package api

import (
	"crypto/rand"
	"encoding/hex"
	"errors"
	"io"
	"mime"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"eai_agentplatform/backend/internal/dal"
	"eai_agentplatform/backend/internal/middleware"
	"eai_agentplatform/backend/internal/model"
	"eai_agentplatform/backend/internal/web"
)

// 团队共享网盘：全公司共享一套目录与文件，company_id 固定为 1（单公司平台）。
const netdiskCompanyID = 1

// 目录 path 合法性相关常量（对齐 pj0034 asset_folder 红线）。
// 不可删除/改名的 system folder：根目录 `/`。
const netdiskRootPath = "/"

func init() {
	netdiskFolderDAO = dal.NetdiskFolderDAO{}
	netdiskFileDAO = dal.NetdiskFileDAO{}
}

var (
	netdiskFolderDAO dal.NetdiskFolderDAO
	netdiskFileDAO   dal.NetdiskFileDAO
)

// netdiskRoot 返回网盘物理存储根目录（不存在则创建）。
func netdiskRoot() string {
	dir := Cfg.NetdiskDataDir
	if dir == "" {
		dir = filepath.Join("data", "netdisk")
	}
	_ = os.MkdirAll(dir, 0o755)
	return dir
}

// netdiskFilePath 由 StoredName 得到物理绝对路径。
func netdiskFilePath(storedName string) string {
	return filepath.Join(netdiskRoot(), filepath.Base(storedName))
}

// ────────────────────────────────────────────────────────────
// 目录 path 工具（参考 pj0034 app/services/dam/folder.py）
// ────────────────────────────────────────────────────────────

var netdiskInvalidSegChars = func() func(r rune) bool {
	invalid := "\\:*?\"<>|"
	return func(r rune) bool { return strings.ContainsRune(invalid, r) }
}()

// netdiskNormalizePath 规范化：去尾 `/`、压缩多 `/`、去段内空白；返 `/` 起的绝对路径。
func netdiskNormalizePath(raw string) string {
	s := strings.TrimSpace(strings.ReplaceAll(raw, "\\", "/"))
	if s == "" {
		return "/"
	}
	if !strings.HasPrefix(s, "/") {
		s = "/" + s
	}
	for strings.Contains(s, "//") {
		s = strings.ReplaceAll(s, "//", "/")
	}
	if len(s) > 1 {
		s = strings.TrimRight(s, "/")
	}
	return s
}

// netdiskValidatePath 校验并返回规范化 path；不合法返回错误。
func netdiskValidatePath(raw string) (string, error) {
	if strings.TrimSpace(raw) == "" {
		return "", errors.New("目录路径不能为空")
	}
	p := netdiskNormalizePath(raw)
	for _, seg := range strings.Split(p, "/") {
		if seg == "" {
			continue
		}
		if seg == "." || seg == ".." {
			return "", errors.New("目录路径不允许 '.' 或 '..'")
		}
		if strings.ContainsFunc(seg, netdiskInvalidSegChars) {
			return "", errors.New("目录名含非法字符 \\ : * ? \" < > |")
		}
		if len(seg) > 100 {
			return "", errors.New("目录名「" + seg + "」超 100 字符")
		}
	}
	if len(p) > 500 {
		return "", errors.New("目录路径总长超 500 字符")
	}
	return p, nil
}

// netdiskIsRoot 是否根目录（system folder，不可删/改名）。
func netdiskIsRoot(path string) bool {
	return netdiskNormalizePath(path) == netdiskRootPath
}

// netdiskDeriveDisplayName 由 path 末段派生显示名。
func netdiskDeriveDisplayName(path string) string {
	p := netdiskNormalizePath(path)
	if p == "/" {
		return "/"
	}
	segs := strings.Split(p, "/")
	return segs[len(segs)-1]
}

// netdiskReplacePrefix 把老前缀整体替换为新前缀（用于目录改名时联动后代）。
func netdiskReplacePrefix(path, oldPrefix, newPrefix string) string {
	if path == oldPrefix {
		return newPrefix
	}
	if strings.HasPrefix(path, oldPrefix+"/") {
		return newPrefix + path[len(oldPrefix):]
	}
	return path
}

// netdiskParentPath 返回父目录路径（根为 "/"）。
func netdiskParentPath(path string) string {
	p := netdiskNormalizePath(path)
	if p == "/" {
		return "/"
	}
	if idx := strings.LastIndex(p, "/"); idx > 0 {
		return p[:idx]
	}
	return "/"
}

// ────────────────────────────────────────────────────────────
// 目录 CRUD
// ────────────────────────────────────────────────────────────

// netdiskListFolders GET /api/netdisk/folders —— 列全部目录
func netdiskListFolders(c *gin.Context) {
	folders := netdiskFolderDAO.ListDescendants(netdiskCompanyID, "")
	web.OK(c, gin.H{"items": folders, "total": len(folders)})
}

// netdiskCreateFolder POST /api/netdisk/folders —— 新建目录 (mkdir)
func netdiskCreateFolder(c *gin.Context) {
	u := middleware.CurrentUser(c)
	var req struct {
		Path        string `json:"path"`
		DisplayName string `json:"display_name"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		web.Fail(c, web.NewBadRequest("请求参数错误"))
		return
	}
	path, err := netdiskValidatePath(req.Path)
	if err != nil {
		web.Fail(c, web.NewBadRequest(err.Error()))
		return
	}
	if netdiskIsRoot(path) {
		web.Fail(c, web.NewBadRequest("根目录已存在，无需创建"))
		return
	}
	if _, found := netdiskFolderDAO.GetByPath(netdiskCompanyID, path); found {
		web.Fail(c, web.NewBadRequest("目录「" + path + "」已存在"))
		return
	}
	name := req.DisplayName
	if name == "" {
		name = netdiskDeriveDisplayName(path)
	}
	folder := model.NetdiskFolder{
		CompanyID:   netdiskCompanyID,
		Path:        path,
		DisplayName: name,
		CreatedByID: u.ID,
		CreatedAt:   time.Now(),
	}
	if !netdiskFolderDAO.Insert(&folder) {
		web.Fail(c, web.NewBadRequest("创建目录失败"))
		return
	}
	web.OK(c, folder)
}

// netdiskPatchFolder PATCH /api/netdisk/folders/:id —— 重命名 / 移动（联动后代与文件）
func netdiskPatchFolder(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	var req struct {
		Path        *string `json:"path"`
		DisplayName *string `json:"display_name"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		web.Fail(c, web.NewBadRequest("请求参数错误"))
		return
	}
	folder, found := netdiskFolderDAO.GetByID(id)
	if !found {
		web.Fail(c, web.NewNotFoundError("目录不存在"))
		return
	}
	if netdiskIsRoot(folder.Path) {
		web.Fail(c, web.NewBadRequest("根目录不可改名或移动"))
		return
	}

	if req.Path != nil {
		newPath, err := netdiskValidatePath(*req.Path)
		if err != nil {
			web.Fail(c, web.NewBadRequest(err.Error()))
			return
		}
		if netdiskNormalizePath(newPath) == netdiskNormalizePath(folder.Path) {
			// 同名，跳过移动
		} else {
			if strings.HasPrefix(newPath+"/", folder.Path+"/") {
				web.Fail(c, web.NewBadRequest("不能把目录移动到自己的子目录下"))
				return
			}
			if _, dup := netdiskFolderDAO.GetByPath(netdiskCompanyID, newPath); dup {
				web.Fail(c, web.NewBadRequest("目标目录「" + newPath + "」已存在"))
				return
			}
			// 联动后代目录
			desc := netdiskFolderDAO.ListDescendants(netdiskCompanyID, folder.Path)
			for i := range desc {
				if desc[i].ID == folder.ID {
					continue
				}
				next := netdiskReplacePrefix(desc[i].Path, folder.Path, newPath)
				if next != desc[i].Path {
					desc[i].Path = next
					netdiskFolderDAO.Update(&desc[i])
				}
			}
			// 联动该目录下（含后代）的文件 folder_path
			netdiskMigrateFilesOnFolderMove(folder.Path, newPath)
			folder.Path = newPath
		}
	}
	if req.DisplayName != nil && strings.TrimSpace(*req.DisplayName) != "" {
		folder.DisplayName = strings.TrimSpace(*req.DisplayName)
	}
	if !netdiskFolderDAO.Update(&folder) {
		web.Fail(c, web.NewBadRequest("更新目录失败"))
		return
	}
	web.OK(c, folder)
}

// netdiskMigrateFilesOnFolderMove 目录改名/移动后，把落在该目录及其后代的文件 folder_path 同步改前缀。
func netdiskMigrateFilesOnFolderMove(oldPrefix, newPrefix string) {
	// 取所有未被回收站软删的文件，逐个修正前缀。
	folders := netdiskFolderDAO.ListDescendants(netdiskCompanyID, "")
	affected := map[string]bool{}
	for _, f := range folders {
		if f.Path == oldPrefix || strings.HasPrefix(f.Path, oldPrefix+"/") {
			affected[f.Path] = true
		}
	}
	if len(affected) == 0 {
		return
	}
	var files []model.NetdiskFile
	var all []model.NetdiskFile
	dal.New(&all).Find(&all)
	for i := range all {
		nf := all[i]
		if nf.CompanyID != netdiskCompanyID || nf.DeletedAt != nil {
			continue
		}
		next := netdiskReplacePrefix(nf.FolderPath, oldPrefix, newPrefix)
		if next != nf.FolderPath {
			nf.FolderPath = next
			files = append(files, nf)
		}
	}
	for i := range files {
		netdiskFileDAO.Update(&files[i])
	}
}

// netdiskDeleteFolder DELETE /api/netdisk/folders/:id —— 删除空目录（非空 409）
func netdiskDeleteFolder(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	folder, found := netdiskFolderDAO.GetByID(id)
	if !found {
		web.Fail(c, web.NewNotFoundError("目录不存在"))
		return
	}
	if netdiskIsRoot(folder.Path) {
		web.Fail(c, web.NewBadRequest("根目录不可删除"))
		return
	}
	if children := netdiskFolderDAO.CountChildren(netdiskCompanyID, folder.Path); children > 0 {
		web.Fail(c, web.NewBadRequest("该目录下还有子目录，请先清空再删除"))
		return
	}
	// 统计该目录下非回收站文件数
	cnt := netdiskCountLiveFilesUnder(folder.Path)
	if cnt > 0 {
		web.Fail(c, web.NewBadRequest("该目录下还有 "+strconv.FormatInt(cnt, 10)+" 个文件，请先移走或删除"))
		return
	}
	if !netdiskFolderDAO.Delete(id) {
		web.Fail(c, web.NewBadRequest("删除失败"))
		return
	}
	web.OK(c, gin.H{"deleted": id})
}

// netdiskCountLiveFilesUnder 统计某目录（含后代路径）下未软删除的文件数。
func netdiskCountLiveFilesUnder(folderPath string) int64 {
	var all []model.NetdiskFile
	dal.New(&all).Find(&all)
	var n int64
	for _, f := range all {
		if f.CompanyID != netdiskCompanyID || f.DeletedAt != nil {
			continue
		}
		if f.FolderPath == folderPath {
			n++
		}
	}
	return n
}

// ────────────────────────────────────────────────────────────
// 文件：列表 / 上传
// ────────────────────────────────────────────────────────────

// netdiskListFiles GET /api/netdisk/files?path=&status= —— 列某目录文件（默认只看 approved）
func netdiskListFiles(c *gin.Context) {
	path := c.DefaultQuery("path", "/")
	norm := netdiskNormalizePath(path)
	status := c.DefaultQuery("status", "approved")
	files := netdiskFileDAO.ListByFolder(netdiskCompanyID, norm, status)
	web.OK(c, gin.H{"items": files, "total": len(files), "path": norm})
}

var blockedNetdiskExt = map[string]bool{
	"exe": true, "bin": true, "dll": true, "so": true, "dylib": true,
	"msi": true, "apk": true, "ipa": true, "deb": true, "rpm": true, "pkg": true, "appimage": true,
	"bat": true, "cmd": true, "com": true, "scr": true, "sys": true, "drv": true,
	"ps1": true, "psm1": true, "vbs": true, "vbe": true, "js": true, "jse": true, "wsf": true, "wsh": true,
	"reg": true, "lnk": true, "iso": true, "img": true, "dmg": true,
}

func netdiskIsUploadable(ext string) bool {
	return !blockedNetdiskExt[strings.ToLower(strings.TrimPrefix(ext, "."))]
}

func netdiskSizeLimit(ext string) int64 {
	ext = strings.ToLower(strings.TrimPrefix(ext, "."))
	switch ext {
	case "mp4", "mov", "avi", "mkv", "webm", "m4v", "wmv", "flv":
		return Cfg.FileMaxVideo
	default:
		return Cfg.FileMaxDoc
	}
}

func netdiskRandomID() string {
	b := make([]byte, 16)
	if _, err := rand.Read(b); err != nil {
		return strconv.FormatInt(time.Now().UnixNano(), 36)
	}
	return hex.EncodeToString(b)
}

// netdiskUpload POST /api/netdisk/upload —— 直传
func netdiskUpload(c *gin.Context) {
	u := middleware.CurrentUser(c)
	folderPath := netdiskNormalizePath(c.PostForm("folder_path"))
	if _, err := netdiskValidatePath(folderPath); err != nil {
		folderPath = "/"
	}
	// 若指定了不存在的目录，回退根目录
	if folderPath != "/" {
		if _, ok := netdiskFolderDAO.GetByPath(netdiskCompanyID, folderPath); !ok {
			folderPath = "/"
		}
	}

	file, header, err := c.Request.FormFile("file")
	if err != nil {
		web.Fail(c, web.NewBadRequest("缺少文件字段 file"))
		return
	}
	defer file.Close()

	ext := strings.ToLower(strings.TrimPrefix(filepath.Ext(header.Filename), "."))
	if !netdiskIsUploadable(ext) {
		web.Fail(c, web.NewBadRequest("不支持的文件类型"))
		return
	}
	if header.Size > netdiskSizeLimit(ext) {
		web.Fail(c, web.NewBadRequest("文件超过大小限制"))
		return
	}

	source := "employee"
	status := "pending"
	if u.Role == "admin" {
		source = "admin"
		status = "approved" // 管理员上传自动通过
	}

	storedName := netdiskRandomID() + "." + ext
	dst := filepath.Join(netdiskRoot(), storedName)
	out, err := os.Create(dst)
	if err != nil {
		web.Fail(c, web.NewBadRequest("保存文件失败"))
		return
	}
	if _, err := io.Copy(out, file); err != nil {
		out.Close()
		os.Remove(dst)
		web.Fail(c, web.NewBadRequest("写入文件失败"))
		return
	}
	out.Close()

	m := model.NetdiskFile{
		CompanyID:   netdiskCompanyID,
		FolderPath:  folderPath,
		Filename:    header.Filename,
		StoredName:  storedName,
		FileExt:     ext,
		MimeType:    mime.TypeByExtension("." + ext),
		FileSize:    header.Size,
		Status:      status,
		Source:      source,
		SubmitterID: u.ID,
		CreatedAt:   time.Now(),
	}
	if !netdiskFileDAO.Insert(&m) {
		os.Remove(dst)
		web.Fail(c, web.NewBadRequest("创建文件记录失败"))
		return
	}
	web.OK(c, gin.H{"file_id": m.ID, "status": m.Status, "filename": m.Filename})
}

// netdiskDownload GET /api/netdisk/files/:id/download —— 下载（仅 approved）
func netdiskDownload(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	f, found := netdiskFileDAO.GetByID(id)
	if !found {
		web.Fail(c, web.NewNotFoundError("文件不存在"))
		return
	}
	if f.Status != "approved" {
		web.Fail(c, web.NewForbiddenError("文件未通过审批，不可下载"))
		return
	}
	c.FileAttachment(netdiskFilePath(f.StoredName), f.Filename)
}

// netdiskPreview GET /api/netdisk/files/:id/preview —— 在线预览（仅 approved）
func netdiskPreview(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	f, found := netdiskFileDAO.GetByID(id)
	if !found {
		web.Fail(c, web.NewNotFoundError("文件不存在"))
		return
	}
	if f.Status != "approved" {
		web.Fail(c, web.NewForbiddenError("文件未通过审批，不可预览"))
		return
	}
	web.OK(c, gin.H{
		"preview_url": "/netdisk-file/" + f.StoredName,
		"file_ext":    f.FileExt,
		"mime_type":   f.MimeType,
	})
}

// netdiskRenameFile PUT /api/netdisk/files/:id/rename —— 重命名（仅改名，不移动）
func netdiskRenameFile(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	var req struct {
		Filename string `json:"filename"`
	}
	if err := c.ShouldBindJSON(&req); err != nil || strings.TrimSpace(req.Filename) == "" {
		web.Fail(c, web.NewBadRequest("文件名不能为空"))
		return
	}
	f, found := netdiskFileDAO.GetByID(id)
	if !found {
		web.Fail(c, web.NewNotFoundError("文件不存在"))
		return
	}
	if f.DeletedAt != nil {
		web.Fail(c, web.NewBadRequest("文件在回收站中"))
		return
	}
	name := strings.TrimSpace(req.Filename)
	if netdiskNormalizePath(name) == "/" || strings.Contains(name, "/") || strings.Contains(name, "\\") {
		web.Fail(c, web.NewBadRequest("文件名不合法"))
		return
	}
	f.Filename = name
	if !netdiskFileDAO.Update(&f) {
		web.Fail(c, web.NewBadRequest("重命名失败"))
		return
	}
	web.OK(c, f)
}

// netdiskMoveFile PUT /api/netdisk/files/:id/move —— 移动到目标目录
func netdiskMoveFile(c *gin.Context) {
	id, ok := parseID(c, "id")
	if !ok {
		return
	}
	var req struct {
		FolderPath string `json:"folder_path"`
	}
	if err := c.ShouldBindJSON(&req); err != nil {
		web.Fail(c, web.NewBadRequest("请求参数错误"))
		return
	}
	target, err := netdiskValidatePath(req.FolderPath)
	if err != nil {
		web.Fail(c, web.NewBadRequest(err.Error()))
		return
	}
	if _, found := netdiskFolderDAO.GetByPath(netdiskCompanyID, target); !found && target != "/" {
		web.Fail(c, web.NewNotFoundError("目标目录不存在"))
		return
	}
	f, found := netdiskFileDAO.GetByID(id)
	if !found {
		web.Fail(c, web.NewNotFoundError("文件不存在"))
		return
	}
	if f.DeletedAt != nil {
		web.Fail(c, web.NewBadRequest("文件在回收站中"))
		return
	}
	f.FolderPath = target
	if !netdiskFileDAO.Update(&f) {
		web.Fail(c, web.NewBadRequest("移动失败"))
		return
	}
	web.OK(c, f)
}