Add utility and cli to discover PURL on AP server

Signed-off-by: Keshav Priyadarshi <git@keshav.space>

Author: keshav-space

aboutcode/federatedcode/cli.py

@@ -10,19 +10,47 @@
 
 import click
 
-from aboutcode.federatedcode.client import get_package_scan
+from aboutcode.federatedcode import client
+
+
+@click.group()
+def handler():
+    pass
 
 
 @click.command()
 @click.argument("purl")
-def handler(purl):
+def scan(purl):
     """
     Get package scan for PURL from FederatedCode git repository.
 
     PURL: PURL to fetch scan result
     """
-    click.echo(get_package_scan(purl=purl))
+    click.echo(client.get_package_scan(purl=purl))
+
+
+@click.command()
+@click.argument("purl")
+def discover(purl):
+    """
+    Discover existing Packages in the FederatedCode AP server.
+
+    PURL: PURL to find in AP server
+    """
+    if response := client.discover_package_in_ap_server(purl=purl):
+        click.echo(click.style(response, fg="green", bold=True))
+    else:
+        click.echo(
+            click.style(
+                f"Error: {purl} not available on {client.FEDERATEDCODE_AP_HOST} AP server.",
+                fg="red",
+                bold=True,
+            )
+        )
+
 
+handler.add_command(scan)
+handler.add_command(discover)
 
 if __name__ == "__main__":
     handler()

aboutcode/federatedcode/client/__init__.py

@@ -24,6 +24,11 @@
     "https://raw.githubusercontent.com/aboutcode-org/",
 )
 
+FEDERATEDCODE_AP_HOST = os.getenv(
+    "FEDERATEDCODE_AP_HOST",
+    "http://localhost:8000/",
+)
+
 
 class ScanNotAvailableError(Exception):
     pass
@@ -68,3 +73,26 @@ def subscribe_package(federatedcode_host, remote_username, purl):
 
     url_path = f"api/v0/users/@{remote_username}/subscribe/?purl={quote(purl)}"
     return requests.get(urljoin(federatedcode_host, url_path))
+
+
+def discover_package_in_ap_server(purl: Union[str, PackageURL]):
+    """Return package profile if PURL exists in AP server."""
+
+    if not FEDERATEDCODE_AP_HOST:
+        raise ValueError("Provide ``FEDERATEDCODE_AP_HOST`` in .env file.")
+
+    if isinstance(purl, str):
+        purl = PackageURL.from_string(purl)
+
+    if purl.version or purl.subpath or purl.qualifiers:
+        purl = PackageURL(
+            type=purl.type,
+            namespace=purl.name,
+            name=purl.name,
+        )
+
+    package = quote(str(purl), safe=":/")
+    url = urljoin(FEDERATEDCODE_AP_HOST, f"/purls/@{package}")
+    response = requests.head(url, allow_redirects=True)
+    if response.status_code == 200:
+        return url