commands: expand template placeholders

Interpret go template constructs in all aerc command arguments based on
the currently selected account, folder and message (if any).

Signed-off-by: Aivars Vaivods <aivars@vaivods.lv>
Signed-off-by: Robin Jarry <robin@jarry.cc>
Reviewed-by: Tim Culverhouse <tim@timculverhouse.com>

4 files changed, 61 insertions, 4 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ccd714bd..67d0d264 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/).
   the `[viewer]` section.
 - The standard Usenet signature delimiter `"-- "` is now prepended to
   `signature-file` and `signature-cmd` if not already present.
+- All `aerc(1)` commands now interpret `aerc-templates(7)` markup.
 
 ### Deprecated
 
diff --git a/commands/commands.go b/commands/commands.go
index 6fe30592..bbd03237 100644
--- a/commands/commands.go
+++ b/commands/commands.go
@@ -1,6 +1,7 @@
 package commands
 
 import (
+	"bytes"
 	"errors"
 	"sort"
 	"strings"
@@ -8,7 +9,11 @@ import (
 
 	"github.com/google/shlex"
 
+	"git.sr.ht/~rjarry/aerc/config"
+	"git.sr.ht/~rjarry/aerc/lib/state"
+	"git.sr.ht/~rjarry/aerc/lib/templates"
 	"git.sr.ht/~rjarry/aerc/log"
+	"git.sr.ht/~rjarry/aerc/models"
 	"git.sr.ht/~rjarry/aerc/widgets"
 )
 
@@ -65,13 +70,52 @@ type CommandSource interface {
 	Commands() *Commands
 }
 
+func templateData(aerc *widgets.Aerc) models.TemplateData {
+	var folder string
+	var cfg *config.AccountConfig
+	var msg *models.MessageInfo
+
+	acct := aerc.SelectedAccount()
+	if acct != nil {
+		folder = acct.SelectedDirectory()
+		cfg = acct.AccountConfig()
+		msg, _ = acct.SelectedMessage()
+	}
+
+	var data state.TemplateData
+
+	data.SetAccount(cfg)
+	data.SetFolder(folder)
+	data.SetInfo(msg, 0, false)
+
+	return &data
+}
+
 func (cmds *Commands) ExecuteCommand(aerc *widgets.Aerc, args []string) 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)
-		return cmd.Execute(aerc, args)
+		var buf bytes.Buffer
+		data := templateData(aerc)
+
+		processedArgs := make([]string, len(args))
+		for i, arg := range args {
+			t, err := templates.ParseTemplate(arg, arg)
+			if err != nil {
+				return err
+			}
+			err = templates.Render(t, &buf, data)
+			if err != nil {
+				return err
+			}
+			arg = buf.String()
+			buf.Reset()
+			processedArgs[i] = arg
+		}
+
+		return cmd.Execute(aerc, processedArgs)
 	}
 	return NoSuchCommand(args[0])
 }
diff --git a/doc/aerc.1.scd b/doc/aerc.1.scd
index aac014c9..d4376be7 100644
--- a/doc/aerc.1.scd
+++ b/doc/aerc.1.scd
@@ -54,6 +54,15 @@ as the terminal emulator, *<c-x>* is used to bring up the command interface.
 Different commands work in different contexts, depending on the kind of tab you
 have selected.
 
+Dynamic arguments are expanded following *aerc-templates*(7) depending on the
+context. For example, if you have a message selected, the following command:
+
+```
+:filter -f "{{index (.From | emails) 0}}"
+```
+
+Will filter all messages sent by the same sender.
+
 Aerc stores a history of commands, which can be cycled through in command mode.
 Pressing the up key cycles backwards in history, while pressing down cycles
 forwards.
diff --git a/lib/state/templates.go b/lib/state/templates.go
index b199cf25..48106295 100644
--- a/lib/state/templates.go
+++ b/lib/state/templates.go
@@ -47,9 +47,12 @@ func (d *TemplateData) SetInfo(info *models.MessageInfo, num int, marked bool) {
 
 func (d *TemplateData) SetAccount(acct *config.AccountConfig) {
 	d.account = acct
-	d.myAddresses = map[string]bool{acct.From.Address: true}
-	for _, addr := range acct.Aliases {
-		d.myAddresses[addr.Address] = true
+	d.myAddresses = make(map[string]bool)
+	if acct != nil {
+		d.myAddresses[acct.From.Address] = true
+		for _, addr := range acct.Aliases {
+			d.myAddresses[addr.Address] = true
+		}
 	}
 }