Add channel subscriptions, counts, creators, and DB query indexes

contract/contracts/hello-world/src/base/channel.rs

@@ -0,0 +1,176 @@
+/// Notification channel types and storage helpers.
+///
+/// Channels are named notification streams that users can subscribe to.
+/// Each channel records its original creator and maintains an active
+/// subscriber count for efficient read-only queries.
+use soroban_sdk::{contractevent, contracttype, Address, BytesN, Env, String, Vec};
+
+use crate::base::events::{NotificationCategory, NotificationPriority};
+
+// ============================================================================
+// Types
+// ============================================================================
+
+/// On-chain notification channel metadata.
+#[contracttype]
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct NotificationChannel {
+    /// Unique channel identifier.
+    pub id: BytesN<32>,
+    /// Wallet that originally created the channel.
+    pub creator: Address,
+    /// Human-readable channel name.
+    pub name: String,
+    /// Number of currently active subscribers.
+    pub subscriber_count: u32,
+    /// Whether the channel accepts new subscriptions.
+    pub is_active: bool,
+    /// Ledger timestamp when the channel was created.
+    pub created_at: u64,
+}
+
+/// Result summary returned by batch subscription.
+#[contracttype]
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct BatchSubscribeResult {
+    /// Number of channels successfully subscribed.
+    pub succeeded: u32,
+    /// Number of channels skipped due to errors (not found, inactive, already subscribed).
+    pub failed: u32,
+    /// Channel ids that were successfully subscribed in this call.
+    pub subscribed_ids: Vec<BytesN<32>>,
+}
+
+// ============================================================================
+// Storage keys
+// ============================================================================
+
+#[contracttype]
+#[derive(Clone)]
+pub enum ChannelDataKey {
+    /// Channel metadata keyed by channel id.
+    Channel(BytesN<32>),
+    /// Ordered list of all channel ids.
+    AllChannels,
+    /// Active subscription flag: (channel_id, subscriber) -> bool.
+    Subscription(BytesN<32>, Address),
+    /// List of subscriber addresses for a channel (for enumeration).
+    ChannelSubscribers(BytesN<32>),
+}
+
+/// Maximum channels allowed in a single `batch_subscribe` call.
+pub const MAX_BATCH_SUBSCRIBE: u32 = 50;
+/// Maximum length for a channel name.
+pub const MAX_CHANNEL_NAME_LENGTH: u32 = 100;
+
+// ============================================================================
+// Storage helpers
+// ============================================================================
+
+pub fn load_channel(env: &Env, id: &BytesN<32>) -> Option<NotificationChannel> {
+    env.storage()
+        .persistent()
+        .get(&ChannelDataKey::Channel(id.clone()))
+}
+
+pub fn save_channel(env: &Env, channel: &NotificationChannel) {
+    env.storage()
+        .persistent()
+        .set(&ChannelDataKey::Channel(channel.id.clone()), channel);
+}
+
+pub fn is_subscribed(env: &Env, channel_id: &BytesN<32>, subscriber: &Address) -> bool {
+    env.storage()
+        .persistent()
+        .get(&ChannelDataKey::Subscription(channel_id.clone(), subscriber.clone()))
+        .unwrap_or(false)
+}
+
+pub fn set_subscribed(env: &Env, channel_id: &BytesN<32>, subscriber: &Address, value: bool) {
+    let key = ChannelDataKey::Subscription(channel_id.clone(), subscriber.clone());
+    if value {
+        env.storage().persistent().set(&key, &true);
+    } else {
+        env.storage().persistent().remove(&key);
+    }
+}
+
+pub fn load_subscribers(env: &Env, channel_id: &BytesN<32>) -> Vec<Address> {
+    env.storage()
+        .persistent()
+        .get(&ChannelDataKey::ChannelSubscribers(channel_id.clone()))
+        .unwrap_or(Vec::new(env))
+}
+
+pub fn save_subscribers(env: &Env, channel_id: &BytesN<32>, subscribers: &Vec<Address>) {
+    env.storage()
+        .persistent()
+        .set(
+            &ChannelDataKey::ChannelSubscribers(channel_id.clone()),
+            subscribers,
+        );
+}
+
+pub fn push_all_channel_id(env: &Env, id: &BytesN<32>) {
+    let key = ChannelDataKey::AllChannels;
+    let mut all: Vec<BytesN<32>> = env.storage().persistent().get(&key).unwrap_or(Vec::new(env));
+    all.push_back(id.clone());
+    env.storage().persistent().set(&key, &all);
+}
+
+// ============================================================================
+// Events
+// ============================================================================
+
+/// Emitted when a notification channel is created.
+#[contractevent(data_format = "single-value")]
+#[derive(Clone)]
+pub struct ChannelCreated {
+    #[topic]
+    pub creator: Address,
+    #[topic]
+    pub category: NotificationCategory,
+    #[topic]
+    pub priority: NotificationPriority,
+    pub channel_id: BytesN<32>,
+}
+
+/// Emitted when a user successfully subscribes to a channel.
+#[contractevent(data_format = "single-value")]
+#[derive(Clone)]
+pub struct ChannelSubscribed {
+    #[topic]
+    pub channel_id: BytesN<32>,
+    #[topic]
+    pub subscriber: Address,
+    #[topic]
+    pub category: NotificationCategory,
+    pub subscriber_count: u32,
+}
+
+/// Emitted when a user unsubscribes from a channel.
+#[contractevent(data_format = "single-value")]
+#[derive(Clone)]
+pub struct ChannelUnsubscribed {
+    #[topic]
+    pub channel_id: BytesN<32>,
+    #[topic]
+    pub subscriber: Address,
+    #[topic]
+    pub category: NotificationCategory,
+    pub subscriber_count: u32,
+}
+
+/// Summary event for a batch subscribe call.
+#[contractevent]
+#[derive(Clone)]
+pub struct BatchSubscribeCompleted {
+    #[topic]
+    pub subscriber: Address,
+    #[topic]
+    pub category: NotificationCategory,
+    #[topic]
+    pub priority: NotificationPriority,
+    pub succeeded: u32,
+    pub failed: u32,
+}