package nechotron

import (
	"strings"
)

type UpdateHandler func(u *Update) error
type dispatchHandler func(u *Update) (bool, error)
type commandHandler func(u *UpdateCommand) error

type Dispatcher struct {
	handlers []dispatchHandler
}

func NewDispatcher() *Dispatcher {
	return &Dispatcher{}
}

func (d *Dispatcher) Run(u *Update) error {
	for _, h := range d.handlers {
		executed, err := h(u)
		if executed {
			return err
		}
	}
	return nil
}

func (d *Dispatcher) HandleCommand(command *Command, handler commandHandler) *Dispatcher {
	newHandler := func(u *Update) (bool, error) {
		if !strings.HasPrefix(u.Text(), command.String()) {
			return false, nil
		}
		if command.IsAdminOnly && !u.IsUserAdmin() && u.ChatID() < 0 {
			return false, nil
		}
		upd := &UpdateCommand{
			Update: *u,
			Param:  command.Param(u.Text()),
		}
		err := handler(upd)
		return true, err
	}
	d.handlers = append(d.handlers, newHandler)
	return d
}

func (d *Dispatcher) HandleFilter(filter FilterFn, handler UpdateHandler) *Dispatcher {
	newHandler := func(u *Update) (bool, error) {
		if !filter(u) {
			return false, nil
		}
		err := handler(u)
		return true, err
	}
	d.handlers = append(d.handlers, newHandler)
	return d
}