fix: use commits-first approach to avoid rate limiting and missing contributors

When date filtering is active, fetch commits in the date range directly
and extract unique authors, instead of iterating all-time contributors
and making a separate API call per contributor to check for commits.

The previous approach made O(N) API calls where N is the number of
all-time contributors, which exhausted rate limits on large repos/orgs.
When rate limiting occurred mid-iteration, the broad exception handler
silently dropped all contributors for the affected repository.

The new approach makes O(M/30) API calls where M is the number of
commits in the date range, which is orders of magnitude fewer for
monthly reports.

Additionally, contribution_count now reflects the actual count for the
specified period rather than the misleading all-time count.

Fixes #392

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: zkoppert

contributors.py

@@ -155,41 +155,53 @@ def get_contributors(repo: object, start_date: str, end_date: str, ghe: str):
     Returns:
         contributors (list): A list of ContributorStats objects
     """
-    all_repo_contributors = repo.contributors()
     contributors = []
+    endpoint = ghe if ghe else "https://github.com"
     try:
-        for user in all_repo_contributors:
-            # Ignore contributors with [bot] in their name
-            if "[bot]" in user.login:
-                continue
-
-            # Check if user has commits in the date range
-            if start_date and end_date:
-                user_commits = repo.commits(
-                    author=user.login, since=start_date, until=end_date
+        if start_date and end_date:
+            # Fetch commits in the date range and extract unique authors.
+            # This is much more efficient than iterating all-time contributors
+            # and checking each one for commits, which causes rate limiting
+            # on large repositories.
+            contributor_data = {}
+            for commit in repo.commits(since=start_date, until=end_date):
+                if commit.author is None:
+                    continue
+                login = commit.author.login
+                if "[bot]" in login:
+                    continue
+                if login not in contributor_data:
+                    contributor_data[login] = {
+                        "avatar_url": commit.author.avatar_url,
+                        "contribution_count": 0,
+                    }
+                contributor_data[login]["contribution_count"] += 1
+
+            for username, data in contributor_data.items():
+                commit_url = f"{endpoint}/{repo.full_name}/commits?author={username}&since={start_date}&until={end_date}"
+                contributor = contributor_stats.ContributorStats(
+                    username,
+                    False,
+                    data["avatar_url"],
+                    data["contribution_count"],
+                    commit_url,
+                    "",
                 )
-
-                # If the user has no commits in the date range, skip them
-                try:
-                    next(user_commits)
-                except StopIteration:
+                contributors.append(contributor)
+        else:
+            for user in repo.contributors():
+                if "[bot]" in user.login:
                     continue
-
-            # Store the contributor information in a ContributorStats object
-            endpoint = ghe if ghe else "https://github.com"
-            if start_date and end_date:
-                commit_url = f"{endpoint}/{repo.full_name}/commits?author={user.login}&since={start_date}&until={end_date}"
-            else:
                 commit_url = f"{endpoint}/{repo.full_name}/commits?author={user.login}"
-            contributor = contributor_stats.ContributorStats(
-                user.login,
-                False,
-                user.avatar_url,
-                user.contributions_count,
-                commit_url,
-                "",
-            )
-            contributors.append(contributor)
+                contributor = contributor_stats.ContributorStats(
+                    user.login,
+                    False,
+                    user.avatar_url,
+                    user.contributions_count,
+                    commit_url,
+                    "",
+                )
+                contributors.append(contributor)
     except Exception as e:
         print(f"Error getting contributors for repository: {repo.full_name}")
         print(e)

test_contributors.py

@@ -2,7 +2,7 @@
 
 import runpy
 import unittest
-from unittest.mock import MagicMock, call, patch
+from unittest.mock import MagicMock, patch
 
 import contributors as contributors_module
 from contributor_stats import ContributorStats
@@ -19,24 +19,24 @@ def test_get_contributors(self, mock_contributor_stats):
         Test the get_contributors function.
         """
         mock_repo = MagicMock()
-        mock_user = MagicMock()
-        mock_user.login = "user"
-        mock_user.avatar_url = "https://avatars.githubusercontent.com/u/12345678?v=4"
-        mock_user.contributions_count = 100
-        mock_repo.contributors.return_value = [mock_user]
+        mock_commit = MagicMock()
+        mock_commit.author.login = "user"
+        mock_commit.author.avatar_url = (
+            "https://avatars.githubusercontent.com/u/12345678?v=4"
+        )
         mock_repo.full_name = "owner/repo"
-        mock_repo.commits.return_value = iter([object()])
+        mock_repo.commits.return_value = iter([mock_commit])
 
         contributors_module.get_contributors(mock_repo, "2022-01-01", "2022-12-31", "")
 
         mock_repo.commits.assert_called_once_with(
-            author="user", since="2022-01-01", until="2022-12-31"
+            since="2022-01-01", until="2022-12-31"
         )
         mock_contributor_stats.assert_called_once_with(
             "user",
             False,
             "https://avatars.githubusercontent.com/u/12345678?v=4",
-            100,
+            1,
             "https://github.com/owner/repo/commits?author=user&since=2022-01-01&until=2022-12-31",
             "",
         )
@@ -129,36 +129,26 @@ def test_get_contributors_skip_users_with_no_commits(self, mock_contributor_stat
         Test the get_contributors function skips users with no commits in the date range.
         """
         mock_repo = MagicMock()
-        mock_user = MagicMock()
-        mock_user.login = "user"
-        mock_user.avatar_url = "https://avatars.githubusercontent.com/u/12345678?v=4"
-        mock_user.contributions_count = 100
-        mock_user2 = MagicMock()
-        mock_user2.login = "user2"
-        mock_user2.avatar_url = "https://avatars.githubusercontent.com/u/12345679?v=4"
-        mock_user2.contributions_count = 102
+        mock_commit = MagicMock()
+        mock_commit.author.login = "user"
+        mock_commit.author.avatar_url = (
+            "https://avatars.githubusercontent.com/u/12345678?v=4"
+        )
 
-        mock_repo.contributors.return_value = [mock_user, mock_user2]
         mock_repo.full_name = "owner/repo"
-        mock_repo.commits.side_effect = [
-            iter([object()]),  # user has commits in range
-            iter([]),  # user2 has no commits in range and should be skipped
-        ]
+        mock_repo.commits.return_value = iter([mock_commit])
         ghe = ""
 
         contributors_module.get_contributors(mock_repo, "2022-01-01", "2022-12-31", ghe)
 
-        mock_repo.commits.assert_has_calls(
-            [
-                call(author="user", since="2022-01-01", until="2022-12-31"),
-                call(author="user2", since="2022-01-01", until="2022-12-31"),
-            ]
+        mock_repo.commits.assert_called_once_with(
+            since="2022-01-01", until="2022-12-31"
         )
         mock_contributor_stats.assert_called_once_with(
             "user",
             False,
             "https://avatars.githubusercontent.com/u/12345678?v=4",
-            100,
+            1,
             "https://github.com/owner/repo/commits?author=user&since=2022-01-01&until=2022-12-31",
             "",
         )
@@ -169,19 +159,19 @@ def test_get_contributors_skip_bot(self, mock_contributor_stats):
         Test if the get_contributors function skips the bot user.
         """
         mock_repo = MagicMock()
-        mock_user = MagicMock()
-        mock_user.login = "[bot]"
-        mock_user.avatar_url = "https://avatars.githubusercontent.com/u/12345678?v=4"
-        mock_user.contributions_count = 100
+        mock_commit = MagicMock()
+        mock_commit.author.login = "[bot]"
+        mock_commit.author.avatar_url = (
+            "https://avatars.githubusercontent.com/u/12345678?v=4"
+        )
 
-        mock_repo.contributors.return_value = [mock_user]
         mock_repo.full_name = "owner/repo"
+        mock_repo.commits.return_value = iter([mock_commit])
         ghe = ""
 
         contributors_module.get_contributors(mock_repo, "2022-01-01", "2022-12-31", ghe)
 
         # Ensure that the bot user is skipped and ContributorStats is never instantiated
-        mock_repo.commits.assert_not_called()
         mock_contributor_stats.assert_not_called()
 
     @patch("contributors.contributor_stats.ContributorStats")
@@ -212,13 +202,8 @@ def test_get_contributors_no_commit_end_date(self, mock_contributor_stats):
         )
 
     def test_get_contributors_skips_when_no_commits_in_range(self):
-        """Test get_contributors skips users with no commits in the date range."""
+        """Test get_contributors returns empty list when no commits in the date range."""
         mock_repo = MagicMock()
-        mock_user = MagicMock()
-        mock_user.login = "user"
-        mock_user.avatar_url = "https://avatars.githubusercontent.com/u/12345678?v=4"
-        mock_user.contributions_count = 100
-        mock_repo.contributors.return_value = [mock_user]
         mock_repo.full_name = "owner/repo"
         mock_repo.commits.return_value = iter([])
 
@@ -228,6 +213,39 @@ def test_get_contributors_skips_when_no_commits_in_range(self):
 
         self.assertEqual(result, [])
 
+    def test_get_contributors_skips_none_author(self):
+        """Test get_contributors skips commits with no linked GitHub author."""
+        mock_repo = MagicMock()
+        mock_repo.full_name = "owner/repo"
+        mock_commit = MagicMock()
+        mock_commit.author = None
+        mock_repo.commits.return_value = iter([mock_commit])
+
+        result = contributors_module.get_contributors(
+            mock_repo, "2022-01-01", "2022-12-31", ""
+        )
+
+        self.assertEqual(result, [])
+
+    def test_get_contributors_aggregates_multiple_commits(self):
+        """Test get_contributors counts multiple commits per author correctly."""
+        mock_repo = MagicMock()
+        mock_repo.full_name = "owner/repo"
+        mock_commit1 = MagicMock()
+        mock_commit1.author.login = "user"
+        mock_commit1.author.avatar_url = "https://avatars.githubusercontent.com/u/1"
+        mock_commit2 = MagicMock()
+        mock_commit2.author.login = "user"
+        mock_commit2.author.avatar_url = "https://avatars.githubusercontent.com/u/1"
+        mock_repo.commits.return_value = iter([mock_commit1, mock_commit2])
+
+        result = contributors_module.get_contributors(
+            mock_repo, "2022-01-01", "2022-12-31", ""
+        )
+
+        self.assertEqual(len(result), 1)
+        self.assertEqual(result[0].contribution_count, 2)
+
     def test_get_contributors_handles_exception(self):
         """Test get_contributors returns None when an exception is raised."""
 
@@ -239,7 +257,7 @@ def __iter__(self):
 
         mock_repo = MagicMock()
         mock_repo.full_name = "owner/repo"
-        mock_repo.contributors.return_value = BoomIterable()
+        mock_repo.commits.return_value = BoomIterable()
 
         with patch("builtins.print") as mock_print:
             result = contributors_module.get_contributors(