补充实现细节

pkg/core/backend.go

@@ -1,23 +1,32 @@
 package core
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
+	"log/slog"
 	"net/http"
 	"os"
+	"strconv"
 	"time"
 
 	"code.d7z.net/d7z-project/gitea-pages/pkg/utils"
 )
 
+type BranchInfo struct {
+	ID           string    `json:"id"`
+	LastModified time.Time `json:"last_modified"`
+}
+
 type Backend interface {
 	// Repos return repo name + default branch
 	Repos(owner string) (map[string]string, error)
 	// Branches return branch + commit id
-	Branches(owner, repo string) (map[string]string, error)
+	Branches(owner, repo string) (map[string]*BranchInfo, error)
 	// Open return file or error
-	Open(client *http.Client, owner, repo, commit, path string, headers map[string]string) (*http.Response, error)
+	Open(client *http.Client, owner, repo, commit, path string, headers http.Header) (*http.Response, error)
 }
 
 type CacheBackend struct {
@@ -60,8 +69,8 @@ func (c *CacheBackend) Repos(owner string) (map[string]string, error) {
 	return ret, nil
 }
 
-func (c *CacheBackend) Branches(owner, repo string) (map[string]string, error) {
-	ret := make(map[string]string)
+func (c *CacheBackend) Branches(owner, repo string) (map[string]*BranchInfo, error) {
+	ret := make(map[string]*BranchInfo)
 	key := fmt.Sprintf("branches/%s/%s", owner, repo)
 	data, err := c.config.Get(key)
 	if err != nil {
@@ -90,6 +99,72 @@ func (c *CacheBackend) Branches(owner, repo string) (map[string]string, error) {
 	return ret, nil
 }
 
-func (c *CacheBackend) Open(client *http.Client, owner, repo, commit, path string, headers map[string]string) (*http.Response, error) {
+func (c *CacheBackend) Open(client *http.Client, owner, repo, commit, path string, headers http.Header) (*http.Response, error) {
 	return c.backend.Open(client, owner, repo, commit, path, headers)
 }
+
+type CacheBackendBlobReader struct {
+	client  *http.Client
+	cache   utils.Cache
+	base    Backend
+	maxSize int
+}
+
+func NewCacheBackendBlobReader(client *http.Client, base Backend, cache utils.Cache, maxCacheSize int) *CacheBackendBlobReader {
+	return &CacheBackendBlobReader{client: client, base: base, cache: cache, maxSize: maxCacheSize}
+}
+
+func (c *CacheBackendBlobReader) Open(owner, repo, commit, path string) (io.ReadCloser, error) {
+	key := fmt.Sprintf("%s/%s/%s%s", owner, repo, commit, path)
+	lastCache, err := c.cache.Get(key)
+	if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return nil, err
+	} else if lastCache == nil && err == nil {
+		// 边界缓存
+		return nil, os.ErrNotExist
+	} else if lastCache != nil {
+		return lastCache, nil
+	}
+	open, err := c.base.Open(c.client, owner, repo, commit, path, http.Header{})
+	if err != nil {
+		if open != nil {
+			if open.StatusCode == http.StatusNotFound {
+				// 缓存 404 路由
+				_ = c.cache.Put(key, nil)
+			}
+			_ = open.Body.Close()
+		}
+		return nil, errors.Join(err, os.ErrNotExist)
+	}
+
+	lastMod, err := time.Parse(http.TimeFormat, open.Header.Get("Last-Modified"))
+	if err != nil {
+		// 无时间，跳过
+		return open.Body, nil
+	}
+	// 没法计算大小，跳过
+	lengthStr := open.Header.Get("Content-Length")
+	if lengthStr == "" {
+		return open.Body, nil
+	}
+	length, err := strconv.Atoi(lengthStr)
+	if err != nil || length > c.maxSize {
+		// 超过最大大小，跳过
+		return open.Body, err
+	}
+	defer open.Body.Close()
+	allBytes, err := io.ReadAll(open.Body)
+	if err != nil {
+		return nil, err
+	}
+	if err = c.cache.Put(key, bytes.NewBuffer(allBytes)); err != nil {
+		slog.Warn("缓存归档失败", "error", err)
+	}
+	return &utils.CacheContent{
+		ReadSeekCloser: utils.NopCloser{
+			ReadSeeker: bytes.NewReader(allBytes),
+		},
+		LastModified: lastMod,
+		Length:       length,
+	}, nil
+}