Add `tea repo fork` (#410)

Adds a new subcommand to fork repos.

To specify the repo to fork, use the `--repo` flag. This feels a bit weird, other tea commands would put this as the first argument.
I decided to follow the flag style, as this is what all other subcommands of `tea repo` do. We might want to reconsider and make the primary subject of such commands an argument, instead of an required flag.. see #430

Co-authored-by: Norwin <git@nroo.de>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-on: https://gitea.com/gitea/tea/pulls/410
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Norwin <noerw@noreply.gitea.io>
Co-committed-by: Norwin <noerw@noreply.gitea.io>

cmd/repos.go

@@ -27,6 +27,7 @@ var CmdRepos = cli.Command{
 		&repos.CmdReposList,
 		&repos.CmdReposSearch,
 		&repos.CmdRepoCreate,
+		&repos.CmdRepoFork,
 	},
 	Flags: repos.CmdReposListFlags,
 }

cmd/repos/fork.go

@@ -0,0 +1,57 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package repos
+
+import (
+	"fmt"
+
+	"code.gitea.io/tea/cmd/flags"
+	"code.gitea.io/tea/modules/context"
+	"code.gitea.io/tea/modules/print"
+
+	"code.gitea.io/sdk/gitea"
+	"github.com/urfave/cli/v2"
+)
+
+// CmdRepoFork represents a sub command of repos to fork an existing repo
+var CmdRepoFork = cli.Command{
+	Name:        "fork",
+	Aliases:     []string{"f"},
+	Usage:       "Fork an existing repository",
+	Description: "Create a repository from an existing repo",
+	Action:      runRepoFork,
+	Flags: append([]cli.Flag{
+		&cli.StringFlag{
+			Name:    "owner",
+			Aliases: []string{"O"},
+			Usage:   "name of fork's owner, defaults to current user",
+		},
+	}, flags.LoginRepoFlags...),
+}
+
+func runRepoFork(cmd *cli.Context) error {
+	ctx := context.InitCommand(cmd)
+	client := ctx.Login.Client()
+
+	opts := gitea.CreateForkOption{}
+	if ctx.IsSet("owner") {
+		owner := ctx.String("owner")
+		opts.Organization = &owner
+	}
+
+	repo, _, err := client.CreateFork(ctx.Owner, ctx.Repo, opts)
+	if err != nil {
+		return err
+	}
+
+	topics, _, err := client.ListRepoTopics(repo.Owner.UserName, repo.Name, gitea.ListRepoTopicsOptions{})
+	if err != nil {
+		return err
+	}
+	print.RepoDetails(repo, topics)
+
+	fmt.Printf("%s\n", repo.HTMLURL)
+	return nil
+}