// +build OMIT
package server

import (
	"bufio"
	"bytes"
	"io"
	"net/http"

	"github.com/influxdata/chronograf"
)

// URLPrefixer is a wrapper for an http.Handler that will prefix all occurrences of a relative URL with the configured Prefix
type URLPrefixer struct {
	Prefix string            // the prefix to be appended after any detected Attrs
	Next   http.Handler      // the http.Handler which will generate the content to be modified by this handler
	Attrs  [][]byte          // a list of attrs that should have their URLs prefixed. For example `src="` or `href="` would be valid
}

func (up *URLPrefixer) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
	...
	// Read next handler's response byte by byte
	src := bufio.NewScanner(nextRead)
	src.Split(bufio.ScanBytes)
	for {
		window := buf.Bytes()
		if matchlen, match := up.match(window, up.Attrs...); matchlen != 0 {
			buf.Next(matchlen) // advance to the relative URL
			for i := 0; i < matchlen; i++ {
				src.Scan()
				buf.Write(src.Bytes())
			}
			rw.Write(match)               // add the src attr to the output
			io.WriteString(rw, up.Prefix) // write the prefix
		} else {...}
	}
}

func NewDefaultURLPrefixer(prefix string, next http.Handler) *URLPrefixer {
	return &URLPrefixer{
		Prefix: prefix,
		Next:   next,
		Logger: lg,
		Attrs: [][]byte{
			[]byte(`src="`),
			[]byte(`href="`),
			[]byte(`url(`),
			[]byte(`data-basepath="`), // for forwarding basepath to frontend
		},
	}
}