config: replace triggers with hooks

Deprecate triggers and replace them with hooks. Now that aerc supports
running arbitrary ex commands over IPC, it is possible to run internal
aerc commands *and* shell commands via external shell scripts. Hooks
only allow running shell commands. Hooks info is passed via environment
variables.

Implements: https://todo.sr.ht/~rjarry/aerc/136
Signed-off-by: Moritz Poldrack <git@moritz.sh>
Signed-off-by: Robin Jarry <robin@jarry.cc>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>

11 files changed, 143 insertions, 90 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cf3c7067..4d5b15b2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   `aerc.conf`.
 - Allow basic shell globbing in `[openers]` MIME types.
 - Dynamic `msglist_*` styling based on email header values in stylesets.
+- Add `mail-received` hook.
 
 ### Changed
 
@@ -38,11 +39,10 @@ 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 - `[ui].index-format` setting has been replaced by `index-columns`.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.
 - `[statusline].render-format` has been replaced by `status-columns`.
 - Removed support for go < 1.17.
 - Removed support for `[ui:subject...]` contextual sections in `aerc.conf`.
+- `[triggers]` setting has been replaced by `[hooks]`.
 
 ## [0.14.0](https://git.sr.ht/~rjarry/aerc/refs/0.14.0) - 2023-01-04
 
diff --git a/config/aerc.conf b/config/aerc.conf
index 02ea96fe..5ff252f5 100644
--- a/config/aerc.conf
+++ b/config/aerc.conf
@@ -506,16 +506,13 @@ message/rfc822=colorize
 # text/plain=gvim {} +125
 # message/rfc822=thunderbird
 
-[triggers]
+[hooks]
 #
-# Triggers specify commands to execute when certain events occur.
-#
-# Example:
-# new-email=exec notify-send "New email from %n" "%s"
+# Hooks are triggered whenever the associated event occurs.
 
 #
 # Executed when a new email arrives in the selected folder
-#new-email=
+#mail-received=notify-send "New mail from $AERC_FROM_NAME" "$AERC_SUBJECT"
 
 [templates]
 # Templates are used to populate email bodies automatically.
diff --git a/config/config.go b/config/config.go
index de8cd0d0..d70bcfe0 100644
--- a/config/config.go
+++ b/config/config.go
@@ -132,7 +132,7 @@ func LoadConfigFromFile(root *string, accts []string) error {
 	if err := parseOpeners(file); err != nil {
 		return err
 	}
-	if err := parseTriggers(file); err != nil {
+	if err := parseHooks(file); err != nil {
 		return err
 	}
 	if err := parseUi(file); err != nil {
diff --git a/config/hooks.go b/config/hooks.go
new file mode 100644
index 00000000..9bbd9031
--- /dev/null
+++ b/config/hooks.go
@@ -0,0 +1,62 @@
+package config
+
+import (
+	"strings"
+
+	"git.sr.ht/~rjarry/aerc/log"
+	"github.com/go-ini/ini"
+)
+
+type HooksConfig struct {
+	MailReceived string `ini:"mail-received"`
+}
+
+var Hooks HooksConfig
+
+func parseHooks(file *ini.File) error {
+	err := MapToStruct(file.Section("hooks"), &Hooks, true)
+	if err != nil {
+		return err
+	}
+
+	newEmail := file.Section("triggers").Key("new-email").String()
+	if Hooks.MailReceived == "" && newEmail != "" {
+		Hooks.MailReceived = convertNewEmailTrigger(newEmail)
+		Warnings = append(Warnings, Warning{
+			Title: "DEPRECATION NOTICE: [triggers].new-email",
+			Body: `
+The new-email trigger has been replaced by [hooks].email-received.
+
+Your configuration in this instance was automatically converted to:
+
+[hooks]
+mail-received = ` + Hooks.MailReceived + `
+
+Please verify the accuracy of the above translation.
+
+Your configuration file was not changed. To make this change permanent and to
+dismiss this deprecation warning on launch, copy the above lines into aerc.conf
+and remove new-email from it. See aerc-config(5) for more details.
+`,
+		})
+	}
+
+	log.Debugf("aerc.conf: [hooks] %#v", Hooks)
+	return nil
+}
+
+func convertNewEmailTrigger(old string) string {
+	translations := map[string]string{
+		"%a": "$AERC_FROM_ADDRESS",
+		"%n": "$AERC_FROM_NAME",
+		"%s": "$AERC_SUBJECT",
+		"%f": "$AERC_FROM_NAME <$AERC_FROM_ADDRESS>",
+		"%u": `$(echo "$AERC_FROM_ADDRESS" | cut -d@ -f1)`,
+		"%v": `$(echo "$AERC_FROM_NAME" | cut -d' ' -f1)`,
+	}
+	for replace, with := range translations {
+		old = strings.ReplaceAll(old, replace, with)
+	}
+	old = strings.TrimPrefix(old, "exec ")
+	return strings.ReplaceAll(old, "%%", "%")
+}
diff --git a/config/triggers.go b/config/triggers.go
deleted file mode 100644
index 82750c2d..00000000
--- a/config/triggers.go
+++ /dev/null
@@ -1,61 +0,0 @@
-package config
-
-import (
-	"github.com/go-ini/ini"
-	"github.com/google/shlex"
-
-	"git.sr.ht/~rjarry/aerc/lib/format"
-	"git.sr.ht/~rjarry/aerc/log"
-)
-
-type TriggersConfig struct {
-	NewEmail []string `ini:"new-email" parse:"ParseNewEmail"`
-}
-
-var Triggers = new(TriggersConfig)
-
-func parseTriggers(file *ini.File) error {
-	if err := MapToStruct(file.Section("triggers"), Triggers, true); err != nil {
-		return err
-	}
-	log.Debugf("aerc.conf: [triggers] %#v", Triggers)
-	return nil
-}
-
-func (t *TriggersConfig) ParseNewEmail(_ *ini.Section, key *ini.Key) ([]string, error) {
-	cmd := indexFmtRegexp.ReplaceAllStringFunc(
-		key.String(),
-		func(s string) string {
-			runes := []rune(s)
-			t, _ := indexVerbToTemplate(runes[len(runes)-1])
-			return t
-		},
-	)
-	args, err := shlex.Split(cmd)
-	if err != nil {
-		return nil, 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(args) + `
-
-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.
-`,
-		})
-	}
-	return args, nil
-}
diff --git a/doc/aerc-config.5.scd b/doc/aerc-config.5.scd
index 54c7df7f..9e11abfe 100644
--- a/doc/aerc-config.5.scd
+++ b/doc/aerc-config.5.scd
@@ -819,23 +819,26 @@ text/plain=gvim {} +125
 message/rfc822=thunderbird
 ```
 
-# TRIGGERS
+## HOOKS
 
-Triggers specify commands to execute when certain events occur. They are
-configured in the *[triggers]* section of _aerc.conf_.
+Hooks are triggered whenever the associated event occurs. The commands are run
+in a shell environment with information added to environment variables.
 
-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_).
+They are configured in the *[hooks]* section of aerc.conf.
 
-*new-email* = _<command>_
-	Executed when a new email arrives in the selected folder. Example:
+*mail-received* = _<command>_
+	Executed when new mail is received in the selected folder. This will
+	only work reliably with maildir and some imap servers.
 
-		exec notify-send 'New email from {{.From | names | join ", "}}' '{{.Subject}}'
+	Variables:
 
-	Templates specifiers from *aerc-templates*(7) are expanded with respect
-	to the new message.
+	- *AERC_FROM_NAME*
+	- *AERC_FROM_ADDRESS*
+	- *AERC_SUBJECT*
+
+	Example:
+
+		*mail-received* = _notify-send "New mail from $AERC_FROM_NAME" "$AERC_SUBJECT"_
 
 # TEMPLATES
 
diff --git a/lib/hooks/exec.go b/lib/hooks/exec.go
new file mode 100644
index 00000000..bea35f32
--- /dev/null
+++ b/lib/hooks/exec.go
@@ -0,0 +1,22 @@
+package hooks
+
+import (
+	"os"
+	"os/exec"
+
+	"git.sr.ht/~rjarry/aerc/log"
+)
+
+func RunHook(h HookType) error {
+	cmd := h.Cmd()
+	if cmd == "" {
+		return nil
+	}
+	env := h.Env()
+	log.Debugf("hooks: running command %q (env %v)", cmd, env)
+
+	proc := exec.Command("sh", "-c", cmd)
+	proc.Env = os.Environ()
+	proc.Env = append(proc.Env, env...)
+	return proc.Run()
+}
diff --git a/lib/hooks/interface.go b/lib/hooks/interface.go
new file mode 100644
index 00000000..ed38c3ac
--- /dev/null
+++ b/lib/hooks/interface.go
@@ -0,0 +1,6 @@
+package hooks
+
+type HookType interface {
+	Cmd() string
+	Env() []string
+}
diff --git a/lib/hooks/mail-received.go b/lib/hooks/mail-received.go
new file mode 100644
index 00000000..66622e9e
--- /dev/null
+++ b/lib/hooks/mail-received.go
@@ -0,0 +1,25 @@
+package hooks
+
+import (
+	"fmt"
+
+	"git.sr.ht/~rjarry/aerc/config"
+	"git.sr.ht/~rjarry/aerc/models"
+)
+
+type MailReceived struct {
+	MsgInfo *models.MessageInfo
+}
+
+func (m *MailReceived) Cmd() string {
+	return config.Hooks.MailReceived
+}
+
+func (m *MailReceived) Env() []string {
+	from := m.MsgInfo.Envelope.From[0]
+	return []string{
+		fmt.Sprintf("AERC_FROM_NAME=%s", from.Name),
+		fmt.Sprintf("AERC_FROM_ADDRESS=%s", from.Address),
+		fmt.Sprintf("AERC_SUBJECT=%s", m.MsgInfo.Envelope.Subject),
+	}
+}
diff --git a/lib/msgstore.go b/lib/msgstore.go
index 38fa82e6..5349aa62 100644
--- a/lib/msgstore.go
+++ b/lib/msgstore.go
@@ -271,7 +271,7 @@ func (store *MessageStore) Update(msg types.WorkerMessage) {
 		}
 		seen := msg.Info.Flags.Has(models.SeenFlag)
 		recent := msg.Info.Flags.Has(models.RecentFlag)
-		if !seen && recent {
+		if !seen && recent && msg.Info.Envelope != nil {
 			store.triggerNewEmail(msg.Info)
 		}
 		if _, ok := store.pendingHeaders[msg.Info.Uid]; msg.Info.Envelope != nil && ok {
diff --git a/widgets/account.go b/widgets/account.go
index fdd33301..fece0846 100644
--- a/widgets/account.go
+++ b/widgets/account.go
@@ -11,6 +11,7 @@ import (
 
 	"git.sr.ht/~rjarry/aerc/config"
 	"git.sr.ht/~rjarry/aerc/lib"
+	"git.sr.ht/~rjarry/aerc/lib/hooks"
 	"git.sr.ht/~rjarry/aerc/lib/marker"
 	"git.sr.ht/~rjarry/aerc/lib/sort"
 	"git.sr.ht/~rjarry/aerc/lib/state"
@@ -288,14 +289,12 @@ func (acct *AccountView) onMessage(msg types.WorkerMessage) {
 				acct.dirlist.UiConfig(name).ReverseThreadOrder,
 				acct.dirlist.UiConfig(name).SortThreadSiblings,
 				func(msg *models.MessageInfo) {
-					if len(config.Triggers.NewEmail) == 0 {
-						return
-					}
-					err := acct.aerc.cmd(
-						config.Triggers.NewEmail,
-						acct.acct, msg)
+					err := hooks.RunHook(&hooks.MailReceived{
+						MsgInfo: msg,
+					})
 					if err != nil {
-						acct.aerc.PushError(err.Error())
+						msg := fmt.Sprintf("mail-received hook: %s", err)
+						acct.aerc.PushError(msg)
 					}
 				}, func() {
 					if acct.dirlist.UiConfig(name).NewMessageBell {