Add full monorepo: virtual-banker, backend, frontend, docs, scripts, deployment

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/mempool/fee/oracle.go

@@ -0,0 +1,95 @@
+package fee
+
+import (
+	"context"
+	"fmt"
+	"math/big"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// Oracle provides gas price estimates
+type Oracle struct {
+	db      *pgxpool.Pool
+	chainID int
+}
+
+// NewOracle creates a new fee oracle
+func NewOracle(db *pgxpool.Pool, chainID int) *Oracle {
+	return &Oracle{
+		db:      db,
+		chainID: chainID,
+	}
+}
+
+// FeeEstimate represents gas price estimates
+type FeeEstimate struct {
+	Slow     string `json:"slow"`
+	Standard string `json:"standard"`
+	Fast     string `json:"fast"`
+	Urgent   string `json:"urgent"`
+}
+
+// GetFeeEstimates gets current fee estimates
+func (o *Oracle) GetFeeEstimates(ctx context.Context) (*FeeEstimate, error) {
+	// Get recent gas prices from last 100 blocks
+	query := `
+		SELECT avg_gas_price
+		FROM gas_price_history
+		WHERE chain_id = $1
+		ORDER BY time DESC
+		LIMIT 100
+	`
+
+	rows, err := o.db.Query(ctx, query, o.chainID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to query gas prices: %w", err)
+	}
+	defer rows.Close()
+
+	var prices []int64
+	for rows.Next() {
+		var price int64
+		if err := rows.Scan(&price); err == nil {
+			prices = append(prices, price)
+		}
+	}
+
+	if len(prices) == 0 {
+		// Return default estimates if no data
+		return &FeeEstimate{
+			Slow:     "20000000000",
+			Standard: "30000000000",
+			Fast:     "50000000000",
+			Urgent:   "100000000000",
+		}, nil
+	}
+
+	// Calculate percentiles
+	p25 := percentile(prices, 0.25)
+	p50 := percentile(prices, 0.50)
+	p75 := percentile(prices, 0.75)
+	p95 := percentile(prices, 0.95)
+
+	return &FeeEstimate{
+		Slow:     big.NewInt(p25).String(),
+		Standard: big.NewInt(p50).String(),
+		Fast:     big.NewInt(p75).String(),
+		Urgent:   big.NewInt(p95).String(),
+	}, nil
+}
+
+// percentile calculates percentile of sorted slice
+func percentile(data []int64, p float64) int64 {
+	if len(data) == 0 {
+		return 0
+	}
+
+	index := int(float64(len(data)) * p)
+	if index >= len(data) {
+		index = len(data) - 1
+	}
+
+	return data[index]
+}
+