package workers

import (
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"syscall/js"
)

// toBody converts JavaScripts sides ReadableStream (can be null) to io.ReadCloser.
// * ReadableStream: https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream
func toBody(streamOrNull js.Value) io.ReadCloser {
	if streamOrNull.IsNull() {
		return nil
	}
	sr := streamOrNull.Call("getReader")
	return io.NopCloser(convertStreamReaderToReader(sr))
}

// toHeader converts JavaScript sides Headers to http.Header.
// * Headers: https://developer.mozilla.org/ja/docs/Web/API/Headers
func toHeader(headers js.Value) http.Header {
	entries := arrayFrom(headers.Call("entries"))
	headerLen := entries.Length()
	h := http.Header{}
	for i := 0; i < headerLen; i++ {
		entry := entries.Index(i)
		key := entry.Index(0).String()
		values := entry.Index(1).String()
		for _, value := range strings.Split(values, ",") {
			h.Add(key, value)
		}
	}
	return h
}

// toRequest converts JavaScript sides Request to *http.Request.
// * Request: https://developer.mozilla.org/ja/docs/Web/API/Request
func toRequest(req js.Value) (*http.Request, error) {
	reqUrl, err := url.Parse(req.Get("url").String())
	if err != nil {
		return nil, err
	}
	header := toHeader(req.Get("headers"))

	// ignore err
	contentLength, _ := strconv.ParseInt(header.Get("Content-Length"), 10, 64)
	return &http.Request{
		Method:           req.Get("method").String(),
		URL:              reqUrl,
		Header:           header,
		Body:             toBody(req.Get("body")),
		ContentLength:    contentLength,
		TransferEncoding: strings.Split(header.Get("Transfer-Encoding"), ","),
		Host:             header.Get("Host"),
	}, nil
}