"
)

var (
	errContextKeyNotFound     = errors.New("context key not found")
	errUnexpectedContextValue = errors.New("unexpected context value")
)

func withOriginalURL(ctx context.Context, url *url.URL) context.Context {
	return context.WithValue(ctx, contextKeyOriginalURL, url)
}

func OriginalURL(ctx context.Context) (*url.URL, error) {
	url, err := ctxValue[*url.URL](ctx, contextKeyOriginalURL)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return url, nil
}

func withLayers(ctx context.Context, layers []*store.Layer) context.Context {
	return context.WithValue(ctx, contextKeyLayers, layers)
}

func ctxLayers(ctx context.Context) ([]*store.Layer, error) {
	layers, err := ctxValue[[]*store.Layer](ctx, contextKeyLayers)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return layers, nil
}

func ctxValue[T any](ctx context.Context, key contextKey) (T, error) {
	raw := ctx.Value(key)
	if raw == nil {
		return *new(T), errors.WithStack(errContextKeyNotFound)
	}

	value, ok := raw.(T)
	if !ok {
		return *new(T), errors.WithStack(errUnexpectedContextValue)
	}

	return value, nil
}

type HandleErrorFunc func(w http.ResponseWriter, r *http.Request, status int, err error)

func withHandleError(ctx context.Context, fn HandleErrorFunc) context.Context {
	return context.WithValue(ctx, contextKeyHandleError, fn)
}

func HandleError(ctx context.Context, w http.ResponseWriter, r *http.Request, status int, err error) {
	err = errors.WithStack(err)

	fn, ok := ctx.Value(contextKeyHandleError).(HandleErrorFunc)
	if !ok {
		logger.Error(ctx, err.Error(), logger.CapturedE(err))
		http.Error(w, http.StatusText(status), status)
		return
	}

	fn(w, r, status, err)
}