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

package resource

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

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
	})
}

// Manage the state of file system objects
type File struct {
	loader YamlLoader
	Path   string `json:"path" yaml:"path"`
	Owner  string `json:"owner" yaml:"owner"`
	Group  string `json:"group" yaml:"group"`
	Mode   string `json:"mode" yaml:"mode"`

	Atime time.Time `json:"atime,omitempty" yaml:"atime,omitempty"`
	Ctime time.Time `json:"ctime,omitempty" yaml:"ctime,omitempty"`
	Mtime time.Time `json:"mtime,omitempty" yaml:"mtime,omitempty"`

	Content  string   `json:"content,omitempty" yaml:"content,omitempty"`
	Target   string   `json:"target,omitempty" yaml:"target,omitempty"`
	FileType FileType `json:"filetype" yaml:"filetype"`
	State    string   `json:"state" yaml:"state"`
}

func NewFile() *File {
	currentUser, _ := user.Current()
	group, _ := user.LookupGroupId(currentUser.Gid)
	return &File{loader: YamlLoadDecl, Owner: currentUser.Username, Group: group.Name, Mode: "0666", 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 e == nil {
		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) Validate() error {
	return fmt.Errorf("failed")
}

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 SymbolicLinkFile:
				linkErr := os.Symlink(f.Target, f.Path)
				if linkErr != nil {
					return linkErr
				}
			case DirectoryFile:
				if mkdirErr := os.MkdirAll(f.Path, os.FileMode(mode)); mkdirErr != nil {
					return mkdirErr
				}
			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 !f.Mtime.IsZero() && !f.Atime.IsZero() {
					if chtimesErr := os.Chtimes(f.Path, f.Atime, f.Mtime); chtimesErr != nil {
						return chtimesErr
					}
				}
			}

			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)
	}
	f.Path = filePath
	return filePath
}

func (f *File) NormalizePath() error {
	filePath, fileAbsErr := filepath.Abs(f.Path)
	if fileAbsErr == nil {
		f.Path = filePath
	}
	return fileAbsErr
}

func (f *File) ReadStat() error {
	info, e := os.Lstat(f.Path)
	if e != nil {
		f.State = "absent"
		return e
	}

	f.Mtime = info.ModTime()

	if stat, ok := info.Sys().(*syscall.Stat_t); ok {
		f.Atime = time.Unix(int64(stat.Atim.Sec), int64(stat.Atim.Nsec))
		f.Ctime = time.Unix(int64(stat.Ctim.Sec), int64(stat.Ctim.Nsec))

		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())
	f.FileType.SetMode(info.Mode())
	return nil
}

func (f *File) Read(ctx context.Context) ([]byte, error) {
	if normalizePathErr := f.NormalizePath(); normalizePathErr != nil {
		return nil, normalizePathErr
	}
	
	statErr := f.ReadStat()
	if statErr != nil {
		return nil, statErr
	}

	switch f.FileType {
	case RegularFile:
		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)
	case SymbolicLinkFile:
		linkTarget, pathErr := os.Readlink(f.Path)
		if pathErr != nil {
			return nil, pathErr
		}
		f.Target = linkTarget
	}
	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")
	}
}

func (f *FileType) SetMode(mode os.FileMode) {
	switch true {
	case mode.IsRegular():
		*f = RegularFile
	case mode.IsDir():
		*f = DirectoryFile
	case mode&os.ModeSymlink != 0:
		*f = SymbolicLinkFile
	case mode&os.ModeNamedPipe != 0:
		*f = NamedPipeFile
	case mode&os.ModeSocket != 0:
		*f = SocketFile
	case mode&os.ModeCharDevice != 0:
		*f = CharacterDeviceFile
	case mode&os.ModeDevice != 0:
		*f = BlockDeviceFile
	}
}