mbox: implement an mbox backend worker

Implement an mbox backend worker. Worker can be used for testing and
development by mocking a backend for the message store. Worker does not
modify the actual mbox file on disk; all operations are performed in
memory.

To use the mbox backend, create an mbox account in the accounts.conf
where the source uses the "mbox://" scheme, such as

source = mbox://~/mbox/

or

source = mbox://~/mbox/file.mbox

If the mbox source points to a directory, all files in this directory
with the .mbox suffix will be opened as folders.

If an outgoing smtp server is defined for the mbox account, replies can
be sent to emails that are stored in the mbox file.

Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

8 files changed, 971 insertions, 8 deletions

diff --git a/go.mod b/go.mod
index 0affccb0..19eedc56 100644
--- a/go.mod
+++ b/go.mod
@@ -12,8 +12,9 @@ require (
 	github.com/emersion/go-imap v1.2.0
 	github.com/emersion/go-imap-sortthread v1.2.0
 	github.com/emersion/go-maildir v0.2.0
+	github.com/emersion/go-mbox v1.0.2
 	github.com/emersion/go-message v0.15.0
-	github.com/emersion/go-msgauth v0.6.5 // indirect
+	github.com/emersion/go-msgauth v0.6.5
 	github.com/emersion/go-pgpmail v0.2.0
 	github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac
 	github.com/emersion/go-smtp v0.15.0
@@ -26,7 +27,6 @@ require (
 	github.com/imdario/mergo v0.3.12
 	github.com/kyoh86/xdg v1.2.0
 	github.com/lithammer/fuzzysearch v1.1.3
-	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
 	github.com/mattn/go-isatty v0.0.14
 	github.com/mattn/go-pointer v0.0.1 // indirect
 	github.com/mattn/go-runewidth v0.0.13
diff --git a/go.sum b/go.sum
index e6e93f2c..b7e770be 100644
--- a/go.sum
+++ b/go.sum
@@ -45,6 +45,7 @@ github.com/arran4/golang-ical v0.0.0-20220517104411-fd89fefb0182/go.mod h1:BSTTr
 github.com/brunnre8/go.notmuch v0.0.0-20201126061756-caa2daf7093c h1:dh58QrW3/S/aCnQPFoeRRE9zMauKooDFd5zh1dLtxXs=
 github.com/brunnre8/go.notmuch v0.0.0-20201126061756-caa2daf7093c/go.mod h1:zJtFvR3NinVdmBiLyB4MyXKmqyVfZEb2cK97ISfTgV8=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
+github.com/cention-sany/utf7 v0.0.0-20170124080048-26cad61bd60a h1:MISbI8sU/PSK/ztvmWKFcI7UGb5/HQT7B+i3a2myKgI=
 github.com/cention-sany/utf7 v0.0.0-20170124080048-26cad61bd60a/go.mod h1:2GxOXOlEPAMFPfp014mK1SWq8G8BN8o7/dfYqJrVGn8=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
 github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
@@ -68,6 +69,8 @@ github.com/emersion/go-imap-sortthread v1.2.0 h1:EMVEJXPWAhXMWECjR82Rn/tza6Mddcv
 github.com/emersion/go-imap-sortthread v1.2.0/go.mod h1:UhenCBupR+vSYRnqJkpjSq84INUCsyAK1MLpogv14pE=
 github.com/emersion/go-maildir v0.2.0 h1:fC4+UVGl8GcQGbFF7AWab2JMf4VbKz+bMNv07xxhzs8=
 github.com/emersion/go-maildir v0.2.0/go.mod h1:I2j27lND/SRLgxROe50Vam81MSaqPFvJ0OHNnDZ7n84=
+github.com/emersion/go-mbox v1.0.2 h1:tE/rT+lEugK9y0myEymCCHnwlZN04hlXPrbKkxRBA5I=
+github.com/emersion/go-mbox v1.0.2/go.mod h1:Yp9IVuuOYLEuMv4yjgDHvhb5mHOcYH6x92Oas3QqEZI=
 github.com/emersion/go-message v0.11.1/go.mod h1:C4jnca5HOTo4bGN9YdqNQM9sITuT3Y0K6bSUw9RklvY=
 github.com/emersion/go-message v0.11.2/go.mod h1:C4jnca5HOTo4bGN9YdqNQM9sITuT3Y0K6bSUw9RklvY=
 github.com/emersion/go-message v0.14.1/go.mod h1:N1JWdZQ2WRUalmdHAX308CWBq747VJ8oUorFI3VCBwU=
@@ -106,7 +109,9 @@ github.com/go-gl/glfw/v3.3/glfw v0.0.0-20191125211704-12ad95a8df72/go.mod h1:tQ2
 github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4/go.mod h1:tQ2UAYgL5IevRw8kRxooKSPJfGvJ9fJQFa0TUsXzTg8=
 github.com/go-ini/ini v1.63.2 h1:kwN3umicd2HF3Tgvap4um1ZG52/WyKT9GGdPx0CJk6Y=
 github.com/go-ini/ini v1.63.2/go.mod h1:ByCAeIL28uOIIG0E3PJtZPDL8WnHpFKFOtgjp+3Ies8=
+github.com/go-test/deep v1.0.7 h1:/VSMRlnY/JSyqxQUzQLKVMAskpY/NZKFA5j2P+0pP2M=
 github.com/go-test/deep v1.0.7/go.mod h1:QV8Hv/iy04NyLBxAdO9njL0iVPN1S4d/A3NVv1V36o8=
+github.com/gogs/chardet v0.0.0-20191104214054-4b6791f73a28 h1:gBeyun7mySAKWg7Fb0GOcv0upX9bdaZScs8QcRo8mEY=
 github.com/gogs/chardet v0.0.0-20191104214054-4b6791f73a28/go.mod h1:Pcatq5tYkCW2Q6yrR2VRHlbHpZ/R4/7qyL1TCF7vl14=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
@@ -164,20 +169,22 @@ github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/hpcloud/tail v1.0.0 h1:nfCOvKYfkgYP8hkirhJocXT2+zOD8yUNjXaWfTlyFKI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/imdario/mergo v0.3.12 h1:b6R2BslTbIEToALKP7LxUvijTsNI9TAe80pLWN2g/HU=
 github.com/imdario/mergo v0.3.12/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
+github.com/jaytaylor/html2text v0.0.0-20200412013138-3577fbdbcff7 h1:g0fAGBisHaEQ0TRq1iBvemFRf+8AEWEmBESSiWB3Vsc=
 github.com/jaytaylor/html2text v0.0.0-20200412013138-3577fbdbcff7/go.mod h1:CVKlgaMiht+LXvHG173ujK6JUhZXKb2u/BQtjPDIvyk=
+github.com/jhillyerd/enmime v0.9.1 h1:HcC2WZA6dMCobs8WeyF/6FRSvdRCrr8O+UiLBae4eNE=
 github.com/jhillyerd/enmime v0.9.1/go.mod h1:S5ge4lnv/dDDBbAWwtoOFlj14NHiXdw/EqMB2lJz3b8=
 github.com/jstemmer/go-junit-report v0.0.0-20190106144839-af01ea7f8024/go.mod h1:6v2b51hI/fHJwM22ozAgKL4VKDeJcHhJFhtBdhmNjmU=
 github.com/jstemmer/go-junit-report v0.9.1/go.mod h1:Brl9GWCQeLvo8nXZwPNNblvFj/XSXhF0NWZEnDohbsk=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
-github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
-github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kyoh86/xdg v1.2.0 h1:CERuT/ShdTDj+A2UaX3hQ3mOV369+Sj+wyn2nIRIIkI=
 github.com/kyoh86/xdg v1.2.0/go.mod h1:/mg8zwu1+qe76oTFUBnyS7rJzk7LLC0VGEzJyJ19DHs=
@@ -202,10 +209,14 @@ github.com/miolini/datacounter v1.0.2 h1:mGTL0vqEAtH7mwNJS1JIpd6jwTAP6cBQQ2P8apa
 github.com/miolini/datacounter v1.0.2/go.mod h1:C45dc2hBumHjDpEU64IqPwR6TDyPVpzOqqRTN7zmBUA=
 github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
+github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
+github.com/olekukonko/tablewriter v0.0.5 h1:P2Ga83D34wi1o9J6Wh1mRuqd4mF/x/lgBS7N7AbDhec=
 github.com/olekukonko/tablewriter v0.0.5/go.mod h1:hPp6KlRPjbx+hW8ykQs1w3UBbZlj6HuIJcUGPhkA7kY=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
+github.com/onsi/ginkgo v1.7.0 h1:WSHQ+IS43OoUrWtD1/bbclrwK8TTH5hzp+umCiuxHgs=
 github.com/onsi/ginkgo v1.7.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
+github.com/onsi/gomega v1.4.3 h1:RE1xgDvH7imwFD45h+u2SgIfERHlS2yNG4DObb5BSKU=
 github.com/onsi/gomega v1.4.3/go.mod h1:ex+gbHU/CVuBBDIJjb2X0qEXbFg53c61hWP/1CpauHY=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -219,10 +230,10 @@ github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJ
 github.com/riywo/loginshell v0.0.0-20200815045211-7d26008be1ab h1:ZjX6I48eZSFetPb41dHudEyVr5v953N15TsNZXlkcWY=
 github.com/riywo/loginshell v0.0.0-20200815045211-7d26008be1ab/go.mod h1:/PfPXh0EntGc3QAAyUaviy4S9tzy4Zp0e2ilq4voC6E=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
+github.com/ssor/bom v0.0.0-20170718123548-6386211fdfcf h1:pvbZ0lM0XWPBqUKqFU8cmavspvIl9nulOYwdy6IFRRo=
 github.com/ssor/bom v0.0.0-20170718123548-6386211fdfcf/go.mod h1:RJID2RhlZKId02nZ62WenDCkgHFerpIOmW0iT7GKmXM=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
-github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
@@ -491,11 +502,13 @@ google.golang.org/protobuf v1.26.0/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQ
 google.golang.org/protobuf v1.27.1 h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
 google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f h1:BLraFXnmrev5lT+xlilqcH8XK9/i0At2xKjWk4p6zsU=
 gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
+gopkg.in/fsnotify.v1 v1.4.7 h1:xOHLXZwVvI9hhs+cLKq5+I5onOuwQLhQwiu63xxlHs4=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
+gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/worker/lib/search.go b/worker/lib/search.go
new file mode 100644
index 00000000..c7d3bee7
--- /dev/null
+++ b/worker/lib/search.go
@@ -0,0 +1,254 @@
+package lib
+
+import (
+	"io/ioutil"
+	"net/textproto"
+	"strings"
+	"unicode"
+
+	"git.sr.ht/~sircmpwn/getopt"
+
+	"git.sr.ht/~rjarry/aerc/models"
+)
+
+type searchCriteria struct {
+	Header textproto.MIMEHeader
+	Body   []string
+	Text   []string
+
+	WithFlags    []models.Flag
+	WithoutFlags []models.Flag
+}
+
+func GetSearchCriteria(args []string) (*searchCriteria, error) {
+	criteria := &searchCriteria{Header: make(textproto.MIMEHeader)}
+
+	opts, optind, err := getopt.Getopts(args, "rux:X:bat:H:f:c:")
+	if err != nil {
+		return nil, err
+	}
+	body := false
+	text := false
+	for _, opt := range opts {
+		switch opt.Option {
+		case 'r':
+			criteria.WithFlags = append(criteria.WithFlags, models.SeenFlag)
+		case 'u':
+			criteria.WithoutFlags = append(criteria.WithoutFlags, models.SeenFlag)
+		case 'x':
+			criteria.WithFlags = append(criteria.WithFlags, getParsedFlag(opt.Value))
+		case 'X':
+			criteria.WithoutFlags = append(criteria.WithoutFlags, getParsedFlag(opt.Value))
+		case 'H':
+			// TODO
+		case 'f':
+			criteria.Header.Add("From", opt.Value)
+		case 't':
+			criteria.Header.Add("To", opt.Value)
+		case 'c':
+			criteria.Header.Add("Cc", opt.Value)
+		case 'b':
+			body = true
+		case 'a':
+			text = true
+		}
+	}
+	if text {
+		criteria.Text = args[optind:]
+	} else if body {
+		criteria.Body = args[optind:]
+	} else {
+		for _, arg := range args[optind:] {
+			criteria.Header.Add("Subject", arg)
+		}
+	}
+	return criteria, nil
+}
+
+func getParsedFlag(name string) models.Flag {
+	var f models.Flag
+	switch strings.ToLower(name) {
+	case "seen":
+		f = models.SeenFlag
+	case "answered":
+		f = models.AnsweredFlag
+	case "flagged":
+		f = models.FlaggedFlag
+	}
+	return f
+}
+
+func Search(messages []RawMessage, criteria *searchCriteria) ([]uint32, error) {
+	requiredParts := getRequiredParts(criteria)
+
+	matchedUids := []uint32{}
+	for _, m := range messages {
+		success, err := searchMessage(m, criteria, requiredParts)
+		if err != nil {
+			return nil, err
+		} else if success {
+			matchedUids = append(matchedUids, m.UID())
+		}
+	}
+
+	return matchedUids, nil
+}
+
+// searchMessage executes the search criteria for the given RawMessage,
+// returns true if search succeeded
+func searchMessage(message RawMessage, criteria *searchCriteria,
+	parts MsgParts) (bool, error) {
+
+	// setup parts of the message to use in the search
+	// this is so that we try to minimise reading unnecessary parts
+	var (
+		flags  []models.Flag
+		header *models.MessageInfo
+		body   string
+		all    string
+		err    error
+	)
+
+	if parts&FLAGS > 0 {
+		flags, err = message.ModelFlags()
+		if err != nil {
+			return false, err
+		}
+	}
+	if parts&HEADER > 0 {
+		header, err = MessageInfo(message)
+		if err != nil {
+			return false, err
+		}
+	}
+	if parts&BODY > 0 {
+		// TODO: select body properly; this is just an 'all' clone
+		reader, err := message.NewReader()
+		if err != nil {
+			return false, err
+		}
+		defer reader.Close()
+		bytes, err := ioutil.ReadAll(reader)
+		if err != nil {
+			return false, err
+		}
+		body = string(bytes)
+	}
+	if parts&ALL > 0 {
+		reader, err := message.NewReader()
+		if err != nil {
+			return false, err
+		}
+		defer reader.Close()
+		bytes, err := ioutil.ReadAll(reader)
+		if err != nil {
+			return false, err
+		}
+		all = string(bytes)
+	}
+
+	// now search through the criteria
+	// implicit AND at the moment so fail fast
+	if criteria.Header != nil {
+		for k, v := range criteria.Header {
+			headerValue := header.RFC822Headers.Get(k)
+			for _, text := range v {
+				if !containsSmartCase(headerValue, text) {
+					return false, nil
+				}
+			}
+		}
+	}
+	if criteria.Body != nil {
+		for _, searchTerm := range criteria.Body {
+			if !containsSmartCase(body, searchTerm) {
+				return false, nil
+			}
+		}
+	}
+	if criteria.Text != nil {
+		for _, searchTerm := range criteria.Text {
+			if !containsSmartCase(all, searchTerm) {
+				return false, nil
+			}
+		}
+	}
+	if criteria.WithFlags != nil {
+		for _, searchFlag := range criteria.WithFlags {
+			if !containsFlag(flags, searchFlag) {
+				return false, nil
+			}
+		}
+	}
+	if criteria.WithoutFlags != nil {
+		for _, searchFlag := range criteria.WithoutFlags {
+			if containsFlag(flags, searchFlag) {
+				return false, nil
+			}
+		}
+	}
+	return true, nil
+}
+
+// containsFlag returns true if searchFlag appears in flags
+func containsFlag(flags []models.Flag, searchFlag models.Flag) bool {
+	match := false
+	for _, flag := range flags {
+		if searchFlag == flag {
+			match = true
+		}
+	}
+	return match
+}
+
+// containsSmartCase is a smarter version of strings.Contains for searching.
+// Is case-insensitive unless substr contains an upper case character
+func containsSmartCase(s string, substr string) bool {
+	if hasUpper(substr) {
+		return strings.Contains(s, substr)
+	}
+	return strings.Contains(strings.ToLower(s), strings.ToLower(substr))
+}
+
+func hasUpper(s string) bool {
+	for _, r := range s {
+		if unicode.IsUpper(r) {
+			return true
+		}
+	}
+	return false
+}
+
+// The parts of a message, kind of
+type MsgParts int
+
+const NONE MsgParts = 0
+const (
+	FLAGS MsgParts = 1 << iota
+	HEADER
+	BODY
+	ALL
+)
+
+// Returns a bitmask of the parts of the message required to be loaded for the
+// given criteria
+func getRequiredParts(criteria *searchCriteria) MsgParts {
+	required := NONE
+	if len(criteria.Header) > 0 {
+		required |= HEADER
+	}
+	if criteria.Body != nil && len(criteria.Body) > 0 {
+		required |= BODY
+	}
+	if criteria.Text != nil && len(criteria.Text) > 0 {
+		required |= ALL
+	}
+	if criteria.WithFlags != nil && len(criteria.WithFlags) > 0 {
+		required |= FLAGS
+	}
+	if criteria.WithoutFlags != nil && len(criteria.WithoutFlags) > 0 {
+		required |= FLAGS
+	}
+
+	return required
+}
diff --git a/worker/mbox/create.go b/worker/mbox/create.go
new file mode 100644
index 00000000..7c4d9f7b
--- /dev/null
+++ b/worker/mbox/create.go
@@ -0,0 +1,60 @@
+package mboxer
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func createMailboxContainer(path string) (*mailboxContainer, error) {
+
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+
+	defer file.Close()
+
+	fileInfo, err := file.Stat()
+	if err != nil {
+		return nil, err
+	}
+
+	mbdata := &mailboxContainer{mailboxes: make(map[string]*container)}
+
+	openMboxFile := func(path string, r io.Reader) error {
+		// read mbox file
+		messages, err := Read(r)
+		if err != nil {
+			return err
+		}
+		_, name := filepath.Split(path)
+		name = strings.TrimSuffix(name, ".mbox")
+		mbdata.mailboxes[name] = &container{filename: path, messages: messages}
+		return nil
+	}
+
+	if fileInfo.IsDir() {
+		files, err := filepath.Glob(filepath.Join(path, "*.mbox"))
+		if err != nil {
+			return nil, err
+		}
+		for _, file := range files {
+			f, err := os.Open(file)
+			if err != nil {
+				continue
+			}
+			if err := openMboxFile(file, f); err != nil {
+				return nil, err
+			}
+			f.Close()
+		}
+	} else {
+		if err := openMboxFile(path, file); err != nil {
+			return nil, err
+		}
+	}
+
+	return mbdata, nil
+}
diff --git a/worker/mbox/io.go b/worker/mbox/io.go
new file mode 100644
index 00000000..38469160
--- /dev/null
+++ b/worker/mbox/io.go
@@ -0,0 +1,50 @@
+package mboxer
+
+import (
+	"io"
+	"io/ioutil"
+	"time"
+
+	"git.sr.ht/~rjarry/aerc/models"
+	"git.sr.ht/~rjarry/aerc/worker/lib"
+	"github.com/emersion/go-mbox"
+)
+
+func Read(r io.Reader) ([]lib.RawMessage, error) {
+	mbr := mbox.NewReader(r)
+	uid := uint32(0)
+	messages := make([]lib.RawMessage, 0)
+	for {
+		msg, err := mbr.NextMessage()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return nil, err
+		}
+
+		content, err := ioutil.ReadAll(msg)
+		if err != nil {
+			return nil, err
+		}
+
+		messages = append(messages, &message{
+			uid: uid, flags: []models.Flag{models.SeenFlag}, content: content,
+		})
+
+		uid++
+	}
+	return messages, nil
+}
+
+func Write(w io.Writer, reader io.Reader, from string, date time.Time) error {
+	wc := mbox.NewWriter(w)
+	mw, err := wc.CreateMessage(from, time.Now())
+	if err != nil {
+		return err
+	}
+	_, err = io.Copy(mw, reader)
+	if err != nil {
+		return err
+	}
+	return wc.Close()
+}
diff --git a/worker/mbox/models.go b/worker/mbox/models.go
new file mode 100644
index 00000000..f97530ed
--- /dev/null
+++ b/worker/mbox/models.go
@@ -0,0 +1,203 @@
+package mboxer
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+
+	"git.sr.ht/~rjarry/aerc/models"
+	"git.sr.ht/~rjarry/aerc/worker/lib"
+)
+
+type mailboxContainer struct {
+	mailboxes map[string]*container
+}
+
+func (md *mailboxContainer) Names() []string {
+	files := make([]string, 0)
+	for file := range md.mailboxes {
+		files = append(files, file)
+	}
+	return files
+}
+
+func (md *mailboxContainer) Mailbox(f string) (*container, bool) {
+	mb, ok := md.mailboxes[f]
+	return mb, ok
+}
+
+func (md *mailboxContainer) Create(file string) *container {
+	md.mailboxes[file] = &container{filename: file}
+	return md.mailboxes[file]
+}
+
+func (md *mailboxContainer) Remove(file string) error {
+	delete(md.mailboxes, file)
+	return nil
+}
+
+func (md *mailboxContainer) DirectoryInfo(file string) *models.DirectoryInfo {
+	var exists int
+	if md, ok := md.Mailbox(file); ok {
+		exists = len(md.Uids())
+	}
+	return &models.DirectoryInfo{
+		Name:           file,
+		Flags:          []string{},
+		ReadOnly:       false,
+		Exists:         exists,
+		Recent:         0,
+		Unseen:         0,
+		AccurateCounts: false,
+		Caps: &models.Capabilities{
+			Sort:   true,
+			Thread: false,
+		},
+	}
+}
+
+func (md *mailboxContainer) Copy(dest, src string, uids []uint32) error {
+	srcmbox, ok := md.Mailbox(src)
+	if !ok {
+		return fmt.Errorf("source %s not found", src)
+	}
+	destmbox, ok := md.Mailbox(dest)
+	if !ok {
+		return fmt.Errorf("destination %s not found", dest)
+	}
+	for _, uidSrc := range srcmbox.Uids() {
+		found := false
+		for _, uid := range uids {
+			if uid == uidSrc {
+				found = true
+				break
+			}
+		}
+		if found {
+			msg, err := srcmbox.Message(uidSrc)
+			if err != nil {
+				return fmt.Errorf("could not get message with uid %d from folder %s", uidSrc, src)
+			}
+			r, err := msg.NewReader()
+			if err != nil {
+				return fmt.Errorf("could not get reader for message with uid %d", uidSrc)
+			}
+			flags, err := msg.ModelFlags()
+			if err != nil {
+				return fmt.Errorf("could not get flags for message with uid %d", uidSrc)
+			}
+			destmbox.Append(r, flags)
+		}
+	}
+	md.mailboxes[dest] = destmbox
+	return nil
+}
+
+type container struct {
+	filename string
+	messages []lib.RawMessage
+}
+
+func (f *container) Uids() []uint32 {
+	uids := make([]uint32, len(f.messages))
+	for i, m := range f.messages {
+		uids[i] = m.UID()
+	}
+	return uids
+}
+
+func (f *container) Message(uid uint32) (lib.RawMessage, error) {
+	for _, m := range f.messages {
+		if uid == m.UID() {
+			return m, nil
+		}
+	}
+	return &message{}, fmt.Errorf("uid [%d] not found", uid)
+}
+
+func (f *container) Delete(uids []uint32) (deleted []uint32) {
+	newMessages := make([]lib.RawMessage, 0)
+	for _, m := range f.messages {
+		del := false
+		for _, uid := range uids {
+			if m.UID() == uid {
+				del = true
+				break
+			}
+		}
+		if del {
+			deleted = append(deleted, m.UID())
+		} else {
+			newMessages = append(newMessages, m)
+		}
+	}
+	f.messages = newMessages
+	return
+}
+
+func (f *container) newUid() (next uint32) {
+	for _, m := range f.messages {
+		if uid := m.UID(); uid > next {
+			next = uid
+		}
+	}
+	next++
+	return
+}
+
+func (f *container) Append(r io.Reader, flags []models.Flag) error {
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return err
+	}
+	f.messages = append(f.messages, &message{
+		uid:     f.newUid(),
+		flags:   flags,
+		content: data,
+	})
+	return nil
+}
+
+// message implements the lib.RawMessage interface
+type message struct {
+	uid     uint32
+	flags   []models.Flag
+	content []byte
+}
+
+func (m *message) NewReader() (io.ReadCloser, error) {
+	return ioutil.NopCloser(bytes.NewReader(m.content)), nil
+}
+
+func (m *message) ModelFlags() ([]models.Flag, error) {
+	return m.flags, nil
+}
+
+func (m *message) Labels() ([]string, error) {
+	return nil, nil
+}
+
+func (m *message) UID() uint32 {
+	return m.uid
+}
+
+func (m *message) SetFlag(flag models.Flag, state bool) error {
+	flagSet := make(map[models.Flag]bool)
+	flags, err := m.ModelFlags()
+	if err != nil {
+		return err
+	}
+	for _, f := range flags {
+		flagSet[f] = true
+	}
+	flagSet[flag] = state
+	newFlags := make([]models.Flag, 0)
+	for flag, isSet := range flagSet {
+		if isSet {
+			newFlags = append(newFlags, flag)
+		}
+	}
+	m.flags = newFlags
+	return nil
+}
diff --git a/worker/mbox/worker.go b/worker/mbox/worker.go
new file mode 100644
index 00000000..c7f105b5
--- /dev/null
+++ b/worker/mbox/worker.go
@@ -0,0 +1,379 @@
+package mboxer
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/url"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"git.sr.ht/~rjarry/aerc/models"
+	"git.sr.ht/~rjarry/aerc/worker/handlers"
+	"git.sr.ht/~rjarry/aerc/worker/lib"
+	"git.sr.ht/~rjarry/aerc/worker/types"
+	gomessage "github.com/emersion/go-message"
+)
+
+func init() {
+	handlers.RegisterWorkerFactory("mbox", NewWorker)
+}
+
+var errUnsupported = fmt.Errorf("unsupported command")
+
+type mboxWorker struct {
+	data   *mailboxContainer
+	name   string
+	folder *container
+	worker *types.Worker
+}
+
+func NewWorker(worker *types.Worker) (types.Backend, error) {
+	return &mboxWorker{
+		worker: worker,
+	}, nil
+}
+
+func (w *mboxWorker) handleMessage(msg types.WorkerMessage) error {
+	var reterr error // will be returned at the end, needed to support idle
+
+	switch msg := msg.(type) {
+
+	case *types.Unsupported:
+		// No-op
+
+	case *types.Configure:
+		u, err := url.Parse(msg.Config.Source)
+		if err != nil {
+			reterr = err
+			break
+		}
+		dir := u.Path
+		if u.Host == "~" {
+			home, err := os.UserHomeDir()
+			if err != nil {
+				reterr = err
+				break
+			}
+			dir = filepath.Join(home, u.Path)
+		} else {
+			dir = filepath.Join(u.Host, u.Path)
+		}
+		w.data, err = createMailboxContainer(dir)
+		if err != nil || w.data == nil {
+			w.data = &mailboxContainer{
+				mailboxes: make(map[string]*container),
+			}
+			reterr = err
+			break
+		} else {
+			w.worker.Logger.Printf("mbox: configured with mbox file %s", dir)
+		}
+
+	case *types.Connect, *types.Reconnect, *types.Disconnect:
+		w.worker.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.ListDirectories:
+		dirs := w.data.Names()
+		sort.Strings(dirs)
+		for _, name := range dirs {
+			w.worker.PostMessage(&types.Directory{
+				Message: types.RespondTo(msg),
+				Dir: &models.Directory{
+					Name:       name,
+					Attributes: nil,
+				},
+			}, nil)
+			w.worker.PostMessage(&types.DirectoryInfo{
+				Info: w.data.DirectoryInfo(name),
+			}, nil)
+		}
+		w.worker.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.OpenDirectory:
+		w.name = msg.Directory
+		var ok bool
+		w.folder, ok = w.data.Mailbox(w.name)
+		if !ok {
+			w.folder = w.data.Create(w.name)
+			w.worker.PostMessage(&types.Done{
+				Message: types.RespondTo(&types.CreateDirectory{})}, nil)
+		}
+		w.worker.PostMessage(&types.DirectoryInfo{
+			Info: w.data.DirectoryInfo(msg.Directory),
+		}, nil)
+		w.worker.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
+		w.worker.Logger.Printf("mbox: %s opened\n", msg.Directory)
+
+	case *types.FetchDirectoryContents:
+		var infos []*models.MessageInfo
+		for _, uid := range w.folder.Uids() {
+			m, err := w.folder.Message(uid)
+			if err != nil {
+				w.worker.Logger.Println("mbox: could not get message", err)
+				continue
+			}
+			info, err := lib.MessageInfo(m)
+			if err != nil {
+				w.worker.Logger.Println("mbox: could not get message info", err)
+				continue
+			}
+			infos = append(infos, info)
+		}
+		uids, err := lib.Sort(infos, msg.SortCriteria)
+		if err != nil {
+			reterr = err
+			break
+		}
+		if len(uids) == 0 {
+			reterr = fmt.Errorf("mbox: no uids in directory")
+			break
+		}
+		w.worker.PostMessage(&types.DirectoryContents{
+			Message: types.RespondTo(msg),
+			Uids:    uids,
+		}, nil)
+		w.worker.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.FetchDirectoryThreaded:
+		reterr = errUnsupported
+
+	case *types.CreateDirectory:
+		w.data.Create(msg.Directory)
+		w.worker.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.RemoveDirectory:
+		if err := w.data.Remove(msg.Directory); err != nil {
+			reterr = err
+			break
+		}
+		w.worker.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.FetchMessageHeaders:
+		for _, uid := range msg.Uids {
+			m, err := w.folder.Message(uid)
+			if err != nil {
+				reterr = err
+				break
+			}
+			msgInfo, err := lib.MessageInfo(m)
+			if err != nil {
+				reterr = err
+				break
+			} else {
+				w.worker.PostMessage(&types.MessageInfo{
+					Message: types.RespondTo(msg),
+					Info:    msgInfo,
+				}, nil)
+			}
+		}
+		w.worker.PostMessage(
+			&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.FetchMessageBodyPart:
+		m, err := w.folder.Message(msg.Uid)
+		if err != nil {
+			w.worker.Logger.Printf("could not get message %d: %v", msg.Uid, err)
+			reterr = err
+			break
+		}
+
+		contentReader, err := m.NewReader()
+		if err != nil {
+			reterr = fmt.Errorf("could not get message reader: %v", err)
+			break
+		}
+
+		fullMsg, err := gomessage.Read(contentReader)
+		if err != nil {
+			reterr = fmt.Errorf("could not read message: %v", err)
+			break
+		}
+
+		r, err := lib.FetchEntityPartReader(fullMsg, msg.Part)
+		if err != nil {
+			w.worker.Logger.Printf(
+				"could not get body part reader for message=%d, parts=%#v: %v",
+				msg.Uid, msg.Part, err)
+			reterr = err
+			break
+		}
+
+		w.worker.PostMessage(&types.MessageBodyPart{
+			Message: types.RespondTo(msg),
+			Part: &models.MessageBodyPart{
+				Reader: r,
+				Uid:    msg.Uid,
+			},
+		}, nil)
+
+	case *types.FetchFullMessages:
+		for _, uid := range msg.Uids {
+			m, err := w.folder.Message(uid)
+			if err != nil {
+				w.worker.Logger.Printf("could not get message for uid %d: %v", uid, err)
+				continue
+			}
+			r, err := m.NewReader()
+			if err != nil {
+				w.worker.Logger.Printf("could not get message reader: %v", err)
+				continue
+			}
+			defer r.Close()
+			b, err := ioutil.ReadAll(r)
+			if err != nil {
+				w.worker.Logger.Printf("could not get message reader: %v", err)
+				continue
+			}
+			w.worker.PostMessage(&types.FullMessage{
+				Message: types.RespondTo(msg),
+				Content: &models.FullMessage{
+					Uid:    uid,
+					Reader: bytes.NewReader(b),
+				},
+			}, nil)
+		}
+		w.worker.PostMessage(&types.Done{
+			Message: types.RespondTo(msg),
+		}, nil)
+
+	case *types.DeleteMessages:
+		deleted := w.folder.Delete(msg.Uids)
+		if len(deleted) > 0 {
+			w.worker.PostMessage(&types.MessagesDeleted{
+				Message: types.RespondTo(msg),
+				Uids:    deleted,
+			}, nil)
+		}
+
+		w.worker.PostMessage(&types.DirectoryInfo{
+			Info: w.data.DirectoryInfo(w.name),
+		}, nil)
+
+		w.worker.PostMessage(
+			&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.FlagMessages:
+		for _, uid := range msg.Uids {
+			m, err := w.folder.Message(uid)
+			if err != nil {
+				w.worker.Logger.Printf("could not get message: %v", err)
+				continue
+			}
+			if err := m.(*message).SetFlag(msg.Flag, msg.Enable); err != nil {
+				w.worker.Logger.Printf("could change flag %v to %v on message: %v", msg.Flag, msg.Enable, err)
+				continue
+			}
+			info, err := lib.MessageInfo(m)
+			if err != nil {
+				w.worker.Logger.Printf("could not get message info: %v", err)
+				continue
+			}
+
+			w.worker.PostMessage(&types.MessageInfo{
+				Message: types.RespondTo(msg),
+				Info:    info,
+			}, nil)
+		}
+
+		w.worker.PostMessage(&types.DirectoryInfo{
+			Info: w.data.DirectoryInfo(w.name),
+		}, nil)
+
+		w.worker.PostMessage(
+			&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.CopyMessages:
+		err := w.data.Copy(msg.Destination, w.name, msg.Uids)
+		if err != nil {
+			reterr = err
+			break
+		}
+
+		w.worker.PostMessage(&types.DirectoryInfo{
+			Info: w.data.DirectoryInfo(w.name),
+		}, nil)
+
+		w.worker.PostMessage(&types.DirectoryInfo{
+			Info: w.data.DirectoryInfo(msg.Destination),
+		}, nil)
+
+		w.worker.PostMessage(
+			&types.Done{Message: types.RespondTo(msg)}, nil)
+
+	case *types.SearchDirectory:
+		criteria, err := lib.GetSearchCriteria(msg.Argv)
+		if err != nil {
+			reterr = err
+			break
+		}
+		w.worker.Logger.Printf("Searching with parsed criteria: %#v", criteria)
+		m := make([]lib.RawMessage, 0, len(w.folder.Uids()))
+		for _, uid := range w.folder.Uids() {
+			msg, err := w.folder.Message(uid)
+			if err != nil {
+				w.worker.Logger.Println("faild to get message for uid:", uid)
+				continue
+			}
+			m = append(m, msg)
+		}
+		uids, err := lib.Search(m, criteria)
+		if err != nil {
+			reterr = err
+			break
+		}
+		w.worker.PostMessage(&types.SearchResults{
+			Message: types.RespondTo(msg),
+			Uids:    uids,
+		}, nil)
+
+	case *types.AppendMessage:
+		if msg.Destination == "" {
+			reterr = fmt.Errorf("AppendMessage with empty destination directory")
+			break
+		}
+		folder, ok := w.data.Mailbox(msg.Destination)
+		if !ok {
+			folder = w.data.Create(msg.Destination)
+			w.worker.PostMessage(&types.Done{
+				Message: types.RespondTo(&types.CreateDirectory{})}, nil)
+		}
+
+		if err := folder.Append(msg.Reader, msg.Flags); err != nil {
+			reterr = err
+			break
+		} else {
+			w.worker.PostMessage(&types.DirectoryInfo{
+				Info: w.data.DirectoryInfo(msg.Destination),
+			}, nil)
+			w.worker.PostMessage(&types.Done{Message: types.RespondTo(msg)}, nil)
+		}
+
+	case *types.AnsweredMessages:
+		reterr = errUnsupported
+	default:
+		reterr = errUnsupported
+	}
+
+	return reterr
+}
+
+func (w *mboxWorker) Run() {
+	for {
+		select {
+		case msg := <-w.worker.Actions:
+			msg = w.worker.ProcessAction(msg)
+			if err := w.handleMessage(msg); err == errUnsupported {
+				w.worker.PostMessage(&types.Unsupported{
+					Message: types.RespondTo(msg),
+				}, nil)
+			} else if err != nil {
+				w.worker.PostMessage(&types.Error{
+					Message: types.RespondTo(msg),
+					Error:   err,
+				}, nil)
+			}
+		}
+	}
+}
diff --git a/worker/worker_enabled.go b/worker/worker_enabled.go
index f0b9dbcb..a644525f 100644
--- a/worker/worker_enabled.go
+++ b/worker/worker_enabled.go
@@ -1,5 +1,9 @@
 package worker
 
 // the following workers are always enabled
-import _ "git.sr.ht/~rjarry/aerc/worker/imap"
-import _ "git.sr.ht/~rjarry/aerc/worker/maildir"
+import (
+	_ "git.sr.ht/~rjarry/aerc/worker/imap"
+	_ "git.sr.ht/~rjarry/aerc/worker/maildir"
+
+	_ "git.sr.ht/~rjarry/aerc/worker/mbox"
+)