fetch_ml/internal/storage/db_metrics.go

package storage

import (
	"context"
	"fmt"
	"time"
)

// Metric represents a recorded metric from WebSocket connections
type Metric struct {
	ID         int64     `json:"id"`
	Name       string    `json:"name"`
	Value      float64   `json:"value"`
	User       string    `json:"user,omitempty"`
	RecordedAt time.Time `json:"recorded_at"`
}

// MetricSummary represents aggregated metric statistics
type MetricSummary struct {
	Name       string    `json:"name"`
	Count      int64     `json:"count"`
	Avg        float64   `json:"avg"`
	Min        float64   `json:"min"`
	Max        float64   `json:"max"`
	Sum        float64   `json:"sum"`
	StartTime  time.Time `json:"start_time"`
	EndTime    time.Time `json:"end_time"`
}

// RecordMetric records a metric to the database
func (db *DB) RecordMetric(ctx context.Context, name string, value float64, user string) error {
	if name == "" {
		return fmt.Errorf("metric name is required")
	}

	var query string
	if db.dbType == DBTypeSQLite {
		query = `INSERT INTO websocket_metrics (metric_name, metric_value, user, recorded_at)
			VALUES (?, ?, ?, ?)`
	} else {
		query = `INSERT INTO websocket_metrics (metric_name, metric_value, user, recorded_at)
			VALUES ($1, $2, $3, $4)`
	}

	_, err := db.conn.ExecContext(ctx, query, name, value, user, time.Now())
	if err != nil {
		return fmt.Errorf("failed to record metric: %w", err)
	}
	return nil
}

// GetMetrics retrieves metrics within a time range
func (db *DB) GetMetrics(ctx context.Context, start, end time.Time) ([]*Metric, error) {
	var query string
	var args []interface{}

	if db.dbType == DBTypeSQLite {
		query = `SELECT id, metric_name, metric_value, user, recorded_at 
			FROM websocket_metrics 
			WHERE recorded_at BETWEEN ? AND ?
			ORDER BY recorded_at DESC`
		args = []interface{}{start, end}
	} else {
		query = `SELECT id, metric_name, metric_value, user, recorded_at 
			FROM websocket_metrics 
			WHERE recorded_at BETWEEN $1 AND $2
			ORDER BY recorded_at DESC`
		args = []interface{}{start, end}
	}

	rows, err := db.conn.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("failed to get metrics: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var metrics []*Metric
	for rows.Next() {
		var m Metric
		if err := rows.Scan(&m.ID, &m.Name, &m.Value, &m.User, &m.RecordedAt); err != nil {
			return nil, fmt.Errorf("failed to scan metric: %w", err)
		}
		metrics = append(metrics, &m)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating metrics: %w", err)
	}

	return metrics, nil
}

// GetMetricsByName retrieves metrics for a specific name within a time range
func (db *DB) GetMetricsByName(ctx context.Context, name string, start, end time.Time) ([]*Metric, error) {
	if name == "" {
		return nil, fmt.Errorf("metric name is required")
	}

	var query string
	var args []interface{}

	if db.dbType == DBTypeSQLite {
		query = `SELECT id, metric_name, metric_value, user, recorded_at 
			FROM websocket_metrics 
			WHERE metric_name = ? AND recorded_at BETWEEN ? AND ?
			ORDER BY recorded_at DESC`
		args = []interface{}{name, start, end}
	} else {
		query = `SELECT id, metric_name, metric_value, user, recorded_at 
			FROM websocket_metrics 
			WHERE metric_name = $1 AND recorded_at BETWEEN $2 AND $3
			ORDER BY recorded_at DESC`
		args = []interface{}{name, start, end}
	}

	rows, err := db.conn.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("failed to get metrics: %w", err)
	}
	defer func() { _ = rows.Close() }()

	var metrics []*Metric
	for rows.Next() {
		var m Metric
		if err := rows.Scan(&m.ID, &m.Name, &m.Value, &m.User, &m.RecordedAt); err != nil {
			return nil, fmt.Errorf("failed to scan metric: %w", err)
		}
		metrics = append(metrics, &m)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating metrics: %w", err)
	}

	return metrics, nil
}

// GetMetricSummary retrieves aggregated statistics for a metric within a time window
func (db *DB) GetMetricSummary(ctx context.Context, name string, window time.Duration) (*MetricSummary, error) {
	if name == "" {
		return nil, fmt.Errorf("metric name is required")
	}

	end := time.Now()
	start := end.Add(-window)

	var query string
	var args []interface{}

	if db.dbType == DBTypeSQLite {
		query = `SELECT 
			COUNT(*) as count,
			AVG(metric_value) as avg,
			MIN(metric_value) as min,
			MAX(metric_value) as max,
			SUM(metric_value) as sum
			FROM websocket_metrics 
			WHERE metric_name = ? AND recorded_at BETWEEN ? AND ?`
		args = []interface{}{name, start, end}
	} else {
		query = `SELECT 
			COUNT(*) as count,
			AVG(metric_value) as avg,
			MIN(metric_value) as min,
			MAX(metric_value) as max,
			SUM(metric_value) as sum
			FROM websocket_metrics 
			WHERE metric_name = $1 AND recorded_at BETWEEN $2 AND $3`
		args = []interface{}{name, start, end}
	}

	row := db.conn.QueryRowContext(ctx, query, args...)

	var summary MetricSummary
	summary.Name = name
	summary.StartTime = start
	summary.EndTime = end

	if err := row.Scan(&summary.Count, &summary.Avg, &summary.Min, &summary.Max, &summary.Sum); err != nil {
		return nil, fmt.Errorf("failed to get metric summary: %w", err)
	}

	return &summary, nil
}