// Copyright 2025 linux.do
// Copyright 2026 Arctel.net
// SPDX-License-Identifier: Apache-2.0

package upload

import (
	"archive/zip"
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"net/url"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/Rain-kl/Wavelet/internal/apps/oauth"
	"github.com/Rain-kl/Wavelet/internal/common"
	"github.com/Rain-kl/Wavelet/internal/db"
	"github.com/Rain-kl/Wavelet/internal/db/idgen"
	"github.com/Rain-kl/Wavelet/internal/logger"
	"github.com/Rain-kl/Wavelet/internal/model"
	"github.com/Rain-kl/Wavelet/internal/storage"
	"github.com/Rain-kl/Wavelet/internal/util"
	"github.com/gin-gonic/gin"
	"gorm.io/gorm"
)

type batchDownloadRequest struct {
	IDs []string `json:"ids" binding:"required,min=1"`
}

// UploadFile 通用上传文件接口
// @Summary 上传文件
// @Description 支持各种类型的通用文件上传，支持自动文件类型检测、哈希计算与“秒传”去重
// @Tags upload
// @Accept multipart/form-data
// @Produce json
// @Param file formData file true "要上传的文件"
// @Param type formData string false "业务分类 (例如: avatar, attachment, doc，默认为 generic)"
// @Param metadata formData string false "额外的 JSON 格式元数据"
// @Security SessionCookie
// @Success 200 {object} util.ResponseAny{data=model.Upload} "上传成功"
// @Failure 400 {object} util.ResponseAny "请求参数错误或文件受限"
// @Failure 401 {object} util.ResponseAny "未登录"
// @Failure 500 {object} util.ResponseAny "内部错误"
// @Router /api/v1/upload [post]
//
//nolint:revive
func UploadFile(c *gin.Context) {
	c.Header("X-Content-Type-Options", "nosniff")
	c.Header("Content-Security-Policy", "sandbox")

	// 限制请求体大小以防止 DoS
	c.Request.Body = http.MaxBytesReader(c.Writer, c.Request.Body, maxUploadSize)

	currUser, _ := util.GetFromContext[*model.User](c, oauth.UserObjKey)
	ctx := c.Request.Context()

	header, err := c.FormFile("file")
	if err != nil {
		c.JSON(http.StatusOK, util.Err(ErrNoFileSelected))
		return
	}

	file, err := header.Open()
	if err != nil {
		c.JSON(http.StatusOK, util.Err(ErrOpenFileFailed))
		return
	}
	defer func() { _ = file.Close() }()

	// 校验大小
	if header.Size > maxUploadSize {
		c.JSON(http.StatusOK, util.Err(ErrGenericFileTooLarge))
		return
	}

	// 2. 提取文件基本元数据
	origName := header.Filename
	ext := strings.ToLower(strings.TrimPrefix(filepath.Ext(origName), "."))
	if ext == "" {
		ext = "bin"
	}

	// 3. 校验文件后缀是否在允许的系统配置列表中
	if errMsg := validateUploadExtension(ctx, ext); errMsg != "" {
		c.JSON(http.StatusOK, util.Err(errMsg))
		return
	}

	// 4. 读取文件并计算 Hash
	hashWriter := sha256.New()
	var buf bytes.Buffer
	size, err := io.Copy(&buf, io.TeeReader(file, hashWriter))
	if err != nil {
		c.JSON(http.StatusOK, util.Err(ErrProcessFileFailed))
		return
	}

	fileHash := hex.EncodeToString(hashWriter.Sum(nil))
	mimeType := detectMimeType(&buf, header, size)

	// 校验真实 MIME Type 是否与常见图片扩展名匹配，防止 Polyglot / HTML 注入攻击
	if isImageExtension(ext) && !strings.HasPrefix(mimeType, "image/") {
		c.JSON(http.StatusOK, util.Err(ErrFileContentExtensionMismatch))
		return
	}

	uploadType := c.DefaultPostForm("type", "generic")

	accessModeStr := c.PostForm("access_mode")
	var accessMode int
	if accessModeStr == "" {
		if uploadType == "avatar" {
			accessMode = 1
		} else {
			accessMode = 0
		}
	} else {
		var err error
		accessMode, err = strconv.Atoi(accessModeStr)
		if err != nil || (accessMode != 0 && accessMode != 1) {
			c.JSON(http.StatusOK, util.Err("无效的 access_mode 参数"))
			return
		}
	}

	// 6. 秒传匹配校验：校验数据库中是否存在相同 Hash 且大小一致的可用文件
	handled, lookupErr := tryInstantUpload(ctx, c, currUser, fileHash, size, mimeType, ext, origName, accessMode)
	if handled {
		return
	}
	if lookupErr != nil && !errors.Is(lookupErr, gorm.ErrRecordNotFound) {
		c.JSON(http.StatusOK, util.Err(ErrFileValidationFailed))
		return
	}

	// 7. 解析可选元数据字段
	meta, errMsg := parseUploadMetadata(c, mimeType)
	if errMsg != "" {
		c.JSON(http.StatusOK, util.Err(errMsg))
		return
	}

	id := idgen.NextUint64ID()
	subPath := fmt.Sprintf("uploads/%s/%d.%s", time.Now().Format("2006/01/02"), id, ext)

	// 8. 写入当前活动存储驱动。
	storageDriver, subPath, errMsg := storeUploadFile(ctx, subPath, size, mimeType, &buf, &meta)
	if errMsg != "" {
		c.JSON(http.StatusOK, util.Err(errMsg))
		return
	}

	// 9. 保存文件记录至数据库
	newUpload := model.Upload{
		ID:            id,
		UserID:        currUser.ID,
		FileName:      origName,
		FilePath:      subPath,
		FileSize:      size,
		MimeType:      mimeType,
		Extension:     ext,
		Hash:          fileHash,
		StorageDriver: storageDriver,
		Type:          uploadType,
		Status:        model.UploadStatusUsed,
		AccessMode:    accessMode,
		Metadata:      meta,
	}

	if err := saveUploadRecord(ctx, &newUpload, storageDriver, subPath); err != "" {
		c.JSON(http.StatusOK, util.Err(err))
		return
	}

	c.JSON(http.StatusOK, util.OK(newUpload))
}

// DownloadFile 通用单文件下载接口
// @Summary 下载单文件
// @Description 根据文件 ID 获取文件，以附件形式 (Attachment) 强制开启客户端浏览器下载
// @Tags admin
// @Produce octet-stream
// @Param id path string true "文件 ID"
// @Param quality query string false "图片质量 (low, medium, high, origin)，默认为 origin"
// @Security SessionCookie
// @Success 200 {file} file "成功下载文件"
// @Failure 400 {object} util.ResponseAny "参数错误"
// @Failure 404 {object} util.ResponseAny "文件不存在"
// @Failure 500 {object} util.ResponseAny "服务内部错误"
// @Router /api/v1/admin/uploads/download/{id} [get]
func DownloadFile(c *gin.Context) {
	upload, err := getUploadRecordByID(c)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			c.AbortWithStatus(http.StatusNotFound)
			return
		}
		if _, ok := err.(*strconv.NumError); ok {
			c.JSON(http.StatusOK, util.Err(ErrInvalidFileID))
			return
		}
		c.JSON(http.StatusOK, util.Err(ErrQueryUploadRecordFailed))
		return
	}

	// 校验文件访问权限
	if err := checkFileAccessPermission(c, upload); err != nil {
		c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error_msg": common.UnAuthorized, "data": nil})
		return
	}

	fileName := upload.FileName
	quality := normalizeImageQuality(c.Query("quality"))
	isImage := strings.HasPrefix(strings.ToLower(upload.MimeType), "image/") || isImageExtension(strings.ToLower(upload.Extension))

	if quality != imageQualityOrigin && isImage {
		ext := filepath.Ext(fileName)
		if ext != "" {
			fileName = strings.TrimSuffix(fileName, ext) + ".webp"
		} else {
			fileName += ".webp"
		}
	}

	// 设置下载 Attachment 响应头 (支持 UTF-8 中文文件名转义)
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename*=UTF-8''%s", url.PathEscape(fileName)))
	ServeUpload(c, upload)
}

// BatchDownloadFiles 批量打包 ZIP 下载接口
// @Summary 批量打包下载
// @Description 传入多个文件 ID，后台实时将其打包压缩为 ZIP 流并输出，自动处理文件名重复冲突
// @Tags admin
// @Accept json
// @Produce octet-stream
// @Param request body upload.batchDownloadRequest true "包含文件 ID 数组 of string 的请求体"
// @Security SessionCookie
// @Success 200 {file} file "成功下载打包后的 ZIP"
// @Failure 400 {object} util.ResponseAny "参数错误"
// @Failure 500 {object} util.ResponseAny "打包失败"
// @Router /api/v1/admin/uploads/download/batch [post]
func BatchDownloadFiles(c *gin.Context) {
	ctx := c.Request.Context()

	var req batchDownloadRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		c.JSON(http.StatusOK, util.Err(ErrInvalidBatchDownloadRequest))
		return
	}

	// 转换 ID 列表
	var ids []uint64
	for _, idStr := range req.IDs {
		id, err := strconv.ParseUint(idStr, 10, 64)
		if err != nil {
			c.JSON(http.StatusOK, util.Err(fmt.Sprintf(ErrInvalidIDValueFormat, idStr)))
			return
		}
		ids = append(ids, id)
	}

	// 查库获取所有匹配且正常的文件记录
	var uploads []model.Upload
	if err := db.DB(ctx).Where("id IN ? AND status IN (?, ?)", ids, model.UploadStatusPending, model.UploadStatusUsed).Find(&uploads).Error; err != nil {
		c.JSON(http.StatusOK, util.Err(ErrRetrieveUploadRecordsFailed))
		return
	}

	if len(uploads) == 0 {
		c.JSON(http.StatusOK, util.Err(ErrNoValidFilesForArchive))
		return
	}

	// 设置 ZIP 格式流的响应头
	c.Header("Content-Type", "application/zip")
	c.Header("Content-Disposition", "attachment; filename=\"batch_download.zip\"")

	// 开启实时 ZIP 压缩器并直接输出给 Response Writer
	zipWriter := zip.NewWriter(c.Writer)
	defer func() { _ = zipWriter.Close() }()

	// 用于解决 ZIP 内部文件名称发生碰撞冲突的问题
	usedNames := make(map[string]int)

	for _, upload := range uploads {
		// 校验文件访问权限
		if err := checkFileAccessPermission(c, &upload); err != nil {
			logger.WarnF(ctx, "Batch download: skip file %d due to permission denied: %v", upload.ID, err)
			continue
		}

		// 校验防冲突重命名逻辑
		fileName := upload.FileName
		if count, exists := usedNames[fileName]; exists {
			usedNames[fileName] = count + 1
			ext := filepath.Ext(fileName)
			base := strings.TrimSuffix(fileName, ext)
			fileName = fmt.Sprintf("%s_%d%s", base, count, ext)
		} else {
			usedNames[fileName] = 1
		}

		// 在 ZIP 包内建新条目
		zipFileEntry, err := zipWriter.Create(fileName)
		if err != nil {
			logger.ErrorF(ctx, "ZIP 添加条目失败 [%s]: %v", fileName, err)
			continue
		}

		// 打开底层文件数据源
		var rc io.ReadCloser
		obj, err := openStoredObject(ctx, &upload)
		if err != nil {
			logger.ErrorF(ctx, "打包时读取文件失败: %v", err)
			continue
		}
		rc = obj.Body

		// 流式拷贝到 ZIP entry
		_, err = io.Copy(zipFileEntry, rc)
		_ = rc.Close()
		if err != nil {
			logger.ErrorF(ctx, "写入 ZIP 流失败: %v", err)
		}
	}
}

// validateUploadExtension 校验文件后缀是否在系统允许的上传扩展名列表中
func validateUploadExtension(ctx context.Context, ext string) string {
	var sc model.SystemConfig
	if err := sc.GetByKey(ctx, model.ConfigKeyUploadAllowedExtensions); err == nil && sc.Value != "" {
		allowedExts := strings.Split(strings.ToLower(sc.Value), ",")
		allowed := false
		for _, allowedExt := range allowedExts {
			if strings.TrimSpace(allowedExt) == ext {
				allowed = true
				break
			}
		}
		if !allowed {
			return ErrUnsupportedFormat
		}
	}
	return ""
}

// tryInstantUpload 尝试秒传：若数据库已存在相同 Hash 且大小一致的可用文件，直接生成新记录
func tryInstantUpload(ctx context.Context, c *gin.Context, currUser *model.User, fileHash string, size int64, mimeType, ext, origName string, accessMode int) (bool, error) {
	var existing model.Upload
	err := db.DB(ctx).Where("hash = ? AND file_size = ? AND status IN (?, ?)", fileHash, size, model.UploadStatusPending, model.UploadStatusUsed).First(&existing).Error
	if err != nil {
		return false, err
	}
	if storageReadOnly(ctx) {
		c.JSON(http.StatusConflict, util.Err(ErrStorageReadOnly))
		return true, nil
	}

	id := idgen.NextUint64ID()
	newUpload := model.Upload{
		ID:            id,
		UserID:        currUser.ID,
		FileName:      origName,
		FilePath:      existing.FilePath,
		FileSize:      size,
		MimeType:      mimeType,
		Extension:     ext,
		Hash:          fileHash,
		StorageDriver: existing.StorageDriver,
		Type:          c.DefaultPostForm("type", "generic"),
		Status:        model.UploadStatusUsed,
		AccessMode:    accessMode,
		Metadata:      existing.Metadata,
	}

	if err := db.DB(ctx).Create(&newUpload).Error; err != nil {
		c.JSON(http.StatusOK, util.Err(ErrSaveUploadRecordFailed))
		return true, err
	}

	logger.InfoF(ctx, "文件触发秒传成功! ID: %d, Path: %s", id, existing.FilePath)
	c.JSON(http.StatusOK, util.OK(newUpload))
	return true, nil
}

// storeUploadFile 将文件写入当前活动存储驱动。
func storeUploadFile(ctx context.Context, subPath string, size int64, mimeType string, buf *bytes.Buffer, meta *model.UploadMetadata) (string, string, string) {
	if storageReadOnly(ctx) {
		return "", "", ErrStorageReadOnly
	}
	driver, backend, err := storage.Active(ctx)
	if err != nil {
		logger.ErrorF(ctx, "初始化活动存储失败: %v", err)
		return "", "", ErrSaveFileFailed
	}
	result, err := backend.Put(ctx, subPath, bytes.NewReader(buf.Bytes()), size, mimeType)
	if err != nil {
		logger.ErrorF(ctx, "写入 %s 存储失败: %v", driver, err)
		return "", "", ErrSaveFileFailed
	}
	meta.Bucket = result.Bucket
	return string(driver), result.Key, ""
}

// isImageExtension 判断文件扩展名是否属于常见图片格式
func isImageExtension(ext string) bool {
	for _, imgExt := range []string{"jpg", "jpeg", "png", "webp", "gif"} {
		if ext == imgExt {
			return true
		}
	}
	return false
}

// parseUploadMetadata 解析上传元数据字段
func parseUploadMetadata(c *gin.Context, mimeType string) (model.UploadMetadata, string) {
	var meta model.UploadMetadata
	metadataStr := c.DefaultPostForm("metadata", "")
	if metadataStr != "" {
		if err := json.Unmarshal([]byte(metadataStr), &meta); err != nil {
			return meta, ErrInvalidMetadataJSON
		}
	}
	meta.OriginalMime = mimeType
	meta.UserAgent = c.Request.UserAgent()
	meta.ClientIP = c.ClientIP()
	return meta, ""
}

// detectMimeType 检测文件的 MIME 类型，优先使用 Content-Type 头部信息
func detectMimeType(buf *bytes.Buffer, header *multipart.FileHeader, size int64) string {
	mimeType := http.DetectContentType(buf.Bytes()[:min(detectContentBytes, int(size))])
	if mimeType == "application/octet-stream" && header.Header.Get("Content-Type") != "" {
		mimeType = header.Header.Get("Content-Type")
	}
	return mimeType
}

// saveUploadRecord 保存上传记录到数据库，失败时清理本地垃圾文件
func saveUploadRecord(ctx context.Context, upload *model.Upload, storageDriver, filePath string) string {
	if err := db.DB(ctx).Create(upload).Error; err != nil {
		backend, backendErr := storage.ForDriver(ctx, storage.Driver(storageDriver))
		if backendErr == nil {
			if deleteErr := backend.Delete(ctx, filePath); deleteErr != nil {
				logger.WarnF(ctx, "清理未写入数据库的上传对象失败: %v", deleteErr)
			}
		}
		return ErrSaveUploadRecordFailed
	}
	return ""
}