perf(provider): optimize HTTP client connections for Copilot requests

Author: m7medVision

internal/config/token_cache.go

@@ -0,0 +1,127 @@
+package config
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+// CopilotTokenCache holds a cached Copilot API token with expiration metadata.
+type CopilotTokenCache struct {
+	Token           string    `json:"token"`
+	ExpiresAt       time.Time `json:"expires_at"`
+	GitHubTokenHash string    `json:"github_token_hash"`
+}
+
+var (
+	memoryCache   *CopilotTokenCache
+	memoryCacheMu sync.RWMutex
+)
+
+func getCacheFilePath() string {
+	return filepath.Join(getConfigDir(), ".lazycommit.token.cache")
+}
+
+func hashToken(token string) string {
+	h := sha256.Sum256([]byte(token))
+	return hex.EncodeToString(h[:])
+}
+
+// GetCachedCopilotToken returns a valid cached token for the given GitHub token, or nil if unavailable.
+func GetCachedCopilotToken(githubToken string) *CopilotTokenCache {
+	tokenHash := hashToken(githubToken)
+
+	memoryCacheMu.RLock()
+	if memoryCache != nil &&
+		memoryCache.GitHubTokenHash == tokenHash &&
+		isTokenValid(memoryCache) {
+		cache := *memoryCache
+		memoryCacheMu.RUnlock()
+		return &cache
+	}
+	memoryCacheMu.RUnlock()
+
+	cache, err := loadCacheFromDisk()
+	if err != nil {
+		return nil
+	}
+
+	if cache.GitHubTokenHash != tokenHash || !isTokenValid(cache) {
+		return nil
+	}
+
+	memoryCacheMu.Lock()
+	memoryCache = cache
+	memoryCacheMu.Unlock()
+
+	return cache
+}
+
+// SaveCopilotTokenCache persists the token to memory and disk.
+func SaveCopilotTokenCache(token string, expiresAtUnix int64, githubToken string) error {
+	cache := &CopilotTokenCache{
+		Token:           token,
+		ExpiresAt:       time.Unix(expiresAtUnix, 0),
+		GitHubTokenHash: hashToken(githubToken),
+	}
+
+	memoryCacheMu.Lock()
+	memoryCache = cache
+	memoryCacheMu.Unlock()
+
+	return saveCacheToDisk(cache)
+}
+
+// InvalidateCopilotTokenCache clears the cached token from memory and disk.
+func InvalidateCopilotTokenCache() {
+	memoryCacheMu.Lock()
+	memoryCache = nil
+	memoryCacheMu.Unlock()
+
+	_ = os.Remove(getCacheFilePath())
+}
+
+func isTokenValid(cache *CopilotTokenCache) bool {
+	if cache == nil || cache.Token == "" {
+		return false
+	}
+	expirationBuffer := 60 * time.Second
+	return time.Now().Add(expirationBuffer).Before(cache.ExpiresAt)
+}
+
+func loadCacheFromDisk() (*CopilotTokenCache, error) {
+	data, err := os.ReadFile(getCacheFilePath())
+	if err != nil {
+		return nil, err
+	}
+
+	var cache CopilotTokenCache
+	if err := json.Unmarshal(data, &cache); err != nil {
+		return nil, err
+	}
+
+	return &cache, nil
+}
+
+func saveCacheToDisk(cache *CopilotTokenCache) error {
+	data, err := json.Marshal(cache)
+	if err != nil {
+		return fmt.Errorf("failed to marshal token cache: %w", err)
+	}
+
+	cacheDir := filepath.Dir(getCacheFilePath())
+	if err := os.MkdirAll(cacheDir, 0700); err != nil {
+		return fmt.Errorf("failed to create cache directory: %w", err)
+	}
+
+	if err := os.WriteFile(getCacheFilePath(), data, 0600); err != nil {
+		return fmt.Errorf("failed to write token cache: %w", err)
+	}
+
+	return nil
+}