updates

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

internal/modules/packages.go

@@ -0,0 +1,115 @@
+package modules
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/mod/module"
+	"golang.org/x/mod/semver"
+)
+
+// ModPrefix returns the module path with no SIV
+func ModPrefix(modpath string) string {
+	prefix, _, ok := module.SplitPathVersion(modpath)
+	if !ok {
+		prefix = modpath
+	}
+	return prefix
+}
+
+// ModMajor returns the major version in vN format
+func ModMajor(modpath string) (string, bool) {
+	_, major, ok := module.SplitPathVersion(modpath)
+	if ok {
+		major = strings.TrimPrefix(major, "/")
+		major = strings.TrimPrefix(major, ".")
+	}
+	return major, ok
+}
+
+// SplitPath splits the package path into the module path and the package subdirectory.
+// It requires the a module path prefix to figure this out.
+func SplitPath(modprefix, pkgpath string) (modpath, pkgdir string, ok bool) {
+	if !strings.HasPrefix(pkgpath, modprefix) {
+		return "", "", false
+	}
+	modpathlen := len(modprefix)
+	if rest := pkgpath[modpathlen:]; len(rest) > 0 && rest[0] != '/' && rest[0] != '.' {
+		return "", "", false
+	}
+	if strings.HasPrefix(pkgpath[modpathlen:], "/") {
+		modpathlen++
+	}
+	if idx := strings.Index(pkgpath[modpathlen:], "/"); idx >= 0 {
+		modpathlen += idx
+	} else {
+		modpathlen = len(pkgpath)
+	}
+	modpath = modprefix
+	if major, ok := ModMajor(pkgpath[:modpathlen]); ok {
+		modpath = JoinPath(modprefix, major, "")
+	}
+	pkgdir = strings.TrimPrefix(pkgpath[len(modpath):], "/")
+	return modpath, pkgdir, true
+}
+
+// SplitSpec splits the path/to/package@query format strings
+func SplitSpec(spec string) (path, query string) {
+	parts := strings.SplitN(spec, "@", 2)
+	if len(parts) == 2 {
+		path = parts[0]
+		query = parts[1]
+	} else {
+		path = spec
+	}
+	return
+}
+
+// JoinPath creates a full package path given a module prefix, version, and package directory.
+func JoinPath(modprefix, version, pkgdir string) string {
+	version = strings.TrimPrefix(version, ".")
+	version = strings.TrimPrefix(version, "/")
+	major := semver.Major(version)
+	pkgpath := modprefix
+	switch {
+	case strings.HasPrefix(pkgpath, "gopkg.in"):
+		pkgpath += "." + major
+	case major != "" && major != "v0" && major != "v1" && !strings.Contains(version, "+incompatible"):
+		if !strings.HasSuffix(pkgpath, "/") {
+			pkgpath += "/"
+		}
+		pkgpath += major
+	}
+	if pkgdir != "" {
+		pkgpath += "/" + pkgdir
+	}
+	return pkgpath
+}
+
+// FindModFile recursively searches up the directory structure until it
+// finds the go.mod, reaches the root of the directory tree, or encounters
+// an error.
+func FindModFile(dir string) (string, error) {
+	var err error
+	dir, err = filepath.Abs(dir)
+	if err != nil {
+		return "", err
+	}
+	for {
+		name := filepath.Join(dir, "go.mod")
+		_, err := os.Stat(name)
+		if err == nil {
+			return name, nil
+		}
+		if !os.IsNotExist(err) {
+			return "", err
+		}
+		parent := filepath.Dir(dir)
+		if parent == dir {
+			return "", fmt.Errorf("cannot find go.mod")
+		}
+		dir = parent
+	}
+}