From 8a262a15d5d53568e18171c8926f8d49ca9bd784 Mon Sep 17 00:00:00 2001
From: HFO4 <912394456@qq.com>
Date: Tue, 31 Dec 2019 13:09:26 +0800
Subject: [PATCH] Modify: Decide whether to redirect when previewing based on
 storage policy

---
 models/migration.go               |   1 +
 models/policy.go                  |   6 ++
 pkg/filesystem/file.go            | 103 ++++++++++++++++++++++--------
 pkg/filesystem/remote/handler.go  |  44 ++++++++++++-
 pkg/filesystem/response/common.go |   4 +-
 routers/controllers/file.go       |   2 +
 service/explorer/file.go          |  18 ++++--
 7 files changed, 144 insertions(+), 34 deletions(-)

diff --git a/models/migration.go b/models/migration.go
index 12b73c7..f1d87f2 100644
--- a/models/migration.go
+++ b/models/migration.go
@@ -102,6 +102,7 @@ solid #e9e9e9;"bgcolor="#fff"><tbody><tr style="font-family: 'Helvetica Neue',He
 		{Name: "oss_timeout", Value: `3600`, Type: "timeout"},
 		{Name: "archive_timeout", Value: `30`, Type: "timeout"},
 		{Name: "download_timeout", Value: `30`, Type: "timeout"},
+		{Name: "preview_timeout", Value: `60`, Type: "timeout"},
 		{Name: "doc_preview_timeout", Value: `60`, Type: "timeout"},
 		{Name: "upload_credential_timeout", Value: `1800`, Type: "timeout"},
 		{Name: "upload_session_timeout", Value: `86400`, Type: "timeout"},
diff --git a/models/policy.go b/models/policy.go
index 78ffae9..e05080e 100644
--- a/models/policy.go
+++ b/models/policy.go
@@ -67,6 +67,12 @@ func GetPolicyByID(ID interface{}) (Policy, error) {
 	return policy, result.Error
 }
 
+// IsDirectlyPreview 返回此策略下文件是否可以直接预览（不需要重定向）
+// TODO 测试
+func (policy *Policy) IsDirectlyPreview() bool {
+	return policy.Type == "local"
+}
+
 // AfterFind 找到存储策略后的钩子
 func (policy *Policy) AfterFind() (err error) {
 	// 解析存储策略设置到OptionsSerialized
diff --git a/pkg/filesystem/file.go b/pkg/filesystem/file.go
index 81967ad..ae19daa 100644
--- a/pkg/filesystem/file.go
+++ b/pkg/filesystem/file.go
@@ -87,6 +87,48 @@ func (fs *FileSystem) GetPhysicalFileContent(ctx context.Context, path string) (
 	return fs.withSpeedLimit(rs), nil
 }
 
+// Preview 预览文件
+// TODO 测试
+func (fs *FileSystem) Preview(ctx context.Context, path string) (*response.ContentResponse, error) {
+	err := fs.resetFileIfNotExist(ctx, path)
+	if err != nil {
+		return nil, err
+	}
+
+	// 是否直接返回文件内容
+	if fs.Policy.IsDirectlyPreview() {
+		resp, err := fs.GetDownloadContent(ctx, path)
+		if err != nil {
+			return nil, err
+		}
+		return &response.ContentResponse{
+			Redirect: false,
+			Content:  resp,
+		}, nil
+	}
+	// 否则重定向到签名的预览URL
+	ttl, err := strconv.ParseInt(model.GetSettingByName("preview_timeout"), 10, 64)
+	if err != nil {
+		return nil,
+			serializer.NewError(
+				serializer.CodeInternalSetting,
+				"无法获取预览地址有效期设定",
+				err,
+			)
+	}
+
+	previewURL, err := fs.signURL(ctx, &fs.FileTarget[0], ttl, false)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response.ContentResponse{
+		Redirect: true,
+		URL:      previewURL,
+	}, nil
+
+}
+
 // GetDownloadContent 获取用于下载的文件流
 func (fs *FileSystem) GetDownloadContent(ctx context.Context, path string) (response.RSCloser, error) {
 	// 获取原始文件流
@@ -109,22 +151,11 @@ func (fs *FileSystem) GetContent(ctx context.Context, path string) (response.RSC
 		return nil, err
 	}
 
-	// 找到文件
-	if len(fs.FileTarget) == 0 {
-		exist, file := fs.IsFileExist(path)
-		if !exist {
-			return nil, ErrObjectNotExist
-		}
-		fs.FileTarget = []model.File{*file}
-	}
-	ctx = context.WithValue(ctx, fsctx.FileModelCtx, fs.FileTarget[0])
-
-	// 将当前存储策略重设为文件使用的
-	fs.Policy = fs.FileTarget[0].GetPolicy()
-	err = fs.dispatchHandler()
+	err = fs.resetFileIfNotExist(ctx, path)
 	if err != nil {
 		return nil, err
 	}
+	ctx = context.WithValue(ctx, fsctx.FileModelCtx, fs.FileTarget[0])
 
 	// 获取文件流
 	rs, err := fs.Handler.Get(ctx, fs.FileTarget[0].SourceName)
@@ -186,17 +217,11 @@ func (fs *FileSystem) GroupFileByPolicy(ctx context.Context, files []model.File)
 
 // GetDownloadURL 创建文件下载链接, timeout 为数据库中存储过期时间的字段
 func (fs *FileSystem) GetDownloadURL(ctx context.Context, path string, timeout string) (string, error) {
-	var fileTarget *model.File
-	// 找到文件
-	if len(fs.FileTarget) == 0 {
-		exist, file := fs.IsFileExist(path)
-		if !exist {
-			return "", ErrObjectNotExist
-		}
-		fileTarget = file
-	} else {
-		fileTarget = &fs.FileTarget[0]
+	err := fs.resetFileIfNotExist(ctx, path)
+	if err != nil {
+		return "", err
 	}
+	fileTarget := &fs.FileTarget[0]
 
 	// 生成下載地址
 	ttl, err := strconv.ParseInt(model.GetSettingByName(timeout), 10, 64)
@@ -251,9 +276,7 @@ func (fs *FileSystem) signURL(ctx context.Context, file *model.File, ttl int64,
 	fs.FileTarget = []model.File{*file}
 	ctx = context.WithValue(ctx, fsctx.FileModelCtx, *file)
 
-	// 将当前存储策略重设为文件使用的
-	fs.Policy = file.GetPolicy()
-	err := fs.dispatchHandler()
+	err := fs.resetPolicyToFirstFile(ctx)
 	if err != nil {
 		return "", err
 	}
@@ -268,3 +291,31 @@ func (fs *FileSystem) signURL(ctx context.Context, file *model.File, ttl int64,
 
 	return source, nil
 }
+
+// resetFileIfNotExist 重设当前目标文件为 path，如果当前目标为空
+func (fs *FileSystem) resetFileIfNotExist(ctx context.Context, path string) error {
+	// 找到文件
+	if len(fs.FileTarget) == 0 {
+		exist, file := fs.IsFileExist(path)
+		if !exist {
+			return ErrObjectNotExist
+		}
+		fs.FileTarget = []model.File{*file}
+	}
+
+	// 将当前存储策略重设为文件使用的
+	return fs.resetPolicyToFirstFile(ctx)
+}
+
+// resetPolicyToFirstFile 将当前存储策略重设为第一个目标文件文件使用的
+func (fs *FileSystem) resetPolicyToFirstFile(ctx context.Context) error {
+	if len(fs.FileTarget) == 0 {
+		return ErrObjectNotExist
+	}
+	fs.Policy = fs.FileTarget[0].GetPolicy()
+	err := fs.dispatchHandler()
+	if err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/pkg/filesystem/remote/handler.go b/pkg/filesystem/remote/handler.go
index 216db83..78448ae 100644
--- a/pkg/filesystem/remote/handler.go
+++ b/pkg/filesystem/remote/handler.go
@@ -3,9 +3,12 @@ package remote
 // TODO 测试
 import (
 	"context"
+	"encoding/base64"
 	"errors"
+	"fmt"
 	model "github.com/HFO4/cloudreve/models"
 	"github.com/HFO4/cloudreve/pkg/auth"
+	"github.com/HFO4/cloudreve/pkg/filesystem/fsctx"
 	"github.com/HFO4/cloudreve/pkg/filesystem/response"
 	"github.com/HFO4/cloudreve/pkg/serializer"
 	"io"
@@ -42,6 +45,7 @@ func (handler Handler) Thumb(ctx context.Context, path string) (*response.Conten
 }
 
 // Source 获取外链URL
+// TODO 测试
 func (handler Handler) Source(
 	ctx context.Context,
 	path string,
@@ -49,11 +53,47 @@ func (handler Handler) Source(
 	ttl int64,
 	isDownload bool,
 ) (string, error) {
-	return "", errors.New("暂未实现")
+	file, ok := ctx.Value(fsctx.FileModelCtx).(model.File)
+	if !ok {
+		return "", errors.New("无法获取文件记录上下文")
+	}
+
+	serverURL, err := url.Parse(handler.Policy.Server)
+	if err != nil {
+		return "", errors.New("无法解析远程服务端地址")
+	}
+
+	var (
+		expires    int64
+		signedURI  *url.URL
+		controller = "/api/v3/slave/download"
+	)
+	if !isDownload {
+		controller = "/api/v3/slave/source"
+	}
+	if ttl > 0 {
+		expires = time.Now().Unix() + ttl
+	}
+
+	// 签名下载地址
+	sourcePath := base64.RawURLEncoding.EncodeToString([]byte(file.SourceName))
+	authInstance := auth.HMACAuth{SecretKey: []byte(handler.Policy.SecretKey)}
+	signedURI, err = auth.SignURI(
+		authInstance,
+		fmt.Sprintf("%s/%s", controller, sourcePath),
+		expires,
+	)
+
+	if err != nil {
+		return "", serializer.NewError(serializer.CodeEncryptError, "无法对URL进行签名", err)
+	}
+
+	finalURL := serverURL.ResolveReference(signedURI).String()
+	return finalURL, nil
+
 }
 
 // Token 获取上传策略和认证Token
-// TODO 测试
 func (handler Handler) Token(ctx context.Context, TTL int64, key string) (serializer.UploadCredential, error) {
 	// 生成回调地址
 	siteURL := model.GetSiteURL()
diff --git a/pkg/filesystem/response/common.go b/pkg/filesystem/response/common.go
index fe95a6c..02a93bc 100644
--- a/pkg/filesystem/response/common.go
+++ b/pkg/filesystem/response/common.go
@@ -7,11 +7,11 @@ import "io"
 // 有些直接写文件数据到浏览器
 type ContentResponse struct {
 	Redirect bool
-	Content  io.ReadSeeker
+	Content  RSCloser
 	URL      string
 }
 
-// 存储策略适配器返回的文件流，有些策略需要带有Closer
+// RSCloser 存储策略适配器返回的文件流，有些策略需要带有Closer
 type RSCloser interface {
 	io.ReadSeeker
 	io.Closer
diff --git a/routers/controllers/file.go b/routers/controllers/file.go
index 2a64b01..01e2436 100644
--- a/routers/controllers/file.go
+++ b/routers/controllers/file.go
@@ -151,7 +151,9 @@ func Preview(c *gin.Context) {
 		// 是否需要重定向
 		if res.Code == -301 {
 			c.Redirect(301, res.Data.(string))
+			return
 		}
+		// 是否有错误发生
 		if res.Code != 0 {
 			c.JSON(200, res)
 		}
diff --git a/service/explorer/file.go b/service/explorer/file.go
index 588a652..20dd8b2 100644
--- a/service/explorer/file.go
+++ b/service/explorer/file.go
@@ -196,14 +196,24 @@ func (service *SingleFileService) PreviewContent(ctx context.Context, c *gin.Con
 	}
 	defer fs.Recycle()
 
-	// 获取文件流
-	rs, err := fs.GetDownloadContent(ctx, service.Path)
+	// 获取文件预览响应
+	resp, err := fs.Preview(ctx, service.Path)
 	if err != nil {
 		return serializer.Err(serializer.CodeNotSet, err.Error(), err)
 	}
-	defer rs.Close()
 
-	http.ServeContent(c.Writer, c.Request, fs.FileTarget[0].Name, fs.FileTarget[0].UpdatedAt, rs)
+	// 重定向到文件源
+	if resp.Redirect {
+		return serializer.Response{
+			Code: -301,
+			Data: resp.URL,
+		}
+	}
+
+	// 直接返回文件内容
+	defer resp.Content.Close()
+
+	http.ServeContent(c.Writer, c.Request, fs.FileTarget[0].Name, fs.FileTarget[0].UpdatedAt, resp.Content)
 
 	return serializer.Response{
 		Code: 0,