/**
* BTCFi Event System — MP3 Task 20.1
* Server-Sent Events for real-time Bitcoin data.
* Polls mempool.space and emits typed events.
*/
import { getRecommendedFees, getMempoolSummary, getMempoolRecent, getBlockHeight } from './bitcoin';
// ============ TYPES ============
export type EventType = 'new_block' | 'whale_tx' | 'fee_change' | 'mempool_surge' | 'heartbeat';
export interface BTCFiEvent {
type: EventType;
data: Record<string, unknown>;
timestamp: string;
}
// ============ STATE ============
let lastBlockHeight = 0;
let lastFastFee = 0;
let lastMempoolCount = 0;
// ============ EVENT GENERATORS ============
/**
* Poll for new events. Returns array of events since last poll.
*/
export async function pollEvents(): Promise<BTCFiEvent[]> {
const events: BTCFiEvent[] = [];
const now = new Date().toISOString();
try {
const [height, fees, mempool] = await Promise.all([
getBlockHeight(),
getRecommendedFees(),
getMempoolSummary(),
]);
// New block detected
if (lastBlockHeight > 0 && height > lastBlockHeight) {
events.push({
type: 'new_block',
data: { height, previousHeight: lastBlockHeight, blocksSkipped: height - lastBlockHeight },
timestamp: now,
});
}
lastBlockHeight = height;
// Fee change > 20%
if (lastFastFee > 0) {
const change = Math.abs(fees.fastestFee - lastFastFee) / lastFastFee;
if (change > 0.2) {
events.push({
type: 'fee_change',
data: {
previous: lastFastFee,
current: fees.fastestFee,
changePercent: (change * 100).toFixed(1),
direction: fees.fastestFee > lastFastFee ? 'up' : 'down',
allFees: fees,
},
timestamp: now,
});
}
}
lastFastFee = fees.fastestFee;
// Mempool surge (>20% increase)
if (lastMempoolCount > 0) {
const change = (mempool.count - lastMempoolCount) / lastMempoolCount;
if (change > 0.2) {
events.push({
type: 'mempool_surge',
data: {
previous: lastMempoolCount,
current: mempool.count,
changePercent: (change * 100).toFixed(1),
vsizeMB: (mempool.vsize / 1_000_000).toFixed(2),
},
timestamp: now,
});
}
}
lastMempoolCount = mempool.count;
} catch (error) {
// Silent — don't crash stream on poll failure
}
return events;
}
/**
* Poll for whale transactions above a BTC threshold.
*/
export async function pollWhaleEvents(minBtc: number = 100): Promise<BTCFiEvent[]> {
const events: BTCFiEvent[] = [];
const now = new Date().toISOString();
try {
const recent = await getMempoolRecent();
const minSats = minBtc * 1e8;
for (const tx of recent.slice(0, 20)) {
const totalOut = ((tx as any).vout || []).reduce((s: number, v: any) => s + (v.value || 0), 0);
if (totalOut >= minSats) {
events.push({
type: 'whale_tx',
data: {
txid: tx.txid,
valueSats: totalOut,
valueBtc: (totalOut / 1e8).toFixed(8),
fee: tx.fee,
size: tx.size,
},
timestamp: now,
});
}
}
} catch {
// Silent
}
return events;
}
/**
* Format event as SSE string.
*/
export function formatSSE(event: BTCFiEvent): string {
return `event: ${event.type}\ndata: ${JSON.stringify(event)}\n\n`;
}
/**
* Format heartbeat as SSE string.
*/
export function formatHeartbeat(): string {
return `: heartbeat ${Date.now()}\n\n`;
}
