Add command spec parsing/handler execution

matrix/commands.go

@@ -0,0 +1,138 @@
+// maubot - A plugin-based Matrix bot system written in Go.
+// Copyright (C) 2018 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package matrix
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	log "maunium.net/go/maulogger"
+
+	"maubot.xyz"
+)
+
+type ParsedCommand struct {
+	Name         string
+	StartsWith   string
+	Matches      *regexp.Regexp
+	MatchAgainst string
+	MatchesEvent *maubot.Event
+}
+
+func (pc *ParsedCommand) parseCommandSyntax(command maubot.Command) error {
+	regexBuilder := &strings.Builder{}
+	swBuilder := &strings.Builder{}
+	argumentEncountered := false
+
+	regexBuilder.WriteRune('^')
+	words := strings.Split(command.Syntax, " ")
+	for i, word := range words {
+		argument, ok := command.Arguments[word]
+		if ok {
+			argumentEncountered = true
+			regex := argument.Matches
+			if argument.Required {
+				regex = fmt.Sprintf("(?:%s)?", regex)
+			}
+			regexBuilder.WriteString(regex)
+		} else {
+			if !argumentEncountered {
+				swBuilder.WriteString(word)
+			}
+			regexBuilder.WriteString(regexp.QuoteMeta(word))
+		}
+
+		if i < len(words) - 1 {
+			if !argumentEncountered {
+				swBuilder.WriteRune(' ')
+			}
+			regexBuilder.WriteRune(' ')
+		}
+	}
+	regexBuilder.WriteRune('$')
+
+	var err error
+	pc.StartsWith = swBuilder.String()
+	// Trim the extra space at the end added in the parse loop
+	pc.StartsWith = pc.StartsWith[:len(pc.StartsWith)-1]
+	pc.Matches, err = regexp.Compile(regexBuilder.String())
+	pc.MatchAgainst = "body"
+	return err
+}
+
+func (pc *ParsedCommand) parsePassiveCommandSyntax(command maubot.PassiveCommand) error {
+	pc.MatchAgainst = command.MatchAgainst
+	var err error
+	pc.Matches, err = regexp.Compile(command.Matches)
+	pc.MatchesEvent = command.MatchEvent
+	return err
+}
+
+func ParseSpec(spec *maubot.CommandSpec) (commands []*ParsedCommand) {
+	for _, command := range spec.Commands {
+		parsing := &ParsedCommand{
+			Name: command.Syntax,
+		}
+		err := parsing.parseCommandSyntax(command)
+		if err != nil {
+			log.Warnf("Failed to parse regex of command %s: %v\n", command.Syntax, err)
+			continue
+		}
+		commands = append(commands, parsing)
+	}
+	for _, command := range spec.PassiveCommands {
+		parsing := &ParsedCommand{
+			Name: command.Name,
+		}
+		err := parsing.parsePassiveCommandSyntax(command)
+		if err != nil {
+			log.Warnf("Failed to parse regex of passive command %s: %v\n", command.Name, err)
+			continue
+		}
+		commands = append(commands, parsing)
+	}
+	return commands
+}
+
+func deepGet(from map[string]interface{}, path string) interface{} {
+	for {
+		dotIndex := strings.IndexRune(path, '.')
+		if dotIndex == -1 {
+			return from[path]
+		}
+
+		var key string
+		key, path = path[:dotIndex], path[dotIndex+1:]
+		var ok bool
+		from, ok = from[key].(map[string]interface{})
+		if !ok {
+			return nil
+		}
+	}
+}
+
+func (pc *ParsedCommand) Match(evt *maubot.Event) bool {
+	matchAgainst, ok := deepGet(evt.Content.Raw, pc.MatchAgainst).(string)
+	if !ok {
+		matchAgainst = evt.Content.Body
+	}
+
+	return strings.HasPrefix(matchAgainst, pc.StartsWith) &&
+		pc.Matches.MatchString(matchAgainst) &&
+		(pc.MatchesEvent == nil || pc.MatchesEvent.Equals(evt))
+}