add(repository): discover repository informations

This implemtation determines the git remote origin url and extracts the
information for the owner and repo names for the api url's. WIP for #2.

internal/gitw/discover.go

@@ -0,0 +1,37 @@
+package gitw
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strings"
+
+	"gitea.yves-biener.de/yves-biener/gitwarrior/internal/gitea"
+)
+
+func Discover() (gitea.Repository, error) {
+	var repository gitea.Repository
+	cmd := exec.Command("git", "remote", "get-url", "origin")
+	out, err := cmd.Output()
+	if err != nil {
+		return repository, err
+	}
+	re := regexp.MustCompile("^git@.*:(.*).git")
+	matches := re.FindAllStringSubmatch(string(out), -1)
+	var match string
+	if len(matches) > 0 && len(matches[0]) == 2 {
+		match = matches[0][1] // get the first match which is the Full_name of the repository
+		if len(match) <= 0 {
+			return repository, errors.New("No matching group found. Are you in a git repository?")
+		}
+	} else {
+		return repository, errors.New("No matching group found. Are you in a git repository?")
+	}
+	repo := strings.Split(match, "/")
+	if len(repo) != 2 {
+		msg := fmt.Sprintf("Expected remote url to contain {owner}/{repo}, but found: %#v", repo)
+		return repository, errors.New(msg)
+	}
+	return gitea.NewRepository(repo[1], repo[0]), nil
+}