package filesystem

/*
	ArOZ Online File System Handler Wrappers
	author: tobychui

	This is a module design to do the followings
	1. Mount / Create a fs when open
	2. Provide the basic function and operations of a file system type
	3. THIS MODULE **SHOULD NOT CONTAIN** CROSS FILE SYSTEM TYPE OPERATIONS
*/

import (
	"crypto/md5"
	"encoding/hex"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	uuid "github.com/satori/go.uuid"
	"imuslab.com/arozos/mod/filesystem/abstractions/ftpfs"
	"imuslab.com/arozos/mod/filesystem/abstractions/localfs"
	sftpfs "imuslab.com/arozos/mod/filesystem/abstractions/sftpfs"
	"imuslab.com/arozos/mod/filesystem/abstractions/smbfs"
	"imuslab.com/arozos/mod/filesystem/abstractions/webdavfs"
	"imuslab.com/arozos/mod/filesystem/arozfs"
	"imuslab.com/arozos/mod/utils"
)

//Options for creating new file system handler
/*
type FileSystemOpeningOptions struct{
	Name      string `json:"name"`						//Display name of this device
	Uuid      string `json:"uuid"`						//UUID of this device, e.g. S1
	Path      string `json:"path"`						//Path for the storage root
	Access    string `json:"access,omitempty"`			//Access right, allow {readonly, readwrite}
	Hierarchy string `json:"hierarchy"`					//Folder hierarchy, allow {public, user}
	Automount bool   `json:"automount"`					//Automount this device if exists
	Filesystem string `json:"filesystem,omitempty"`		//Support {"ext4","ext2", "ext3", "fat", "vfat", "ntfs"}
	Mountdev  string `json:"mountdev,omitempty"`		//Device file (e.g. /dev/sda1)
	Mountpt  string `json:"mountpt,omitempty"`			//Device mount point (e.g. /media/storage1)
}
*/

/*
An interface for storing data related to a specific hierarchy settings.
Example like the account information of network drive,
backup mode of backup drive etc
*/
type HierarchySpecificConfig interface{}

type FileSystemAbstraction interface {
	//Fundamental Functions
	Chmod(string, os.FileMode) error
	Chown(string, int, int) error
	Chtimes(string, time.Time, time.Time) error
	Create(string) (arozfs.File, error)
	Mkdir(string, os.FileMode) error
	MkdirAll(string, os.FileMode) error
	Name() string
	Open(string) (arozfs.File, error)
	OpenFile(string, int, os.FileMode) (arozfs.File, error)
	Remove(string) error
	RemoveAll(string) error
	Rename(string, string) error
	Stat(string) (os.FileInfo, error)
	Close() error

	//Utils Functions
	VirtualPathToRealPath(string, string) (string, error)
	RealPathToVirtualPath(string, string) (string, error)
	FileExists(string) bool
	IsDir(string) bool
	Glob(string) ([]string, error)
	GetFileSize(string) int64
	GetModTime(string) (int64, error)
	WriteFile(string, []byte, os.FileMode) error
	ReadFile(string) ([]byte, error)
	ReadDir(string) ([]fs.DirEntry, error)
	WriteStream(string, io.Reader, os.FileMode) error
	ReadStream(string) (io.ReadCloser, error)
	Walk(string, filepath.WalkFunc) error
	Heartbeat() error
}

// Runtime persistence config, use to pass through startup paramters related to file system handlers
type RuntimePersistenceConfig struct {
	LocalBufferPath string
}

// System Handler for returing
type FileSystemHandler struct {
	Name                     string
	UUID                     string
	Path                     string
	Hierarchy                string
	HierarchyConfig          HierarchySpecificConfig
	ReadOnly                 bool
	RequireBuffer            bool //Set this to true if the fsh do not provide file header functions like Open() or Create(), require WriteStream() and ReadStream()
	Parentuid                string
	InitiationTime           int64
	FileSystemAbstraction    FileSystemAbstraction
	Filesystem               string
	StartOptions             FileSystemOption
	RuntimePersistenceConfig RuntimePersistenceConfig
	Closed                   bool
}

// Create a list of file system handler from the given json content
func NewFileSystemHandlersFromJSON(jsonContent []byte, runtimePersistenceConfig RuntimePersistenceConfig) ([]*FileSystemHandler, error) {
	//Generate a list of handler option from json file
	options, err := loadConfigFromJSON(jsonContent)
	if err != nil {
		return []*FileSystemHandler{}, err
	}

	resultingHandlers := []*FileSystemHandler{}
	for _, option := range options {
		thisHandler, err := NewFileSystemHandler(option, runtimePersistenceConfig)
		if err != nil {
			log.Println("[File System] Failed to create system handler for " + option.Name)
			//log.Println(err.Error())
			continue
		}
		resultingHandlers = append(resultingHandlers, thisHandler)
	}

	return resultingHandlers, nil
}

// Create a new file system handler with the given config
func NewFileSystemHandler(option FileSystemOption, RuntimePersistenceConfig RuntimePersistenceConfig) (*FileSystemHandler, error) {
	fstype := strings.ToLower(option.Filesystem)
	if inSlice([]string{"ext4", "ext2", "ext3", "fat", "vfat", "ntfs"}, fstype) || fstype == "" {
		//Check if the target fs require mounting
		if option.Automount == true {
			err := MountDevice(option.Mountpt, option.Mountdev, option.Filesystem)
			if err != nil {
				return &FileSystemHandler{}, err
			}
		}

		//Check if the path exists
		if !FileExists(option.Path) {
			return &FileSystemHandler{}, errors.New("Mount point not exists!")
		}

		//Handle Hierarchy branching
		if option.Hierarchy == "user" {
			//Create user hierarchy for this virtual device
			os.MkdirAll(filepath.ToSlash(filepath.Clean(option.Path))+"/users", 0755)
		}

		rootpath := filepath.ToSlash(filepath.Clean(option.Path)) + "/"
		return &FileSystemHandler{
			Name:                     option.Name,
			UUID:                     option.Uuid,
			Path:                     filepath.ToSlash(filepath.Clean(option.Path)) + "/",
			ReadOnly:                 option.Access == arozfs.FsReadOnly,
			RequireBuffer:            false,
			Hierarchy:                option.Hierarchy,
			HierarchyConfig:          DefaultEmptyHierarchySpecificConfig,
			InitiationTime:           time.Now().Unix(),
			FileSystemAbstraction:    localfs.NewLocalFileSystemAbstraction(option.Uuid, rootpath, option.Hierarchy, option.Access == arozfs.FsReadOnly),
			Filesystem:               fstype,
			StartOptions:             option,
			RuntimePersistenceConfig: RuntimePersistenceConfig,
			Closed:                   false,
		}, nil

	} else if fstype == "webdav" {
		//WebDAV. Create an object and mount it
		root := option.Path
		user := option.Username
		password := option.Password

		webdavfs, err := webdavfs.NewWebDAVMount(option.Uuid, option.Hierarchy, root, user, password)
		if err != nil {
			return nil, err
		}
		return &FileSystemHandler{
			Name:                  option.Name,
			UUID:                  option.Uuid,
			Path:                  option.Path,
			ReadOnly:              option.Access == arozfs.FsReadOnly,
			RequireBuffer:         true,
			Hierarchy:             option.Hierarchy,
			HierarchyConfig:       nil,
			InitiationTime:        time.Now().Unix(),
			FileSystemAbstraction: webdavfs,
			Filesystem:            fstype,
			StartOptions:          option,
			Closed:                false,
		}, nil
	} else if fstype == "smb" {
		//SMB. Create an object and mount it
		pathChunks := strings.Split(strings.ReplaceAll(option.Path, "\\", "/"), "/")

		if len(pathChunks) < 2 {
			log.Println("[File System] Invalid configured smb filepath: Path format not matching [ip_addr]:[port]/[root_share path]")
			return nil, errors.New("Invalid configured smb filepath: Path format not matching [ip_addr]:[port]/[root_share path]")
		}

		ipAddr := pathChunks[0]
		rootShare := strings.Join(pathChunks[1:], "/")
		user := option.Username
		password := option.Password
		smbfs, err := smbfs.NewServerMessageBlockFileSystemAbstraction(
			option.Uuid,
			option.Hierarchy,
			ipAddr,
			rootShare,
			user,
			password,
		)
		if err != nil {
			return nil, err
		}

		thisFsh := FileSystemHandler{
			Name:                  option.Name,
			UUID:                  option.Uuid,
			Path:                  option.Path,
			ReadOnly:              option.Access == arozfs.FsReadOnly,
			RequireBuffer:         false,
			Hierarchy:             option.Hierarchy,
			HierarchyConfig:       nil,
			InitiationTime:        time.Now().Unix(),
			FileSystemAbstraction: smbfs,
			Filesystem:            fstype,
			StartOptions:          option,
			Closed:                false,
		}

		return &thisFsh, nil
	} else if fstype == "sftp" {
		//SFTP
		pathChunks := strings.Split(strings.ReplaceAll(option.Path, "\\", "/"), "/")
		ipAddr := pathChunks[0]
		port := 22
		if strings.Contains(ipAddr, ":") {
			//Custom port defined
			ipChunks := strings.Split(ipAddr, ":")
			ipAddr = ipChunks[0]
			p, err := strconv.Atoi(ipChunks[1])
			if err == nil {
				port = p
			}
		}
		rootShare := pathChunks[1:]
		user := option.Username
		password := option.Password
		sftpfs, err := sftpfs.NewSFTPFileSystemAbstraction(
			option.Uuid,
			option.Hierarchy,
			ipAddr,
			port,
			"/"+strings.Join(rootShare, "/"),
			user,
			password,
		)
		if err != nil {
			fmt.Println(err.Error())
			return nil, err
		}

		thisFsh := FileSystemHandler{
			Name:                  option.Name,
			UUID:                  option.Uuid,
			Path:                  option.Path,
			ReadOnly:              option.Access == arozfs.FsReadOnly,
			RequireBuffer:         false,
			Hierarchy:             option.Hierarchy,
			HierarchyConfig:       nil,
			InitiationTime:        time.Now().Unix(),
			FileSystemAbstraction: sftpfs,
			Filesystem:            fstype,
			StartOptions:          option,
			Closed:                false,
		}

		return &thisFsh, nil
	} else if fstype == "ftp" {

		ftpfs, err := ftpfs.NewFTPFSAbstraction(option.Uuid, option.Hierarchy, option.Path, option.Username, option.Password)
		if err != nil {
			return nil, err
		}
		return &FileSystemHandler{
			Name:                  option.Name,
			UUID:                  option.Uuid,
			Path:                  option.Path,
			ReadOnly:              option.Access == arozfs.FsReadOnly,
			RequireBuffer:         true,
			Hierarchy:             option.Hierarchy,
			HierarchyConfig:       nil,
			InitiationTime:        time.Now().Unix(),
			FileSystemAbstraction: ftpfs,
			Filesystem:            fstype,
			StartOptions:          option,
			Closed:                false,
		}, nil

	} else if option.Filesystem == "virtual" {
		//Virtual filesystem, deprecated
		log.Println("[File System] Deprecated file system type: Virtual")
	}

	return nil, errors.New("Not supported file system: " + fstype)
}

// Check if a fsh is a network drive
func (fsh *FileSystemHandler) IsNetworkDrive() bool {
	return arozfs.IsNetworkDrive(fsh.Filesystem)
}

// Check if a fsh is a local disk drive
func (fsh *FileSystemHandler) IsLocalDrive() bool {
	//Check if network drive
	if arozfs.IsNetworkDrive(fsh.Filesystem) {
		return false
	}

	//Check if mounted locally
	if _, err := os.Stat(fsh.Path); os.IsNotExist(err) {
		return false
	}

	return true
}

// Buffer a file to local tmp folder and return the tmp location for further processing
func (fsh *FileSystemHandler) BufferRemoteToLocal(rpath string) (string, error) {
	//Check if the remote file exists
	fsa := fsh.FileSystemAbstraction
	if !fsa.FileExists(rpath) {
		//Target file not exists
		return "", errors.New("target file not exists on remote")
	}

	//Check if the remote is a file (not support dir)
	if fsa.IsDir(rpath) {
		return "", errors.New("directory cannot be buffered to local")
	}

	//Get the tmp folder directory
	tmpdir := fsh.RuntimePersistenceConfig.LocalBufferPath
	if !utils.FileExists(tmpdir) {
		//Create the tmp dir if not exists
		os.MkdirAll(tmpdir, 0775)
	}

	//Generate a filename for the buffer file
	tmpFilename := uuid.NewV4().String()
	tmpFilepath := arozfs.ToSlash(filepath.Join(tmpdir, tmpFilename+filepath.Ext(rpath)))

	//Copy the file from remote location to local
	src, err := fsh.FileSystemAbstraction.ReadStream(rpath)
	if err != nil {
		return "", err
	}
	defer src.Close()

	dest, err := os.OpenFile(tmpFilepath, os.O_CREATE|os.O_WRONLY, 0777)
	if err != nil {
		return "", errors.New("unable to write to buffer location: " + err.Error())
	}
	defer dest.Close()

	_, err = io.Copy(dest, src)
	if err != nil {
		return "", errors.New("file buffer failed: " + err.Error())
	}

	//Return the buffered filepath on local disk
	return tmpFilepath, nil
}

func (fsh *FileSystemHandler) IsRootOf(vpath string) bool {
	return strings.HasPrefix(vpath, fsh.UUID+":")
}

func (fsh *FileSystemHandler) GetUniquePathHash(vpath string, username string) (string, error) {
	fshAbs := fsh.FileSystemAbstraction
	rpath := ""
	if strings.Contains(vpath, ":/") {
		r, err := fshAbs.VirtualPathToRealPath(vpath, username)
		if err != nil {
			return "", err
		}
		rpath = filepath.ToSlash(r)
	} else {
		//Passed in realpath as vpath.
		rpath = vpath
	}
	hash := md5.Sum([]byte(fsh.UUID + "_" + rpath))
	return hex.EncodeToString(hash[:]), nil
}

func (fsh *FileSystemHandler) GetDirctorySizeFromRealPath(rpath string, includeHidden bool) (int64, int) {
	var size int64 = 0
	var fileCount int = 0
	err := fsh.FileSystemAbstraction.Walk(rpath, func(thisFilename string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.IsDir() {
			if includeHidden {
				//append all into the file count and size
				size += info.Size()
				fileCount++
			} else {
				//Check if this is hidden
				if !IsInsideHiddenFolder(thisFilename) {
					size += info.Size()
					fileCount++
				}

			}

		}
		return nil
	})
	if err != nil {
		return 0, fileCount
	}
	return size, fileCount
}

func (fsh *FileSystemHandler) GetDirctorySizeFromVpath(vpath string, username string, includeHidden bool) (int64, int) {
	realpath, _ := fsh.FileSystemAbstraction.VirtualPathToRealPath(vpath, username)
	return fsh.GetDirctorySizeFromRealPath(realpath, includeHidden)
}

// Reload the target file system abstraction
func (fsh *FileSystemHandler) ReloadFileSystelAbstraction() error {
	log.Println("[File System] Reloading File System Abstraction for " + fsh.Name)
	//Load the start option for this fsh
	originalStartOption := fsh.StartOptions
	runtimePersistenceConfig := fsh.RuntimePersistenceConfig
	//Close the file system handler
	fsh.Close()

	//Give it a few ms to do physical disk stuffs
	time.Sleep(800 * time.Millisecond)

	//Generate a new fsh from original start option
	reloadedFsh, err := NewFileSystemHandler(originalStartOption, runtimePersistenceConfig)
	if err != nil {
		return err
	}

	//Overwrite the pointers to target fsa
	fsh.FileSystemAbstraction = reloadedFsh.FileSystemAbstraction
	fsh.Closed = false
	return nil
}

// Close an openeded File System
func (fsh *FileSystemHandler) Close() {
	//Set the close flag to true so others function wont access it
	fsh.Closed = true

	//Close the file system object
	err := fsh.FileSystemAbstraction.Close()
	if err != nil {
		log.Println("[File System]  Unable to close File System Abstraction for Handler: " + fsh.UUID + ". Skipping.")
	}
}

// Helper function
func inSlice(slice []string, val string) bool {
	for _, item := range slice {
		if item == val {
			return true
		}
	}
	return false
}

func FileExists(filename string) bool {
	_, err := os.Stat(filename)
	if os.IsNotExist(err) {
		return false
	}
	return true
}