// Copyright 2012 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build !cmd_go_bootstrap

// This code is compiled into the real 'go' binary, but it is not
// compiled into the binary that is built during all.bash, so as
// to avoid needing to build net (and thus use cgo) during the
// bootstrap process.

package main

import (
	"encoding/xml"
	"io"
	"strings"
)

// parseMetaGoImports returns meta imports from the HTML in r.
// Parsing ends at the end of the <head> section or the beginning of the <body>.
func parseMetaGoImports(r io.Reader) (imports []metaImport) {
	d := xml.NewDecoder(r)
	d.Strict = false
	for {
		t, err := d.Token()
		if err != nil {
			return
		}
		if e, ok := t.(xml.StartElement); ok && strings.EqualFold(e.Name.Local, "body") {
			return
		}
		if e, ok := t.(xml.EndElement); ok && strings.EqualFold(e.Name.Local, "head") {
			return
		}
		e, ok := t.(xml.StartElement)
		if !ok || !strings.EqualFold(e.Name.Local, "meta") {
			continue
		}
		if attrValue(e.Attr, "name") != "go-import" {
			continue
		}
		if f := strings.Fields(attrValue(e.Attr, "content")); len(f) == 3 {
			imports = append(imports, metaImport{
				Prefix:   f[0],
				VCS:      f[1],
				RepoRoot: f[2],
			})
		}
	}
}

// attrValue returns the attribute value for the case-insensitive key
// `name', or the empty string if nothing is found.
func attrValue(attrs []xml.Attr, name string) string {
	for _, a := range attrs {
		if strings.EqualFold(a.Name.Local, name) {
			return a.Value
		}
	}
	return ""
}
