feat: Add Open Graph tag support (#195)

* feat: Add Open Graph tag support (og-tags)

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Fix: Prevent nil pointer dereference in test (og-tags)

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat!: Implement Open Graph tag caching and passthrough functionality (WIP)

I'm going to sleep. currently tags are passed to renderIndex.

see https://github.com/TecharoHQ/anubis/issues/131

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat: Add configuration for air tool with build and logger settings

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat: Move OG tags to base template (og-tags)

Moves the Open Graph (OG) tags from the index template to
the base template. This allows OG tags to be set on any
page, not just the index.  Also adds a
BaseWithOGTags function to the web package to allow
passing OG tags to the base template.  Removes the
ogTags parameter from the Index function and template.

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Delete CHANGELOG.md

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat: Add language attribute to HTML tag in template

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* fix(tests):  Fix nil pointer ref

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat(og-tags): Add timeout to http client (og-tags)

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* style: fix line endings & indentation

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* style: add inspection comment for GoBoolExpressions in UnchangingCache

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat(og-tags): Implement Open Graph tag fetching and caching

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* fix(og-tags): Simplify Open Graph tag extraction logic

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* fix(og-tags): Add nil check in isOGMetaTag and enhance test cases

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat(og-tags): Add approved tags and prefixes for Open Graph extraction

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* test(og-tags): Update tests with approved tags and improve clarity

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* chore: Add changelog notes

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* fix: Improve stability of the target fetcher?

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* fix: Update template error handling and improve Open Graph tag integration

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* style: format files and remove deubg logs

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat: Credit CELPHASE for mascot design (og-tags)

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat: Credit CELPHASE for mascot design (og-tags)

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat: Allow twitter prefixed OG tags by default

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* chore: replace /tmp with /var

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Update docs/docs/CHANGELOG.md

Co-authored-by: Xe Iaso <me@xeiaso.net>
Signed-off-by: Jason Cameron <jasoncameron.all@gmail.com>

* Update docs/docs/admin/configuration/open-graph.mdx

Co-authored-by: Xe Iaso <me@xeiaso.net>
Signed-off-by: Jason Cameron <jasoncameron.all@gmail.com>

* chore: add fediverse to default prefixes (#og-tags)

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat(og-tags): Remove og-query-distinct flag

This commit removes the `og-query-distinct` flag and
associated logic.  URLs with different query parameters
will now always be treated as the same cache key for Open
Graph tags.  This simplifies the caching logic and
improves performance.

Additionally, the http client used for fetching OG tags
is now a member of the OGTagCache struct, rather than a
global variable. This improves testability and allows
for more flexible configuration in the future.

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Update docs/docs/admin/configuration/open-graph.mdx

Co-authored-by: Xe Iaso <me@xeiaso.net>
Signed-off-by: Jason Cameron <jasoncameron.all@gmail.com>

* docs: remove og tags references

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* refactor: rename url > u to not overlap package name

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Update internal/ogtags/cache.go

Co-authored-by: Xe Iaso <me@xeiaso.net>
Signed-off-by: Jason Cameron <jasoncameron.all@gmail.com>

* Update internal/ogtags/cache.go

Co-authored-by: Xe Iaso <me@xeiaso.net>
Signed-off-by: Jason Cameron <jasoncameron.all@gmail.com>

* fix(tests): Don't use network when network access is disabled

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Fix: Handle nil URL in GetOGTags (og-tags)

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* chore: sort installation docs alphabetically

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* fix(tests): validate that no duplicate requests are made

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* style(tests): remove unused ok var

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* docs: convert to table fmt

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat(og-tags): Enhance OG tag fetching and caching

Adds additional approved OG tags (`keywords`, `author`), improves

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* chore: update generated templ's after format

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* fix(tests): update integration_test.go to reflect the new behavior of fetchHTMLDocument

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Revert "data/botPolicies: allow iMessage scraper by default (#178)"

This reverts commit 21a9d777

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Fix: Simplify ogTags access in cache test.

Didn't know this was possible! wow!

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Fix: Handle request timeouts when fetching OG tags (#og-tags)

Cache a nil result for half the TTL to avoid repeatedly
requesting a timed-out URL.

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Fix: make OG tags passthrough option function.

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* Fix: Handle timeouts and non-200 responses when fetching OG tags (og-tags)

- Cache empty results for timeouts and non-200 status codes
  to avoid spamming the server.
- Use a non-nil empty map to represent empty results in the
  cache, as nil would be a cache miss.

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* feat(og-tags): switch to http.MaxBytesReader

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

* chore(og-tags): add noindex, nofollow meta tag and update error line numbers

Signed-off-by: Jason Cameron <git@jasoncameron.dev>

---------

Signed-off-by: Jason Cameron <git@jasoncameron.dev>
Signed-off-by: Jason Cameron <jasoncameron.all@gmail.com>
Co-authored-by: Xe Iaso <me@xeiaso.net>

9 files changed, 1043 insertions, 0 deletions

diff --git a/internal/ogtags/cache.go b/internal/ogtags/cache.go
new file mode 100644
index 0000000..0d1a615
--- /dev/null
+++ b/internal/ogtags/cache.go
@@ -0,0 +1,51 @@
+package ogtags
+
+import (
+	"errors"
+	"log/slog"
+	"net/url"
+	"syscall"
+)
+
+// GetOGTags is the main function that retrieves Open Graph tags for a URL
+func (c *OGTagCache) GetOGTags(url *url.URL) (map[string]string, error) {
+	if url == nil {
+		return nil, errors.New("nil URL provided, cannot fetch OG tags")
+	}
+	urlStr := c.getTarget(url)
+	// Check cache first
+	if cachedTags := c.checkCache(urlStr); cachedTags != nil {
+		return cachedTags, nil
+	}
+
+	// Fetch HTML content
+	doc, err := c.fetchHTMLDocument(urlStr)
+	if errors.Is(err, syscall.ECONNREFUSED) {
+		slog.Debug("Connection refused, returning empty tags")
+		return nil, nil
+	} else if errors.Is(err, ErrNotFound) {
+		// not even worth a debug log...
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// Extract OG tags
+	ogTags := c.extractOGTags(doc)
+
+	// Store in cache
+	c.cache.Set(urlStr, ogTags, c.ogTimeToLive)
+
+	return ogTags, nil
+}
+
+// checkCache checks if we have the tags cached and returns them if so
+func (c *OGTagCache) checkCache(urlStr string) map[string]string {
+	if cachedTags, ok := c.cache.Get(urlStr); ok {
+		slog.Debug("cache hit", "tags", cachedTags)
+		return cachedTags
+	}
+	slog.Debug("cache miss", "url", urlStr)
+	return nil
+}
diff --git a/internal/ogtags/cache_test.go b/internal/ogtags/cache_test.go
new file mode 100644
index 0000000..cd32414
--- /dev/null
+++ b/internal/ogtags/cache_test.go
@@ -0,0 +1,122 @@
+package ogtags
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+	"time"
+)
+
+func TestCheckCache(t *testing.T) {
+	cache := NewOGTagCache("http://example.com", true, time.Minute)
+
+	// Set up test data
+	urlStr := "http://example.com/page"
+	expectedTags := map[string]string{
+		"og:title":       "Test Title",
+		"og:description": "Test Description",
+	}
+
+	// Test cache miss
+	tags := cache.checkCache(urlStr)
+	if tags != nil {
+		t.Errorf("expected nil tags on cache miss, got %v", tags)
+	}
+
+	// Manually add to cache
+	cache.cache.Set(urlStr, expectedTags, time.Minute)
+
+	// Test cache hit
+	tags = cache.checkCache(urlStr)
+	if tags == nil {
+		t.Fatal("expected non-nil tags on cache hit, got nil")
+	}
+
+	for key, expectedValue := range expectedTags {
+		if value, ok := tags[key]; !ok || value != expectedValue {
+			t.Errorf("expected %s: %s, got: %s", key, expectedValue, value)
+		}
+	}
+}
+
+func TestGetOGTags(t *testing.T) {
+	var loadCount int // Counter to track how many times the test route is loaded
+
+	// Create a test server to serve a sample HTML page with OG tags
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		loadCount++
+		if loadCount > 1 {
+			t.Fatalf("Test route loaded more than once, cache failed")
+		}
+		w.Header().Set("Content-Type", "text/html")
+		w.Write([]byte(`
+			<!DOCTYPE html>
+			<html>
+			<head>
+				<meta property="og:title" content="Test Title" />
+				<meta property="og:description" content="Test Description" />
+				<meta property="og:image" content="http://example.com/image.jpg" />
+			</head>
+			<body>
+				<p>Hello, world!</p>
+			</body>
+			</html>
+		`))
+	}))
+	defer ts.Close()
+
+	// Create an instance of OGTagCache with a short TTL for testing
+	cache := NewOGTagCache(ts.URL, true, 1*time.Minute)
+
+	// Parse the test server URL
+	parsedURL, err := url.Parse(ts.URL)
+	if err != nil {
+		t.Fatalf("failed to parse test server URL: %v", err)
+	}
+
+	// Test fetching OG tags from the test server
+	ogTags, err := cache.GetOGTags(parsedURL)
+	if err != nil {
+		t.Fatalf("failed to get OG tags: %v", err)
+	}
+
+	// Verify the fetched OG tags
+	expectedTags := map[string]string{
+		"og:title":       "Test Title",
+		"og:description": "Test Description",
+		"og:image":       "http://example.com/image.jpg",
+	}
+
+	for key, expectedValue := range expectedTags {
+		if value, ok := ogTags[key]; !ok || value != expectedValue {
+			t.Errorf("expected %s: %s, got: %s", key, expectedValue, value)
+		}
+	}
+
+	// Test fetching OG tags from the cache
+	ogTags, err = cache.GetOGTags(parsedURL)
+	if err != nil {
+		t.Fatalf("failed to get OG tags from cache: %v", err)
+	}
+
+	// Test fetching OG tags from the cache (3rd time)
+	newOgTags, err := cache.GetOGTags(parsedURL)
+	if err != nil {
+		t.Fatalf("failed to get OG tags from cache: %v", err)
+	}
+
+	// Verify the cached OG tags
+	for key, expectedValue := range expectedTags {
+		if value, ok := ogTags[key]; !ok || value != expectedValue {
+			t.Errorf("expected %s: %s, got: %s", key, expectedValue, value)
+		}
+
+		initialValue := ogTags[key]
+		cachedValue, ok := newOgTags[key]
+		if !ok || initialValue != cachedValue {
+			t.Errorf("Cache does not line up: expected %s: %s, got: %s", key, initialValue, cachedValue)
+		}
+
+	}
+}
diff --git a/internal/ogtags/fetch.go b/internal/ogtags/fetch.go
new file mode 100644
index 0000000..3ea9aac
--- /dev/null
+++ b/internal/ogtags/fetch.go
@@ -0,0 +1,69 @@
+package ogtags
+
+import (
+	"errors"
+	"fmt"
+	"golang.org/x/net/html"
+	"log/slog"
+	"mime"
+	"net"
+	"net/http"
+)
+
+var (
+	ErrNotFound = errors.New("page not found") /*todo: refactor into common errors lib? */
+	emptyMap    = map[string]string{}          // used to indicate an empty result in the cache. Can't use nil as it would be a cache miss.
+)
+
+func (c *OGTagCache) fetchHTMLDocument(urlStr string) (*html.Node, error) {
+	resp, err := c.client.Get(urlStr)
+	if err != nil {
+		var netErr net.Error
+		if errors.As(err, &netErr) && netErr.Timeout() {
+			slog.Debug("og: request timed out", "url", urlStr)
+			c.cache.Set(urlStr, emptyMap, c.ogTimeToLive/2) // Cache empty result for half the TTL to not spam the server
+		}
+		return nil, fmt.Errorf("http get failed: %w", err)
+	}
+	// this defer will call MaxBytesReader's Close, which closes the original body.
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		slog.Debug("og: received non-OK status code", "url", urlStr, "status", resp.StatusCode)
+		c.cache.Set(urlStr, emptyMap, c.ogTimeToLive) // Cache empty result for non-successful status codes
+		return nil, ErrNotFound
+	}
+
+	// Check content type
+	ct := resp.Header.Get("Content-Type")
+	if ct == "" {
+		// assume non html body
+		return nil, fmt.Errorf("missing Content-Type header")
+	} else {
+		mediaType, _, err := mime.ParseMediaType(ct)
+		if err != nil {
+			// Malformed Content-Type header
+			return nil, fmt.Errorf("invalid Content-Type '%s': %w", ct, err)
+		}
+
+		if mediaType != "text/html" && mediaType != "application/xhtml+xml" {
+			return nil, fmt.Errorf("unsupported Content-Type: %s", mediaType)
+		}
+	}
+
+	resp.Body = http.MaxBytesReader(nil, resp.Body, c.maxContentLength)
+
+	doc, err := html.Parse(resp.Body)
+	if err != nil {
+		// Check if the error is specifically because the limit was exceeded
+		var maxBytesErr *http.MaxBytesError
+		if errors.As(err, &maxBytesErr) {
+			slog.Debug("og: content exceeded max length", "url", urlStr, "limit", c.maxContentLength)
+			return nil, fmt.Errorf("content too large: exceeded %d bytes", c.maxContentLength)
+		}
+		// parsing error (e.g., malformed HTML)
+		return nil, fmt.Errorf("failed to parse HTML: %w", err)
+	}
+
+	return doc, nil
+}
diff --git a/internal/ogtags/fetch_test.go b/internal/ogtags/fetch_test.go
new file mode 100644
index 0000000..60af957
--- /dev/null
+++ b/internal/ogtags/fetch_test.go
@@ -0,0 +1,119 @@
+package ogtags
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestFetchHTMLDocument(t *testing.T) {
+	tests := []struct {
+		name          string
+		htmlContent   string
+		contentType   string
+		statusCode    int
+		contentLength int64
+		expectError   bool
+	}{
+		{
+			name: "Valid HTML",
+			htmlContent: `<!DOCTYPE html>
+				<html>
+				<head><title>Test</title></head>
+				<body><p>Test content</p></body>
+				</html>`,
+			contentType: "text/html",
+			statusCode:  http.StatusOK,
+			expectError: false,
+		},
+		{
+			name:        "Empty HTML",
+			htmlContent: "",
+			contentType: "text/html",
+			statusCode:  http.StatusOK,
+			expectError: false,
+		},
+		{
+			name:        "Not found error",
+			htmlContent: "",
+			contentType: "text/html",
+			statusCode:  http.StatusNotFound,
+			expectError: true,
+		},
+		{
+			name:        "Unsupported Content-Type",
+			htmlContent: "*Insert rick roll here*",
+			contentType: "video/mp4",
+			statusCode:  http.StatusOK,
+			expectError: true,
+		},
+		{
+			name:          "Too large content",
+			contentType:   "text/html",
+			statusCode:    http.StatusOK,
+			expectError:   true,
+			contentLength: 5 * 1024 * 1024, // 5MB (over 2MB limit)
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				if tt.contentType != "" {
+					w.Header().Set("Content-Type", tt.contentType)
+				}
+				if tt.contentLength > 0 {
+					// Simulate content length but avoid sending too much actual data
+					w.Header().Set("Content-Length", fmt.Sprintf("%d", tt.contentLength))
+					io.CopyN(w, strings.NewReader("X"), tt.contentLength)
+				} else {
+					w.WriteHeader(tt.statusCode)
+					w.Write([]byte(tt.htmlContent))
+				}
+			}))
+			defer ts.Close()
+
+			cache := NewOGTagCache("", true, time.Minute)
+			doc, err := cache.fetchHTMLDocument(ts.URL)
+
+			if tt.expectError {
+				if err == nil {
+					t.Error("expected error, got nil")
+				}
+				if doc != nil {
+					t.Error("expected nil document on error, got non-nil")
+				}
+			} else {
+				if err != nil {
+					t.Errorf("unexpected error: %v", err)
+				}
+				if doc == nil {
+					t.Error("expected non-nil document, got nil")
+				}
+			}
+		})
+	}
+}
+
+func TestFetchHTMLDocumentInvalidURL(t *testing.T) {
+	if os.Getenv("DONT_USE_NETWORK") != "" {
+		t.Skip("test requires theoretical network egress")
+	}
+
+	cache := NewOGTagCache("", true, time.Minute)
+
+	doc, err := cache.fetchHTMLDocument("http://invalid.url.that.doesnt.exist.example")
+
+	if err == nil {
+		t.Error("expected error for invalid URL, got nil")
+	}
+
+	if doc != nil {
+		t.Error("expected nil document for invalid URL, got non-nil")
+	}
+}
diff --git a/internal/ogtags/integration_test.go b/internal/ogtags/integration_test.go
new file mode 100644
index 0000000..9eaaa3a
--- /dev/null
+++ b/internal/ogtags/integration_test.go
@@ -0,0 +1,155 @@
+package ogtags
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+	"time"
+)
+
+func TestIntegrationGetOGTags(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "text/html")
+
+		switch r.URL.Path {
+		case "/simple":
+			w.Write([]byte(`
+				<!DOCTYPE html>
+				<html>
+				<head>
+					<meta property="og:title" content="Simple Page" />
+					<meta property="og:type" content="website" />
+				</head>
+				<body><p>Simple page content</p></body>
+				</html>
+			`))
+		case "/complete":
+			w.Write([]byte(`
+				<!DOCTYPE html>
+				<html>
+				<head>
+					<meta property="og:title" content="Complete Page" />
+					<meta property="og:description" content="A page with many OG tags" />
+					<meta property="og:image" content="http://example.com/image.jpg" />
+					<meta property="og:url" content="http://example.com/complete" />
+					<meta property="og:type" content="article" />
+				</head>
+				<body><p>Complete page content</p></body>
+				</html>
+			`))
+		case "/no-og":
+			w.Write([]byte(`
+				<!DOCTYPE html>
+				<html>
+				<head>
+					<title>No OG Tags</title>
+				</head>
+				<body><p>No OG tags here</p></body>
+				</html>
+			`))
+		default:
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+	defer ts.Close()
+
+	// Test with different configurations
+	testCases := []struct {
+		name         string
+		path         string
+		query        string
+		expectedTags map[string]string
+		expectError  bool
+	}{
+		{
+			name:  "Simple page",
+			path:  "/simple",
+			query: "",
+			expectedTags: map[string]string{
+				"og:title": "Simple Page",
+				"og:type":  "website",
+			},
+			expectError: false,
+		},
+		{
+			name:  "Complete page",
+			path:  "/complete",
+			query: "ref=test",
+			expectedTags: map[string]string{
+				"og:title":       "Complete Page",
+				"og:description": "A page with many OG tags",
+				"og:image":       "http://example.com/image.jpg",
+				"og:url":         "http://example.com/complete",
+				"og:type":        "article",
+			},
+			expectError: false,
+		},
+		{
+			name:         "Page with no OG tags",
+			path:         "/no-og",
+			query:        "",
+			expectedTags: map[string]string{},
+			expectError:  false,
+		},
+		{
+			name:         "Non-existent page",
+			path:         "/not-found",
+			query:        "",
+			expectedTags: nil,
+			expectError:  false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Create cache instance
+			cache := NewOGTagCache(ts.URL, true, 1*time.Minute)
+
+			// Create URL for test
+			testURL, _ := url.Parse(ts.URL)
+			testURL.Path = tc.path
+			testURL.RawQuery = tc.query
+
+			// Get OG tags
+			ogTags, err := cache.GetOGTags(testURL)
+
+			// Check error expectation
+			if tc.expectError {
+				if err == nil {
+					t.Error("expected error, got nil")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			// Verify all expected tags are present
+			for key, expectedValue := range tc.expectedTags {
+				if value, ok := ogTags[key]; !ok || value != expectedValue {
+					t.Errorf("expected %s: %s, got: %s", key, expectedValue, value)
+				}
+			}
+
+			// Verify no extra tags are present
+			if len(ogTags) != len(tc.expectedTags) {
+				t.Errorf("expected %d tags, got %d", len(tc.expectedTags), len(ogTags))
+			}
+
+			// Test cache retrieval
+			cachedOGTags, err := cache.GetOGTags(testURL)
+			if err != nil {
+				t.Fatalf("failed to get OG tags from cache: %v", err)
+			}
+
+			// Verify cached tags match
+			for key, expectedValue := range tc.expectedTags {
+				if value, ok := cachedOGTags[key]; !ok || value != expectedValue {
+					t.Errorf("cached value - expected %s: %s, got: %s", key, expectedValue, value)
+				}
+			}
+		})
+	}
+}
diff --git a/internal/ogtags/ogtags.go b/internal/ogtags/ogtags.go
new file mode 100644
index 0000000..72185bb
--- /dev/null
+++ b/internal/ogtags/ogtags.go
@@ -0,0 +1,51 @@
+package ogtags
+
+import (
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/TecharoHQ/anubis/decaymap"
+)
+
+type OGTagCache struct {
+	cache            *decaymap.Impl[string, map[string]string]
+	target           string
+	ogPassthrough    bool
+	ogTimeToLive     time.Duration
+	approvedTags     []string
+	approvedPrefixes []string
+	client           *http.Client
+	maxContentLength int64
+}
+
+func NewOGTagCache(target string, ogPassthrough bool, ogTimeToLive time.Duration) *OGTagCache {
+	// Predefined approved tags and prefixes
+	// In the future, these could come from configuration
+	defaultApprovedTags := []string{"description", "keywords", "author"}
+	defaultApprovedPrefixes := []string{"og:", "twitter:", "fediverse:"}
+	client := &http.Client{
+		Timeout: 5 * time.Second, /*make this configurable?*/
+	}
+
+	const maxContentLength = 16 << 20 // 16 MiB in bytes
+
+	return &OGTagCache{
+		cache:            decaymap.New[string, map[string]string](),
+		target:           target,
+		ogPassthrough:    ogPassthrough,
+		ogTimeToLive:     ogTimeToLive,
+		approvedTags:     defaultApprovedTags,
+		approvedPrefixes: defaultApprovedPrefixes,
+		client:           client,
+		maxContentLength: maxContentLength,
+	}
+}
+
+func (c *OGTagCache) getTarget(u *url.URL) string {
+	return c.target + u.Path
+}
+
+func (c *OGTagCache) Cleanup() {
+	c.cache.Cleanup()
+}
diff --git a/internal/ogtags/ogtags_test.go b/internal/ogtags/ogtags_test.go
new file mode 100644
index 0000000..8cd5b0d
--- /dev/null
+++ b/internal/ogtags/ogtags_test.go
@@ -0,0 +1,100 @@
+package ogtags
+
+import (
+	"net/url"
+	"testing"
+	"time"
+)
+
+func TestNewOGTagCache(t *testing.T) {
+	tests := []struct {
+		name          string
+		target        string
+		ogPassthrough bool
+		ogTimeToLive  time.Duration
+	}{
+		{
+			name:          "Basic initialization",
+			target:        "http://example.com",
+			ogPassthrough: true,
+			ogTimeToLive:  5 * time.Minute,
+		},
+		{
+			name:          "Empty target",
+			target:        "",
+			ogPassthrough: false,
+			ogTimeToLive:  10 * time.Minute,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cache := NewOGTagCache(tt.target, tt.ogPassthrough, tt.ogTimeToLive)
+
+			if cache == nil {
+				t.Fatal("expected non-nil cache, got nil")
+			}
+
+			if cache.target != tt.target {
+				t.Errorf("expected target %s, got %s", tt.target, cache.target)
+			}
+
+			if cache.ogPassthrough != tt.ogPassthrough {
+				t.Errorf("expected ogPassthrough %v, got %v", tt.ogPassthrough, cache.ogPassthrough)
+			}
+
+			if cache.ogTimeToLive != tt.ogTimeToLive {
+				t.Errorf("expected ogTimeToLive %v, got %v", tt.ogTimeToLive, cache.ogTimeToLive)
+			}
+		})
+	}
+}
+
+func TestGetTarget(t *testing.T) {
+	tests := []struct {
+		name     string
+		target   string
+		path     string
+		query    string
+		expected string
+	}{
+		{
+			name:     "No path or query",
+			target:   "http://example.com",
+			path:     "",
+			query:    "",
+			expected: "http://example.com",
+		},
+		{
+			name:     "With complex path",
+			target:   "http://example.com",
+			path:     "/pag(#*((#@)ΓΓΓΓe/Γ",
+			query:    "id=123",
+			expected: "http://example.com/pag(#*((#@)ΓΓΓΓe/Γ",
+		},
+		{
+			name:     "With query and path",
+			target:   "http://example.com",
+			path:     "/page",
+			query:    "id=123",
+			expected: "http://example.com/page",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cache := NewOGTagCache(tt.target, false, time.Minute)
+
+			u := &url.URL{
+				Path:     tt.path,
+				RawQuery: tt.query,
+			}
+
+			result := cache.getTarget(u)
+
+			if result != tt.expected {
+				t.Errorf("expected %s, got %s", tt.expected, result)
+			}
+		})
+	}
+}
diff --git a/internal/ogtags/parse.go b/internal/ogtags/parse.go
new file mode 100644
index 0000000..8828e59
--- /dev/null
+++ b/internal/ogtags/parse.go
@@ -0,0 +1,81 @@
+package ogtags
+
+import (
+	"strings"
+
+	"golang.org/x/net/html"
+)
+
+// extractOGTags traverses the HTML document and extracts approved Open Graph tags
+func (c *OGTagCache) extractOGTags(doc *html.Node) map[string]string {
+	ogTags := make(map[string]string)
+
+	var traverseNodes func(*html.Node)
+	traverseNodes = func(n *html.Node) {
+		// isOGMetaTag only checks if it's a <meta> tag.
+		// The actual filtering happens in extractMetaTagInfo now.
+		if isOGMetaTag(n) {
+			property, content := c.extractMetaTagInfo(n)
+			if property != "" {
+				ogTags[property] = content
+			}
+		}
+
+		for child := n.FirstChild; child != nil; child = child.NextSibling {
+			traverseNodes(child)
+		}
+	}
+
+	traverseNodes(doc)
+	return ogTags
+}
+
+// isOGMetaTag checks if a node is *any* meta tag
+func isOGMetaTag(n *html.Node) bool {
+	if n == nil {
+		return false
+	}
+	return n.Type == html.ElementNode && n.Data == "meta"
+}
+
+// extractMetaTagInfo extracts property and content from a meta tag
+// *and* checks if the property is approved.
+// Returns empty property string if the tag is not approved.
+func (c *OGTagCache) extractMetaTagInfo(n *html.Node) (property, content string) {
+	var rawProperty string // Store the property found before approval check
+
+	for _, attr := range n.Attr {
+		if attr.Key == "property" || attr.Key == "name" {
+			rawProperty = attr.Val
+		}
+		if attr.Key == "content" {
+			content = attr.Val
+		}
+	}
+
+	// Check if the rawProperty is approved
+	isApproved := false
+	for _, prefix := range c.approvedPrefixes {
+		if strings.HasPrefix(rawProperty, prefix) {
+			isApproved = true
+			break
+		}
+	}
+	// Check exact approved tags if not already approved by prefix
+	if !isApproved {
+		for _, tag := range c.approvedTags {
+			if rawProperty == tag {
+				isApproved = true
+				break
+			}
+		}
+	}
+
+	// Only return the property if it's approved
+	if isApproved {
+		property = rawProperty
+	}
+
+	// Content is returned regardless, but property will be "" if not approved
+	return property, content
+}
diff --git a/internal/ogtags/parse_test.go b/internal/ogtags/parse_test.go
new file mode 100644
index 0000000..54815b3
--- /dev/null
+++ b/internal/ogtags/parse_test.go
@@ -0,0 +1,295 @@
+package ogtags
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+
+	"golang.org/x/net/html"
+)
+
+// TestExtractOGTags updated with correct expectations based on filtering logic
+func TestExtractOGTags(t *testing.T) {
+	// Use a cache instance that reflects the default approved lists
+	testCache := NewOGTagCache("", false, time.Minute)
+	// Manually set approved tags/prefixes based on the user request for clarity
+	testCache.approvedTags = []string{"description"}
+	testCache.approvedPrefixes = []string{"og:"}
+
+	tests := []struct {
+		name     string
+		htmlStr  string
+		expected map[string]string
+	}{
+		{
+			name: "Basic OG tags", // Includes standard 'description' meta tag
+			htmlStr: `<!DOCTYPE html>
+				<html>
+				<head>
+					<meta property="og:title" content="Test Title" />
+					<meta property="og:description" content="Test Description" />
+					<meta name="description" content="Regular Description" />
+					<meta name="keywords" content="test, keyword" />
+				</head>
+				<body></body>
+				</html>`,
+			expected: map[string]string{
+				"og:title":       "Test Title",
+				"og:description": "Test Description",
+				"description":    "Regular Description",
+			},
+		},
+		{
+			name: "OG tags with name attribute",
+			htmlStr: `<!DOCTYPE html>
+				<html>
+				<head>
+					<meta name="og:title" content="Test Title" />
+					<meta property="og:description" content="Test Description" />
+					<meta name="twitter:card" content="summary" />
+				</head>
+				<body></body>
+				</html>`,
+			expected: map[string]string{
+				"og:title":       "Test Title",
+				"og:description": "Test Description",
+				// twitter:card is still not approved
+			},
+		},
+		{
+			name: "No approved OG tags", // Contains only standard 'description'
+			htmlStr: `<!DOCTYPE html>
+				<html>
+				<head>
+					<meta name="description" content="Test Description" />
+					<meta name="keywords" content="Test" />
+				</head>
+				<body></body>
+				</html>`,
+			expected: map[string]string{
+				"description": "Test Description",
+			},
+		},
+		{
+			name: "Empty content",
+			htmlStr: `<!DOCTYPE html>
+				<html>
+				<head>
+					<meta property="og:title" content="" />
+					<meta property="og:description" content="Test Description" />
+				</head>
+				<body></body>
+				</html>`,
+			expected: map[string]string{
+				"og:title":       "",
+				"og:description": "Test Description",
+			},
+		},
+		{
+			name: "Explicitly approved tag",
+			htmlStr: `<!DOCTYPE html>
+						<html>
+						<head>
+							<meta property="description" content="Approved Description Tag" />
+						</head>
+						<body></body>
+						</html>`,
+			expected: map[string]string{
+				// This is approved because "description" is in cache.approvedTags
+				"description": "Approved Description Tag",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			doc, err := html.Parse(strings.NewReader(tt.htmlStr))
+			if err != nil {