1 files changed, 174 insertions, 0 deletions
diff --git a/worker/imap/cache.go b/worker/imap/cache.go
new file mode 100644
index 00000000..ecbedd89
--- /dev/null
+++ b/worker/imap/cache.go
@@ -0,0 +1,174 @@
+package imap
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/gob"
+	"fmt"
+	"os"
+	"path"
+	"time"
+
+	"git.sr.ht/~rjarry/aerc/models"
+	"git.sr.ht/~rjarry/aerc/worker/types"
+	"github.com/emersion/go-message"
+	"github.com/emersion/go-message/mail"
+	"github.com/emersion/go-message/textproto"
+	"github.com/mitchellh/go-homedir"
+	"github.com/syndtr/goleveldb/leveldb"
+)
+
+type CachedHeader struct {
+	BodyStructure models.BodyStructure
+	Envelope      models.Envelope
+	InternalDate  time.Time
+	Uid           uint32
+	Header        []byte
+	Created       time.Time
+}
+
+// initCacheDb opens (or creates) the database for the cache. One database is
+// created per account
+func (w *IMAPWorker) initCacheDb(acct string) {
+	cd, err := cacheDir()
+	if err != nil {
+		w.cache = nil
+		w.worker.Logger.Panicf("cache: unable to find cache directory: %v", err)
+		return
+	}
+	p := path.Join(cd, acct)
+	db, err := leveldb.OpenFile(p, nil)
+	if err != nil {
+		w.cache = nil
+		w.worker.Logger.Printf("cache: error opening cache db: %v", err)
+		return
+	}
+	w.cache = db
+	w.worker.Logger.Printf("cache: cache db opened: %s", p)
+	if w.config.cacheMaxAge.Hours() > 0 {
+		go w.cleanCache()
+	}
+}
+
+func (w *IMAPWorker) cacheHeader(mi *models.MessageInfo) {
+	uv := fmt.Sprintf("%d", w.selected.UidValidity)
+	uid := fmt.Sprintf("%d", mi.Uid)
+	w.worker.Logger.Printf("cache: caching header for message %s.%s", uv, uid)
+	hdr := bytes.NewBuffer(nil)
+	err := textproto.WriteHeader(hdr, mi.RFC822Headers.Header.Header)
+	if err != nil {
+		w.worker.Logger.Printf("cache: error writing header %s.%s: %v", uv, uid, err)
+		return
+	}
+	h := &CachedHeader{
+		BodyStructure: *mi.BodyStructure,
+		Envelope:      *mi.Envelope,
+		InternalDate:  mi.InternalDate,
+		Uid:           mi.Uid,
+		Header:        hdr.Bytes(),
+		Created:       time.Now(),
+	}
+	data := bytes.NewBuffer(nil)
+	enc := gob.NewEncoder(data)
+	err = enc.Encode(h)
+	if err != nil {
+		w.worker.Logger.Printf("cache: error encoding message %s.%s: %v", uv, uid, err)
+		return
+	}
+	err = w.cache.Put([]byte("header."+uv+"."+uid), data.Bytes(), nil)
+	if err != nil {
+		w.worker.Logger.Printf("cache: error writing header to database for message %s.%s: %v", uv, uid, err)
+		return
+	}
+}
+
+func (w *IMAPWorker) getCachedHeaders(msg *types.FetchMessageHeaders) []uint32 {
+	w.worker.Logger.Println("Retrieving headers from cache")
+	var need, found []uint32
+	uv := fmt.Sprintf("%d", w.selected.UidValidity)
+	for _, uid := range msg.Uids {
+		u := fmt.Sprintf("%d", uid)
+		data, err := w.cache.Get([]byte("header."+uv+"."+u), nil)
+		if err != nil {
+			need = append(need, uid)
+			continue
+		}
+		ch := &CachedHeader{}
+		dec := gob.NewDecoder(bytes.NewReader(data))
+		err = dec.Decode(ch)
+		if err != nil {
+			w.worker.Logger.Printf("cache: error decoding cached header %s.%s: %v", uv, u, err)
+			need = append(need, uid)
+			continue
+		}
+		hr := bytes.NewReader(ch.Header)
+		textprotoHeader, err := textproto.ReadHeader(bufio.NewReader(hr))
+		if err != nil {
+			w.worker.Logger.Printf("cache: error reading cached header %s.%s: %v", uv, u, err)
+			need = append(need, uid)
+			continue
+		}
+
+		hdr := &mail.Header{Header: message.Header{Header: textprotoHeader}}
+		mi := &models.MessageInfo{
+			BodyStructure: &ch.BodyStructure,
+			Envelope:      &ch.Envelope,
+			Flags:         []models.Flag{models.SeenFlag}, // Always return a SEEN flag
+			Uid:           ch.Uid,
+			RFC822Headers: hdr,
+		}
+		found = append(found, uid)
+		w.worker.Logger.Printf("cache: located cached header %s.%s", uv, u)
+		w.worker.PostMessage(&types.MessageInfo{
+			Message: types.RespondTo(msg),
+			Info:    mi,
+		}, nil)
+	}
+	if len(found) > 0 {
+		w.worker.PostAction(&types.FetchMessageFlags{
+			Uids: found,
+		}, nil)
+	}
+	return need
+}
+
+func cacheDir() (string, error) {
+	dir, err := os.UserCacheDir()
+	if err != nil {
+		dir, err = homedir.Expand("~/.cache")
+		if err != nil {
+			return "", err
+		}
+	}
+	return path.Join(dir, "aerc"), nil
+}
+
+// cleanCache removes stale entries from the selected mailbox cachedb
+func (w *IMAPWorker) cleanCache() {
+	start := time.Now()
+	var scanned, removed int
+	iter := w.cache.NewIterator(nil, nil)
+	for iter.Next() {
+		data := iter.Value()
+		ch := &CachedHeader{}
+		dec := gob.NewDecoder(bytes.NewReader(data))
+		err := dec.Decode(ch)
+		if err != nil {
+			w.worker.Logger.Printf("cache: error cleaning database %d: %v", w.selected.UidValidity, err)
+			continue
+		}
+		exp := ch.Created.Add(w.config.cacheMaxAge)
+		if exp.Before(time.Now()) {
+			err = w.cache.Delete(iter.Key(), nil)
+			if err != nil {
+				w.worker.Logger.Printf("cache: error cleaning database %d: %v", w.selected.UidValidity, err)
+				continue
+			}
+			removed = removed + 1
+		}
+		scanned = scanned + 1
+	}
+	iter.Release()
+	elapsed := time.Since(start)
+	w.worker.Logger.Printf("cache: cleaned cache, removed %d of %d entries in %f seconds", removed, scanned, elapsed.Seconds())
+}