worker: implement folder-map middleware

Implement a folder-map middleware that will translate the folder names
between the ui and the backend according to a provided key-value map.

Fixes: https://todo.sr.ht/~rjarry/aerc/175
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>
Signed-off-by: Robin Jarry <robin@jarry.cc>

1 files changed, 152 insertions, 0 deletions

diff --git a/worker/middleware/foldermapper.go b/worker/middleware/foldermapper.go
new file mode 100644
index 00000000..c78833a2
--- /dev/null
+++ b/worker/middleware/foldermapper.go
@@ -0,0 +1,152 @@
+package middleware
+
+import (
+	"strings"
+	"sync"
+
+	"git.sr.ht/~rjarry/aerc/worker/types"
+)
+
+type folderMapper struct {
+	sync.Mutex
+	types.WorkerInteractor
+	fm    folderMap
+	table map[string]string
+}
+
+func NewFolderMapper(base types.WorkerInteractor, mapping map[string]string,
+	order []string,
+) types.WorkerInteractor {
+	base.Infof("loading worker middleware: foldermapper")
+	return &folderMapper{
+		WorkerInteractor: base,
+		fm:               folderMap{mapping, order},
+		table:            make(map[string]string),
+	}
+}
+
+func (f *folderMapper) incoming(msg types.WorkerMessage, dir string) string {
+	f.Lock()
+	defer f.Unlock()
+	mapped := f.table[dir]
+	return mapped
+}
+
+func (f *folderMapper) outgoing(msg types.WorkerMessage, dir string) string {
+	f.Lock()
+	defer f.Unlock()
+	for k, v := range f.table {
+		if v == dir {
+			mapped := k
+			return mapped
+		}
+	}
+	return dir
+}
+
+func (f *folderMapper) store(s string) {
+	f.Lock()
+	defer f.Unlock()
+	display := f.fm.Apply(s)
+	f.table[display] = s
+	f.Tracef("store display folder '%s' to '%s'", display, s)
+}
+
+func (f *folderMapper) create(s string) string {
+	f.Lock()
+	defer f.Unlock()
+	backend := f.fm.Create(s)
+	f.table[s] = backend
+	f.Tracef("create display folder '%s' as '%s'", s, backend)
+	return backend
+}
+
+func (f *folderMapper) ProcessAction(msg types.WorkerMessage) types.WorkerMessage {
+	switch msg := msg.(type) {
+	case *types.CheckMail:
+		for i := range msg.Directories {
+			msg.Directories[i] = f.incoming(msg, msg.Directories[i])
+		}
+	case *types.CopyMessages:
+		msg.Destination = f.incoming(msg, msg.Destination)
+	case *types.AppendMessage:
+		msg.Destination = f.incoming(msg, msg.Destination)
+	case *types.MoveMessages:
+		msg.Destination = f.incoming(msg, msg.Destination)
+	case *types.CreateDirectory:
+		msg.Directory = f.create(msg.Directory)
+	case *types.RemoveDirectory:
+		msg.Directory = f.incoming(msg, msg.Directory)
+	case *types.OpenDirectory:
+		msg.Directory = f.incoming(msg, msg.Directory)
+	}
+
+	return f.WorkerInteractor.ProcessAction(msg)
+}
+
+func (f *folderMapper) PostMessage(msg types.WorkerMessage, cb func(m types.WorkerMessage)) {
+	switch msg := msg.(type) {
+	case *types.Done:
+		switch msg := msg.InResponseTo().(type) {
+		case *types.CheckMail:
+			for i := range msg.Directories {
+				msg.Directories[i] = f.outgoing(msg, msg.Directories[i])
+			}
+		case *types.CopyMessages:
+			msg.Destination = f.outgoing(msg, msg.Destination)
+		case *types.AppendMessage:
+			msg.Destination = f.outgoing(msg, msg.Destination)
+		case *types.MoveMessages:
+			msg.Destination = f.outgoing(msg, msg.Destination)
+		case *types.CreateDirectory:
+			msg.Directory = f.outgoing(msg, msg.Directory)
+		case *types.RemoveDirectory:
+			msg.Directory = f.outgoing(msg, msg.Directory)
+		case *types.OpenDirectory:
+			msg.Directory = f.outgoing(msg, msg.Directory)
+		}
+	case *types.Directory:
+		f.store(msg.Dir.Name)
+		msg.Dir.Name = f.outgoing(msg, msg.Dir.Name)
+	case *types.DirectoryInfo:
+		msg.Info.Name = f.outgoing(msg, msg.Info.Name)
+	}
+	f.WorkerInteractor.PostMessage(msg, cb)
+}
+
+// folderMap contains the mapping between the ui and backend folder names
+type folderMap struct {
+	mapping map[string]string
+	order   []string
+}
+
+// Apply applies the mapping from the folder map to the backend folder
+func (f *folderMap) Apply(s string) string {
+	for _, k := range f.order {
+		v := f.mapping[k]
+		strict := true
+		if strings.HasSuffix(v, "*") {
+			v = strings.TrimSuffix(v, "*")
+			strict = false
+		}
+		if (strings.HasPrefix(s, v) && !strict) || (s == v && strict) {
+			s = k + strings.TrimPrefix(s, v)
+		}
+	}
+	return s
+}
+
+// Create reverses the mapping of a new folder name
+func (f *folderMap) Create(s string) string {
+	max, key := 0, ""
+	for k := range f.mapping {
+		if strings.HasPrefix(s, k) && len(k) > max {
+			max, key = len(k), k
+		}
+	}
+	if max > 0 && key != "" {
+		s = strings.TrimSuffix(f.mapping[key], "*") +
+			strings.TrimPrefix(s, key)
+	}
+	return s
+}