feat: add purl details to policy inputs (#129)

test/testdata/local-policy-inputs/doi/policy.rego

@@ -0,0 +1,43 @@
+package attest
+
+import rego.v1
+
+keys := [{
+	"id": "a0c296026645799b2a297913878e81b0aefff2a0c301e97232f717e14402f3e4",
+	"key": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEgH23D1i2+ZIOtVjmfB7iFvX8AhVN\n9CPJ4ie9axw+WRHozGnRy99U2dRge3zueBBg2MweF0zrToXGig2v3YOrdw==\n-----END PUBLIC KEY-----",
+	"from": "2023-12-15T14:00:00Z",
+	"to": null,
+	"status": "active",
+	"signing-format": "dssev1",
+}]
+
+provs(pred) := p if {
+	res := attest.fetch(pred)
+	not res.error
+	p := res.value
+}
+
+atts := union({
+	provs("https://slsa.dev/provenance/v0.2"),
+	provs("https://spdx.dev/Document"),
+})
+
+success if {
+	input.domain == "docker.io"
+	input.familiar_name == "test-image"
+	input.normalized_name == "library/test-image"
+	input.platform == "linux/amd64"
+	input.tag == "test"
+}
+
+result := {
+	"success": success,
+	"violations": set(),
+	"attestations": set(),
+	"summary": {
+		"subjects": set(),
+		"slsa_level": "SLSA_BUILD_LEVEL_3",
+		"verifier": "docker-official-images",
+		"policy_uri": "https://docker.com/official/policy/v0.1",
+	},
+}