add github provider (WIP)

internal/gitproviders/github.go

@@ -0,0 +1,64 @@
+package gitproviders
+
+import (
+	"context"
+	"net/http"
+	"sync"
+
+	"github.com/google/go-github/github"
+	"go.uber.org/zap"
+)
+
+type Github struct {
+	logger       *zap.Logger
+	githubmu     sync.Mutex
+	githubClient map[string]*github.Client
+}
+
+func NewGitHub(logger *zap.Logger) *Github {
+	return &Github{
+		logger:   logger,
+		githubmu: sync.Mutex{},
+	}
+}
+
+func (g *Github) ListRepositoriesForOrganization(
+	ctx context.Context,
+	server string,
+	organisation string,
+) ([]string, error) {
+	client, err := g.getOrCreateClient(ctx, server)
+
+	repos, _, err := client.Repositories.ListByOrg(ctx, organisation, &github.RepositoryListByOrgOptions{
+		ListOptions: github.ListOptions{
+			Page:    0,
+			PerPage: 0,
+		},
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	repoUrls := make([]string, len(repos))
+	for i, repo := range repos {
+		repoUrls[i] = repo.GetCloneURL()
+	}
+
+	return repoUrls, nil
+}
+
+func (g *Github) getOrCreateClient(ctx context.Context, server string) (*github.Client, error) {
+	g.githubmu.Lock()
+	defer g.githubmu.Unlock()
+
+	client, ok := g.githubClient[server]
+	if !ok || client == nil {
+		httpClient := &http.Client{}
+		client := github.NewClient(httpClient)
+		g.githubClient[server] = client
+		return client, nil
+	}
+
+	return client, nil
+}