use 'go list' to get the URL

goList.go

@@ -2,7 +2,7 @@ package repostatus
 
 import (
 	"encoding/json"
-	"errors"
+	"time"
 
 	"go.wit.com/lib/gui/shell"
 	"go.wit.com/log"
@@ -20,15 +20,95 @@ import (
 // 	"GoVersion": "1.22.0"
 // }
 
+type Module struct {
+	Path       string       // module path
+	Query      string       // version query corresponding to this version
+	Version    string       // module version
+	Versions   []string     // available module versions
+	Replace    *Module      // replaced by this module
+	Time       *time.Time   // time version was created
+	Update     *Module      // available update (with -u)
+	Main       bool         // is this the main module?
+	Indirect   bool         // module is only indirectly needed by main module
+	Dir        string       // directory holding local copy of files, if any
+	GoMod      string       // path to go.mod file describing module, if any
+	GoVersion  string       // go version used in module
+	Retracted  []string     // retraction information, if any (with -retracted or -u)
+	Deprecated string       // deprecation message, if any (with -u)
+	Error      *ModuleError // error loading module
+	Sum        string       // checksum for path, version (as in go.sum)
+	GoModSum   string       // checksum for go.mod (as in go.sum)
+	Reuse      bool         // reuse of old module info is safe
+	Origin     Origin
+}
+
+type ModuleError struct {
+	Err string // the error itself
+}
+
+// An Origin describes the provenance of a given repo method result.
+// It can be passed to CheckReuse (usually in a different go command invocation)
+// to see whether the result remains up-to-date.
+type Origin struct {
+	VCS    string `json:",omitempty"` // "git" etc
+	URL    string `json:",omitempty"` // URL of repository
+	Subdir string `json:",omitempty"` // subdirectory in repo
+
+	Hash string `json:",omitempty"` // commit hash or ID
+
+	// If TagSum is non-empty, then the resolution of this module version
+	// depends on the set of tags present in the repo, specifically the tags
+	// of the form TagPrefix + a valid semver version.
+	// If the matching repo tags and their commit hashes still hash to TagSum,
+	// the Origin is still valid (at least as far as the tags are concerned).
+	// The exact checksum is up to the Repo implementation; see (*gitRepo).Tags.
+	TagPrefix string `json:",omitempty"`
+	TagSum    string `json:",omitempty"`
+
+	// If Ref is non-empty, then the resolution of this module version
+	// depends on Ref resolving to the revision identified by Hash.
+	// If Ref still resolves to Hash, the Origin is still valid (at least as far as Ref is concerned).
+	// For Git, the Ref is a full ref like "refs/heads/main" or "refs/tags/v1.2.3",
+	// and the Hash is the Git object hash the ref maps to.
+	// Other VCS might choose differently, but the idea is that Ref is the name
+	// with a mutable meaning while Hash is a name with an immutable meaning.
+	Ref string `json:",omitempty"`
+
+	// If RepoSum is non-empty, then the resolution of this module version
+	// failed due to the repo being available but the version not being present.
+	// This depends on the entire state of the repo, which RepoSum summarizes.
+	// For Git, this is a hash of all the refs and their hashes.
+	RepoSum string `json:",omitempty"`
+}
+
+// A Tags describes the available tags in a code repository.
+
 func runGoList(url string) (string, error) {
-	r := shell.RunPath("", []string{"go", "list", "-json", "-m", url + "@latest"})
-	log.Info("runGoList() r.Output =", r.Output)
-	var modInfo any
-	err := json.Unmarshal(r.Output, &modInfo)
+	ver, err := getLatestVersion(url)
 	if err != nil {
+		return "", err
+	}
+	r := shell.Output("", []string{"go", "list", "-json", "-m", url + "@" + ver})
+	var modInfo Module
+	err = json.Unmarshal(r.Output, &modInfo)
+	if err != nil {
+		log.Info("runGoList() r.Output =", string(r.Output))
 		log.Info("runGoList() json.Unmarshal() error =", err)
 		return "", err
 	}
-	log.Spew(modInfo)
-	return "", errors.New("todo: parse json")
+	log.Info("runGoList() Output.Origin.URL =", modInfo.Origin.URL)
+	return modInfo.Origin.URL, err
+}
+
+func getLatestVersion(url string) (string, error) {
+	r := shell.Output("", []string{"go", "list", "-json", "-m", url + "@latest"})
+	var modInfo Module
+	err := json.Unmarshal(r.Output, &modInfo)
+	if err != nil {
+		log.Info("runGoList() r.Output =", string(r.Output))
+		log.Info("runGoList() json.Unmarshal() error =", err)
+		return "", err
+	}
+	log.Info("runGoList() Output.Version =", modInfo.Version)
+	return modInfo.Version, err
 }