latexgrambot: inline LaTeX bot for Telegram in Go

Renders LaTeX expressions into PNG pictures, PDF documents and native
Telegram rich text messages, entirely locally with TeX Live and poppler.

- Chat mode with /image, /pdf, /rich plus per-user preamble and DPI
- Inline mode delivering picture, PDF and rich text results
- Broad default package set preloaded into a TeX format at image build
- MongoDB persistence: settings, users, groups, render statistics
- Private S3-compatible bucket with short-lived presigned URLs
- OpenTelemetry traces over OTLP
- Kubernetes manifests and Argo CD application, Docker Compose, GitHub
  Actions CI, BSD 3-Clause license

internal/files/files_test.go

@@ -0,0 +1,176 @@
+package files
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/google/uuid"
+)
+
+func TestPutUploadsUniqueUUIDObjectsWithPresignedURLs(t *testing.T) {
+	var puts atomic.Int32
+	keys := make(chan string, 4)
+	client := &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+		status := http.StatusOK
+		switch request.Method {
+		case http.MethodPut:
+			puts.Add(1)
+			keys <- request.URL.Path
+		}
+		return &http.Response{
+			StatusCode: status,
+			Status:     http.StatusText(status),
+			Header:     make(http.Header),
+			Body:       io.NopCloser(strings.NewReader("")),
+			Request:    request,
+		}, nil
+	})}
+
+	store, err := New(context.Background(), Config{
+		Endpoint:        "https://s3.internal",
+		PublicEndpoint:  "https://s3.example",
+		Region:          "us-east-1",
+		Bucket:          "latexgrambot",
+		AccessKeyID:     "access",
+		SecretAccessKey: "secret",
+		Prefix:          "content",
+		PresignTTL:      time.Hour,
+		HTTPClient:      client,
+	})
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+
+	seen := map[string]bool{}
+	for range 2 {
+		signed, err := store.Put(context.Background(), "jpg", "image/jpeg", []byte("image"))
+		if err != nil {
+			t.Fatalf("Put: %v", err)
+		}
+		parsed, err := url.Parse(signed)
+		if err != nil {
+			t.Fatalf("parse signed URL: %v", err)
+		}
+		base := strings.TrimSuffix(strings.TrimPrefix(parsed.Path, "/latexgrambot/content/"), ".jpg")
+		if _, err := uuid.Parse(base); err != nil || uuid.MustParse(base).Version() != 4 {
+			t.Errorf("object name %q is not a UUIDv4", base)
+		}
+		if seen[parsed.Path] {
+			t.Errorf("object name %q was reused", parsed.Path)
+		}
+		seen[parsed.Path] = true
+		if parsed.Query().Get("X-Amz-Signature") == "" || parsed.Query().Get("X-Amz-Expires") != "3600" {
+			t.Errorf("URL is not signed for one hour: %s", signed)
+		}
+	}
+	if got := puts.Load(); got != 2 {
+		t.Fatalf("PUT requests = %d, want 2 (one object per request)", got)
+	}
+}
+
+func TestDeleteExpired(t *testing.T) {
+	var deleted []string
+	client := &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+		header := make(http.Header)
+		body := ""
+		status := http.StatusOK
+		switch request.Method {
+		case http.MethodGet: // ListObjectsV2
+			header.Set("Content-Type", "application/xml")
+			body = `<?xml version="1.0" encoding="UTF-8"?>
+<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+<Name>latexgrambot</Name><Prefix>content/</Prefix><KeyCount>2</KeyCount><MaxKeys>1000</MaxKeys><IsTruncated>false</IsTruncated>
+<Contents><Key>content/old.jpg</Key><LastModified>2000-01-01T00:00:00.000Z</LastModified><ETag>"a"</ETag><Size>1</Size><StorageClass>STANDARD</StorageClass></Contents>
+<Contents><Key>content/fresh.pdf</Key><LastModified>2099-01-01T00:00:00.000Z</LastModified><ETag>"b"</ETag><Size>1</Size><StorageClass>STANDARD</StorageClass></Contents>
+</ListBucketResult>`
+		case http.MethodDelete:
+			deleted = append(deleted, request.URL.Path)
+			status = http.StatusNoContent
+		}
+		return &http.Response{
+			StatusCode: status,
+			Status:     http.StatusText(status),
+			Header:     header,
+			Body:       io.NopCloser(strings.NewReader(body)),
+			Request:    request,
+		}, nil
+	})}
+
+	store, err := New(context.Background(), Config{
+		Endpoint:        "https://s3.internal",
+		PublicEndpoint:  "https://s3.example",
+		Region:          "us-east-1",
+		Bucket:          "latexgrambot",
+		AccessKeyID:     "access",
+		SecretAccessKey: "secret",
+		Prefix:          "content",
+		PresignTTL:      time.Hour,
+		HTTPClient:      client,
+	})
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+
+	removed, err := store.DeleteExpired(context.Background(), time.Hour)
+	if err != nil {
+		t.Fatalf("DeleteExpired: %v", err)
+	}
+	if removed != 1 {
+		t.Fatalf("removed = %d, want 1", removed)
+	}
+	if len(deleted) != 1 || !strings.HasSuffix(deleted[0], "/content/old.jpg") {
+		t.Fatalf("deleted = %v, want the expired object only", deleted)
+	}
+}
+
+func TestS3Integration(t *testing.T) {
+	endpoint := os.Getenv("LATEXGRAMBOT_S3_TEST_ENDPOINT")
+	accessKey := os.Getenv("LATEXGRAMBOT_S3_TEST_ACCESS_KEY")
+	secretKey := os.Getenv("LATEXGRAMBOT_S3_TEST_SECRET_KEY")
+	if endpoint == "" || accessKey == "" || secretKey == "" {
+		t.Skip("S3 integration environment is not configured")
+	}
+	store, err := New(context.Background(), Config{
+		Endpoint:        endpoint,
+		PublicEndpoint:  endpoint,
+		Region:          "us-east-1",
+		Bucket:          "latexgrambot",
+		AccessKeyID:     accessKey,
+		SecretAccessKey: secretKey,
+		Prefix:          "integration",
+		PresignTTL:      5 * time.Minute,
+	})
+	if err != nil {
+		t.Fatalf("New: %v", err)
+	}
+	const payload = "latexgrambot S3 integration probe\n"
+	signed, err := store.Put(context.Background(), "txt", "text/plain", []byte(payload))
+	if err != nil {
+		t.Fatalf("Put: %v", err)
+	}
+	response, err := http.Get(signed)
+	if err != nil {
+		t.Fatalf("GET presigned URL: %v", err)
+	}
+	defer response.Body.Close()
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		t.Fatalf("read presigned response: %v", err)
+	}
+	if response.StatusCode != http.StatusOK || string(body) != payload {
+		t.Fatalf("presigned GET = %s, body %q", response.Status, body)
+	}
+}
+
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (f roundTripFunc) RoundTrip(request *http.Request) (*http.Response, error) {
+	return f(request)
+}