triggers: use templates instead of % mini language

Since previous commit, all commands now support expanding text/template
markup. Reuse that for the new-email trigger command.

Update commands.ExecuteCommand to take optional *AccountConfig and
*MessageInfo arguments. If these are nil, fallback to using the
currently selected account and message (if any).

Pass the proper *AccountConfig and *MessageInfo objects when firing the
trigger command so that these are used instead of the currently selected
ones.

If new-email contains % placeholders, try to convert them to template
markup reusing the same conversion added in commit 535300cfdbfc
("config: add columns based index format"). Warn the user that they need
to update their configuration file.

Signed-off-by: Robin Jarry <robin@jarry.cc>
Reviewed-by: Moritz Poldrack <moritz@poldrack.dev>

9 files changed, 178 insertions, 144 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 67d0d264..7bd13e6b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Deprecated
 
 - `[ui].index-format` setting has been replaced by `index-columns`.
+- `[triggers].new-email` now needs to use `aerc-templates(7)` syntax instead
+  of the (now deprecated) `index-format` placeholders.
 
 ## [0.14.0](https://git.sr.ht/~rjarry/aerc/refs/0.14.0) - 2023-01-04
 
diff --git a/aerc.go b/aerc.go
index d563ccf8..36dcde0e 100644
--- a/aerc.go
+++ b/aerc.go
@@ -27,6 +27,7 @@ import (
 	"git.sr.ht/~rjarry/aerc/lib/templates"
 	libui "git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
+	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/widgets"
 	"git.sr.ht/~rjarry/aerc/worker/types"
 )
@@ -60,10 +61,13 @@ func getCommands(selected libui.Drawable) []*commands.Commands {
 	}
 }
 
-func execCommand(aerc *widgets.Aerc, ui *libui.UI, cmd []string) error {
+func execCommand(
+	aerc *widgets.Aerc, ui *libui.UI, cmd []string,
+	acct *config.AccountConfig, msg *models.MessageInfo,
+) error {
 	cmds := getCommands(aerc.SelectedTabContent())
 	for i, set := range cmds {
-		err := set.ExecuteCommand(aerc, cmd)
+		err := set.ExecuteCommand(aerc, cmd, acct, msg)
 		if err != nil {
 			if errors.As(err, new(commands.NoSuchCommand)) {
 				if i == len(cmds)-1 {
@@ -189,8 +193,11 @@ func main() {
 	}
 	defer c.Close()
 
-	aerc = widgets.NewAerc(c, func(cmd []string) error {
-		return execCommand(aerc, ui, cmd)
+	aerc = widgets.NewAerc(c, func(
+		cmd []string, acct *config.AccountConfig,
+		msg *models.MessageInfo,
+	) error {
+		return execCommand(aerc, ui, cmd, acct, msg)
 	}, func(cmd string) []string {
 		return getCompletions(aerc, cmd)
 	}, &commands.CmdHistory, deferLoop)
diff --git a/commands/commands.go b/commands/commands.go
index bbd03237..cf96a39e 100644
--- a/commands/commands.go
+++ b/commands/commands.go
@@ -70,15 +70,21 @@ type CommandSource interface {
 	Commands() *Commands
 }
 
-func templateData(aerc *widgets.Aerc) models.TemplateData {
+func templateData(
+	aerc *widgets.Aerc,
+	cfg *config.AccountConfig,
+	msg *models.MessageInfo,
+) models.TemplateData {
 	var folder string
-	var cfg *config.AccountConfig
-	var msg *models.MessageInfo
 
 	acct := aerc.SelectedAccount()
 	if acct != nil {
 		folder = acct.SelectedDirectory()
+	}
+	if cfg == nil && acct != nil {
 		cfg = acct.AccountConfig()
+	}
+	if msg == nil && acct != nil {
 		msg, _ = acct.SelectedMessage()
 	}
 
@@ -91,14 +97,19 @@ func templateData(aerc *widgets.Aerc) models.TemplateData {
 	return &data
 }
 
-func (cmds *Commands) ExecuteCommand(aerc *widgets.Aerc, args []string) error {
+func (cmds *Commands) ExecuteCommand(
+	aerc *widgets.Aerc,
+	args []string,
+	account *config.AccountConfig,
+	msg *models.MessageInfo,
+) error {
 	if len(args) == 0 {
 		return errors.New("Expected a command.")
 	}
 	if cmd, ok := cmds.dict()[args[0]]; ok {
 		log.Tracef("executing command %v", args)
 		var buf bytes.Buffer
-		data := templateData(aerc)
+		data := templateData(aerc, account, msg)
 
 		processedArgs := make([]string, len(args))
 		for i, arg := range args {
diff --git a/config/triggers.go b/config/triggers.go
index 906928ae..c0e70d40 100644
--- a/config/triggers.go
+++ b/config/triggers.go
@@ -1,82 +1,62 @@
 package config
 
 import (
-	"errors"
-	"fmt"
-
 	"github.com/go-ini/ini"
 	"github.com/google/shlex"
 
 	"git.sr.ht/~rjarry/aerc/lib/format"
 	"git.sr.ht/~rjarry/aerc/log"
-	"git.sr.ht/~rjarry/aerc/models"
 )
 
 type TriggersConfig struct {
-	NewEmail       string `ini:"new-email"`
-	ExecuteCommand func(command []string) error
+	NewEmail []string `ini:"-"`
 }
 
 var Triggers = &TriggersConfig{}
 
 func parseTriggers(file *ini.File) error {
+	var cmd string
 	triggers, err := file.GetSection("triggers")
 	if err != nil {
 		goto out
 	}
-	if err := triggers.MapTo(&Triggers); err != nil {
-		return err
-	}
-out:
-	log.Debugf("aerc.conf: [triggers] %#v", Triggers)
-	return nil
-}
-
-func (trig *TriggersConfig) ExecTrigger(triggerCmd string,
-	triggerFmt func(string) (string, error),
-) error {
-	if len(triggerCmd) == 0 {
-		return errors.New("Trigger command empty")
-	}
-	triggerCmdParts, err := shlex.Split(triggerCmd)
-	if err != nil {
-		return err
-	}
-
-	var command []string
-	for _, part := range triggerCmdParts {
-		formattedPart, err := triggerFmt(part)
+	if key := triggers.Key("new-email"); key != nil {
+		cmd = indexFmtRegexp.ReplaceAllStringFunc(
+			key.String(),
+			func(s string) string {
+				runes := []rune(s)
+				t, _ := indexVerbToTemplate(runes[len(runes)-1])
+				return t
+			},
+		)
+		Triggers.NewEmail, err = shlex.Split(cmd)
 		if err != nil {
 			return err
 		}
-		command = append(command, formattedPart)
-	}
-	return trig.ExecuteCommand(command)
-}
-
-func (trig *TriggersConfig) ExecNewEmail(
-	account *AccountConfig, msg *models.MessageInfo,
-) {
-	err := trig.ExecTrigger(trig.NewEmail,
-		func(part string) (string, error) {
-			formatstr, args, err := format.ParseMessageFormat(
-				part, Ui.TimestampFormat,
-				Ui.ThisDayTimeFormat,
-				Ui.ThisWeekTimeFormat,
-				Ui.ThisYearTimeFormat,
-				Ui.IconAttachment,
-				format.Ctx{
-					FromAddress: format.AddressForHumans(account.From),
-					AccountName: account.Name,
-					MsgInfo:     msg,
-				},
-			)
-			if err != nil {
-				return "", err
-			}
-			return fmt.Sprintf(formatstr, args...), nil
-		})
-	if err != nil {
-		log.Errorf("failed to run new-email trigger: %v", err)
+		if cmd != key.String() {
+			log.Warnf("%s %s",
+				"The new-email trigger now uses templates instead of %-based placeholders.",
+				"Backward compatibility will be removed in aerc 0.17.")
+			Warnings = append(Warnings, Warning{
+				Title: "FORMAT CHANGED: [triggers].new-email",
+				Body: `
+The new-email trigger now uses templates instead of %-based placeholders.
+
+Your configuration in this instance was automatically converted to:
+
+[triggers]
+new-email = ` + format.ShellQuote(Triggers.NewEmail) + `
+
+Your configuration file was not changed. To make this change permanent and to
+dismiss this warning on launch, replace the above line into aerc.conf. See
+aerc-config(5) for more details.
+
+The automatic conversion of new-email will be removed in aerc 0.17.
+`,
+			})
+		}
 	}
+out:
+	log.Debugf("aerc.conf: [triggers] %#v", Triggers)
+	return nil
 }
diff --git a/config/ui.go b/config/ui.go
index db596d97..b59c9b09 100644
--- a/config/ui.go
+++ b/config/ui.go
@@ -391,75 +391,12 @@ func convertIndexFormat(indexFormat string) ([]*ColumnDef, error) {
 		alignWidth := m[1]
 		verb := m[3]
 
-		var f string
 		var width float64 = 0
 		var flags ColumnFlags = ALIGN_LEFT
-		name := ""
-
-		switch verb {
-		case "%":
-			f = verb
-		case "a":
-			f = `{{(index .From 0).Address}}`
-			name = "sender"
-		case "A":
-			f = `{{if eq (len .ReplyTo) 0}}{{(index .From 0).Address}}{{else}}{{(index .ReplyTo 0).Address}}{{end}}`
-			name = "reply-to"
-		case "C":
-			f = "{{.Number}}"
-			name = "num"
-		case "d", "D":
-			f = "{{.DateAutoFormat .Date.Local}}"
-			name = "date"
-		case "f":
-			f = `{{index (.From | persons) 0}}`
-			name = "from"
-		case "F":
-			f = `{{.Peer | names | join ", "}}`
-			name = "peers"
-		case "g":
-			f = `{{.Labels | join ", "}}`
-			name = "labels"
-		case "i":
-			f = "{{.MessageId}}"
-			name = "msg-id"
-		case "n":
-			f = `{{index (.From | names) 0}}`
-			name = "name"
-		case "r":
-			f = `{{.To | persons | join ", "}}`
-			name = "to"
-		case "R":
-			f = `{{.Cc | persons | join ", "}}`
-			name = "cc"
-		case "s":
-			f = "{{.Subject}}"
-			name = "subject"
-		case "t":
-			f = "{{(index .To 0).Address}}"
-			name = "to0"
-		case "T":
-			f = "{{.Account}}"
-			name = "account"
-		case "u":
-			f = "{{index (.From | mboxes) 0}}"
-			name = "mboxes"
-		case "v":
-			f = "{{index (.From | names) 0}}"
-			name = "name"
-		case "Z":
-			f = `{{.Flags | join ""}}`
-			name = "flags"
+		f, name := indexVerbToTemplate([]rune(verb)[0])
+		if verb == "Z" {
 			width = 4
 			flags = ALIGN_RIGHT
-		case "l":
-			f = "{{.Size}}"
-			name = "size"
-		default:
-			f = "%" + verb
-		}
-		if name == "" {
-			name = "wtf"
 		}
 
 		t, err := templates.ParseTemplate(fmt.Sprintf("column-%s", name), f)
@@ -495,6 +432,73 @@ func convertIndexFormat(indexFormat string) ([]*ColumnDef, error) {
 	return columns, nil
 }
 
+func indexVerbToTemplate(verb rune) (f, name string) {
+	switch verb {
+	case '%':
+		f = string(verb)
+	case 'a':
+		f = `{{(index .From 0).Address}}`
+		name = "sender"
+	case 'A':
+		f = `{{if eq (len .ReplyTo) 0}}{{(index .From 0).Address}}{{else}}{{(index .ReplyTo 0).Address}}{{end}}`
+		name = "reply-to"
+	case 'C':
+		f = "{{.Number}}"
+		name = "num"
+	case 'd', 'D':
+		f = "{{.DateAutoFormat .Date.Local}}"
+		name = "date"
+	case 'f':
+		f = `{{index (.From | persons) 0}}`
+		name = "from"
+	case 'F':
+		f = `{{.Peer | names | join ", "}}`
+		name = "peers"
+	case 'g':
+		f = `{{.Labels | join ", "}}`
+		name = "labels"
+	case 'i':
+		f = "{{.MessageId}}"
+		name = "msg-id"
+	case 'n':
+		f = `{{index (.From | names) 0}}`
+		name = "name"
+	case 'r':
+		f = `{{.To | persons | join ", "}}`
+		name = "to"
+	case 'R':
+		f = `{{.Cc | persons | join ", "}}`
+		name = "cc"
+	case 's':
+		f = "{{.Subject}}"
+		name = "subject"
+	case 't':
+		f = "{{(index .To 0).Address}}"
+		name = "to0"
+	case 'T':
+		f = "{{.Account}}"
+		name = "account"
+	case 'u':
+		f = "{{index (.From | mboxes) 0}}"
+		name = "mboxes"
+	case 'v':
+		f = "{{index (.From | names) 0}}"
+		name = "name"
+	case 'Z':
+		f = `{{.Flags | join ""}}`
+		name = "flags"
+	case 'l':
+		f = "{{.Size}}"
+		name = "size"
+	default:
+		f = "%" + string(verb)
+	}
+	if name == "" {
+		name = "wtf"
+	}
+	return
+}
+
 func (ui *UIConfig) loadStyleSet(styleSetDirs []string) error {
 	ui.style = NewStyleSet()
 	err := ui.style.LoadStyleSet(ui.StyleSetName, styleSetDirs)
diff --git a/doc/aerc-config.5.scd b/doc/aerc-config.5.scd
index 3669d26e..6e20fd71 100644
--- a/doc/aerc-config.5.scd
+++ b/doc/aerc-config.5.scd
@@ -821,17 +821,21 @@ message/rfc822=thunderbird
 
 # TRIGGERS
 
-Triggers specify commands to execute when certain events occur.
+Triggers specify commands to execute when certain events occur. They are
+configured in the *[triggers]* section of _aerc.conf_.
 
-They are configured in the *[triggers]* section of _aerc.conf_.
+The commands are not shell commands (i.e. they are not executed with _sh -c_)
+and will be split in multiple arguments following basic shell quoting. They need
+to use one of the commands described in *aerc*(1) without the leading colon *:*
+(e.g. _exec foo bar_ instead of _:exec foo bar_).
 
 *new-email* = _<command>_
-	Executed when a new email arrives in the selected folder.
+	Executed when a new email arrives in the selected folder. Example:
 
-	e.g. new-email=exec notify-send "New email from %n" "%s"
+		exec notify-send 'New email from {{.From | names | join ", "}}' '{{.Subject}}'
 
-	Format specifiers from *index-format* are expanded with respect to the new
-	message.
+	Templates specifiers from *aerc-templates*(7) are expanded with respect
+	to the new message.
 
 # TEMPLATES
 
diff --git a/lib/format/format.go b/lib/format/format.go
index ad0b778c..7466cfd5 100644
--- a/lib/format/format.go
+++ b/lib/format/format.go
@@ -93,6 +93,23 @@ func TruncateHead(s string, w int, head string) string {
 	return head + s[pos:]
 }
 
+func ShellQuote(args []string) string {
+	quoted := make([]string, len(args))
+
+	for i, arg := range args {
+		if strings.ContainsAny(arg, " '\"|&!#$;[](){}<>*\n\t") {
+			if strings.ContainsAny(arg, "!\"$") {
+				arg = "'" + arg + "'"
+			} else {
+				arg = "\"" + arg + "\""
+			}
+		}
+		quoted[i] = arg
+	}
+
+	return strings.Join(quoted, " ")
+}
+
 type Ctx struct {
 	FromAddress string
 	AccountName string
diff --git a/widgets/account.go b/widgets/account.go
index 3176a2bf..ded71f99 100644
--- a/widgets/account.go
+++ b/widgets/account.go
@@ -293,7 +293,15 @@ func (acct *AccountView) onMessage(msg types.WorkerMessage) {
 				acct.dirlist.UiConfig(name).ReverseThreadOrder,
 				acct.dirlist.UiConfig(name).SortThreadSiblings,
 				func(msg *models.MessageInfo) {
-					config.Triggers.ExecNewEmail(acct.acct, msg)
+					if len(config.Triggers.NewEmail) == 0 {
+						return
+					}
+					err := acct.aerc.cmd(
+						config.Triggers.NewEmail,
+						acct.acct, msg)
+					if err != nil {
+						acct.aerc.PushError(err.Error())
+					}
 				}, func() {
 					if acct.dirlist.UiConfig(name).NewMessageBell {
 						acct.host.Beep()
diff --git a/widgets/aerc.go b/widgets/aerc.go
index b946b158..b8be1100 100644
--- a/widgets/aerc.go
+++ b/widgets/aerc.go
@@ -20,12 +20,13 @@ import (
 	"git.sr.ht/~rjarry/aerc/lib/crypto"
 	"git.sr.ht/~rjarry/aerc/lib/ui"
 	"git.sr.ht/~rjarry/aerc/log"
+	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/worker/types"
 )
 
 type Aerc struct {
 	accounts    map[string]*AccountView
-	cmd         func(cmd []string) error
+	cmd         func([]string, *config.AccountConfig, *models.MessageInfo) error
 	cmdHistory  lib.History
 	complete    func(cmd string) []string
 	focused     ui.Interactive
@@ -51,7 +52,8 @@ type Choice struct {
 }
 
 func NewAerc(
-	crypto crypto.Provider, cmd func(cmd []string) error,
+	crypto crypto.Provider,
+	cmd func([]string, *config.AccountConfig, *models.MessageInfo) error,
 	complete func(cmd string) []string, cmdHistory lib.History,
 	deferLoop chan struct{},
 ) *Aerc {
@@ -86,7 +88,6 @@ func NewAerc(
 	}
 
 	statusline.SetAerc(aerc)
-	config.Triggers.ExecuteCommand = cmd
 
 	for _, acct := range config.Accounts {
 		view, err := NewAccountView(aerc, acct, aerc, deferLoop)
@@ -608,7 +609,7 @@ func (aerc *Aerc) BeginExCommand(cmd string) {
 		if err != nil {
 			aerc.PushError(err.Error())
 		}
-		err = aerc.cmd(parts)
+		err = aerc.cmd(parts, nil, nil)
 		if err != nil {
 			aerc.PushError(err.Error())
 		}
@@ -634,7 +635,7 @@ func (aerc *Aerc) RegisterPrompt(prompt string, cmd []string) {
 		if text != "" {
 			cmd = append(cmd, text)
 		}
-		err := aerc.cmd(cmd)
+		err := aerc.cmd(cmd, nil, nil)
 		if err != nil {
 			aerc.PushError(err.Error())
 		}
@@ -661,7 +662,7 @@ func (aerc *Aerc) RegisterChoices(choices []Choice) {
 		if !ok {
 			return
 		}
-		err := aerc.cmd(cmd)
+		err := aerc.cmd(cmd, nil, nil)
 		if err != nil {
 			aerc.PushError(err.Error())
 		}