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>

1 files changed, 254 insertions, 0 deletions

diff --git a/worker/lib/search.go b/worker/lib/search.go
new file mode 100644
index 0000000..c7d3bee
--- /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
+}