// Copyright 2024 Matthew Rich <matthewrich.conf@gmail.com>. All rights reserved.
package resource

import (
  "context"
  "errors"
  "fmt"
  "os"
  "os/user"
  "io"
  "syscall"
  "gopkg.in/yaml.v3"
  "strconv"
  "path/filepath"
  "net/url"
)

type FileType string

const (
  RegularFile FileType = "regular"
  DirectoryFile FileType = "directory"
  BlockDeviceFile FileType = "block"
  CharacterDeviceFile FileType = "char"
  NamedPipeFile FileType = "pipe"
  SymbolicLinkFile FileType = "symlink"
  SocketFile FileType = "socket"
)

var ErrInvalidResourceURI error = errors.New("Invalid resource URI")

func init() {
  ResourceTypes.Register("file", func(u *url.URL) Resource {
    f := NewFile()
    f.Path = filepath.Join(u.Hostname(), u.Path)
    return f
  })
}

type File struct {
  loader YamlLoader
  Path string `yaml:"path"`
  Owner string `yaml:"owner"`
  Group string `yaml:"group"`
  Mode string `yaml:"mode"`
  Content string `yaml:"content",omitempty`
  FileType FileType `yaml:"filetype"`
  State string `yaml:"state"`
}

func NewFile() *File {
  return &File{ loader: YamlLoadDecl, FileType: RegularFile }
}

func (f *File) URI() string {
  return fmt.Sprintf("file://%s", f.Path)
}

func (f *File) SetURI(uri string) error {
  resourceUri, e := url.Parse(uri)
  if resourceUri.Scheme == "file" {
    f.Path, e = filepath.Abs(filepath.Join(resourceUri.Hostname(), resourceUri.RequestURI()))
  } else {
    e = fmt.Errorf("%w: %s is not a file", ErrInvalidResourceURI, uri)
  }
  return e
}

func (f *File) Apply() error {

  switch f.State {
  case "absent":
    removeErr := os.Remove(f.Path)
    if removeErr != nil {
      return removeErr
    }
  case "present": {
    uid,uidErr := LookupUID(f.Owner)
    if uidErr != nil {
      return uidErr
    }

    gid,gidErr := LookupGID(f.Group)
    if gidErr != nil {
      return gidErr
    }

    mode,modeErr := strconv.ParseInt(f.Mode, 8, 64)
    if modeErr != nil {
      return modeErr
    }

    //e := os.Stat(f.path)
    //if os.IsNotExist(e) {
    switch f.FileType {
    case DirectoryFile:
      os.MkdirAll(f.Path, os.FileMode(mode))
    default:
      fallthrough
    case RegularFile:
      createdFile,e := os.Create(f.Path)
      if e != nil {
        return e
      }
      defer createdFile.Close()

      if chmodErr := createdFile.Chmod(os.FileMode(mode)); chmodErr != nil {
        return chmodErr
      }
      _,writeErr := createdFile.Write([]byte(f.Content))
      if writeErr != nil {
        return writeErr
      }
    }

    if chownErr := os.Chown(f.Path, uid, gid); chownErr != nil {
      return chownErr
    }

  }
  }

  return nil
}

func (f *File) LoadDecl(yamlFileResourceDeclaration string) error {
  return f.loader(yamlFileResourceDeclaration, f)
}

func (f *File) ResolveId(ctx context.Context) string {
  filePath, fileAbsErr := filepath.Abs(f.Path)
  if fileAbsErr != nil {
    panic(fileAbsErr)
  }
  return filePath
}

func (f *File) Read(ctx context.Context) ([]byte, error) {
  filePath, fileAbsErr := filepath.Abs(f.Path)
  if fileAbsErr != nil {
    panic(fileAbsErr)
  }
  f.Path = filePath

  info, e := os.Stat(f.Path)

  if e != nil {
    panic(e)
  }

  if stat, ok := info.Sys().(*syscall.Stat_t); ok {
    userId := strconv.Itoa(int(stat.Uid))
    groupId := strconv.Itoa(int(stat.Gid))
    fileUser, userErr := user.LookupId(userId)
    if userErr != nil { //UnknownUserIdError
      //panic(userErr)
      f.Owner = userId
    } else {
      f.Owner = fileUser.Name
    }
    fileGroup, groupErr := user.LookupGroupId(groupId)
    if groupErr != nil {
      //panic(groupErr)
      f.Group = groupId
    } else {
      f.Group = fileGroup.Name
    }
  }

  f.Mode = fmt.Sprintf("%04o", info.Mode().Perm())

  file, fileErr := os.Open(f.Path)
  if fileErr != nil {
    panic(fileErr)
  }
 
  fileContent, ioErr := io.ReadAll(file)
  if ioErr != nil {
    panic(ioErr)
  }
  f.Content = string(fileContent)
  f.State = "present"
  return yaml.Marshal(f)
}

func (f *File) Type() string { return "file" }

func (f *FileType) UnmarshalYAML(value *yaml.Node) error {
  var s string
  if err := value.Decode(&s); err != nil {
    return err
  }

  switch s {
  case string(RegularFile), string(DirectoryFile), string(BlockDeviceFile), string(CharacterDeviceFile), string(NamedPipeFile), string(SymbolicLinkFile), string(SocketFile):
    *f = FileType(s)
    return nil
  default:
    return errors.New("invalid FileType value")
  }
}