package internal

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"regexp"

	"github.com/apex/log"
	readability "github.com/go-shiori/go-readability"
)

const (
	cacheDir = "cache"
)

func Scrape(conf *Config, url string) (*Entry, error) {
	if url == "" {
		return nil, ErrInvalidURL
	}

	match, err := regexp.MatchString(`^https?://.*`, url)
	if err != nil {
		log.WithError(err).Error("error parsing url")
		return nil, fmt.Errorf("error parsing url %s: %w", url, err)
	}

	if !match {
		return nil, ErrInvalidURL
	}

	res, err := Request(conf, "GET", url, nil)
	if err != nil {
		log.WithError(err).Error("error fetching url")
		return nil, fmt.Errorf("error fetching url %s: %w", url, err)
	}
	defer res.Body.Close()

	article, err := readability.FromReader(res.Body, url)
	if err != nil {
		log.WithError(err).Error("error processing url")
		return nil, fmt.Errorf("error processing url %s: %w", url, err)
	}

	entry := &Entry{
		URL:         url,
		Title:       article.Title,
		Author:      article.Byline,
		Length:      article.Length,
		Summary:     article.Excerpt,
		Content:     article.TextContent,
		HTMLContent: article.Content,
	}

	p := filepath.Join(conf.Data, cacheDir)
	if err := os.MkdirAll(p, 0755); err != nil {
		log.WithError(err).Error("error creating cache directory")
		return nil, fmt.Errorf("error creating cache directory: %w", err)
	}

	fn := filepath.Join(p, fmt.Sprintf("%s.json", entry.Hash()))

	data, err := entry.Bytes()
	if err != nil {
		log.WithError(err).Error("error serializing entry")
		return nil, fmt.Errorf("error serializing entry: %s", err)
	}

	if err := ioutil.WriteFile(fn, data, 0644); err != nil {
		log.WithError(err).Error("error persisting entry")
		return nil, fmt.Errorf("error persisting entry: %w", err)
	}

	return entry, nil
}