From 845763cb1f1f8b7acdfc8e94e0a2d61ff78f6b9d Mon Sep 17 00:00:00 2001
From: Koni Marti <koni.marti@gmail.com>
Date: Mon, 11 Jul 2022 20:11:20 +0200
Subject: [PATCH] account: export folder to mbox file

Export all message in the current folder to an mbox file. If an error
occurs during the export, aerc retries a few times before giving up to
prevent a hang.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>
---
 commands/account/export-mbox.go | 126 ++++++++++++++++++++++++++++++++
 doc/aerc.1.scd                  |   3 +
 worker/maildir/worker.go        |   3 +
 3 files changed, 132 insertions(+)
 create mode 100644 commands/account/export-mbox.go

diff --git a/commands/account/export-mbox.go b/commands/account/export-mbox.go
new file mode 100644
index 0000000..528934e
--- /dev/null
+++ b/commands/account/export-mbox.go
@@ -0,0 +1,126 @@
+package account
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"git.sr.ht/~rjarry/aerc/widgets"
+	mboxer "git.sr.ht/~rjarry/aerc/worker/mbox"
+	"git.sr.ht/~rjarry/aerc/worker/types"
+)
+
+type ExportMbox struct{}
+
+func init() {
+	register(ExportMbox{})
+}
+
+func (ExportMbox) Aliases() []string {
+	return []string{"export-mbox"}
+}
+
+func (ExportMbox) Complete(aerc *widgets.Aerc, args []string) []string {
+	if acct := aerc.SelectedAccount(); acct != nil {
+		if path := acct.SelectedDirectory(); path != "" {
+			if f := filepath.Base(path); f != "" {
+				return []string{f + ".mbox"}
+			}
+		}
+	}
+	return nil
+}
+
+func (ExportMbox) Execute(aerc *widgets.Aerc, args []string) error {
+	if len(args) != 2 {
+		return exportFolderUsage(args[0])
+	}
+	filename := args[1]
+
+	acct := aerc.SelectedAccount()
+	if acct == nil {
+		return errors.New("No account selected")
+	}
+	store := acct.Store()
+	if store == nil {
+		return errors.New("No message store selected")
+	}
+
+	aerc.PushStatus("Exporting to "+filename, 10*time.Second)
+
+	go func() {
+		file, err := os.Create(filename)
+		if err != nil {
+			acct.Logger().Println(args[0], err.Error())
+			aerc.PushError(err.Error())
+			return
+		}
+		defer file.Close()
+
+		var mu sync.Mutex
+		var ctr uint32
+		var retries int
+
+		done := make(chan bool)
+		uids := make([]uint32, len(store.Uids()))
+		copy(uids, store.Uids())
+		t := time.Now()
+
+		for len(uids) > 0 {
+			if retries > 0 {
+				if retries > 10 {
+					errorMsg := fmt.Sprintln(args[0], "too many retries:", retries, "; stopping export")
+					acct.Logger().Println(errorMsg)
+					aerc.PushError(errorMsg)
+					break
+				}
+				sleeping := time.Duration(retries * 1e9 * 2)
+				acct.Logger().Println(args[0], "sleeping for", sleeping, "before retrying; retries:", retries)
+				time.Sleep(sleeping)
+			}
+
+			acct.Logger().Println(args[0], "fetching", len(uids), "for export")
+			acct.Worker().PostAction(&types.FetchFullMessages{
+				Uids: uids,
+			}, func(msg types.WorkerMessage) {
+				switch msg := msg.(type) {
+				case *types.Done:
+					acct.Logger().Println(args[0], "done")
+					done <- true
+				case *types.Error:
+					errMsg := fmt.Sprintln(args[0], "error encountered:", msg.Error.Error())
+					acct.Logger().Println(errMsg)
+					aerc.PushError(errMsg)
+					done <- false
+				case *types.FullMessage:
+					mu.Lock()
+					mboxer.Write(file, msg.Content.Reader, "", t)
+					for i, uid := range uids {
+						if uid == msg.Content.Uid {
+							uids = append(uids[:i], uids[i+1:]...)
+							break
+						}
+					}
+					ctr++
+					mu.Unlock()
+				}
+			})
+			if ok := <-done; ok {
+				break
+			}
+			retries++
+		}
+		statusInfo := fmt.Sprintf("Exported %d of %d messages to %s.", ctr, len(store.Uids()), filename)
+		aerc.PushStatus(statusInfo, 10*time.Second)
+		acct.Logger().Println(args[0], statusInfo)
+	}()
+
+	return nil
+}
+
+func exportFolderUsage(cmd string) error {
+	return fmt.Errorf("Usage: %s <filename>", cmd)
+}
diff --git a/doc/aerc.1.scd b/doc/aerc.1.scd
index 5928bf0..97a9eab 100644
--- a/doc/aerc.1.scd
+++ b/doc/aerc.1.scd
@@ -311,6 +311,9 @@ message list, the message in the message viewer, etc).
 	Expands or collapses the current folder when the directory tree is
 	enabled.
 
+*export-mbox* <file>
+	Exports all messages in the current folder to an mbox file.
+
 *next-result*, *prev-result*
 	Selects the next or previous search result.
 
diff --git a/worker/maildir/worker.go b/worker/maildir/worker.go
index cc03ec8..b217bd2 100644
--- a/worker/maildir/worker.go
+++ b/worker/maildir/worker.go
@@ -550,6 +550,9 @@ func (w *Worker) handleFetchFullMessages(msg *types.FetchFullMessages) error {
 			},
 		}, nil)
 	}
+	w.worker.PostMessage(&types.Done{
+		Message: types.RespondTo(msg),
+	}, nil)
 	return nil
 }