package main

import (
	"errors"
	"strings"

	"github.com/andybalholm/cascadia"
)

type sel struct{}

func (sel) Execute(args []string, ins []<-chan Datum, out chan Datum) error {
	defer func() {
		out <- Datum{End: true}
		close(out)
	}()
	if len(args) == 0 {
		return errors.New("usage: sel <selector>")
	}
	s, err := cascadia.Parse(strings.Join(args[1:], " "))
	if err != nil {
		return err
	}

	for _, d := Select(ins); d != nil; _, d = Select(ins) {
		if d.End {
			continue
		}
		if d.HTML == nil {
			return errors.New("type error: expected html, got text")
		}
		for _, n := range cascadia.QueryAll(d.HTML, s) {
			out <- Datum{HTML: n}
		}
	}
	return nil
}

func init() {
	Filters["sel"] = sel{}
}