feat(auth): guide login, readable status and switch without --host

tea auth login without a method flag asks on a terminal for the instance
(prefilled from the repository, default_host or the only instance), how
to log in (token, browser, SSH key), the pasted token without echo with
a link to the applications page, where to keep it and whether git
should use tea for the instance. Bare hosts are accepted. Logging in to
an account tea already has replaces its credential after a
confirmation, or with --yes; a named account is confirmed before the
token is asked for. Every login ends with "Logged in to HOST as USER
(token, keyring)". OAuth requests write scopes for everything but
administration by default, and --scopes chooses others; --web is an
alias of --oauth.

auth status prints a block per instance with the active account, how
each account authenticates, its expiry, verification and token scopes,
whether git uses tea, and the GITEA_TOKEN of the environment. Piped it
prints tab-separated fields. It fails with exit code 4 when no account
or no usable credential exists instead of printing nothing.

auth switch takes the instance of the repository, --host, default_host
or the sole instance instead of requiring --host, toggles between two
accounts, asks on a terminal with more, and accepts --user. auth logout
takes the account as an argument, names it in its errors, and asks git's
other credential helpers to forget what they stored for the account.
auth refresh points token accounts to tea auth login --with-token, and
the new auth token prints the token of an account for scripts.

Every auth command reports what it did on a terminal and has a long
help text and examples.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/auth_test.go

@@ -4,6 +4,8 @@
 package app
 
 import (
+	"bytes"
+	"cmp"
 	"context"
 	"crypto/ed25519"
 	"crypto/rand"
@@ -24,6 +26,7 @@ import (
 	"gitea.dev/tea/internal/auth"
 	"gitea.dev/tea/internal/clierr"
 	"gitea.dev/tea/internal/settings"
+	"gitea.dev/tea/internal/terminal"
 	"gitea.dev/tea/internal/transport"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/crypto/ssh"
@@ -161,7 +164,7 @@ func TestLogoutRejectsUnknownAccountBeforeConfirmation(t *testing.T) {
 	configureHost(t, deps, "https://example.org", settings.Host{User: "alice", Users: tokenAccounts(settings.StoreKeyring, "alice")})
 	err := Execute(context.Background(), deps, []string{"auth", "logout", "--host", "https://example.org", "--user", "bob", "--no-input"})
 	require.Equal(t, clierr.Usage, clierr.ExitCode(err))
-	require.ErrorContains(t, err, "account is not configured")
+	require.EqualError(t, err, `account "bob" is not logged in on https://example.org (accounts: alice)`)
 	require.Empty(t, out.String())
 	require.Empty(t, diagnostics.String())
 	require.Empty(t, keyring.reads)
@@ -179,14 +182,17 @@ func TestAuthStatusFiltersBeforeReadingCredentials(t *testing.T) {
 	}
 	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "status", "--host", "https://EXAMPLE.org/base/", "--user", "BOB", "--json"}))
 	require.Equal(t, []string{auth.Identity("https://example.org/base", "bob")}, keyring.reads)
-	require.JSONEq(t, `[{"host":"https://example.org/base","user":"bob","active":false,"credential_store":"keyring","credential_available":true,"expires_at":null,"verified":null,"error":""}]`, out.String())
+	require.JSONEq(t, `[{"host":"https://example.org/base","user":"bob","active":false,"method":"token","credential_store":"keyring","credential_available":true,"expires_at":null,"verified":null,"error":""}]`, out.String())
 	out.Reset()
 	keyring.reads = nil
 	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "status", "--host", "https://unconfigured.example.org", "--json"}))
 	require.JSONEq(t, `[]`, out.String())
 	require.Empty(t, keyring.reads)
 	out.Reset()
-	require.Equal(t, clierr.Usage, clierr.ExitCode(Execute(context.Background(), deps, []string{"auth", "status", "--host", "invalid-host"})))
+	require.Equal(t, clierr.Usage, clierr.ExitCode(Execute(context.Background(), deps, []string{"auth", "status", "--host", "ftp://invalid-host"})))
+	err := Execute(context.Background(), deps, []string{"auth", "status", "--host", "unconfigured.example.org"})
+	require.Equal(t, clierr.Authentication, clierr.ExitCode(err))
+	require.EqualError(t, err, "not logged in to https://unconfigured.example.org; run tea auth login --host https://unconfigured.example.org")
 	require.Empty(t, out.String())
 	require.Empty(t, keyring.reads)
 }
@@ -352,7 +358,11 @@ func TestAuthLoginMethodFlagsAreMutuallyExclusive(t *testing.T) {
 		t.Run(strings.Join(args[3:], " "), func(t *testing.T) {
 			err := Execute(context.Background(), deps, args)
 			require.Equal(t, clierr.Usage, clierr.ExitCode(err))
-			require.ErrorContains(t, err, "select exactly one")
+			if strings.Count(strings.Join(args, " "), "--") > 2 {
+				require.ErrorContains(t, err, "select one of --with-token, --oauth, --ssh-key")
+			} else {
+				require.ErrorContains(t, err, "select how to log in: --with-token, --oauth or --ssh-key")
+			}
 			require.Empty(t, out.String())
 		})
 	}
@@ -360,8 +370,10 @@ func TestAuthLoginMethodFlagsAreMutuallyExclusive(t *testing.T) {
 
 func TestAuthLoginValidatesMethodBeforePromptingForHost(t *testing.T) {
 	for args, want := range map[string]string{
-		"auth login":                            "select exactly one",
+		"auth login --with-token --oauth":       "select one of",
 		"auth login --with-token --client-id x": "--client-id requires --oauth",
+		"auth login --with-token --scopes all":  "--scopes requires --oauth",
+		"auth login --oauth --scopes nope":      "--scopes must be all, read:activitypub",
 	} {
 		t.Run(args, func(t *testing.T) {
 			deps, out, _ := testDeps(t)
@@ -433,13 +445,18 @@ func TestAuthRefreshRejectsTokenAccounts(t *testing.T) {
 func TestAuthStatusVerifyChecksStoredCredentials(t *testing.T) {
 	requests := 0
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		requests++
-		require.Equal(t, "/api/v1/user", r.URL.Path)
-		if r.Header.Get("Authorization") != "token valid-status-token" {
-			w.WriteHeader(http.StatusUnauthorized)
-			return
+		if r.URL.Path == "/api/v1/user" {
+			requests++
+		}
+		switch {
+		case r.Header.Get("Authorization") != "token valid-status-token":
+			w.WriteHeader(http.StatusUnauthorized)
+		case r.URL.Path == "/api/v1/token":
+			_, _ = w.Write([]byte(`{"scopes":["write:repository","read:user"]}`))
+		default:
+			require.Equal(t, "/api/v1/user", r.URL.Path)
+			_, _ = w.Write([]byte(`{"login":"alice"}`))
 		}
-		_, _ = w.Write([]byte(`{"login":"alice"}`))
 	}))
 	defer server.Close()
 	deps, out, _ := testDeps(t)
@@ -451,7 +468,7 @@ func TestAuthStatusVerifyChecksStoredCredentials(t *testing.T) {
 	configureHost(t, deps, server.URL, settings.Host{User: "alice", Users: accounts})
 	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "status", "--json=user,verified,error"}))
 	require.Zero(t, requests)
-	require.JSONEq(t, `[{"user":"alice","verified":null,"error":""},{"user":"bob","verified":null,"error":""},{"user":"carol","verified":null,"error":""}]`, out.String())
+	require.JSONEq(t, `[{"user":"alice","verified":null,"error":""},{"user":"bob","verified":null,"error":""},{"user":"carol","verified":null,"error":"credential unavailable; run tea auth login for this instance and account"}]`, out.String())
 	out.Reset()
 	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "status", "--verify", "--json"}))
 	require.Equal(t, 2, requests)
@@ -476,7 +493,7 @@ func TestAuthStatusVerifyChecksStoredCredentials(t *testing.T) {
 	require.NotContains(t, out.String(), "status-token")
 	out.Reset()
 	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "status", "--verify", "--user", "alice"}))
-	require.Equal(t, server.URL+"\talice\tactive=true\tcredentials=true\texpires=2030-01-02T03:04:05Z\tverified=true\n", out.String())
+	require.Equal(t, server.URL+"\talice\ttrue\toauth\tfile\ttrue\ttrue\t2030-01-02T03:04:05Z\t\n", out.String())
 }
 
 func TestOAuthLoginOpensAuthorizationURLInBrowser(t *testing.T) {
@@ -540,3 +557,228 @@ func TestOAuthLoginOpensAuthorizationURLInBrowser(t *testing.T) {
 	require.NoError(t, err)
 	require.Contains(t, snapshot.Hosts.Hosts[normalized].Users, "alice")
 }
+
+// loginPrompter answers the interactive login and account choices, recording what it was asked.
+type loginPrompter struct {
+	scriptedPrompter
+	answers   terminal.LoginAnswers
+	questions terminal.LoginQuestions
+	prefilled terminal.LoginAnswers
+	choice    int
+	options   []string
+}
+
+func (p *loginPrompter) Login(_ context.Context, questions terminal.LoginQuestions, answers *terminal.LoginAnswers) error {
+	p.questions, p.prefilled = questions, *answers
+	host := answers.Host
+	*answers = p.answers
+	answers.Host = cmp.Or(answers.Host, host)
+	return nil
+}
+
+func (p *loginPrompter) Choose(_ context.Context, _ string, choices []terminal.Choice, _ string) (string, error) {
+	p.options = make([]string, len(choices))
+	for i, choice := range choices {
+		p.options[i] = choice.Label
+	}
+	return choices[p.choice].Value, nil
+}
+
+// terminalDeps returns testDeps on a terminal, where tea prompts and reports mutations.
+func terminalDeps(t *testing.T) (Dependencies, *bytes.Buffer, *bytes.Buffer) {
+	t.Helper()
+	deps, out, diagnostics := testDeps(t)
+	deps.Streams.InTTY, deps.Streams.OutTTY, deps.Streams.ErrTTY = true, true, true
+	return deps, out, diagnostics
+}
+
+func TestAuthLoginAsksHowToLogIn(t *testing.T) {
+	server := newAuthenticatedServer(http.NotFoundHandler())
+	defer server.Close()
+	deps, _, diagnostics := terminalDeps(t)
+	prompt := &loginPrompter{answers: terminal.LoginAnswers{Method: terminal.LoginToken, Token: "pasted-token", Store: settings.StoreFile}}
+	deps.Prompter = prompt
+	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "login", "--host", server.URL}))
+	require.Equal(t, terminal.LoginAnswers{Host: server.URL, Method: terminal.LoginToken, Store: settings.StoreKeyring, SSHKey: prompt.prefilled.SSHKey, SetupGit: true}, prompt.prefilled)
+	require.False(t, prompt.questions.Host)
+	require.True(t, prompt.questions.Method && prompt.questions.Store && prompt.questions.SetupGit)
+	require.Equal(t, "Create one at https://gitea.com/user/settings/applications", prompt.questions.TokenHint("https://gitea.com"))
+	credential, err := deps.Credentials.Load(server.URL, "alice", settings.StoreFile)
+	require.NoError(t, err)
+	require.Equal(t, "pasted-token", credential.AccessToken)
+	require.Equal(t, "✓ Logged in to "+server.URL+" as alice (token, file store)\n", withoutANSI(diagnostics.String()))
+	// Without --host, the sole instance is the suggestion; logging in again replaces the token.
+	diagnostics.Reset()
+	prompt.answers.Token, prompt.accept = "rotated-token", true
+	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "login"}))
+	require.True(t, prompt.questions.Host)
+	require.Equal(t, server.URL, prompt.prefilled.Host)
+	require.Equal(t, []string{"alice is already logged in to " + server.URL + ". Replace the stored credential?"}, prompt.confirmations)
+	credential, err = deps.Credentials.Load(server.URL, "alice", settings.StoreFile)
+	require.NoError(t, err)
+	require.Equal(t, "rotated-token", credential.AccessToken)
+}
+
+func TestAuthLoginReplacesACredentialOnlyWhenConfirmed(t *testing.T) {
+	server := newAuthenticatedServer(http.NotFoundHandler())
+	defer server.Close()
+	deps, _, _ := testDeps(t)
+	configureAccounts(t, deps, server.URL, "alice", "alice")
+	login := func(extra ...string) error {
+		deps.Streams.In = strings.NewReader("new-token\n")
+		return Execute(context.Background(), deps, append([]string{"auth", "login", "--host", server.URL, "--with-token", "--credential-store", "file", "--no-input"}, extra...))
+	}
+	err := login()
+	require.Equal(t, clierr.Usage, clierr.ExitCode(err))
+	require.EqualError(t, err, "confirmation required to replace the stored credential of alice on "+server.URL+"; rerun with --yes")
+	credential, err := deps.Credentials.Load(server.URL, "alice", settings.StoreFile)
+	require.NoError(t, err)
+	require.Equal(t, "alice-token", credential.AccessToken)
+	require.NoError(t, login("--yes"))
+	credential, err = deps.Credentials.Load(server.URL, "alice", settings.StoreFile)
+	require.NoError(t, err)
+	require.Equal(t, "new-token", credential.AccessToken)
+	// A named account is confirmed before tea asks for its token.
+	deps, _, _ = terminalDeps(t)
+	configureAccounts(t, deps, server.URL, "alice", "alice")
+	prompt := &scriptedPrompter{secret: "unused"}
+	deps.Prompter = prompt
+	err = Execute(context.Background(), deps, []string{"auth", "login", "--host", server.URL, "--with-token", "--user", "alice"})
+	require.Equal(t, clierr.Canceled, clierr.ExitCode(err))
+	require.Len(t, prompt.confirmations, 1)
+	require.Empty(t, prompt.secrets)
+}
+
+func TestAuthStatusShowsAccountsByInstance(t *testing.T) {
+	const instance = "https://example.org"
+	helper := "config --global --get-all credential." + instance + ".helper"
+	for _, tc := range []struct {
+		name     string
+		users    []string
+		env      map[string]string
+		helper   bool
+		want     string
+		failure  string
+		exitCode int
+	}{
+		{
+			name: "accounts", users: []string{"alice", "bob"}, helper: true,
+			want: instance + "\n  ✓ Logged in as alice (token, file store) · active\n  ✓ Logged in as bob (token, file store)\n  - Git credential helper: configured (global)\n",
+		},
+		{
+			name: "environment token", users: []string{"alice"}, env: map[string]string{"GITEA_TOKEN": "env", "TEA_HOST": "example.org"},
+			want: instance + "\n  ✓ Using GITEA_TOKEN from the environment\n  ✓ Logged in as alice (token, file store) · active\n  - Git credential helper: not configured; run tea auth setup-git\n",
+		},
+		{
+			name: "environment token only", env: map[string]string{"GITEA_TOKEN": "env", "GITEA_INSTANCE_URL": instance},
+			want: instance + "\n  ✓ Using GITEA_TOKEN from the environment\n",
+		},
+		{name: "logged out", failure: "not logged in to any Gitea instance; run tea auth login", exitCode: clierr.Authentication},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			deps, out, _ := terminalDeps(t)
+			deps.Getenv = envFunc(tc.env)
+			if tc.helper {
+				deps.Git = &fakeGit{results: map[string]string{helper: "!'/usr/bin/tea' auth git-credential --host " + instance}}
+			}
+			if len(tc.users) > 0 {
+				configureAccounts(t, deps, instance, tc.users[0], tc.users...)
+			}
+			err := Execute(context.Background(), deps, []string{"auth", "status"})
+			if tc.failure != "" {
+				require.Equal(t, tc.exitCode, clierr.ExitCode(err))
+				require.EqualError(t, err, tc.failure)
+			} else {
+				require.NoError(t, err)
+			}
+			require.Equal(t, tc.want, withoutANSI(out.String()))
+		})
+	}
+	deps, out, _ := testDeps(t)
+	configureHost(t, deps, instance, settings.Host{User: "alice", Users: tokenAccounts(settings.StoreFile, "alice")})
+	err := Execute(context.Background(), deps, []string{"auth", "status"})
+	require.Equal(t, clierr.Authentication, clierr.ExitCode(err))
+	require.EqualError(t, err, "1 of 1 credentials cannot authenticate; log in again with tea auth login")
+	require.Equal(t, instance+"\talice\ttrue\ttoken\tfile\tfalse\t\t\tcredential unavailable; run tea auth login for this instance and account\n", out.String())
+}
+
+func TestAuthSwitchSelectsInstanceAndAccount(t *testing.T) {
+	const instance = "https://example.org"
+	deps, _, diagnostics := terminalDeps(t)
+	configureAccounts(t, deps, instance, "alice", "alice")
+	err := Execute(context.Background(), deps, []string{"auth", "switch"})
+	require.EqualError(t, err, "alice is the only account on "+instance+"; log in to another with tea auth login --host "+instance)
+	configureAccounts(t, deps, instance, "alice", "alice", "bob")
+	active := func() string {
+		s, err := deps.Settings.Load()
+		require.NoError(t, err)
+		return s.Hosts.Hosts[instance].User
+	}
+	for _, tc := range []struct {
+		args       []string
+		want, diag string
+	}{
+		{nil, "bob", "✓ Switched active account for " + instance + " to bob\n"},
+		{nil, "alice", "✓ Switched active account for " + instance + " to alice\n"},
+		{[]string{"ALICE"}, "alice", "! alice is already the active account on " + instance + "\n"},
+		{[]string{"--user", "bob"}, "bob", "✓ Switched active account for " + instance + " to bob\n"},
+	} {
+		diagnostics.Reset()
+		require.NoError(t, Execute(context.Background(), deps, append([]string{"auth", "switch"}, tc.args...)))
+		require.Equal(t, tc.want, active())
+		require.Equal(t, tc.diag, withoutANSI(diagnostics.String()))
+	}
+	configureAccounts(t, deps, instance, "bob", "alice", "bob", "carol")
+	prompt := &loginPrompter{choice: 2}
+	deps.Prompter = prompt
+	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "switch"}))
+	require.Equal(t, []string{"alice", "bob (active)", "carol"}, prompt.options)
+	require.Equal(t, "carol", active())
+	err = Execute(context.Background(), deps, []string{"auth", "switch", "--no-input"})
+	require.Equal(t, clierr.Usage, clierr.ExitCode(err))
+	require.EqualError(t, err, "name the account: tea auth switch <user> (accounts on "+instance+": alice, bob, carol)")
+	err = Execute(context.Background(), deps, []string{"auth", "switch", "dave"})
+	require.EqualError(t, err, `account "dave" is not logged in on `+instance+" (accounts: alice, bob, carol)")
+}
+
+func TestAuthTokenPrintsTheCredential(t *testing.T) {
+	const instance = "https://example.org"
+	deps, out, _ := testDeps(t)
+	configureAccounts(t, deps, instance, "alice", "alice")
+	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "token"}))
+	require.Equal(t, "alice-token\n", out.String())
+	err := Execute(context.Background(), deps, []string{"auth", "token", "--user", "bob"})
+	require.Equal(t, clierr.Authentication, clierr.ExitCode(err))
+	out.Reset()
+	deps.Getenv = envFunc(map[string]string{"GITEA_TOKEN": "env-token", "TEA_HOST": instance})
+	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "token"}))
+	require.Equal(t, "env-token\n", out.String())
+	deps.Getenv = envFunc(nil)
+	configureHost(t, deps, instance, settings.Host{User: "alice", Users: map[string]settings.Account{"alice": {AuthMethod: settings.AuthHTTPSign, SSHKey: "/keys/id"}}})
+	require.EqualError(t, Execute(context.Background(), deps, []string{"auth", "token"}), "alice on "+instance+" signs requests with an SSH key and has no token")
+	require.EqualError(t, Execute(context.Background(), deps, []string{"auth", "token", "--json"}), "auth token prints the token; --json is not supported")
+}
+
+// rejectingGit records the input of Git commands that read standard input.
+type rejectingGit struct {
+	fakeGit
+	inputs []string
+}
+
+func (g *rejectingGit) Input(_ context.Context, _, input string, args ...string) (string, error) {
+	g.inputs = append(g.inputs, strings.Join(args, " ")+"\n"+input)
+	return "", nil
+}
+
+func TestLogoutAsksGitToForgetTheAccount(t *testing.T) {
+	const instance = "https://example.org:3000"
+	deps, _, diagnostics := terminalDeps(t)
+	runner := &rejectingGit{}
+	deps.Git = runner
+	configureAccounts(t, deps, instance, "alice", "alice", "bob")
+	require.NoError(t, Execute(context.Background(), deps, []string{"auth", "logout", "--yes"}))
+	require.Equal(t, []string{"credential reject\nprotocol=https\nhost=example.org:3000\nusername=alice\n\n"}, runner.inputs)
+	require.Equal(t, "✓ Logged out of "+instance+" (alice)\n✓ Switched active account for "+instance+" to bob\n", withoutANSI(diagnostics.String()))
+	err := Execute(context.Background(), deps, []string{"auth", "logout", "carol", "--yes"})
+	require.EqualError(t, err, `account "carol" is not logged in on `+instance+" (accounts: bob)")
+}