feat: add Kiro OAuth web, rate limiter, metrics, fingerprint, background refresh and model converter

internal/auth/kiro/metrics.go

@@ -0,0 +1,187 @@
+package kiro
+
+import (
+	"math"
+	"sync"
+	"time"
+)
+
+// TokenMetrics holds performance metrics for a single token.
+type TokenMetrics struct {
+	SuccessRate    float64   // Success rate (0.0 - 1.0)
+	AvgLatency     float64   // Average latency in milliseconds
+	QuotaRemaining float64   // Remaining quota (0.0 - 1.0)
+	LastUsed       time.Time // Last usage timestamp
+	FailCount      int       // Consecutive failure count
+	TotalRequests  int       // Total request count
+	successCount   int       // Internal: successful request count
+	totalLatency   float64   // Internal: cumulative latency
+}
+
+// TokenScorer manages token metrics and scoring.
+type TokenScorer struct {
+	mu      sync.RWMutex
+	metrics map[string]*TokenMetrics
+
+	// Scoring weights
+	successRateWeight    float64
+	quotaWeight          float64
+	latencyWeight        float64
+	lastUsedWeight       float64
+	failPenaltyMultiplier float64
+}
+
+// NewTokenScorer creates a new TokenScorer with default weights.
+func NewTokenScorer() *TokenScorer {
+	return &TokenScorer{
+		metrics:               make(map[string]*TokenMetrics),
+		successRateWeight:     0.4,
+		quotaWeight:           0.25,
+		latencyWeight:         0.2,
+		lastUsedWeight:        0.15,
+		failPenaltyMultiplier: 0.1,
+	}
+}
+
+// getOrCreateMetrics returns existing metrics or creates new ones.
+func (s *TokenScorer) getOrCreateMetrics(tokenKey string) *TokenMetrics {
+	if m, ok := s.metrics[tokenKey]; ok {
+		return m
+	}
+	m := &TokenMetrics{
+		SuccessRate:    1.0,
+		QuotaRemaining: 1.0,
+	}
+	s.metrics[tokenKey] = m
+	return m
+}
+
+// RecordRequest records the result of a request for a token.
+func (s *TokenScorer) RecordRequest(tokenKey string, success bool, latency time.Duration) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	m := s.getOrCreateMetrics(tokenKey)
+	m.TotalRequests++
+	m.LastUsed = time.Now()
+	m.totalLatency += float64(latency.Milliseconds())
+
+	if success {
+		m.successCount++
+		m.FailCount = 0
+	} else {
+		m.FailCount++
+	}
+
+	// Update derived metrics
+	if m.TotalRequests > 0 {
+		m.SuccessRate = float64(m.successCount) / float64(m.TotalRequests)
+		m.AvgLatency = m.totalLatency / float64(m.TotalRequests)
+	}
+}
+
+// SetQuotaRemaining updates the remaining quota for a token.
+func (s *TokenScorer) SetQuotaRemaining(tokenKey string, quota float64) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	m := s.getOrCreateMetrics(tokenKey)
+	m.QuotaRemaining = quota
+}
+
+// GetMetrics returns a copy of the metrics for a token.
+func (s *TokenScorer) GetMetrics(tokenKey string) *TokenMetrics {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	if m, ok := s.metrics[tokenKey]; ok {
+		copy := *m
+		return &copy
+	}
+	return nil
+}
+
+// CalculateScore computes the score for a token (higher is better).
+func (s *TokenScorer) CalculateScore(tokenKey string) float64 {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	m, ok := s.metrics[tokenKey]
+	if !ok {
+		return 1.0 // New tokens get a high initial score
+	}
+
+	// Success rate component (0-1)
+	successScore := m.SuccessRate
+
+	// Quota component (0-1)
+	quotaScore := m.QuotaRemaining
+
+	// Latency component (normalized, lower is better)
+	// Using exponential decay: score = e^(-latency/1000)
+	// 1000ms latency -> ~0.37 score, 100ms -> ~0.90 score
+	latencyScore := math.Exp(-m.AvgLatency / 1000.0)
+	if m.TotalRequests == 0 {
+		latencyScore = 1.0
+	}
+
+	// Last used component (prefer tokens not recently used)
+	// Score increases as time since last use increases
+	timeSinceUse := time.Since(m.LastUsed).Seconds()
+	// Normalize: 60 seconds -> ~0.63 score, 0 seconds -> 0 score
+	lastUsedScore := 1.0 - math.Exp(-timeSinceUse/60.0)
+	if m.LastUsed.IsZero() {
+		lastUsedScore = 1.0
+	}
+
+	// Calculate weighted score
+	score := s.successRateWeight*successScore +
+		s.quotaWeight*quotaScore +
+		s.latencyWeight*latencyScore +
+		s.lastUsedWeight*lastUsedScore
+
+	// Apply consecutive failure penalty
+	if m.FailCount > 0 {
+		penalty := s.failPenaltyMultiplier * float64(m.FailCount)
+		score = score * math.Max(0, 1.0-penalty)
+	}
+
+	return score
+}
+
+// SelectBestToken selects the token with the highest score.
+func (s *TokenScorer) SelectBestToken(tokens []string) string {
+	if len(tokens) == 0 {
+		return ""
+	}
+	if len(tokens) == 1 {
+		return tokens[0]
+	}
+
+	bestToken := tokens[0]
+	bestScore := s.CalculateScore(tokens[0])
+
+	for _, token := range tokens[1:] {
+		score := s.CalculateScore(token)
+		if score > bestScore {
+			bestScore = score
+			bestToken = token
+		}
+	}
+
+	return bestToken
+}
+
+// ResetMetrics clears all metrics for a token.
+func (s *TokenScorer) ResetMetrics(tokenKey string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	delete(s.metrics, tokenKey)
+}
+
+// ResetAllMetrics clears all stored metrics.
+func (s *TokenScorer) ResetAllMetrics() {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.metrics = make(map[string]*TokenMetrics)
+}