commands: add menu

Add a new :menu command that can be used to spawn a shell command in an
interactive dialog and execute aerc commands for each of the lines
printed on its standard output like xargs(1) would do in a shell.

The shell command can be configured in aerc.conf under
[general].default-menu-cmd and overridden via the :menu -c <cmd> option.

There are two flags to provide input text to the shell command which can
be useful in combination with other aerc commands:

	-a: All account names, one per line:
		'<account>' LF

	-d: All current account directory names, one per line:
		'<directory>' LF

	-ad: All directories of all accounts, one per line:
		'<account>' '<directory>' LF

Here are some examples:

	:menu -adc fzf :cf -a
	:menu -c 'fzf --multi' :attach
	:menu -dc 'fzf --multi' :cp

And also for key bindings:

	<C-p> = :menu -adc fzf :cf -a<Enter>

Changelog-added: New `:menu` command to invoke other aerc commands
 based on a shell command output.
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>
Tested-by: Johannes Thyssen Tishman <johannes@thyssentishman.com>

2 files changed, 188 insertions, 1 deletions

diff --git a/commands/commands.go b/commands/commands.go
index fa8ef287..b617bade 100644
--- a/commands/commands.go
+++ b/commands/commands.go
@@ -113,7 +113,7 @@ func (err NoSuchCommand) Error() string {
 //	im --> import-mbox
 func ExpandAbbreviations(name string) (string, Command, error) {
 	context := CurrentContext()
-	name = strings.TrimLeft(name, ":")
+	name = strings.TrimLeft(name, ": \t")
 
 	cmd, found := allCommands[name]
 	if found && cmd.Context()&context != 0 {
diff --git a/commands/menu.go b/commands/menu.go
new file mode 100644
index 00000000..953c6b45
--- /dev/null
+++ b/commands/menu.go
@@ -0,0 +1,187 @@
+package commands
+
+import (
+	"errors"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+
+	"git.sr.ht/~rjarry/aerc/app"
+	"git.sr.ht/~rjarry/aerc/config"
+	"git.sr.ht/~rjarry/aerc/lib/ui"
+	"git.sr.ht/~rjarry/aerc/log"
+	"git.sr.ht/~rjarry/aerc/models"
+	"git.sr.ht/~rjarry/go-opt"
+)
+
+type Menu struct {
+	ErrExit     bool   `opt:"-e"`
+	Background  bool   `opt:"-b"`
+	Accounts    bool   `opt:"-a"`
+	Directories bool   `opt:"-d"`
+	Command     string `opt:"-c"`
+	Xargs       string `opt:"..." complete:"CompleteXargs"`
+}
+
+func init() {
+	Register(Menu{})
+}
+
+func (Menu) Context() CommandContext {
+	return GLOBAL
+}
+
+func (Menu) Aliases() []string {
+	return []string{"menu"}
+}
+
+func (*Menu) CompleteXargs(arg string) []string {
+	return FilterList(ActiveCommandNames(), arg, nil)
+}
+
+func (m Menu) Execute([]string) error {
+	if m.Command == "" {
+		m.Command = config.General.DefaultMenuCmd
+	}
+	if m.Command == "" {
+		return errors.New(
+			"Either -c <command> or default-menu-cmd is required.")
+	}
+	if _, _, err := ResolveCommand(m.Xargs, nil, nil); err != nil {
+		return err
+	}
+
+	lines, err := m.feedLines()
+	if err != nil {
+		return err
+	}
+
+	pick, err := os.CreateTemp("", "aerc-menu-*")
+	if err != nil {
+		return err
+	}
+
+	var proc *exec.Cmd
+	if strings.Contains(m.Command, "%f") {
+		proc = exec.Command("sh", "-c",
+			strings.ReplaceAll(m.Command, "%f", opt.QuoteArg(pick.Name())))
+	} else {
+		proc = exec.Command("sh", "-c", m.Command+" >&3")
+		proc.ExtraFiles = append(proc.ExtraFiles, pick)
+	}
+	if len(lines) > 0 {
+		proc.Stdin = strings.NewReader(strings.Join(lines, "\n"))
+	}
+
+	xargs := func(err error) {
+		var buf []byte
+		if err == nil {
+			_, err = pick.Seek(0, io.SeekStart)
+		}
+		if err == nil {
+			buf, err = io.ReadAll(pick)
+		}
+		pick.Close()
+		os.Remove(pick.Name())
+		if err != nil {
+			app.PushError("command failed: " + err.Error())
+			return
+		}
+		if len(buf) == 0 {
+			return
+		}
+		var cmd Command
+		var cmdline string
+
+		for _, line := range strings.Split(string(buf), "\n") {
+			line = strings.TrimSpace(line)
+			if line == "" {
+				continue
+			}
+			cmdline = m.Xargs + " " + line
+			cmdline, cmd, err = ResolveCommand(cmdline, nil, nil)
+			if err == nil {
+				err = ExecuteCommand(cmd, cmdline)
+			}
+			if err != nil {
+				app.PushError(m.Xargs + ": " + err.Error())
+				if m.ErrExit {
+					return
+				}
+			}
+		}
+	}
+
+	if m.Background {
+		go func() {
+			defer log.PanicHandler()
+			xargs(proc.Run())
+		}()
+	} else {
+		term, err := app.NewTerminal(proc)
+		if err != nil {
+			return err
+		}
+		term.Focus(true)
+		term.OnClose = func(err error) {
+			app.CloseDialog()
+			xargs(err)
+		}
+
+		title := " :" + strings.TrimLeft(m.Xargs, ": \t") + " ... "
+
+		app.AddDialog(app.NewDialog(
+			ui.NewBox(term, title, "", app.SelectedAccountUiConfig()),
+			// start pos on screen
+			func(h int) int {
+				return h / 4
+			},
+			// dialog height
+			func(h int) int {
+				return h / 2
+			},
+		))
+	}
+
+	return nil
+}
+
+func (m Menu) feedLines() ([]string, error) {
+	var lines []string
+
+	switch {
+	case m.Accounts && m.Directories:
+		for _, a := range app.AccountNames() {
+			account, _ := app.Account(a)
+			a = opt.QuoteArg(a)
+			for _, d := range account.Directories().List() {
+				dir := account.Directories().Directory(d)
+				if dir != nil && dir.Role != models.QueryRole {
+					d = opt.QuoteArg(d)
+				}
+				lines = append(lines, a+" "+d)
+			}
+		}
+
+	case m.Accounts:
+		for _, account := range app.AccountNames() {
+			lines = append(lines, opt.QuoteArg(account))
+		}
+
+	case m.Directories:
+		account := app.SelectedAccount()
+		if account == nil {
+			return nil, errors.New("No account selected.")
+		}
+		for _, d := range account.Directories().List() {
+			dir := account.Directories().Directory(d)
+			if dir != nil && dir.Role != models.QueryRole {
+				d = opt.QuoteArg(d)
+			}
+			lines = append(lines, d)
+		}
+	}
+
+	return lines, nil
+}