fix(model): Rework purl conversion according to the specs

Implement the pseudo-algorithm described at [1]. Most importantly, '/'
in namespaces are now not escaped anymore (also see the lengthy
discussion at [2]), key names are lower-cased, and qualifiers are sorted
for comparability.

[1]: https://github.com/package-url/purl-spec/blob/master/PURL-SPECIFICATION.rst#how-to-build-purl-string-from-its-components
[2]: package-url/purl-spec#176

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

model/src/main/kotlin/utils/PurlUtils.kt

@@ -92,28 +92,33 @@ internal fun createPurl(
 ): String =
  buildString {
  append("pkg:")
- append(type)
+ append(type.lowercase())
+ append('/')
 
  if (namespace.isNotEmpty()) {
+ append(namespace.trim('/').split('/').joinToString("/") { it.percentEncode() })
  append('/')
- append(namespace.percentEncode())
+ append(name.trim('/').percentEncode())
+ } else {
+ append(name.percentEncode())
  }
 
- append('/')
- append(name.percentEncode())
-
- append('@')
- append(version.percentEncode())
+ if (version.isNotEmpty()) {
+ append('@')
+ append(version.percentEncode())
+ }
 
- qualifiers.onEachIndexed { index, entry ->
+ qualifiers.filterValues { it.isNotEmpty() }.toSortedMap().onEachIndexed { index, entry ->
  if (index == 0) append("?") else append("&")
- append(entry.key.percentEncode())
+ append(entry.key.lowercase())
  append("=")
  append(entry.value.percentEncode())
  }
 
  if (subpath.isNotEmpty()) {
- val value = subpath.split('/').joinToString("/", prefix = "#") { it.percentEncode() }
+ val value = subpath.trim('/').split('/')
+ .filter { it.isNotEmpty() && it != "." && it != ".." }
+ .joinToString("/", prefix = "#") { it.percentEncode() }
  append(value)
  }
  }

model/src/test/kotlin/utils/PurlExtensionsTest.kt

@@ -68,10 +68,10 @@ class PurlExtensionsTest : WordSpec({
  purl shouldBe "pkg:generic/name@version"
  }
 
- "percent-encode namespaces with segments" {
- val purl = Identifier("generic", "name/space", "name", "version").toPurl()
+ "percent-encode namespace segments" {
+ val purl = Identifier("generic", "name space/with spaces", "name", "version").toPurl()
 
- purl shouldBe "pkg:generic/name%2Fspace/name@version"
+ purl shouldBe "pkg:generic/name%20space/with%20spaces/name@version"
  }
 
  "percent-encode the name" {
@@ -95,7 +95,7 @@ class PurlExtensionsTest : WordSpec({
  mapOf("argName" to "argValue")
  )
 
- purl shouldBe "pkg:type/namespace/name@version?argName=argValue"
+ purl shouldBe "pkg:type/namespace/name@version?argname=argValue"
  }
 
  "allow multiple qualifiers" {
@@ -107,7 +107,7 @@ class PurlExtensionsTest : WordSpec({
  mapOf("argName1" to "argValue1", "argName2" to "argValue2")
  )
 
- purl shouldBe "pkg:type/namespace/name@version?argName1=argValue1&argName2=argValue2"
+ purl shouldBe "pkg:type/namespace/name@version?argname1=argValue1&argname2=argValue2"
  }
 
  "allow subpath" {
@@ -140,8 +140,8 @@ class PurlExtensionsTest : WordSpec({
  val purl = id.toPurl(extras.qualifiers, extras.subpath)
 
  purl shouldBe "pkg:maven/com.example/sources@1.2.3?" +
- "download_url=https%3A%2F%2Fexample.com%2Fsources.zip&" +
- "checksum=md5%3Addce269a1e3d054cae349621c198dd52"
+ "checksum=md5%3Addce269a1e3d054cae349621c198dd52&" +
+ "download_url=https%3A%2F%2Fexample.com%2Fsources.zip"
  purl.toProvenance() shouldBe provenance
  }
 
@@ -161,10 +161,10 @@ class PurlExtensionsTest : WordSpec({
  val purl = id.toPurl(extras.qualifiers, extras.subpath)
 
  purl shouldBe "pkg:maven/com.example/sources@1.2.3?" +
- "vcs_type=Git&" +
- "vcs_url=https%3A%2F%2Fgithub.com%2Fapache%2Fcommons-text.git&" +
+ "resolved_revision=7643b12421100d29fd2b78053e77bcb04a251b2e&" +
  "vcs_revision=7643b12421100d29fd2b78053e77bcb04a251b2e&" +
- "resolved_revision=7643b12421100d29fd2b78053e77bcb04a251b2e" +
+ "vcs_type=Git&" +
+ "vcs_url=https%3A%2F%2Fgithub.com%2Fapache%2Fcommons-text.git" +
  "#subpath"
  purl.toProvenance() shouldBe provenance
  }