package main

import(
  "compress/zlib"
  "fmt"
  "log"
  "os"
  "encoding/json"
  "syscall"
  "path/filepath"
)

// Imported from https://github.com/haiwen/seafile-server/blob/master/fileserver/fsmgr/fsmgr.go
// License AGPLv3

//SeafDir is a dir object
type DirElem struct {
  Version int           `json:"version"`
  DirType int           `json:"type,omitempty"`
  DirId   string        `json:"dir_id,omitempty"`
  Entries []*DirEnt     `json:"dirents"`
}

// SeafDirent is a dir entry object
type DirEnt struct {
  Mode     uint32 `json:"mode"`
  Id       string `json:"id"`
  Name     string `json:"name"`
  Mtime    int64  `json:"mtime"`
  Modifier string `json:"modifier"`
  Size     int64  `json:"size"`
}

type FileElem struct {
  Version  int      `json:"version"`
  FileType int      `json:"type,omitempty"`
  FileId   string   `json:"file_id,omitempty"`
  FileSize uint64   `json:"size"`
  BlkIds   []string `json:"block_ids"`
}

type DirNode struct {
  Config *configCollect
  Ent *DirEnt
  Elem DirElem
  Folders []*DirNode
  Files []*FileNode
  Parent *DirNode
  AbsolutePath string
}

type FileNode struct {
  Config *configCollect
  Ent *DirEnt
  Elem FileElem
  AbsolutePath string
}

type RepoFs struct {
  Config *configCollect
  EntryNode *DirNode
}

func NewRepoFs(config *configCollect) *RepoFs {
  rf := new(RepoFs)
  rf.Config = config
  rf.EntryNode = new(DirNode)
  rf.EntryNode.Ent = new(DirEnt)
  rf.EntryNode.Ent.Id = config.PathId
  rf.EntryNode.Ent.Name = ""
  rf.EntryNode.AbsolutePath = "/"
  rf.EntryNode.Files = make([]*FileNode,0)
  rf.EntryNode.Folders = make([]*DirNode,0)
  rf.EntryNode.Config = config

  return rf
}

func NewDirNode(parent *DirNode, ent *DirEnt) *DirNode {
  dn := new(DirNode)
  dn.Ent = ent
  dn.Config = parent.Config
  dn.Files = make([]*FileNode,0)
  dn.Folders = make([]*DirNode,0)
  dn.Parent = parent
  dn.AbsolutePath = dn.Parent.AbsolutePath + ent.Name + "/"

  return dn
}

func (dn* DirNode) String() string {
  return fmt.Sprintf("%v %v", dn.Ent.Id[:6], dn.AbsolutePath)
}

func (fn* FileNode) String() string {
  return fmt.Sprintf("%v %v", fn.Ent.Id[:6], fn.AbsolutePath)
}

func NewFileNode(parent *DirNode, ent *DirEnt) *FileNode {
  fn := new (FileNode)
  fn.Ent = ent
  fn.Config = parent.Config
  fn.AbsolutePath = parent.AbsolutePath + ent.Name

  return fn
}

func (dn* DirNode) Parse() {
  path := filepath.Join(dn.Config.Storage, "fs", dn.Config.RepoId, dn.Ent.Id[:2], dn.Ent.Id[2:])

  file, err := os.Open(path)
  if err != nil { log.Fatal(err) }
  defer file.Close()

  zfile, err := zlib.NewReader(file)
  if err != nil { log.Fatal(err) }

  jdec := json.NewDecoder(zfile)
  err = jdec.Decode(&dn.Elem)
  if err != nil { log.Fatal(err) }

  for _, el := range dn.Elem.Entries {
    if IsDir(el.Mode) {
      dn.Folders = append(dn.Folders, NewDirNode(dn, el))
    } else if IsRegular(el.Mode) {
      dn.Files = append(dn.Files, NewFileNode(dn, el))
    } else {
      log.Fatal("Unknown mode", el.Mode, "for", el.Name, "in object id", dn.Ent.Id)
    }
  }
}

func (fn* FileNode) Parse() {
  path := filepath.Join(fn.Config.Storage, "fs", fn.Config.RepoId, fn.Ent.Id[:2], fn.Ent.Id[2:])

  file, err := os.Open(path)
  if err != nil { log.Fatal(err) }
  defer file.Close()

  zfile, err := zlib.NewReader(file)
  if err != nil { log.Fatal(err) }

  jdec := json.NewDecoder(zfile)
  err = jdec.Decode(&fn.Elem)
  if err != nil { log.Fatal(err) }
}

type ExpandStrat int
const (
  ExpandOnlyDirectory ExpandStrat = iota
  ExpandAll
)

func (dn* DirNode) Walk(strat ExpandStrat, depth int) {
  qNode := []*DirNode{dn}
  for len(qNode) > 0 && depth != 0{
    if depth > 0 { depth = depth - 1 }

    cursor := qNode[0]
    qNode = qNode[1:]
    cursor.Parse()

    for _, ndn := range dn.Folders {
      qNode = append(qNode, ndn)
    }

    if ExpandAll == strat {
      for _, nfn := range dn.Files {
        nfn.Parse()
      }
    }
  }
}

/*func (rf* RepoFs) Walk() {
  qPathIds := make([]string, 0)
  qPathIds = append(qPathIds, rf.PathId)

  for limit := 0 ; limit < 20000 && len(pathIds) > 0 ; limit++ {
    pathId := qPathIds[0]
    qPathIds = qPathIds[1:]
    NewDirNode(filepath.Join(rf.Config.Storage, "fs", rf.Config.RepoId), pathId)
    
  }
}*/


// IsDir check if the mode is dir.
func IsDir(m uint32) bool {
  return (m & syscall.S_IFMT) == syscall.S_IFDIR
}

// IsRegular Check if the mode is regular.
func IsRegular(m uint32) bool {
  return (m & syscall.S_IFMT) == syscall.S_IFREG
}