use shared puppet slug helpers

docs/puppet/remote.md

@@ -5,3 +5,6 @@ Shared classification, TTL and eviction rules: [caching](../common/caching.md).
 | Type | Mutable (auto-detected) | Immutable (auto-detected) |
 |---|---|---|
 | `puppet` | `v3/modules/*`, `v3/releases*` | `.tar.gz` |
+
+`/v3/releases` forwards the `module`, `limit` and `offset` query params
+upstream; set `base_url` to the Forge API root, e.g. `https://forgeapi.puppet.com`.

internal/provider/puppet/puppet.go

@@ -3,6 +3,7 @@ package puppet
 import (
 	"context"
 	"net/http"
+	"strconv"
 	"strings"
 
 	"git.unkin.net/unkin/artifactapi/internal/auth"
@@ -39,6 +40,32 @@ func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
 	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
 }
 
+// ForwardedQuery keeps the module filter and pagination on release listings.
+func (p *Provider) ForwardedQuery(path string) map[string]provider.QueryValidator {
+	if path != "v3/releases" {
+		return nil
+	}
+	return map[string]provider.QueryValidator{"module": moduleParam, "limit": pageLimit, "offset": pageOffset}
+}
+
+func moduleParam(v string) (string, bool) {
+	v = NormalizeSlug(v)
+	return v, ValidSlug(v)
+}
+
+func pageLimit(v string) (string, bool) {
+	n, err := strconv.ParseUint(v, 10, 32)
+	if err != nil || n == 0 {
+		return "", false
+	}
+	return strconv.FormatUint(min(n, 100), 10), true
+}
+
+func pageOffset(v string) (string, bool) {
+	n, err := strconv.ParseUint(v, 10, 32)
+	return strconv.FormatUint(n, 10), err == nil
+}
+
 func (p *Provider) RewritesResponse() {}
 
 func (p *Provider) RewriteResponse(body []byte, remote models.Remote, proxyBaseURL string) ([]byte, error) {

internal/provider/puppet/puppet_test.go

@@ -76,3 +76,28 @@ func TestAuthHeaders(t *testing.T) {
 		t.Error("no credentials, no header")
 	}
 }
+
+func TestForwardedQuery(t *testing.T) {
+	p := &Provider{}
+	if p.ForwardedQuery("v3/files/a-b-1.0.0.tar.gz") != nil || p.ForwardedQuery("v3/modules/a-b") != nil {
+		t.Fatal("only release listings forward a query")
+	}
+	f := p.ForwardedQuery("v3/releases")
+	for name, c := range map[string]struct {
+		in, want string
+		ok       bool
+	}{
+		"module": {"Puppetlabs/stdlib", "puppetlabs-stdlib", true},
+		"limit":  {"500", "100", true},
+		"offset": {"40", "40", true},
+	} {
+		if got, ok := f[name](c.in); got != c.want || ok != c.ok {
+			t.Errorf("%s(%q) = %q %v, want %q %v", name, c.in, got, ok, c.want, c.ok)
+		}
+	}
+	for name, bad := range map[string]string{"module": "../x", "limit": "0", "offset": "-1"} {
+		if _, ok := f[name](bad); ok {
+			t.Errorf("%s(%q) accepted", name, bad)
+		}
+	}
+}