tg/context.go

package tg

import (
	"fmt"
	"io"
	"net/http"
	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
	//"path"
)


// Interface to interact with the user.
type Context struct {
	// The session contains all
	// the information between the contexts.
	session *Session
	// The update that called the Context usage.
	update Update
	// Used as way to provide outer values redirection
	// into widgets and actions. It is like arguments
	// for REST API request etc.
	arg any
	typ ContextType
	// Instead of updates as argument.
	input *UpdateChan
}

// Run commands as other user. Was implemented to
// make other user to leave the bot at first but
// maybe you will find another usage for this.
// Returns users context by specified session ID
// or false if the user is not logged in.
func (c Context) As(sid SessionID) (Context, bool) {
	s, ok := c.Bot().GotSession(sid)
	if !ok {
		return Context{}, false
	}

	c.session = s
	return c, true
}

// General type function to define actions, single component widgets
// and components themselves.
type Func func(Context)
func (f Func) Act(c Context) {
	f(c)
}
func (f Func) Serve(c Context) {
	f(c)
}
func(f Func) Filter(_ Update) bool {
	return false
}
func (f Func) Render(_ Context) UI {
	return UI{
		f,
	}
}

// The type represents type
// of current context the processing is happening
// in.
type ContextType uint8
const (
	NoContextType ContextType = iota
	WidgetContextType
	ActionContextType
)

// Goroutie function to handle each user.
func (c Context) serve() {
	beh := c.Bot().behaviour
	c.Run(beh.Init)
	for {
		defer func(){
			if err := recover() ; err != nil {
				// Need to add some handling later.
			}
		}()
		beh.Root.Serve(c)
	}
}

func (c Context) Arg() any {
	return c.arg
}

func (c Context) Run(a Action) {
	if a != nil {
		a.Act(c)
	}
}


// Sends to the Sendable object to the session user.
func (c Context) Send(v Sendable) (*Message, error) {
	config := v.SendConfig(c.SessionID(), c.Bot())
	if config.Error != nil {
		return nil, config.Error
	}

	msg, err := c.Bot().API().Send(config.ToAPI())
	if err != nil {
		return nil, err
	}
	return &msg, nil
}

// Sends the formatted with fmt.Sprintf message to the user
// using default Markdown parsing format.
func (c Context) Sendf(format string, v ...any) (*Message, error) {
	return c.Send(Messagef(format, v...))
}

// Same as Sendf but uses Markdown 2 format for parsing.
func (c Context) Sendf2(format string, v ...any) (*Message, error) {
	return c.Send(Messagef(format, v...).MD2())
}

// Same as Sendf but uses HTML format for parsing.
func (c Context) SendfHTML(format string, v ...any) (*Message, error) {
	return c.Send(Messagef(format, v...).HTML())
}

// Send the message in raw format escaping all the special characters.
func (c Context) SendfR(format string, v ...any) (*Message, error) {
	return c.Send(Messagef("%s", Escape2(fmt.Sprintf(format, v...))).MD2())
}

// Get the input for current widget.
// Should be used inside handlers (aka "Serve").
func (c Context) Input() chan Update {
	return c.input.Chan()
}

func (c Context) WithArg(v any) Context {
	c.arg = v
	return c
}

func (c Context) WithUpdate(u Update) Context {
	c.update = u
	return c
}

func (c Context) WithInput(input *UpdateChan) Context {
	c.input = input
	return c
}

// Customized actions for the bot.
type Action interface {
	Act(Context)
}

type ActionFunc func(Context)

func (af ActionFunc) Act(c Context) {
	af(c)
}

// Simple way to read strings for widgets with
// the specified prompt.
func (c Context) ReadString(promptf string, args ...any) string {
	var text string
	if promptf != "" {
		c.Sendf(promptf, args...)
	}
	for u := range c.Input() {
		if u.Message == nil {
			continue
		}
		text = u.Message.Text
		break
	}
	return text
}

func (c Context) CallbackUpdate() *Update {
	return &c.update
}

// Returns the reader for specified file ID and path.
func (c Context) GetFile(fileID FileID) (io.ReadCloser, string, error) {
	file, err := c.Bot().API().GetFile(tgbotapi.FileConfig{
		FileID: string(fileID),
	})
	if err != nil {
		return nil, "", err
	}
	r, err := http.Get(fmt.Sprintf(
		"https://api.telegram.org/file/bot%s/%s",
		c.Bot().API().Token,
		file.FilePath,
	))
	if err != nil {
		return nil, "", err
	}
	if r.StatusCode != 200 {
		return nil, "", StatusCodeErr
	}

	return r.Body, file.FilePath, nil
}

// Reads all the content from the specified file.
func (c Context) ReadFile(fileID FileID) ([]byte, string, error)  {
	file, pth, err := c.GetFile(fileID)
	if err != nil {
		return nil, "", err
	}
	defer file.Close()

	bts, err := io.ReadAll(file)
	if err != nil {
		return nil, "", err
	}

	return bts, pth, nil
}

func (c Context) runCompo(compo Component, arg any) (*UpdateChan, error) {
	if compo == nil {
		return nil, nil
	}
	sendable, canSend := compo.(Sendable)
	if canSend {
		msg, err := c.Send(sendable)
		if err != nil {
			return nil, err
		}
		sendable.SetMessage(msg)
	}
	updates := NewUpdateChan()
	go func() {
		compo.Serve(
			c.WithInput(updates).
				WithArg(arg),
		)
		// To let widgets finish themselves before
		// the channel is closed and close it by themselves.
		updates.Close()
	}()
	return updates, nil
}

// Run widget in background returning the new input channel for it.
func (c Context) runWidget(widget Widget, arg any) (*UpdateChan, error) {
	var err error
	if widget == nil {
		return nil, EmptyWidgetErr
	}

	compos := widget.Render(c.WithArg(arg))
	// Leave if changed path or components are empty.
	if compos == nil {
		return nil, EmptyCompoErr
	}
	chns := make([]*UpdateChan, len(compos))
	for i, compo := range compos {
		chns[i], err = c.runCompo(compo, arg)
		if err != nil {
			for _, chn := range chns {
				chn.Close()
			}
			return nil, err
		}
	}

	ret := NewUpdateChan()
	go func() {
		ln := len(compos)
		//ation: u != nil (mismatchedtypes Update and untyped nil)
		UPDATE:
		for u := range ret.Chan() {
			cnt := 0
			for i, compo := range compos {
				chn := chns[i]
				if chn.Closed() {
					cnt++
					continue
				}
				if !compo.Filter(u) {
					chn.Send(u)
					continue UPDATE
				}
			}
			if cnt == ln {
				break
			}
		}
		ret.Close()
		for _, chn := range chns {
			chn.Close()
		}
	}()

	return ret, nil
}

// Simple go without an argument for context.
func (c Context) Go(pth Widget) error {
	return c.GoWithArg(pth, nil)
}

// Go to the specified widget with the
// specificed argument.
func (c Context) GoWithArg(pth Widget, arg any) error {
	var err error
	if pth == nil {
		c.session.pathHistory = []Widget{}
		return nil
	}

	var back bool
	if pth == Back {
		if len(c.session.pathHistory) < 2 {
			return c.GoWithArg(nil, arg)
		}
		pth = c.session.pathHistory[len(c.session.pathHistory)-2]
		c.session.pathHistory =
			c.session.pathHistory[:len(c.session.pathHistory)-1]
		back = true
	}

	if !back {
		c.session.pathHistory = append(c.session.pathHistory, pth)
	}

	// Stopping the current widget.
	c.session.skippedUpdates.Close()

	// Running the new one.
	c.session.skippedUpdates, err = c.runWidget(pth, arg)
	if err != nil {
		return err
	}

	return nil
}

func (c Context) Session() Session {
	return *c.session
}

func (c Context) SetSessionData(v any) {
	c.session.Data = v
}

func (c Context) SessionData() any {
	return c.session.Data
}

func (c Context) SessionID() SessionID {
	return c.session.ID
}

func (c Context) SessionScope() SessionScope {
	return c.session.Scope
}

// Only for the root widget usage.
// Skip the update sending it down to
// the underlying widget.
func (c Context) SkipUpdate(u Update) {
	c.session.skippedUpdates.Send(u)
}

// Return the session related bot.
func (c Context) Bot() *Bot {
	return c.session.bot
}

// Return context's session's path history.
func (c Context) PathHistory() []Widget {
	return c.session.pathHistory
}

func (c Context) Path() Widget {
	ln := len(c.session.pathHistory)
	if ln == 0 {
		return nil
	}
	return c.session.pathHistory[ln-1]
}