package tg

import (
	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
)


type CommandType uint8
const (
	PrivateCommandType CommandType = iota
	GroupCommandType
	ChannelCommandType
)

type CommandName string
type Command struct {
	Name CommandName
	Type CommandType
	Description string
	Action Action
	Widget Widget
	WidgetArg any
}

type CommandMap map[CommandName]Command

func NewCommand(name CommandName, desc string) Command {
	if name == "" || desc == "" {
		panic("name and description cannot be an empty string")
	}
	return Command{
		Name: name,
		Description: desc,
	}
}

func (c Command) WithAction(a Action) Command {
	c.Action = a
	return c
}

func (c Command) WithWidget(w Widget) Command {
	c.Widget = w
	return c
}

// Convert command into the tgbotapi.BotCommand
func (c Command) ToAPI() tgbotapi.BotCommand {
	ret := tgbotapi.BotCommand{}
	ret.Command = string(c.Name)
	ret.Description = c.Description
	return ret
}

// Simple command to go to another screen.
func (c Command) Go(pth Widget) Command {
	return c.WithAction(WidgetGo{
		Path: pth,
	})
}

func (c Command) GoWithArg(pth Widget, arg any) Command {
	return c.WithAction(WidgetGo{
		Path: pth,
		Arg: arg,
	})
}

// The type is used to recognize commands and execute
// its actions and widgets .
type CommandCompo struct {
	PreStart Action
	Commands  CommandMap
	Usage Action
}

// Returns new empty CommandCompo.
func NewCommandCompo(cmds ...Command) *CommandCompo {
	ret := (&CommandCompo{}).SetCommands(cmds...)
	return ret
}

// Set the commands to handle.
func (w *CommandCompo) SetCommands(cmds ...Command) *CommandCompo {
	if w.Commands == nil {
		w.Commands = make(CommandMap)
	}
	for _, cmd := range cmds {
		if cmd.Name == "" {
			panic("empty command name")
		}
		_, ok := w.Commands[cmd.Name]
		if ok {
			panic("duplicate command definition")
		}
		w.Commands[cmd.Name] = cmd
	}
	return w
}

// Set the prestart action.
func (w *CommandCompo) SetPreStart(a Action) *CommandCompo {
	w.PreStart = a
	return w
}

// Set the usage action.
func (w *CommandCompo) SetUsage(a Action) *CommandCompo {
	w.Usage = a
	return w
}

// Filtering all the non commands.
func (widget *CommandCompo) Filter(
	u Update,
) bool {
	if u.Message == nil || !u.Message.IsCommand() {
		return false
	}

	return false
}

// Implementing server.
func (compo *CommandCompo) Serve(c Context) {
	// First should bring the new command into the action.
	c.Bot().DeleteCommands()
	err := c.Bot().SetCommands(
		tgbotapi.NewBotCommandScopeChat(c.SessionID().ToAPI()),
		compo.Commands,
	)

	if err != nil {
		c.Sendf("error: %q", err)
	}

	var cmdUpdates *UpdateChan
	for u := range c.Input() {
		if c.Path() == nil && u.Message != nil {
			// Skipping and executing the preinit action
			// while we have the empty screen.
			// E. g. the session did not start.
			if !u.Message.IsCommand() ||
					u.Message.Command() != "start" {
				c.WithUpdate(u).Run(compo.PreStart)
				continue
			}
		}

		if u.Message != nil && u.Message.IsCommand() {
			// Command handling.
			cmdName := CommandName(u.Message.Command())
			cmd, ok := compo.Commands[cmdName]
			if !ok {
				c.WithUpdate(u).Run(compo.Usage)
				continue
			}

			c.WithUpdate(u).Run(cmd.Action)
			if cmd.Widget != nil {
				// Closing current widget
				cmdUpdates.Close()
				// And running the other one.
				cmdUpdates, _ = c.WithArg(cmd.WidgetArg).RunWidget(cmd.Widget)
			}
			continue
		}
		
		if !cmdUpdates.Closed()  {
			// Send to the commands channel if we are
			// executing one.
			cmdUpdates.Send(u)
		} else {
			c.SkipUpdate(u)
		}
	}
}