From 5a644d466a7f346ad799f59619017c821decb2cd Mon Sep 17 00:00:00 2001
From: Oliver Sanders <oliver.sanders@metoffice.gov.uk>
Date: Tue, 30 Mar 2021 17:27:05 +0100
Subject: [PATCH] cli: list installed plugins and entry points

---
 cylc/flow/scripts/cylc.py      | 49 ++++++++++++++++++++++++++++++++--
 setup.cfg                      |  4 +++
 tests/functional/cli/01-help.t |  4 +--
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/cylc/flow/scripts/cylc.py b/cylc/flow/scripts/cylc.py
index 4a9bdf24090..1730f418a9d 100644
--- a/cylc/flow/scripts/cylc.py
+++ b/cylc/flow/scripts/cylc.py
@@ -334,12 +334,57 @@ def cli_help():
     sys.exit(0)
 
 
-def cli_version(long=False):
+def cli_version(long_fmt=False):
     """Wrapper for get_version."""
-    click.echo(get_version(long))
+    click.echo(get_version(long_fmt))
+    if long_fmt:
+        list_plugins()
     sys.exit(0)
 
 
+def list_plugins():
+    entry_point_names = [
+        entry_point_name
+        for entry_point_name
+        in pkg_resources.get_entry_map('cylc-flow').keys()
+        if entry_point_name.startswith('cylc.')
+    ]
+
+    entry_point_groups = {
+        entry_point_name: [
+            entry_point
+            for entry_point
+            in pkg_resources.iter_entry_points(entry_point_name)
+            if not entry_point.module_name.startswith('cylc.flow')
+        ]
+        for entry_point_name in entry_point_names
+    }
+
+    dists = {
+        entry_point.dist
+        for entry_points in entry_point_groups.values()
+        for entry_point in entry_points
+    }
+
+    if dists:
+        print('\nPlugins:')
+        maxlen1 = max(len(dist.project_name) for dist in dists) + 2
+        maxlen2 = max(len(dist.version) for dist in dists) + 2
+        for dist in dists:
+            print(
+                f'  {dist.project_name.ljust(maxlen1)}'
+                f' {dist.version.ljust(maxlen2)}'
+                f' {dist.module_path}'
+            )
+
+        print('\nEntry Points:')
+        for entry_point_name, entry_points in entry_point_groups.items():
+            if entry_points:
+                print(f'  {entry_point_name}:')
+                for entry_point in entry_points:
+                    print(f'    {entry_point}')
+
+
 @contextmanager
 def pycoverage(cmd_args):
     """Capture code coverage if configured to do so.
diff --git a/setup.cfg b/setup.cfg
index 1723efa2d60..5edf5854577 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -123,3 +123,7 @@ cylc.main_loop =
     log_main_loop = cylc.flow.main_loop.log_main_loop
     log_memory = cylc.flow.main_loop.log_memory
     prune_flow_labels = cylc.flow.main_loop.prune_flow_labels
+# NOTE: all entry points should be listed here even if Cylc Flow does not
+# provide any implementations to make entry point scraping easier
+cylc.pre_configure =
+cylc.post_install =
diff --git a/tests/functional/cli/01-help.t b/tests/functional/cli/01-help.t
index b49965e7d60..21f54fffbcd 100755
--- a/tests/functional/cli/01-help.t
+++ b/tests/functional/cli/01-help.t
@@ -70,12 +70,12 @@ cmp_ok "${TEST_NAME_BASE}-version.stdout" "${TEST_NAME_BASE}---version.stdout"
 cmp_ok "${TEST_NAME_BASE}-version.stdout" "${TEST_NAME_BASE}-V.stdout"
 
 # Check "cylc version --long" output is correct.
-cylc version --long > long1
+cylc version --long | head -n 1 > long1
 WHICH="$(command -v cylc)"
 PARENT1="$(dirname "${WHICH}")"
 PARENT2="$(dirname "${PARENT1}")"
 echo "$(cylc version) (${PARENT2})" > long2
-# the concise version of the above is a shellcheck quoting nightmare:
+# the concise version of the above is a bash quoting nightmare:
 # echo "$(cylc version) ($(dirname $(dirname $(which cylc))))" > long2
 cmp_ok long1 long2