Add filter, add READMES

backend_go/sparql.go

@@ -0,0 +1,169 @@
+package main
+
+import (
+	"context"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+)
+
+type AnzoGraphClient struct {
+	cfg        Config
+	endpoint   string
+	authHeader string
+	client     *http.Client
+}
+
+func NewAnzoGraphClient(cfg Config) *AnzoGraphClient {
+	endpoint := cfg.EffectiveSparqlEndpoint()
+	authHeader := ""
+	user := strings.TrimSpace(cfg.SparqlUser)
+	pass := strings.TrimSpace(cfg.SparqlPass)
+	if user != "" && pass != "" {
+		token := base64.StdEncoding.EncodeToString([]byte(user + ":" + pass))
+		authHeader = "Basic " + token
+	}
+
+	return &AnzoGraphClient{
+		cfg:        cfg,
+		endpoint:   endpoint,
+		authHeader: authHeader,
+		client:     &http.Client{},
+	}
+}
+
+func (c *AnzoGraphClient) Startup(ctx context.Context) error {
+	if err := c.waitReady(ctx); err != nil {
+		return err
+	}
+
+	if c.cfg.SparqlClearOnStart {
+		if err := c.update(ctx, "CLEAR ALL"); err != nil {
+			return err
+		}
+		if err := c.waitReady(ctx); err != nil {
+			return err
+		}
+	}
+
+	if c.cfg.SparqlLoadOnStart {
+		df := strings.TrimSpace(c.cfg.SparqlDataFile)
+		if df == "" {
+			return fmt.Errorf("SPARQL_LOAD_ON_START=true but SPARQL_DATA_FILE is not set")
+		}
+		giri := strings.TrimSpace(c.cfg.SparqlGraphIRI)
+		if giri != "" {
+			if err := c.update(ctx, fmt.Sprintf("LOAD <%s> INTO GRAPH <%s>", df, giri)); err != nil {
+				return err
+			}
+		} else {
+			if err := c.update(ctx, fmt.Sprintf("LOAD <%s>", df)); err != nil {
+				return err
+			}
+		}
+		if err := c.waitReady(ctx); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (c *AnzoGraphClient) Shutdown(ctx context.Context) error {
+	_ = ctx
+	return nil
+}
+
+func (c *AnzoGraphClient) Query(ctx context.Context, query string) ([]byte, error) {
+	return c.queryWithTimeout(ctx, query, c.cfg.SparqlTimeout)
+}
+
+func (c *AnzoGraphClient) queryWithTimeout(ctx context.Context, query string, timeout time.Duration) ([]byte, error) {
+	ctx2, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	form := url.Values{}
+	form.Set("query", query)
+
+	req, err := http.NewRequestWithContext(ctx2, http.MethodPost, c.endpoint, strings.NewReader(form.Encode()))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.Header.Set("Accept", "application/sparql-results+json")
+	if c.authHeader != "" {
+		req.Header.Set("Authorization", c.authHeader)
+	}
+
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return nil, fmt.Errorf("sparql query failed: %s: %s", resp.Status, strings.TrimSpace(string(body)))
+	}
+	return body, nil
+}
+
+func (c *AnzoGraphClient) update(ctx context.Context, update string) error {
+	ctx2, cancel := context.WithTimeout(ctx, c.cfg.SparqlTimeout)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx2, http.MethodPost, c.endpoint, strings.NewReader(update))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/sparql-update")
+	req.Header.Set("Accept", "application/json")
+	if c.authHeader != "" {
+		req.Header.Set("Authorization", c.authHeader)
+	}
+
+	resp, err := c.client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		body, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("sparql update failed: %s: %s", resp.Status, strings.TrimSpace(string(body)))
+	}
+	return nil
+}
+
+func (c *AnzoGraphClient) waitReady(ctx context.Context) error {
+	var lastErr error
+	for i := 0; i < c.cfg.SparqlReadyRetries; i++ {
+		select {
+		case <-ctx.Done():
+			if lastErr != nil {
+				return fmt.Errorf("anzograph not ready at %s: %w", c.endpoint, lastErr)
+			}
+			return ctx.Err()
+		default:
+		}
+
+		body, err := c.queryWithTimeout(ctx, "ASK WHERE { ?s ?p ?o }", c.cfg.SparqlReadyTimeout)
+		if err == nil {
+			// Ensure it's JSON, not HTML/text during boot.
+			if strings.HasPrefix(strings.TrimSpace(string(body)), "{") {
+				return nil
+			}
+			err = fmt.Errorf("unexpected readiness response: %s", strings.TrimSpace(string(body)))
+		}
+		lastErr = err
+		time.Sleep(c.cfg.SparqlReadyDelay)
+	}
+	return fmt.Errorf("anzograph not ready at %s: %w", c.endpoint, lastErr)
+}