feat: add log-backed receive message source

internal/isphere/source.go

@@ -0,0 +1,95 @@
+package isphere
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"isphere-ai-bridge/internal/isphere/logcodec"
+	"isphere-ai-bridge/internal/isphere/packetlog"
+)
+
+type Message struct {
+	ID               string
+	ConversationID   string
+	ConversationType string
+	SenderID         string
+	ReceiverID       string
+	Text             string
+	Timestamp        string
+	Subject          string
+	ReceiptID        string
+	Read             bool
+}
+
+type ReceiveMessagesQuery struct {
+	Limit int
+}
+
+type ReceiveMessagesResult struct {
+	Messages []Message
+}
+
+type EncryptedPacketLogSource struct {
+	Lines []string
+}
+
+func (s EncryptedPacketLogSource) ReceiveMessages(ctx context.Context, query ReceiveMessagesQuery) (ReceiveMessagesResult, error) {
+	limit := query.Limit
+	if limit <= 0 || limit > len(s.Lines) {
+		limit = len(s.Lines)
+	}
+	messages := make([]Message, 0, limit)
+	for index, line := range s.Lines {
+		if len(messages) == limit {
+			break
+		}
+		select {
+		case <-ctx.Done():
+			return ReceiveMessagesResult{}, ctx.Err()
+		default:
+		}
+		plaintext, err := logcodec.DecryptLine(line)
+		if err != nil {
+			return ReceiveMessagesResult{}, fmt.Errorf("decrypt packet log line %d: %w", index, err)
+		}
+		parsed, err := packetlog.ParseMessageLog(plaintext)
+		if err != nil {
+			return ReceiveMessagesResult{}, fmt.Errorf("parse packet log line %d: %w", index, err)
+		}
+		messages = append(messages, normalizePacketMessage(parsed))
+	}
+	return ReceiveMessagesResult{Messages: messages}, nil
+}
+
+func normalizePacketMessage(msg packetlog.Message) Message {
+	sender := bareJID(msg.From)
+	receiver := bareJID(msg.To)
+	return Message{
+		ID:               msg.ID,
+		ConversationID:   conversationID(sender, receiver),
+		ConversationType: msg.Type,
+		SenderID:         sender,
+		ReceiverID:       receiver,
+		Text:             msg.Body,
+		Timestamp:        msg.SendTime,
+		Subject:          msg.Subject,
+		ReceiptID:        msg.ReceiptID,
+		Read:             msg.Read,
+	}
+}
+
+func bareJID(value string) string {
+	beforeResource, _, _ := strings.Cut(value, "/")
+	return beforeResource
+}
+
+func conversationID(sender string, receiver string) string {
+	if sender == "" {
+		return receiver
+	}
+	if receiver == "" {
+		return sender
+	}
+	return sender + "|" + receiver
+}