initial commit

pkg/vcs/vcs.go

@@ -0,0 +1,90 @@
+package vcs
+
+import (
+	"context"
+	"encoding/xml"
+	"errors"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+)
+
+type logger = func(v ...interface{})
+
+type Version string
+
+var reSemVer = regexp.MustCompile(`^v\d+\.\d+\.\d+$`)
+
+func (v Version) IsSemVer() bool { return reSemVer.MatchString(string(v)) }
+func (v Version) Hash() string {
+	fields := strings.Split(string(v), "-")
+	if len(fields) != 3 {
+		return ""
+	}
+	return fields[2]
+}
+
+type Module interface {
+	Timestamp(ctx context.Context, version Version) (time.Time, error)
+	Zip(ctx context.Context, version Version) (io.ReadCloser, error)
+}
+
+type VCS interface {
+	List(ctx context.Context) ([]Version, error)
+	Module
+}
+
+type Auth struct {
+	Username string
+	Password string
+	Key      string
+}
+
+func NoAuth() Auth                            { return Auth{} }
+func Password(username, password string) Auth { return Auth{Username: username, Password: password} }
+func Key(key string) Auth                     { return Auth{Key: key} }
+
+func MetaImports(ctx context.Context, module string) (string, error) {
+	if strings.HasPrefix(module, "github.com/") || strings.HasPrefix(module, "bitbucket.org/") {
+		return module, nil
+	}
+	// TODO: use context
+	res, err := http.Get("https://" + module + "?go-get=1")
+	if err != nil {
+		return "", err
+	}
+	defer res.Body.Close()
+	html := struct {
+		HTML string `xml:"html"`
+		Head struct {
+			Meta []struct {
+				Name    string `xml:"name,attr"`
+				Content string `xml:"content,attr"`
+			} `xml:"meta"`
+		} `xml:"head"`
+	}{}
+	dec := xml.NewDecoder(res.Body)
+	dec.Strict = false
+	dec.AutoClose = xml.HTMLAutoClose
+	dec.Entity = xml.HTMLEntity
+	if err := dec.Decode(&html); err != nil {
+		return "", err
+	}
+	for _, meta := range html.Head.Meta {
+		if meta.Name == "go-import" {
+			if f := strings.Fields(meta.Content); len(f) == 3 {
+				if f[0] != module {
+					return "", errors.New("prefix does not match the module")
+				}
+				url := f[2]
+				if i := strings.Index(url, "://"); i >= 0 {
+					url = url[i+3:]
+				}
+				return url, nil
+			}
+		}
+	}
+	return "", errors.New("go-import meta tag not found")
+}