Franz Kafka
7be03b4017
Update LICENSE file and add AGPL header to all source files. AGPLv3 ensures that if someone runs Kafka as a network service and modifies it, they must release their source code under the same license.
140 lines
3.7 KiB
Go
140 lines
3.7 KiB
Go
// kafka — a privacy-respecting metasearch engine
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// Copyright (C) 2026-present metamorphosis-dev
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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package autocomplete
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import (
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"context"
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"encoding/json"
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"errors"
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"io"
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"net/http"
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"net/url"
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"strings"
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"time"
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)
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// Service fetches search suggestions from an upstream metasearch instance
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// or falls back to Wikipedia's OpenSearch API.
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type Service struct {
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upstreamURL string
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http *http.Client
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}
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func NewService(upstreamURL string, timeout time.Duration) *Service {
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if timeout <= 0 {
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timeout = 5 * time.Second
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}
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return &Service{
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upstreamURL: strings.TrimRight(upstreamURL, "/"),
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http: &http.Client{Timeout: timeout},
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}
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}
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// Suggestions returns search suggestions for the given query.
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func (s *Service) Suggestions(ctx context.Context, query string) ([]string, error) {
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if strings.TrimSpace(query) == "" {
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return nil, nil
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}
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if s.upstreamURL != "" {
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return s.upstreamSuggestions(ctx, query)
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}
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return s.wikipediaSuggestions(ctx, query)
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}
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// upstreamSuggestions proxies to an upstream /autocompleter endpoint.
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func (s *Service) upstreamSuggestions(ctx context.Context, query string) ([]string, error) {
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u := s.upstreamURL + "/autocompleter?" + url.Values{"q": {query}}.Encode()
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, u, nil)
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if err != nil {
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return nil, err
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}
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req.Header.Set("Accept", "application/json")
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resp, err := s.http.Do(req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, errors.New("upstream autocompleter failed")
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}
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body, err := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
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if err != nil {
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return nil, err
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}
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// The /autocompleter endpoint returns a plain JSON array of strings.
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var out []string
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if err := json.Unmarshal(body, &out); err != nil {
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return nil, err
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}
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return out, nil
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}
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// wikipediaSuggestions fetches suggestions from Wikipedia's OpenSearch API.
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func (s *Service) wikipediaSuggestions(ctx context.Context, query string) ([]string, error) {
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u := "https://en.wikipedia.org/w/api.php?" + url.Values{
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"action": {"opensearch"},
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"format": {"json"},
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"formatversion": {"2"},
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"search": {query},
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"namespace": {"0"},
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"limit": {"10"},
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}.Encode()
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, u, nil)
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if err != nil {
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return nil, err
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}
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req.Header.Set(
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"User-Agent",
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"gosearch-go/0.1 (compatible; +https://github.com/metamorphosis-dev/kafka)",
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)
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resp, err := s.http.Do(req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, errors.New("wikipedia opensearch failed")
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}
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body, err := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
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if err != nil {
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return nil, err
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}
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// Wikipedia OpenSearch returns: [query, [suggestions], ...]
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var data []json.RawMessage
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if err := json.Unmarshal(body, &data); err != nil {
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return nil, err
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}
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if len(data) < 2 {
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return nil, nil
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}
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var suggestions []string
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if err := json.Unmarshal(data[1], &suggestions); err != nil {
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return nil, err
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}
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return suggestions, nil
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}
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