feat: Phase 2 — Git 核心功能，go-git 克隆、SSE 进度、D3.js 图形、diff2html 查看器

services/cache.go

@@ -0,0 +1,143 @@
+package services
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// CacheCleanupResult holds the outcome of a cleanup operation.
+type CacheCleanupResult struct {
+	RemovedCount int   `json:"removed_count"`
+	FreedBytes   int64 `json:"freed_bytes"`
+	RemovedPaths []string `json:"removed_paths"`
+}
+
+type repoEntry struct {
+	name    string
+	path    string
+	modTime time.Time
+	size    int64
+}
+
+// CleanupExpiredRepos removes repos older than maxAge days from reposDir.
+func CleanupExpiredRepos(reposDir string, maxAgeDays int) (*CacheCleanupResult, error) {
+	result := &CacheCleanupResult{}
+	cutoff := time.Now().AddDate(0, 0, -maxAgeDays)
+
+	entries, err := os.ReadDir(reposDir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return result, nil
+		}
+		return nil, fmt.Errorf("read repos dir: %w", err)
+	}
+
+	for _, entry := range entries {
+		if !entry.IsDir() {
+			continue
+		}
+		info, err := entry.Info()
+		if err != nil {
+			continue
+		}
+		if info.ModTime().Before(cutoff) {
+			repoPath := filepath.Join(reposDir, entry.Name())
+			size := dirSize(repoPath)
+			if err := os.RemoveAll(repoPath); err != nil {
+				continue
+			}
+			result.RemovedCount++
+			result.FreedBytes += size
+			result.RemovedPaths = append(result.RemovedPaths, entry.Name())
+		}
+	}
+
+	return result, nil
+}
+
+// CleanupBySize removes oldest repos until total size is under maxMB.
+func CleanupBySize(reposDir string, maxMB int) (*CacheCleanupResult, error) {
+	result := &CacheCleanupResult{}
+	maxBytes := int64(maxMB) * 1024 * 1024
+
+	entries, err := os.ReadDir(reposDir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return result, nil
+		}
+		return nil, err
+	}
+
+	// Collect repo info with mod time
+	var repos []repoEntry
+	var totalSize int64
+
+	for _, entry := range entries {
+		if !entry.IsDir() {
+			continue
+		}
+		info, err := entry.Info()
+		if err != nil {
+			continue
+		}
+		repoPath := filepath.Join(reposDir, entry.Name())
+		size := dirSize(repoPath)
+		repos = append(repos, repoEntry{
+			name:    entry.Name(),
+			path:    repoPath,
+			modTime: info.ModTime(),
+			size:    size,
+		})
+		totalSize += size
+	}
+
+	if totalSize <= maxBytes {
+		return result, nil
+	}
+
+	// Sort oldest first
+	sortReposByModTime(repos)
+
+	for _, repo := range repos {
+		if totalSize <= maxBytes {
+			break
+		}
+		if err := os.RemoveAll(repo.path); err != nil {
+			continue
+		}
+		totalSize -= repo.size
+		result.RemovedCount++
+		result.FreedBytes += repo.size
+		result.RemovedPaths = append(result.RemovedPaths, repo.name)
+	}
+
+	return result, nil
+}
+
+// GetCacheStats returns current cache statistics.
+func GetCacheStats(reposDir string) (count int, totalBytes int64) {
+	entries, err := os.ReadDir(reposDir)
+	if err != nil {
+		return 0, 0
+	}
+	for _, entry := range entries {
+		if !entry.IsDir() {
+			continue
+		}
+		count++
+		totalBytes += dirSize(filepath.Join(reposDir, entry.Name()))
+	}
+	return
+}
+
+func sortReposByModTime(repos []repoEntry) {
+	for i := 0; i < len(repos); i++ {
+		for j := i + 1; j < len(repos); j++ {
+			if repos[j].modTime.Before(repos[i].modTime) {
+				repos[i], repos[j] = repos[j], repos[i]
+			}
+		}
+	}
+}