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

package resource

import (
	"context"
	"fmt"
	"gopkg.in/yaml.v3"
_	"log/slog"
	"net/url"
_	"os"
	"os/exec"
	"os/user"
	"io"
	"encoding/json"
	"errors"
	"gitea.rosskeen.house/rosskeen.house/machine"
	"strings"
	"decl/internal/codec"
	"decl/internal/command"
	"decl/internal/data"
	"decl/internal/folio"
)

type decodeUser User

type UserType string

const (
	UserTypeName TypeName = "user"
	UserTypeBusyBox UserType = "busybox"
	UserTypeShadow UserType = "shadow"
)

var ErrUnsupportedUserType error = errors.New("The UserType is not supported on this system")
var ErrInvalidUserType error = errors.New("invalid UserType value")

var SupportedUserTypes []UserType = []UserType{UserTypeShadow, UserTypeBusyBox}

var SystemUserType UserType = FindSystemUserType()

type User struct {
	*Common             `json:",inline" yaml:",inline"`
	stater		machine.Stater	`json:"-" yaml:"-"`
	Name       string   `json:"name" yaml:"name"`
	UID        string   `json:"uid,omitempty" yaml:"uid,omitempty"`
	Group      string   `json:"group,omitempty" yaml:"group,omitempty"`
	Groups     []string `json:"groups,omitempty" yaml:"groups,omitempty"`
	AppendGroups bool   `json:"appendgroups,omitempty" yaml:"appendgroups,omitempty"`
	Gecos      string   `json:"gecos,omitempty" yaml:"gecos,omitempty"`
	Home       string   `json:"home" yaml:"home"`
	CreateHome bool     `json:"createhome,omitempty" yaml:"createhome,omitempty"`
	Shell      string   `json:"shell,omitempty" yaml:"shell,omitempty"`
	UserType   UserType `json:"type,omitempty" yaml:"type,omitempty"`

	userStatus  *user.User  `json:"-" yaml:"-"`
	groupStatus *user.Group `json:"-" yaml:"-"`

	CreateCommand *command.Command `json:"-" yaml:"-"`
	ReadCommand *command.Command   `json:"-" yaml:"-"`
	UpdateCommand *command.Command `json:"-" yaml:"-"`
	DeleteCommand *command.Command `json:"-" yaml:"-"`
	Resources data.ResourceMapper `json:"-" yaml:"-"`
}

func NewUser() *User {
	u := &User{ CreateHome: true, AppendGroups: true, UserType: SystemUserType }
	u.Common = NewCommon(UserTypeName, false)
	u.Common.NormalizePath = u.NormalizePath
	return u
}

func init() {
	folio.DocumentRegistry.ResourceTypes.Register([]string{"user"}, func(u *url.URL) (user data.Resource) {
		user = NewUser()
		if u != nil {
			if err := folio.CastParsedURI(u).ConstructResource(user); err != nil {
				panic(err)
			}
		}
		return
	})
}

func FindSystemUserType() UserType {
	for _, userType := range SupportedUserTypes {
		c := userType.NewCreateCommand()
		if c.Exists() {
			return userType
		}
	}
	return UserTypeShadow
}

func (u *User) Init(uri data.URIParser) error {
	if uri == nil {
		uri = folio.URI(u.URI()).Parse()
	} else {
		u.Name = uri.URL().Hostname()
	}
	u.UID = LookupUIDString(uri.URL().Hostname())
	u.CreateCommand, u.ReadCommand, u.UpdateCommand, u.DeleteCommand = u.UserType.NewCRUD()
	return u.SetParsedURI(uri)
}

func (u *User) NormalizePath() error {
	return nil
}

func (u *User) SetResourceMapper(resources data.ResourceMapper) {
	u.Resources = resources
}

func (u *User) Clone() data.Resource {
	newu := &User {
		Common: u.Common,
		Name: u.Name,
		UID: u.UID,
		Group: u.Group,
		Groups: u.Groups,
		Gecos: u.Gecos,
		Home: u.Home,
		CreateHome: u.CreateHome,
		Shell: u.Shell,
		UserType: u.UserType,
	}
	newu.CreateCommand, newu.ReadCommand, newu.UpdateCommand, newu.DeleteCommand = u.UserType.NewCRUD()
	return newu
}

func (u *User) StateMachine() machine.Stater {
	if u.stater == nil {
		u.stater = StorageMachine(u)
	}
	return u.stater
}

func (u *User) Notify(m *machine.EventMessage) {
	ctx := context.Background()
	switch m.On {
	case machine.ENTERSTATEEVENT:
		switch m.Dest {
		case "start_stat":
			if statErr := u.ReadStat(); statErr == nil {
				if triggerErr := u.StateMachine().Trigger("exists"); triggerErr == nil {
					return
				}
			} else {
				if triggerErr := u.StateMachine().Trigger("notexists"); triggerErr == nil {
					return
				}
			}
		case "start_read":
			if _,readErr := u.Read(ctx); readErr == nil {
				if triggerErr := u.StateMachine().Trigger("state_read"); triggerErr == nil {
					return
				} else {
					u.Common.State = "absent"
					panic(triggerErr)
				}
			} else {
				u.Common.State = "absent"
				panic(readErr)
			}
		case "start_update":
			if updateErr := u.Update(ctx); updateErr == nil {
				if triggerErr := u.stater.Trigger("updated"); triggerErr == nil {
					return
				} else {
					u.Common.State = "absent"
				}
			} else {      
				u.Common.State = "absent"
				panic(updateErr)
			}
		case "start_delete":
			if deleteErr := u.Delete(ctx); deleteErr == nil {
				if triggerErr := u.StateMachine().Trigger("deleted"); triggerErr == nil {
					return
				} else {
					u.Common.State = "present"
					panic(triggerErr)
				}
			} else {
				u.Common.State = "present"
				panic(deleteErr)
			}
		case "start_create":
			if e := u.Create(ctx); e == nil {
				if triggerErr := u.stater.Trigger("created"); triggerErr == nil {
					return
				}
			}
			u.Common.State = "absent"
		case "absent":
			u.Common.State = "absent"
		case "present", "created", "read":
			u.Common.State = "present"
		}
	case machine.EXITSTATEEVENT:
	}
}

func (u *User) URI() string {
	return fmt.Sprintf("user://%s", u.Name)
}

func (u *User) ResolveId(ctx context.Context) string {
	if u.config != nil {
		if configUser, configUserErr := u.config.GetValue("user"); configUserErr == nil && u.Name == "self" {
			u.Name = configUser.(string)
		}
	}
	return LookupUIDString(u.Name)
}

func (u *User) Validate() error {
	return fmt.Errorf("failed")
}

func (u *User) Apply() error {
	ctx := context.Background()
	switch u.Common.State {
	case "present":
		_, NoUserExists := LookupUID(u.Name)
		if NoUserExists != nil {
			cmdErr := u.Create(context.Background())
			return cmdErr
		}
	case "absent":
		cmdErr := u.Delete(ctx)
		return cmdErr
	}
	return nil
}

func (u *User) Load(docData []byte, f codec.Format) (err error) {
	err = f.StringDecoder(string(docData)).Decode(u)
	return
}

func (u *User) LoadReader(r io.ReadCloser, f codec.Format) (err error) {
	err = f.Decoder(r).Decode(u)
	return
}

func (u *User) LoadString(docData string, f codec.Format) (err error) {
	err = f.StringDecoder(docData).Decode(u)
	return
}

func (u *User) LoadDecl(yamlResourceDeclaration string) error {
	return u.LoadString(yamlResourceDeclaration, codec.FormatYaml)
}

func (u *User) Type() string { return "user" }

func (u *User) Create(ctx context.Context) (error) {
	_, err := u.CreateCommand.Execute(u)
	if err != nil {
		return err
	}

	_,e := u.Read(ctx)
	return e
}

func (u *User) ReadStat() (err error) {
	if u.userStatus == nil {
		if u.userStatus, err = user.Lookup(u.Name); err != nil {
			return err
		}
	}
	if len(u.userStatus.Uid) < 1 {
		return ErrResourceStateAbsent
	}
	u.UID = u.userStatus.Uid
	if len(u.Group) > 1 {
		if u.groupStatus == nil {
			if u.groupStatus, err = user.LookupGroup(u.Group); err != nil {
				return err
			}
		}
		if len(u.groupStatus.Gid) < 1 {
			return ErrResourceStateAbsent
		}
	}
	return
}

func (u *User) Read(ctx context.Context) ([]byte, error) {
	exErr := u.ReadCommand.Extractor(nil, u)
	if exErr != nil {
		u.Common.State = "absent"
	}
	_ = u.ReadGroups()
	if yamlDoc, yamlErr := yaml.Marshal(u); yamlErr != nil {
		return yamlDoc, yamlErr
	} else {
		return yamlDoc, exErr
	}
}

func (u *User) ReadGroups() (err error) {
	knownSecondaryGroups := make(map[string]bool)
	for _, secondaryGroupName := range u.Groups {
		knownSecondaryGroups[secondaryGroupName] = true
	}
	if u.ReadStat() == nil {
		if groups, groupsErr := u.userStatus.GroupIds(); groupsErr == nil {
			for _, secondaryGroup := range groups {
				if readGroup, groupErr := user.LookupGroupId(secondaryGroup); groupErr == nil {
					if ! knownSecondaryGroups[readGroup.Name] {
						u.Groups = append(u.Groups, readGroup.Name)
						knownSecondaryGroups[readGroup.Name] = true
					}
				} else {
					err = groupErr
				}
			}
		} else {
			err = groupsErr
		}
	}
	return
}

func (u *User) Update(ctx context.Context) (error) {
	_, err := u.UpdateCommand.Execute(u)
	if err != nil {
		return err
	}

	_,e := u.Read(ctx)
	return e
}

func (u *User) Delete(ctx context.Context) (error) {
	_, err := u.DeleteCommand.Execute(u)
	if err != nil {
		return err
	}

	return err
}

func (u *User) UnmarshalJSON(data []byte) error {
	if unmarshalErr := json.Unmarshal(data, (*decodeUser)(u)); unmarshalErr != nil {
		return unmarshalErr
	}
	u.CreateCommand, u.ReadCommand, u.UpdateCommand, u.DeleteCommand = u.UserType.NewCRUD()
	return nil
}

func (u *User) UnmarshalYAML(value *yaml.Node) error {
	if unmarshalErr := value.Decode((*decodeUser)(u)); unmarshalErr != nil {
		return unmarshalErr
	}
	u.CreateCommand, u.ReadCommand, u.UpdateCommand, u.DeleteCommand = u.UserType.NewCRUD()
	return nil
}

func (u *UserType) NewCRUD() (create *command.Command, read *command.Command, update *command.Command, del *command.Command) {
	switch *u {
	case UserTypeShadow:
		return NewUserShadowCreateCommand(), NewUserReadCommand(), NewUserShadowUpdateCommand(), NewUserShadowDeleteCommand()
	case UserTypeBusyBox:
		return NewUserBusyBoxCreateCommand(), NewUserReadCommand(), NewUserBusyBoxUpdateCommand(), NewUserBusyBoxDeleteCommand()
	default:
		if _, addUserPathErr := exec.LookPath("adduser"); addUserPathErr == nil {
			*u = UserTypeBusyBox
			return NewUserBusyBoxCreateCommand(), NewUserReadCommand(), NewUserBusyBoxUpdateCommand(), NewUserBusyBoxDeleteCommand()
		}
		if _, pathErr := exec.LookPath("useradd"); pathErr == nil {
			*u = UserTypeShadow
			return NewUserShadowCreateCommand(), NewUserReadCommand(), NewUserShadowUpdateCommand(), NewUserShadowDeleteCommand()
		}
		return NewUserShadowCreateCommand(), NewUserReadCommand(), NewUserShadowUpdateCommand(), NewUserShadowDeleteCommand()
	}
}

func (u *UserType) NewReadCommand() (read *command.Command) {
	return NewUserReadCommand()
}

func (u *UserType) NewCreateCommand() (create *command.Command) {
	switch *u {
	case UserTypeShadow:
		return NewUserShadowCreateCommand()
	case UserTypeBusyBox:
		return NewUserBusyBoxCreateCommand()
	default:
	}
	return nil
}

func (p *UserType) NewReadUsersCommand() (*command.Command) {
	return NewReadUsersCommand()
}


func (u *UserType) UnmarshalValue(value string) error {
	switch value {
	case string(UserTypeShadow), string(UserTypeBusyBox):
		*u = UserType(value)
	return nil
	default:
		return ErrInvalidUserType
	}
}

func (u *UserType) UnmarshalJSON(data []byte) error {
	var s string
	if unmarshalUserTypeErr := json.Unmarshal(data, &s); unmarshalUserTypeErr != nil {
		return unmarshalUserTypeErr
	}
	return u.UnmarshalValue(s)
}

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

func NewReadUsersCommand() *command.Command {
	c := command.NewCommand()
	c.Path = "getent"
	c.Args = []command.CommandArg{
		command.CommandArg("passwd"),
	}

	c.Extractor = func(out []byte, target any) error {
		Users := target.(*[]*User)
		lines := strings.Split(strings.TrimSpace(string(out)), "\n")
		lineIndex := 0
		for _, line := range lines {
			userRecord := strings.Split(strings.TrimSpace(line), ":")
			if len(*Users) <= lineIndex + 1 {
				*Users = append(*Users, NewUser())
			}
			u := (*Users)[lineIndex]
			u.Name = userRecord[0]
			u.UID = userRecord[2]
			u.Gecos = userRecord[4]
			u.Home = userRecord[5]
			u.Shell = userRecord[6]
			if readUser, userErr := user.Lookup(u.Name); userErr == nil {
				if groups, groupsErr := readUser.GroupIds(); groupsErr == nil {
					for _, secondaryGroup := range groups {
						if readGroup, groupErr := user.LookupGroupId(secondaryGroup); groupErr == nil {
							u.Groups = append(u.Groups, readGroup.Name)
						}
					}
				}
			}
			if readGroup, groupErr := user.LookupGroupId(userRecord[3]); groupErr == nil {
				u.Group = readGroup.Name
			}
			u.Common.State = "present"
			u.UserType = SystemUserType
			lineIndex++
		}
		return nil
	}
	return c
}

func NewUserShadowCreateCommand() *command.Command {
	c := command.NewCommand()
	c.Path = "useradd"
	c.Args = []command.CommandArg{
		command.CommandArg("{{ if .UID }}-u {{ .UID }}{{ end }}"),
		command.CommandArg("{{ if .Gecos }}-c {{ .Gecos }}{{ end }}"),
		command.CommandArg("{{ if .Group }}-g {{ .Group }}{{ end }}"),
		command.CommandArg("{{ if .Groups }}-G {{ range .Groups }}{{ . }},{{- end }}{{ end }}"),
		command.CommandArg("{{ if .Home }}-d {{ .Home }}{{ end }}"),
		command.CommandArg("{{ if .CreateHome }}-m{{ else }}-M{{ end }}"),
		command.CommandArg("{{ .Name }}"),
	}
	c.Extractor = func(out []byte, target any) error {
		return nil
	}
	return c
}

func NewUserBusyBoxCreateCommand() *command.Command {
	c := command.NewCommand()
	c.Path = "adduser"
	c.Args = []command.CommandArg{
		command.CommandArg("{{ if .UID }}-u {{ .UID }}{{ end }}"),
		command.CommandArg("{{ if .Gecos }}-g {{ .Gecos }}{{ end }}"),
		command.CommandArg("{{ if .Group }}-G {{ .Group }}{{ end }}"),
		command.CommandArg("{{ if .Home }}-h {{ .Home }}{{ end }}"),
		command.CommandArg("{{ if not .CreateHome }}-H{{ end }}"),
		command.CommandArg("-D"),
		command.CommandArg("{{ .Name }}"),
	}
	c.Extractor = func(out []byte, target any) error {
		return nil
	}
	return c
}

func NewUserReadCommand() *command.Command {
	c := command.NewCommand()
	c.Extractor = func(out []byte, target any) error {
		u := target.(*User)
		u.Common.State = "absent"
		var readUser *user.User
		var e error
		if u.Name != "" {
			readUser, e = user.Lookup(u.Name)
		} else {
			if u.UID != "" {
				readUser, e = user.LookupId(u.UID)
			}
		}

		if e == nil {
			u.Name = readUser.Username
			u.UID = readUser.Uid
			u.Home = readUser.HomeDir
			u.Gecos = readUser.Name
			if readGroup, groupErr := user.LookupGroupId(readUser.Gid); groupErr == nil {
				u.Group = readGroup.Name
			} else {
				return groupErr
			}
			if u.UID != "" {
				u.Common.State = "present"
			}
		}
		return e
	}
	return c
}

func NewUserBusyBoxUpdateCommand() *command.Command {
	c := command.NewCommand()
	c.Path = "xargs"
	c.StdinAvailable = true
	c.Input = command.CommandInput("{{ if .Groups }}{{ range .Groups }}{{ . }}\n{{ end }}{{ end }}")
	c.Args = []command.CommandArg{
		command.CommandArg("adduser"),
		command.CommandArg("{{ .Name }}"),
	}
	c.Extractor = func(out []byte, target any) error {
		return nil
	}
	return c
}

func NewUserShadowUpdateCommand() *command.Command {
	c := command.NewCommand()
	c.Path = "usermod"
	c.Args = []command.CommandArg{
		command.CommandArg("{{ if .UID }}-u {{ .UID }}{{ end }}"),
		command.CommandArg("{{ if .Gecos }}-c {{ .Gecos }}{{ end }}"),
		command.CommandArg("{{ if .Group }}-g {{ .groupStatus.Gid }}{{ end }}"),
		command.CommandArg("{{ if .Home }}-d {{ .Home }}{{ if .CreateHome }} -m{{- end }}{{ end }}"),
		command.CommandArg("{{ if .Groups }}-G {{- range $i, $g := .Groups -}}{{ if $i }}, {{- end }}{{ . }}{{- end }}{{ if .AppendGroups }} -a{{- end }}{{- end }}"),
		command.CommandArg("{{ if .Shell }}-s {{ .Shell }}{{ end }}"),
		command.CommandArg("{{ .Name }}"),
	}
	c.Extractor = func(out []byte, target any) error {
		return nil
	}
	return c
}

func NewUserShadowDeleteCommand() *command.Command {
	c := command.NewCommand()
	c.Path = "userdel"
	c.Args = []command.CommandArg{
		command.CommandArg("{{ .Name }}"),
	}
	c.Extractor = func(out []byte, target any) error {
		return nil
	}
	return c
}

func NewUserBusyBoxDeleteCommand() *command.Command {
	c := command.NewCommand()
	c.Path = "deluser"
	c.Args = []command.CommandArg{
		command.CommandArg("{{ .Name }}"),
	}
	c.Extractor = func(out []byte, target any) error {
		return nil
	}
	return c
}