Add :save and :pipe commands to viewer

* :save takes a path and saves the current message part to that location
* :pipe is the same as pipe on the account page, but uses the current
  message part rather than the whole email (ie :pipe gzip -d)
* Refactored account:pipe and extracted common pipe code to
  commands.util.QuickTerm
* Added helper command aerc.PushError

8 files changed, 194 insertions, 37 deletions

diff --git a/commands/account/pipe.go b/commands/account/pipe.go
index 9675fe46..d3cc80ae 100644
--- a/commands/account/pipe.go
+++ b/commands/account/pipe.go
@@ -3,12 +3,9 @@ package account
 import (
 	"errors"
 	"io"
-	"os/exec"
-	"time"
 
+	"git.sr.ht/~sircmpwn/aerc/commands"
 	"git.sr.ht/~sircmpwn/aerc/widgets"
-
-	"github.com/gdamore/tcell"
 )
 
 func init() {
@@ -23,44 +20,13 @@ func Pipe(aerc *widgets.Aerc, args []string) error {
 	store := acct.Messages().Store()
 	msg := acct.Messages().Selected()
 	store.FetchFull([]uint32{msg.Uid}, func(reader io.Reader) {
-		cmd := exec.Command(args[1], args[2:]...)
-		pipe, err := cmd.StdinPipe()
-		if err != nil {
-			aerc.PushStatus(" "+err.Error(), 10*time.Second).
-				Color(tcell.ColorDefault, tcell.ColorRed)
-			return
-		}
-		term, err := widgets.NewTerminal(cmd)
+		term, err := commands.QuickTerm(aerc, args[1:], reader)
 		if err != nil {
-			aerc.PushStatus(" "+err.Error(), 10*time.Second).
-				Color(tcell.ColorDefault, tcell.ColorRed)
+			aerc.PushError(" " + err.Error())
 			return
 		}
 		name := args[1] + " <" + msg.Envelope.Subject
 		aerc.NewTab(term, name)
-		term.OnClose = func(err error) {
-			if err != nil {
-				aerc.PushStatus(" "+err.Error(), 10*time.Second).
-					Color(tcell.ColorDefault, tcell.ColorRed)
-			} else {
-				aerc.PushStatus("Process complete, press any key to close.",
-					10*time.Second)
-				term.OnEvent = func(event tcell.Event) bool {
-					aerc.RemoveTab(term)
-					return true
-				}
-			}
-		}
-		term.OnStart = func() {
-			go func() {
-				_, err := io.Copy(pipe, reader)
-				if err != nil {
-					aerc.PushStatus(" "+err.Error(), 10*time.Second).
-						Color(tcell.ColorDefault, tcell.ColorRed)
-				}
-				pipe.Close()
-			}()
-		}
 	})
 	return nil
 }
diff --git a/commands/msgview/pipe.go b/commands/msgview/pipe.go
new file mode 100644
index 00000000..81cef7df
--- /dev/null
+++ b/commands/msgview/pipe.go
@@ -0,0 +1,45 @@
+package msgview
+
+import (
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"mime/quotedprintable"
+
+	"git.sr.ht/~sircmpwn/aerc/commands"
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+)
+
+func init() {
+	register("pipe", Pipe)
+}
+
+func Pipe(aerc *widgets.Aerc, args []string) error {
+	if len(args) < 2 {
+		return errors.New("Usage: :pipe <cmd> [args...]")
+	}
+
+	mv := aerc.SelectedTab().(*widgets.MessageViewer)
+	p := mv.CurrentPart()
+
+	p.Store.FetchBodyPart(p.Msg.Uid, p.Index, func(reader io.Reader) {
+		// email parts are encoded as 7bit (plaintext), quoted-printable, or base64
+		switch p.Part.Encoding {
+		case "base64":
+			reader = base64.NewDecoder(base64.StdEncoding, reader)
+		case "quoted-printable":
+			reader = quotedprintable.NewReader(reader)
+		}
+
+		term, err := commands.QuickTerm(aerc, args[1:], reader)
+		if err != nil {
+			aerc.PushError(" " + err.Error())
+			return
+		}
+		name := fmt.Sprintf("%s <%s/[%d]", args[1], p.Msg.Envelope.Subject, p.Index)
+		aerc.NewTab(term, name)
+	})
+
+	return nil
+}
diff --git a/commands/msgview/save.go b/commands/msgview/save.go
new file mode 100644
index 00000000..4dabd524
--- /dev/null
+++ b/commands/msgview/save.go
@@ -0,0 +1,59 @@
+package msgview
+
+import (
+	"encoding/base64"
+	"errors"
+	"io"
+	"mime/quotedprintable"
+	"os"
+	"time"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+	"github.com/mitchellh/go-homedir"
+)
+
+func init() {
+	register("save", Save)
+}
+
+func Save(aerc *widgets.Aerc, args []string) error {
+	if len(args) < 2 {
+		return errors.New("Usage: :save <path>")
+	}
+
+	mv := aerc.SelectedTab().(*widgets.MessageViewer)
+	p := mv.CurrentPart()
+
+	p.Store.FetchBodyPart(p.Msg.Uid, p.Index, func(reader io.Reader) {
+		// email parts are encoded as 7bit (plaintext), quoted-printable, or base64
+		switch p.Part.Encoding {
+		case "base64":
+			reader = base64.NewDecoder(base64.StdEncoding, reader)
+		case "quoted-printable":
+			reader = quotedprintable.NewReader(reader)
+		}
+
+		target, err := homedir.Expand(args[1])
+		if err != nil {
+			aerc.PushError(" " + err.Error())
+			return
+		}
+
+		f, err := os.Create(target)
+		if err != nil {
+			aerc.PushError(" " + err.Error())
+			return
+		}
+		defer f.Close()
+
+		_, err = io.Copy(f, reader)
+		if err != nil {
+			aerc.PushError(" " + err.Error())
+			return
+		}
+
+		aerc.PushStatus("Saved to "+target, 10*time.Second)
+	})
+
+	return nil
+}
diff --git a/commands/util.go b/commands/util.go
new file mode 100644
index 00000000..e9fd2055
--- /dev/null
+++ b/commands/util.go
@@ -0,0 +1,56 @@
+package commands
+
+import (
+	"io"
+	"os/exec"
+	"time"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+	"github.com/gdamore/tcell"
+)
+
+// QuickTerm is an ephemeral terminal for running a single command and quiting.
+func QuickTerm(aerc *widgets.Aerc, args []string, stdin io.Reader) (*widgets.Terminal, error) {
+	cmd := exec.Command(args[0], args[1:]...)
+	pipe, err := cmd.StdinPipe()
+	if err != nil {
+		return nil, err
+	}
+
+	term, err := widgets.NewTerminal(cmd)
+	if err != nil {
+		return nil, err
+	}
+
+	term.OnClose = func(err error) {
+		if err != nil {
+			aerc.PushError(" " + err.Error())
+			// remove the tab on error, otherwise it gets stuck
+			aerc.RemoveTab(term)
+		} else {
+			aerc.PushStatus("Process complete, press any key to close.",
+				10*time.Second)
+			term.OnEvent = func(event tcell.Event) bool {
+				aerc.RemoveTab(term)
+				return true
+			}
+		}
+	}
+
+	term.OnStart = func() {
+		status := make(chan error, 1)
+
+		go func() {
+			_, err := io.Copy(pipe, stdin)
+			defer pipe.Close()
+			status <- err
+		}()
+
+		err := <-status
+		if err != nil {
+			aerc.PushError(" " + err.Error())
+		}
+	}
+
+	return term, nil
+}
diff --git a/config/binds.conf b/config/binds.conf
index 6a3ff230..91688858 100644
--- a/config/binds.conf
+++ b/config/binds.conf
@@ -51,6 +51,7 @@ Rr = :reply -a<Enter>
 Rq = :reply -aq<Enter>
 <C-k> = :prev-part<Enter>
 <C-j> = :next-part<Enter>
+S = :save<space>
 
 [compose]
 # Keybindings used when the embedded terminal is not selected in the compose
diff --git a/doc/aerc.1.scd b/doc/aerc.1.scd
index be595884..4f0137ce 100644
--- a/doc/aerc.1.scd
+++ b/doc/aerc.1.scd
@@ -91,6 +91,13 @@ These commands work in any context.
 
 ## MESSAGE VIEW COMMANDS
 
+*pipe* <cmd>
+	Downloads and pipes the current message part into the given shell command,
+	and opens a new terminal tab to show the result.
+
+*save* <path>
+	Saves the current message part to the given path.
+
 *close*
 	Closes the message viewer.
 
diff --git a/widgets/aerc.go b/widgets/aerc.go
index 3c6566de..5b1b151f 100644
--- a/widgets/aerc.go
+++ b/widgets/aerc.go
@@ -243,6 +243,10 @@ func (aerc *Aerc) PushStatus(text string, expiry time.Duration) *StatusMessage {
 	return aerc.statusline.Push(text, expiry)
 }
 
+func (aerc *Aerc) PushError(text string) {
+	aerc.PushStatus(text, 10*time.Second).Color(tcell.ColorDefault, tcell.ColorRed)
+}
+
 func (aerc *Aerc) focus(item libui.Interactive) {
 	if aerc.focused == item {
 		return
diff --git a/widgets/msgviewer.go b/widgets/msgviewer.go
index e0fe6aac..d31e0512 100644
--- a/widgets/msgviewer.go
+++ b/widgets/msgviewer.go
@@ -199,6 +199,18 @@ func (mv *MessageViewer) OnInvalidate(fn func(d ui.Drawable)) {
 	})
 }
 
+func (mv *MessageViewer) CurrentPart() *PartInfo {
+	switcher := mv.switcher
+	part := switcher.parts[switcher.selected]
+
+	return &PartInfo{
+		Index: part.index,
+		Msg:   part.msg,
+		Part:  part.part,
+		Store: part.store,
+	}
+}
+
 func (mv *MessageViewer) PreviousPart() {
 	switcher := mv.switcher
 	for {
@@ -291,6 +303,13 @@ type PartViewer struct {
 	term    *Terminal
 }
 
+type PartInfo struct {
+	Index []int
+	Msg   *types.MessageInfo
+	Part  *imap.BodyStructure
+	Store *lib.MessageStore
+}
+
 func NewPartViewer(conf *config.AercConfig,
 	store *lib.MessageStore, msg *types.MessageInfo,
 	part *imap.BodyStructure, index []int) (*PartViewer, error) {