lurk/handler/reddit.go

package handler

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"
	"regexp"
	"strings"
	"time"

	"go.etztech.xyz/lurk/config"

	"github.com/turnage/graw/reddit"
	"go.jolheiser.com/beaver"
)

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

type Webhook struct {
	Username  string  `json:"username"`
	AvatarURL string  `json:"avatar_url"`
	Embeds    []Embed `json:"embeds"`
}

type Embed struct {
	Title       string    `json:"title"`
	URL         string    `json:"url"`
	Description string    `json:"description"`
	Color       int64     `json:"color"`
	Timestamp   time.Time `json:"timestamp"`
	Author      Author    `json:"author"`
}

type Author struct {
	Name string `json:"name"`
	URL  string `json:"url"`
}

type Reddit struct {
	Config *config.Config
}

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 {
		beaver.Debugf("%s: %v", p.Subreddit, err)
		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 := Webhook{
		Username:  "/r/" + p.Subreddit,
		AvatarURL: sub.IconURL,
		Embeds: []Embed{
			{
				Title:       title,
				URL:         p.URL,
				Description: description,
				Color:       16312092, // Yellow
				Timestamp:   time.Now(),
				Author: Author{
					Name: "/u/" + p.Author,
					URL:  fmt.Sprintf("https://reddit.com/user/%s", p.Author),
				},
			},
		},
	}
	data, err := json.Marshal(e)
	if err != nil {
		beaver.Error(err)
		return nil
	}
	beaver.Debug(string(data))

	if sub.Webhook == "" {
		beaver.Errorf("no webhook for %s", p.Subreddit)
		return nil
	}

	payload := bytes.NewBuffer(data)
	resp, err := httpClient.Post(sub.Webhook, "application/json", payload)
	if err != nil {
		beaver.Error(err)
		return nil
	}

	if resp.StatusCode != http.StatusNoContent {
		beaver.Error(resp.Status)
		return nil
	}

	return nil
}

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

	// Check blacklist first
	// Any match means we ignore
	if matchesAny(p.LinkFlairText, sub.FlairBlacklistRe) {
		return fmt.Errorf("flair matched blacklisted regex: %s", p.LinkFlairText)
	}
	if matchesAny(p.Title, sub.TitleBlacklistRe) {
		return fmt.Errorf("title matched blacklisted regex: %s", p.Title)
	}
	if matchesAny(p.SelfText, sub.BodyBlacklistRe) {
		return fmt.Errorf("body matched blacklisted regex: %s", p.SelfText)
	}

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