Use URLBuilder instead of Url in mappers and HttpFetcher

[ayanyev]

There is an issue when full resource url is split between httpClient config and asyncPainterResource call:

defaultRequest {
     url("https://kamel.media")
}
asyncPainterResource("/image.jpg")

If mapper and fetcher use Url respectively as output and input data, the resulting resource url will look like:
https://localhost:80/image.jpg

This happens due to DefaultRequest.mergeUrls(...) implementation.

DefaultRequestConfigTest is added.

[luca992]

Does fun URLBuilder.takeFrom(url: Url): URLBuilder not work? (instead of URLBuilder.takeFrom(url: URLBuilder))

[ayanyev]

The problem is when mapper maps to Url, localhost:80 added to /image.jpg with applyOrigin().

    public fun build(): Url {
        applyOrigin()
        return Url(
            protocol = protocol,
            host = host,

When it comes to DefaultRequest.mergeUrls(), execution is stopped at the very beginning because host is not empty.

        private fun mergeUrls(baseUrl: Url, requestUrl: URLBuilder) {
            if (requestUrl.protocol == URLProtocol.HTTP) {
                requestUrl.protocol = baseUrl.protocol
            }
            if (requestUrl.host.isNotEmpty()) return

It ends up fetching image from localhost.

[eskatos]

This might be related to the upstream ktor issues

• Add Url capability: parsing/validating url strings ktorio/ktor#1903
• https://youtrack.jetbrains.com/issue/KTOR-360

[luca992]

@ayanyev finally got to take a deeper look at this. I think you're right about using UrlBuilder.... I don't think it's a great idea to fully remove support from ktor Urls though. I think adding a Url to UrlBuilder mapper that's in the default kamel config would be a good idea.

@eskatos https://youtrack.jetbrains.com/issue/KTOR-360 looks like it's relevant. But, who knows when that will be implemented. Probably best to not wait for it