Add additional flagging functionality

More mail flags can now be set, unset, and toggled, not just the
read/seen flag.

This functionality is implemented with a new `:flag` and `:unflag`
command, which are extensions to the matching `:read` and `:unread`
commands, adding support for different flags.  In fact, the
`read`/`unread` commands are now recognized aliases to `flag`/`unflag`.
The new commands are also well documented in aerc(1).

The change mostly extends the previous read/unread setting functionality
by adding a selection for the flag to change.

1 files changed, 135 insertions, 86 deletions

diff --git a/commands/msg/read.go b/commands/msg/read.go
index 1e264c27..08881894 100644
--- a/commands/msg/read.go
+++ b/commands/msg/read.go
@@ -1,9 +1,9 @@
 package msg
 
 import (
-	"errors"
 	"sync"
 	"time"
+	"fmt"
 
 	"git.sr.ht/~sircmpwn/getopt"
 
@@ -13,36 +13,106 @@ import (
 	"git.sr.ht/~sircmpwn/aerc/worker/types"
 )
 
-type Read struct{}
+type FlagMsg struct{}
 
 func init() {
-	register(Read{})
+	register(FlagMsg{})
 }
 
-func (Read) Aliases() []string {
-	return []string{"read", "unread"}
+func (FlagMsg) Aliases() []string {
+	return []string{"flag", "unflag", "read", "unread"}
 }
 
-func (Read) Complete(aerc *widgets.Aerc, args []string) []string {
+func (FlagMsg) Complete(aerc *widgets.Aerc, args []string) []string {
 	return nil
 }
 
-func (Read) Execute(aerc *widgets.Aerc, args []string) error {
-	opts, optind, err := getopt.Getopts(args, "t")
+// If this was called as 'flag' or 'unflag', without the toggle (-t)
+// option, then it will flag the corresponding messages with the given
+// flag.  If the toggle option was given, it will individually toggle
+// the given flag for the corresponding messages.
+//
+// If this was called as 'read' or 'unread', it has the same effect as
+// 'flag' or 'unflag', respectively, but the 'Seen' flag is affected.
+func (FlagMsg) Execute(aerc *widgets.Aerc, args []string) error {
+
+	// The flag to change
+	var flag models.Flag
+	// User-readable name of the flag to change
+	var flagName string
+	// Whether to toggle the flag (true) or to enable/disable it (false)
+	var toggle bool
+	// Whether to enable (true) or disable (false) the flag
+	enable := (args[0] == "read" || args[0] == "flag")
+	// User-readable name for the action being performed
+	var actionName string
+	// Getopt option string, varies by command name
+	var getoptString string
+	// Help message to provide on parsing failure
+	var helpMessage string
+	// Used during parsing to prevent choosing a flag muliple times
+	// A default flag will be used if this is false
+	flagChosen := false
+
+	if args[0] == "read" || args[0] == "unread" {
+		flag = models.SeenFlag
+		flagName = "read"
+		getoptString = "t"
+		helpMessage = "Usage: " + args[0] + " [-t]"
+	} else { // 'flag' / 'unflag'
+		flag = models.FlaggedFlag
+		flagName = "flagged"
+		getoptString = "tax:"
+		helpMessage = "Usage: " + args[0] + " [-t] [-a | -x <flag>]"
+	}
+
+	opts, optind, err := getopt.Getopts(args, getoptString)
 	if err != nil {
 		return err
 	}
-	if optind != len(args) {
-		return errors.New("Usage: " + args[0] + " [-t]")
-	}
-	var toggle bool
-
 	for _, opt := range opts {
 		switch opt.Option {
 		case 't':
 			toggle = true
+		case 'a':
+			if flagChosen {
+				return fmt.Errorf("Cannot choose a flag multiple times! " + helpMessage)
+			}
+			flag = models.AnsweredFlag
+			flagName = "answered"
+			flagChosen = true
+		case 'x':
+			if flagChosen {
+				return fmt.Errorf("Cannot choose a flag multiple times! " + helpMessage)
+			}
+			// TODO: Support all flags?
+			switch opt.Value {
+			case "Seen":
+				flag = models.SeenFlag
+				flagName = "seen"
+			case "Answered":
+				flag = models.AnsweredFlag
+				flagName = "answered"
+			case "Flagged":
+				flag = models.FlaggedFlag
+				flagName = "flagged"
+			default:
+				return fmt.Errorf("Unknown / Prohibited flag \"%v\"", opt.Value)
+			}
+			flagChosen = true
 		}
 	}
+	if toggle {
+		actionName = "Toggling"
+	} else if enable {
+		actionName = "Setting"
+	} else {
+		actionName = "Unsetting"
+	}
+	if optind != len(args) {
+		// Any non-option arguments: Error
+		return fmt.Errorf(helpMessage)
+	}
 
 	h := newHelper(aerc)
 	store, err := h.store()
@@ -50,57 +120,68 @@ func (Read) Execute(aerc *widgets.Aerc, args []string) error {
 		return err
 	}
 
-	if toggle {
-		// ignore command given, simply toggle all the read states
-		return submitToggle(aerc, store, h)
-	}
-	msgUids, err := h.markedOrSelectedUids()
-	if err != nil {
-		return err
-	}
-	switch args[0] {
-	case "read":
-		submitReadChange(aerc, store, msgUids, true)
-	case "unread":
-		submitReadChange(aerc, store, msgUids, false)
-
-	}
-	return nil
-}
+	// UIDs of messages to enable or disable the flag for.
+	var toEnable []uint32
+	var toDisable []uint32
 
-func splitMessages(msgs []*models.MessageInfo) (read []uint32, unread []uint32) {
-	for _, m := range msgs {
-		var seen bool
-		for _, flag := range m.Flags {
-			if flag == models.SeenFlag {
-				seen = true
-				break
+	if toggle {
+		// If toggling, split messages into those that need to
+		// be enabled / disabled.
+		msgs, err := h.messages()
+		if err != nil {
+			return err
+		}
+		for _, m := range msgs {
+			var enabled bool
+			for _, mFlag := range m.Flags {
+				if mFlag == flag {
+					enabled = true
+					break
+				}
 			}
+			if enabled {
+				toDisable = append(toDisable, m.Uid)
+			} else {
+				toEnable = append(toEnable, m.Uid)
+			}
+		}
+	} else {
+		msgUids, err := h.markedOrSelectedUids()
+		if err != nil {
+			return err
 		}
-		if seen {
-			read = append(read, m.Uid)
+		if enable {
+			toEnable = msgUids
 		} else {
-			unread = append(unread, m.Uid)
+			toDisable = msgUids
 		}
 	}
-	return read, unread
-}
 
-func submitReadChange(aerc *widgets.Aerc, store *lib.MessageStore,
-	uids []uint32, newState bool) {
-	store.Read(uids, newState, func(msg types.WorkerMessage) {
-		switch msg := msg.(type) {
-		case *types.Done:
-			aerc.PushStatus(msg_success, 10*time.Second)
-		case *types.Error:
-			aerc.PushError(" " + msg.Error.Error())
+	var wg sync.WaitGroup
+	success := true
+
+	if len(toEnable) != 0 {
+		submitFlagChange(aerc, store, toEnable, flag, true, &wg, &success)
+	}
+	if len(toDisable) != 0 {
+		submitFlagChange(aerc, store, toDisable, flag, false, &wg, &success)
+	}
+
+	// We need to do flagging in the background, else we block the main thread
+	go func() {
+		wg.Wait()
+		if success {
+			aerc.PushStatus(actionName + " flag '" + flagName + "' successful", 10*time.Second)
 		}
-	})
+	}()
+
+	return nil
 }
 
-func submitReadChangeWg(aerc *widgets.Aerc, store *lib.MessageStore,
-	uids []uint32, newState bool, wg *sync.WaitGroup, success *bool) {
-	store.Read(uids, newState, func(msg types.WorkerMessage) {
+func submitFlagChange(aerc *widgets.Aerc, store *lib.MessageStore,
+	uids []uint32, flag models.Flag, newState bool,
+	wg *sync.WaitGroup, success *bool) {
+	store.Flag(uids, flag, newState, func(msg types.WorkerMessage) {
 		wg.Add(1)
 		switch msg := msg.(type) {
 		case *types.Done:
@@ -112,35 +193,3 @@ func submitReadChangeWg(aerc *widgets.Aerc, store *lib.MessageStore,
 		}
 	})
 }
-
-func submitToggle(aerc *widgets.Aerc, store *lib.MessageStore, h *helper) error {
-	msgs, err := h.messages()
-	if err != nil {
-		return err
-	}
-	read, unread := splitMessages(msgs)
-
-	var wg sync.WaitGroup
-	success := true
-
-	if len(read) != 0 {
-		newState := false
-		submitReadChangeWg(aerc, store, read, newState, &wg, &success)
-	}
-
-	if len(unread) != 0 {
-		newState := true
-		submitReadChangeWg(aerc, store, unread, newState, &wg, &success)
-	}
-	// we need to do that in the background, else we block the main thread
-	go func() {
-		wg.Wait()
-		if success {
-			aerc.PushStatus(msg_success, 10*time.Second)
-		}
-	}()
-	return nil
-
-}
-
-const msg_success = "read state set successfully"