Basic impl added

internal/domain/queue.go

@@ -0,0 +1,111 @@
+package domain
+
+import (
+	"context"
+)
+
+// QueueMessage wraps a notification with queue-specific metadata
+type QueueMessage struct {
+	// ID is a unique identifier for this queue message
+	ID string `json:"id"`
+
+	// Notification is the actual notification to be sent
+	Notification *Notification `json:"notification"`
+
+	// Attempt is the current delivery attempt number
+	Attempt int `json:"attempt"`
+
+	// EnqueuedAt is when the message was added to the queue
+	EnqueuedAt int64 `json:"enqueued_at"`
+}
+
+// Queue defines the interface for a notification queue
+type Queue interface {
+	// Enqueue adds a notification to the queue
+	Enqueue(ctx context.Context, notification *Notification) error
+
+	// EnqueueBatch adds multiple notifications to the queue
+	EnqueueBatch(ctx context.Context, notifications []*Notification) error
+
+	// Dequeue retrieves the next notification from the queue
+	// Returns nil if the queue is empty
+	Dequeue(ctx context.Context) (*QueueMessage, error)
+
+	// Ack acknowledges successful processing of a message
+	Ack(ctx context.Context, messageID string) error
+
+	// Nack indicates processing failure and may requeue the message
+	Nack(ctx context.Context, messageID string, requeue bool) error
+
+	// Size returns the current number of messages in the queue
+	Size(ctx context.Context) (int64, error)
+
+	// Purge removes all messages from the queue
+	Purge(ctx context.Context) error
+
+	// Close cleanly shuts down the queue
+	Close() error
+
+	// HealthCheck verifies the queue is operational
+	HealthCheck(ctx context.Context) error
+}
+
+// QueueConfig contains configuration for queue implementations
+type QueueConfig struct {
+	// Type specifies the queue implementation (local, kafka, etc.)
+	Type string `mapstructure:"type"`
+
+	// MaxSize is the maximum number of messages the queue can hold
+	MaxSize int64 `mapstructure:"max_size"`
+
+	// WorkerCount is the number of concurrent workers processing the queue
+	WorkerCount int `mapstructure:"worker_count"`
+
+	// RetryAttempts is the number of times to retry failed notifications
+	RetryAttempts int `mapstructure:"retry_attempts"`
+
+	// RetryBackoff is the backoff strategy for retries (exponential, linear, fixed)
+	RetryBackoff string `mapstructure:"retry_backoff"`
+
+	// Local queue specific config
+	Local *LocalQueueConfig `mapstructure:"local,omitempty"`
+
+	// Kafka specific config
+	Kafka *KafkaQueueConfig `mapstructure:"kafka,omitempty"`
+}
+
+// LocalQueueConfig contains configuration for the in-memory queue
+type LocalQueueConfig struct {
+	// BufferSize is the channel buffer size
+	BufferSize int `mapstructure:"buffer_size"`
+
+	// PersistToDisk enables writing queue state to disk for recovery
+	PersistToDisk bool `mapstructure:"persist_to_disk"`
+
+	// PersistPath is where to store the queue state
+	PersistPath string `mapstructure:"persist_path"`
+}
+
+// KafkaQueueConfig contains configuration for Kafka queue
+type KafkaQueueConfig struct {
+	// Brokers is the list of Kafka broker addresses
+	Brokers []string `mapstructure:"brokers"`
+
+	// Topic is the Kafka topic for notifications
+	Topic string `mapstructure:"topic"`
+
+	// ConsumerGroup is the Kafka consumer group ID
+	ConsumerGroup string `mapstructure:"consumer_group"`
+
+	// PartitionCount is the number of partitions for the topic
+	PartitionCount int `mapstructure:"partition_count"`
+
+	// ReplicationFactor is the replication factor for the topic
+	ReplicationFactor int `mapstructure:"replication_factor"`
+
+	// EnableIdempotence ensures exactly-once delivery semantics
+	EnableIdempotence bool `mapstructure:"enable_idempotence"`
+
+	// CompressionType defines compression (none, gzip, snappy, lz4, zstd)
+	CompressionType string `mapstructure:"compression_type"`
+}