// gotoolchain provides information about the Go toolchain used on the host by
// rules_go.
package gotoolchain

import (
	"fmt"
	"path/filepath"
	"strings"

	"github.com/bazelbuild/rules_go/go/runfiles"
)

func mustRunfile(s string) string {
	// TODO(tim): I couldn't find out why there is a prefix.
	s = strings.TrimPrefix(s, "external/")
	res, err := runfiles.Rlocation(s)
	if err != nil {
		panic(fmt.Sprintf("runfile %q not found: %v", s, err))
	}
	abs, err := filepath.Abs(res)
	if err != nil {
		panic(fmt.Sprintf("cant make runfile %q absolute: %v", s, err))
	}
	return abs
}

var (
	// Go is a path to the `go` executable.
	Go = mustRunfile(`GOTOOL`)
	// Root is the GOROOT path.
	Root = mustRunfile(`GOROOT`)
)