package nechotron

import (
	"strings"
)

type UpdateHandler func(u *Update) error
type dispatchHandler func(u *Update) (bool, 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 UpdateHandler) *Dispatcher {
	newHandler := func(u *Update) (bool, error) {
		if !strings.HasPrefix(u.Text(), command.String()) {
			return false, nil
		}
		if command.IsAdminOnly && !IsUserAdmin(u) && u.ChatID() < 0 {
			return false, nil
		}
		err := handler(u)
		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
}

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

func ChainRun(u *Update, disps ...*Dispatcher) error {
	for _, d := range disps {
		if err := d.Run(u); err != nil {
			return err
		}
	}
	return nil
}