kafka/internal/engines/reddit.go

// kafka — a privacy-respecting metasearch engine
// Copyright (C) 2026-present metamorphosis-dev
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

package engines

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"

	"github.com/metamorphosis-dev/kafka/internal/contracts"
)

// RedditEngine searches Reddit posts via the public JSON API.
type RedditEngine struct {
	client *http.Client
}

func (e *RedditEngine) Name() string { return "reddit" }

func (e *RedditEngine) Search(ctx context.Context, req contracts.SearchRequest) (contracts.SearchResponse, error) {
	if strings.TrimSpace(req.Query) == "" {
		return contracts.SearchResponse{Query: req.Query}, nil
	}
	if e == nil || e.client == nil {
		return contracts.SearchResponse{}, errors.New("reddit engine not initialized")
	}

	endpoint := fmt.Sprintf(
		"https://www.reddit.com/search.json?q=%s&limit=25&sort=relevance&t=all",
		url.QueryEscape(req.Query),
	)

	httpReq, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
	if err != nil {
		return contracts.SearchResponse{}, err
	}
	httpReq.Header.Set("User-Agent", "kafka/0.1 (compatible; +https://git.ashisgreat.xyz/penal-colony/gosearch)")

	resp, err := e.client.Do(httpReq)
	if err != nil {
		return contracts.SearchResponse{}, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		io.Copy(io.Discard, io.LimitReader(resp.Body, 4096))
		return contracts.SearchResponse{}, fmt.Errorf("reddit api error: status %d", resp.StatusCode)
	}

	var data struct {
		Data struct {
			Children []struct {
				Data struct {
					Title      string `json:"title"`
					URL        string `json:"url"`
					Permalink  string `json:"permalink"`
					Score      int    `json:"score"`
					NumComments int   `json:"num_comments"`
					Subreddit  string `json:"subreddit"`
					CreatedUTC float64 `json:"created_utc"`
					IsSelf     bool   `json:"is_self"`
					Over18     bool   `json:"over_18"`
				} `json:"data"`
			} `json:"children"`
		} `json:"data"`
	}

	if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
		return contracts.SearchResponse{}, err
	}

	results := make([]contracts.MainResult, 0, len(data.Data.Children))
	for _, child := range data.Data.Children {
		post := child.Data

		// Skip NSFW results unless explicitly allowed.
		if post.Over18 && req.Safesearch > 0 {
			continue
		}

		// For self-posts, link to the Reddit thread.
		linkURL := post.URL
		if post.IsSelf || strings.HasPrefix(linkURL, "/r/") {
			linkURL = "https://www.reddit.com" + post.Permalink
		}

		content := fmt.Sprintf("r/%s · ⬆ %d · 💬 %d", post.Subreddit, post.Score, post.NumComments)
		if req.Safesearch == 0 {
			// No additional content for safe mode
		}

		title := post.Title
		urlPtr := linkURL

		results = append(results, contracts.MainResult{
			Template: "default.html",
			Title:    title,
			Content:  content,
			URL:      &urlPtr,
			Engine:   "reddit",
			Score:    float64(post.Score),
			Category: "general",
			Engines:  []string{"reddit"},
		})
	}

	return contracts.SearchResponse{
		Query:               req.Query,
		NumberOfResults:    len(results),
		Results:             results,
		Answers:             []map[string]any{},
		Corrections:         []string{},
		Infoboxes:           []map[string]any{},
		Suggestions:         []string{},
		UnresponsiveEngines: [][2]string{},
	}, nil
}