lurk/handler/reddit.go

package handler

import (
	"context"
	"fmt"
	"net/http"
	"regexp"
	"strings"
	"time"

	"go.jolheiser.com/lurk/config"

	"github.com/rs/zerolog/log"
	"github.com/turnage/graw"
	"github.com/turnage/graw/reddit"
	"go.jolheiser.com/disco"
)

var httpClient = &http.Client{Timeout: time.Minute}

type Reddit struct {
	Bot    reddit.Bot
	Config *config.Config
}

func (r *Reddit) Run() error {
	_, wait, err := graw.Run(r, r.Bot, graw.Config{
		Subreddits: r.Config.Reddit.SubRedditNames(),
	})
	if err != nil {
		return err
	}
	return wait()
}

func (r *Reddit) Post(p *reddit.Post) error {
	sub := r.Config.Reddit.Map[strings.ToLower(p.Subreddit)]

	if err := checkPost(r.Config, p); err != nil {
		log.Debug().Err(err).Msg(p.Subreddit)
		return nil
	}

	title := p.Title
	if len(title) > sub.TitleLimit {
		title = title[:sub.TitleLimit] + "..."
	}
	description := p.SelfText
	if len(description) > sub.BodyLimit {
		description = description[:sub.BodyLimit] + "..."
	}

	e := &disco.Webhook{
		Username:  "/r/" + p.Subreddit,
		AvatarURL: sub.IconURL,
		Embeds: []*disco.Embed{
			{
				Title:       title,
				URL:         p.URL,
				Description: description,
				Color:       0x007D96,
				Timestamp:   disco.Now(),
				Author: &disco.Author{
					Name: "/u/" + p.Author,
					URL:  fmt.Sprintf("https://reddit.com/user/%s", p.Author),
				},
			},
		},
	}

	for _, webhook := range sub.Webhooks {
		req, err := e.Request(context.Background(), webhook)
		if err != nil {
			log.Err(err).Msg("")
			continue
		}

		resp, err := httpClient.Do(req)
		if err != nil {
			log.Err(err).Msg("")
			continue
		}

		if resp.StatusCode != http.StatusNoContent {
			log.Error().Msgf(resp.Status)
			continue
		}
	}

	return nil
}

func checkPost(c *config.Config, p *reddit.Post) error {
	sub := c.Reddit.Map[strings.ToLower(p.Subreddit)]

	// Check blocklist first
	// Any match means we ignore
	if matchesAny(p.LinkFlairText, sub.FlairBlocklistRe) {
		return fmt.Errorf("flair matched blocklisted regex: %s", p.LinkFlairText)
	}
	if matchesAny(p.Title, sub.TitleBlocklistRe) {
		return fmt.Errorf("title matched blocklisted regex: %s", p.Title)
	}
	if matchesAny(p.SelfText, sub.BodyBlocklistRe) {
		return fmt.Errorf("body matched blocklisted regex: %s", p.SelfText)
	}

	// Check allowlist
	// Any match means we pass
	// If no allowlist, pass
	if len(sub.FlairAllowlistRe) > 0 && !matchesAny(p.LinkFlairText, sub.FlairAllowlistRe) {
		return fmt.Errorf("flair didn't match any allowlisted regex: %s", p.LinkFlairText)
	}
	if len(sub.TitleAllowlistRe) > 0 && !matchesAny(p.Title, sub.TitleAllowlistRe) {
		return fmt.Errorf("title didn't match any allowlisted regex: %s", p.Title)
	}
	if len(sub.BodyAllowlistRe) > 0 && !matchesAny(p.SelfText, sub.BodyAllowlistRe) {
		return fmt.Errorf("body didn't match any allowlisted regex: %s", p.SelfText)
	}

	return nil
}

func matchesAny(input string, re []*regexp.Regexp) bool {
	for _, r := range re {
		if r.MatchString(input) {
			return true
		}
	}
	return false
}