From e7c6fe9851a25a4b24ea0ed7ada663ad5f9406d1 Mon Sep 17 00:00:00 2001
From: wood chen <wood@czl.net>
Date: Sun, 29 Sep 2024 00:09:18 +0800
Subject: [PATCH] =?UTF-8?q?=E8=BF=99=E4=B8=AA=E4=BF=AE=E6=94=B9=E7=89=88?=
 =?UTF-8?q?=E6=9C=AC=E7=9A=84=20pingURL=20=E5=87=BD=E6=95=B0=E6=9C=89?=
 =?UTF-8?q?=E4=BB=A5=E4=B8=8B=E6=94=B9=E8=BF=9B=EF=BC=9A?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

如果无法获取 ETag，尝试使用 Last-Modified 头部信息。
如果 ETag 和 Last-Modified 都不可用，使用一个基于 URL 和当前时间的回退标识符。
在出现错误或意外状态码时，也使用回退标识符。
增加了更详细的日志记录，有助于问题诊断。
---
 handler/remote.go | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/handler/remote.go b/handler/remote.go
index a8ee679..be377aa 100644
--- a/handler/remote.go
+++ b/handler/remote.go
@@ -121,22 +121,36 @@ func fetchRemoteImg(url string, subdir string) config.MetaFile {
 }
 
 func pingURL(url string) string {
-	// this function will try to return identifiable info, currently include etag, content-length as string
-	// anything goes wrong, will return ""
 	var etag, length string
 	resp, err := http.Head(url)
 	if err != nil {
-		log.Errorln("Connection to remote error when pingUrl!")
-		return ""
+			log.Errorf("Connection to remote error when pingUrl: %v", err)
+			return generateFallbackIdentifier(url)
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode == fiber.StatusOK {
-		etag = resp.Header.Get("etag")
-		length = resp.Header.Get("content-length")
-	}
-	if etag == "" {
-		log.Info("Remote didn't return etag in header when getRemoteImageInfo, please check.")
+			etag = resp.Header.Get("ETag")
+			length = resp.Header.Get("Content-Length")
+			
+			if etag == "" {
+					log.Warn("Remote didn't return ETag in header, using Last-Modified if available")
+					etag = resp.Header.Get("Last-Modified")
+			}
+			
+			if etag == "" {
+					log.Warn("Neither ETag nor Last-Modified available, using fallback identifier")
+					etag = generateFallbackIdentifier(url)
+			}
+	} else {
+			log.Warnf("Unexpected status code: %d when pinging URL: %s", resp.StatusCode, url)
+			return generateFallbackIdentifier(url)
 	}
+
 	return etag + length
 }
+
+func generateFallbackIdentifier(url string) string {
+	// 使用 URL 和当前时间生成一个唯一标识符
+	return "fallback-" + helper.HashString(url + time.Now().String())
+}