feat: build Go-based SearXNG-compatible search service

Implement an API-first Go rewrite with local engine adapters, upstream fallback, and Nix-based tooling so searches can run without matching the original UI while preserving response compatibility.

Made-with: Cursor

internal/engines/wikipedia.go

@@ -0,0 +1,151 @@
+package engines
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/ashie/gosearch/internal/contracts"
+)
+
+type WikipediaEngine struct {
+	client *http.Client
+}
+
+func (e *WikipediaEngine) Name() string { return "wikipedia" }
+
+func (e *WikipediaEngine) Search(ctx context.Context, req contracts.SearchRequest) (contracts.SearchResponse, error) {
+	if e == nil || e.client == nil {
+		return contracts.SearchResponse{}, errors.New("wikipedia engine not initialized")
+	}
+	if strings.TrimSpace(req.Query) == "" {
+		return contracts.SearchResponse{Query: req.Query}, nil
+	}
+
+	lang := strings.TrimSpace(req.Language)
+	if lang == "" || lang == "auto" {
+		lang = "en"
+	}
+	// Wikipedia subdomains are based on the language code; keep it simple for MVP.
+	lang = strings.SplitN(lang, "-", 2)[0]
+	lang = strings.ReplaceAll(lang, "_", "-")
+	wikiNetloc := fmt.Sprintf("%s.wikipedia.org", lang)
+
+	endpoint := fmt.Sprintf(
+		"https://%s/api/rest_v1/page/summary/%s",
+		wikiNetloc,
+		url.PathEscape(req.Query),
+	)
+
+	httpReq, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
+	if err != nil {
+		return contracts.SearchResponse{}, err
+	}
+	// Wikimedia APIs require a descriptive User-Agent.
+	httpReq.Header.Set(
+		"User-Agent",
+		"gosearch-go/0.1 (compatible; +https://github.com/ashie/gosearch)",
+	)
+	// Best-effort: hint content language.
+	if req.Language != "" && req.Language != "auto" {
+		httpReq.Header.Set("Accept-Language", req.Language)
+	}
+
+	resp, err := e.client.Do(httpReq)
+	if err != nil {
+		return contracts.SearchResponse{}, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode == http.StatusNotFound {
+		return contracts.SearchResponse{
+			Query:            req.Query,
+			NumberOfResults: 0,
+			Results:          []contracts.MainResult{},
+			Answers:          []map[string]any{},
+			Corrections:      []string{},
+			Infoboxes:        []map[string]any{},
+			Suggestions:      []string{},
+			UnresponsiveEngines: [][2]string{},
+		}, nil
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		body, _ := io.ReadAll(io.LimitReader(resp.Body, 16*1024))
+		return contracts.SearchResponse{}, fmt.Errorf("wikipedia upstream error: status=%d body=%q", resp.StatusCode, string(body))
+	}
+
+	var api struct {
+		Title       string `json:"title"`
+		Description string `json:"description"`
+		Titles      struct {
+			Display string `json:"display"`
+		} `json:"titles"`
+		ContentURLs struct {
+			Desktop struct {
+				Page string `json:"page"`
+			} `json:"desktop"`
+		} `json:"content_urls"`
+	}
+
+	if err := json.NewDecoder(resp.Body).Decode(&api); err != nil {
+		return contracts.SearchResponse{}, err
+	}
+
+	pageURL := api.ContentURLs.Desktop.Page
+	if pageURL == "" {
+		// API returned a non-standard payload; treat as no result.
+		return contracts.SearchResponse{
+			Query:               req.Query,
+			NumberOfResults:    0,
+			Results:             []contracts.MainResult{},
+			Answers:             []map[string]any{},
+			Corrections:         []string{},
+			Infoboxes:           []map[string]any{},
+			Suggestions:         []string{},
+			UnresponsiveEngines: [][2]string{},
+		}, nil
+	}
+
+	title := api.Titles.Display
+	if title == "" {
+		title = api.Title
+	}
+
+	content := api.Description
+
+	urlPtr := pageURL
+	pub := (*string)(nil)
+
+	results := []contracts.MainResult{
+		{
+			Template: "default.html",
+			Title:    title,
+			Content:  content,
+			URL:      &urlPtr,
+			Pubdate:  pub,
+			Engine:   "wikipedia",
+			Score:    0,
+			Category: "general",
+			Priority: "",
+			Positions: nil,
+			Engines:  []string{"wikipedia"},
+		},
+	}
+
+	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
+}
+